Samsung VP-W80 Digital Camcorder & Video Recorder, size: 2.2 MB
Part Number: VP W80
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Samsung VP W80 Hi8 Camcorder Review
User reviews and opinions
|bogzab||1:57pm on Wednesday, June 16th, 2010|
|I recently bought this camcorder off the net from E-bay. Price, Ease of use, Looks No LCD, No remote control, No accessory socket|
|heviarti||10:00pm on Saturday, May 29th, 2010|
|Purchased this camcorder just before Christmas last year from the Littlewoods Catalogue at the bargain price of £179. Easy to use I recently bought this camcorder off the net from E-bay. It was brand new and I payed just over £115 for it which I consider a bargin.|
|booksite||8:38pm on Monday, May 17th, 2010|
|We bought this camera on hols and got a major bargin as we also got the bag three tapes night lens and all the cable for putting to you tv so on and w...|
|anti_skid||5:04am on Sunday, May 16th, 2010|
|simple! I think this camcorder is absolutely brilliant.I bought it for my first ever camcorder and it is so easy to use!|
|jbatt||11:45pm on Saturday, April 3rd, 2010|
|Worth of its value Samsung 22 X Analogue 880 x Digital 8mm format camcorders are so good based on features, design, usability and value for money. Worth of its value Samsung 22 X Analogue 880 x Digital 8mm format camcorders are so good based on features, design, usability and value for money. simple! I think this camcorder is absolutely brilliant.I bought it for my first ever camcorder and it is so easy to use!|
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To learn more about the new Samsung Camcorders, or to find your nearest retailer, please visit: www.samsung.com
imagine Turning Moments into Memories
Samsung Electronics Co., Ltd. Head Office (Suwon Korea) 416, Maetan-3Dong, Yeongtong-Gu Suwon City, Gyunggi-Do, Korea 443-742
A smarter way to shoot. The VP-HMX20 and VP-MX20 flash memory camcorders offer a more exciting approach to home movie making. With longer battery and recording time, they make sure that you never miss the opportunity to record a magical moment and give you more memories to treasure, forever. For more information, please visit www.samsung.com.
The Latest in Cutting-Edge Video Technology
If you are looking for the very latest in advanced video technology, the VP-HMX20C sets the standard. With 1920 x 1080 Full HD, the highest quality video available today, Flash memory for instant start-up with parts-free durability and convenience, a bright F1.8 HD lens, and a light, compact body packed full of useful features and sophisticated technology, the VP-HMX20C lets you do it all, or can do it all for you!
Seeing is Believing The Reality of Full HD
Samsungs VP-HMX20C captures video at todays highest resolution, 1920 x 1080 Full HD. With a full complement of advanced technological features, the VP-HMX20C provides the best image quality available and the ability to enjoy crisp, clear, natural images in a wide variety of formats. The incomparable image quality leaves you with videos so real, they must be experienced to be believed.
Full HD is Real HD
The VP-HMX20C takes video at the highest digital visual resolution available today, 1920 x 1080 Full HD. 1920 x 1080 Full HD video means much more visual information, much greater clarity, brightness and detail than ever before. It also means that your video will be an exact pixel-by-pixel match for todays very best large screen HDTVs. The result is life-like video with more natural color and clarity, without the blurring or digital noise you might well be used to.
8-Megapixel Stills for Large Format Photos
Samsungs Pixel-Rising technology utilizes a pixel-interpolation filter to convert recorded stills to the equivalent of 8-megapixels, enabling large format (11 x 17 in.) detailed prints of your images. This same technology allows you to enlarge part of an image while retaining extraordinary detail.
2304X1728 (4M pixel) 3264X2448 (8M pixel)
4:3 recording, 16:9 output 46.7M pixel/sec 16:9 recording, 16:9 output 62.2M pixel/sec
As Sensitive to Light as You Are (ISO3200) Progressive HD (1920 x 1080 Full HD)
Samsungs VP-HMX20C delivers the very highest quality video by using progressive scan technology. It records HD quality video in progressive mode (30fps), so that the video is crisp and clear, regardless of how fast moving the subject may be. Progressive scan technology produces smooth images even when videos are played back at 2x, 4x or even 8x the normal speed! Even with just 1 lux of illumination (candlelight, for example) the VPHMX20C has a High Sensitivity Mode that allows the amazing ISO3200 camcorder to take clear video or shoot 8-megapixel stills. This extra light sensitivity means you get great stills in difficult lighting situations, without the blur caused by longer exposure times.
High-Speed Capture for Slow-Motion Detail
With the high-speed capture feature, the VP-HMX20C also lets you take up to 10 seconds of video at an astonishing 300 frames per second (fps), giving you ultra-detailed, crystal clear slow motion playback, useful for analyzing a golf swing, dance movement, or any other motion that is faster than the human eye.
Blurring by Hand Shaking ISO3200 & EIS
A Wider, Brighter F1.8 Lens
The VP-HMX20Cs wide F1.8 aperture 10x Optical Zoom lens lets more light through to the sensor, giving you rich, bright, detailed images that accurately reflect what you see with the naked eye. The highperformance HD lens is manufactured to extremely exacting standards to ensure minimal image distortion and astigmatic aberration, resulting in the most natural, accurate, compelling video and stills available from a camcorder today.
Smoother Video and Clearer Stills
Samsungs Electronic Image Stabilizer (EIS) system gives you crisp, clean images whether you are shooting movies or taking still photos. Sophisticated software is able to detect unintentional camcorder movement and compensate with micro adjustments to the image sensor, resulting in blur-free photo stills and smoother, more natural video.
The Latest Technology and the Greatest Ease
While fully loaded with the most useful and advanced features, the VP-HMX20C is also a triumph of contemporary design. The sleek and stylish camcorder is light, compact, and durable. With Flash Memory, fewer moving parts, a longer battery life, and sophisticated software innovations, the VP-HMX20C makes taking great video and stills much, much easier. Loaded with the most advanced video technology available today, with the VP-HMX20C you can do it all, or let it do it all for you!
Quick Start Helps You Catch the Moment
Never miss another one of life's precious moments with the Quick Start capability. The VP-HMX20C is ready to shoot when you are; just turn it on and go. It doesn't get any easieror fasterthan that! With Samsung's powerful, built-in flash memory you no longer need to waste your time waiting for your camcorder to boot up, read a disk or load a tape. Our new line of camcorders will be ready to shoot in 3 seconds or lessthats 4x faster than a standard DVD camcorder! And with that kind of speed, you wont miss another precious moment.
Snap While You Shoot with Dual Recording
The VP-HMX20Cs innovative dual recording capabilities make it easy to snap a still, even while you are recording a Full-HD movie! Simply press the shutter button as you are taking video and the VP-HMX20C will take a 2-megapixel still without interrupting the video.
Advanced Noise Reduction
The cutting-edge ANR (Advanced Noise Reduction) system reduces sensor noise dramatically while reserving the original scene, which produces a more vivid and life-like video.
Easy on the Eyes; Satisfying Results
The high-resolution wide-format 2.7 LCD Touch screen makes a huge difference. The 16:9 wide-screen format matches HDTVs so what you see as you shoot will be what you see when you get home. And navigating through the VP-HMX20Cs many helpful features is a breeze thanks to the easy-to-use Touch screen.
1, 2, 3 Seconds, Shoot!
Conventional Camcorder SC-HMX20C
Face Detection for Better Results A Better, Longer Life
Samsung camcorders run more efficiently than our competitors. The result is lower power consumption and a longer battery life so you dont have to worry that dead batteries might make you miss the most important moment Recording Time 8GB Super Fine Fine Normal Battery Time 70 min. 95 min. 120 min. 90 min. With Samsungs Face Detection technology, the VP-HMX20C makes sure that the video you take is the video you want to keep. Face Detection technology is a sophisticated image processing algorithm that automatically detects up to 12 faces within the frame, adjusting focus and exposure to make sure that your video shows your subjects in the best possible light.
Our unique Swivel Hand-Grip design makes shooting difficult angles a snap. With a flick of the wrist, you can change the shoot angle of the camcorder to take the perfect video every timeall with one hand! The ergonomic design will open new doors to the way you shoot video.
HD (1920 x 1080 / 50i ) 12sec
Anynet+ (HDMI CEC)
The VP-HMX20C supports every video output terminal that is currently used by HDTVs: HDMI, Component, S-video and Composite. Plus, Samsungs unique Anynet+ technology lets you to control the camcorder with any Anynet+ enabled TV remote control. And using just one line of HDMI cable makes connection easy while keeping the quality superb; that means you can experience the highest quality digital video/audio on your HDTV without any data loss.
Faster, Smarter and Reliable
With the built-in 8GB flash memory, there are no moving parts to slow you down, no tapes or discs to lose, and no Hard Drive to protect. So the VP-HMX20C is ready to shoot when you are, keeps your video in a safe place, and gives you greater flexibility, reliability, and durability when you are out and about.
The docking cradle is one of the important features that puts Samsung camcorders head and shoulders above the competition. The cradle allows you to recharge the camcorder, use the built-in USB port, and connect to additional AV devices via HDMIall at the same time!
More than Merely Portable
The compact design allows for easy storage and packing so you'll never have to leave your camcorder behind.
Take it Easy with Easy Q
Samsungs innovative Easy Q function puts the VP-HMX20C into Full Auto mode to let you relax and enjoy what is happening while the camcorder does the work. Docking Cradle
Reliable, Flexible and Durable
When it comes to durability, Samsung's flash memory sets the standard. Compared to tape or disk-based camcorders, flash memory contains zero moving parts less to wear outresulting in a longer lifespan! The lack of moving parts also ensures that your recorded memories will survive the rigors of spills, falls and everyday mishaps.
Digital Analog Converter
Component AV out
Shoot and share your memories
Shoot, share, and enjoy easier home movie making with the VP-MX20 flash memory camcorder. Its Samsung chip provides higher quality images and longer battery and recording time. The footage you capture can be conveniently transferred to media players and the web, giving you the opportunity to share your memories with the world.
Digital Video Excellence
The Samsung VP-MX25/MX20 provides you with video footage of such a high quality that it brings your memories to life with vivid, natural beauty. The VP-MX25/MX20s state-of-the-art imaging technologies combine to create a camcorder that gives you the very best of everything; natural color reproduction, image stability, advanced noise reduction, the highest quality lens, and the most pristine video footage youve ever seen.
New Integrated Chip Solution with Samsung Technology
Experience the most naturally beautiful images with new Samsung technology. Advanced Color Expression, Hyper Digital Image Stabilizer, Super LCD plus, and Face Detection Auto Focus combine to make your digital image dreams a reality.
3D Noise Reduction
The VP-MX25/MX20 transcends the boundaries of convention by introducing 3D noise reduction that dramatically eliminates noise whilst maintaining the original edge and pattern of the image. By analyzing motion between the frames, the frames are split into pattern/edge frames and differential frames and are passed through separate filters which maintain the pattern and edge and remove noise. After filtering, the frames are combined once more to make a cleaner, clearer image.
Longer battery life, extended recording time, and higher quality digital imaging are enabled by the VP-MX25/MX20s Samsung chip. By designing and implementing a powerful single chip control system, power consumption is dramatically reduced, allowing you to capture more memories that can be treasured for the rest of your life.
Tradeoff between N.R. and edge loss
LFP Frame Edge Enhancement Lowpass filter is applied frame by frame for noise reduction, which causes edge loss
Original pattern is preserved due to pattern extraction between frames
Pattern Matching Frame
Color as vivid as your memories 3D Motion Optimizer
3D Motion Optimizer Processing creates clearer, cleaner images. Unlike conventional 2D processing, 3D processing compares previous and following frames, divides the current frame into pixel blocks, detects noise occurrence, and eliminates it efficiently without filtering the entire image. Digital Natural Color Processing creates an expanded palette of colors that are closer to those seen in nature. By internally adjusting images beyond RGB into 4 color CMYG spectral color matching, the VPMX25/MX20 is able to accurately recreate colors that are closer to those your eyes see, closer to your memories, and closer to reality.
Target pixel Analyzing targets Not analyzing pixels
VP-MX25 / MX20
0 CCIR709 / sRGB
0 CCIR709 / sRGB 300
Target frame Before
Target frame Spatial analysis
Next frame Time analysis
Shoot without a care
For your convenience the stylish Samsung VP-MX25/MX20 is loaded with powerful features that are designed to make your life easier and your video footage better. The worlds longest battery life and recording time are enabled by recording in H.264 codec, providing you with footage that can be played on the H.264 supporting MP3 players and PMPs without transcoding.
Unstable hands can cause camcorder footage to be shaky and blurred. Thanks to its advanced computational power, the VP-MX25/MX20 realizes precision image stabilizing by multi-directional motion analysis unlike most other digital image stabilizers using bi-directional one. Enjoy clean and steady footage.
Upgraded gamma correction
Real, natural color reproduction is enabled by our upgraded gamma correction. Conventional adjustment separates the Gamma Curve into 8 steps but the Samsung chip divides it into 128 steps and adjusts each of the RGB curves individually, to give an exquisitely detailed range of color expression.
Occurs Discontinuity Improved Gamma Curve
More recording time, more memories to treasure
Enjoy recording the highest quality video footage for longer with the VPMX25/MX20. Thanks to high performance H.264 Codec, Samsung VPMX25/MX20 record more of your memories than MPEG2 codec adapted camcorders. Within the same capacity, VP-MX25/MX20 records 1.5 times more than MPEG2 codec. Its compressed video files are faster to e-mail and upload to the web, which makes sharing as easy as can be, with no loss of Image quality.
Recording Time on 1 DVD Disc
Share your memories, share your life
Sharing your life with friends and family becomes easier with the VPMX25/MX20. By selecting Web & Mobile mode, you can shoot in a format perfected for H.264 supporting MP3 players and YouTube. The video files recorded by the VP-MX25/MX20 can easily be applied to a transfer program and played on an H.264 supporting MP3 player. The YouTube uploader in the Mediashow software bundle enables direct YouTube upload which bypasses the YouTube homesite.
Super LCD screen clarity
The VP-MX25/MX20s LCD screen maintains its visibility on even the sunniest of days. With Advanced Outdoor LCD Enhancement, the VPMX25/MX20 is able to compensate up to 50,000 lux of light, an improvement of 30,000 lux on the industry standard. This dramatic improvement is enabled by an upgraded 3-D LUT (Look Up Table) algorithm that provides images that retain their detail, brightness, contrast, and clarity whatever the weather.
Outdoor ~50,000 Lux Perceived Color Appearance Processing
Conventional Gamma Curve
H.264 (VP-MX25 /MX20)
MP3 Player & YouTube Connection
USB or Card
Conventional : Y/C Gamma
Samsung : Y/C Gamma
Samsung Memory Camcorder MX20 with H.264 Codec 32G Memory
Competitor HDD cam with MPEG2 30G Competitor Memory Card with MPEG2 32G
Outdoor ~20,000 Lux
Download to MP3 Player Upload to YouTube by MediaShow (Samsung Software)
36 DVD Disc
22 DVD Disc
LCD Enhancement Technology Powered by 3D-LUT (Look up table) compensation
A world class lens, a world class camcorder
R_LUT 100.00 200.00 0.00 100.00 200.00 B_LUT
Battery life that wont let you down
With its Long Time Battery, the Samsung VP-MX25/MX20 allows you to record, play, and have fun for as long as you like. Long Time Battery gives an incredible 3 hours of recording freedom (1.9W, 850mAh) compared with Company As 1 hour 10minutes (2.9W, 1000mAh) and Company Bs 1 hour 20 minutes (3.8W, 800mAh), giving you all the time you need to make memories that last a lifetime.
As stylish as you are
With sensational Samsung style, the VP-MX25/MX20 delivers the most comfortable camcorder experience imaginable. With an ergonomic design that looks as good as it feels, it fits exquisitely into your palm and is held securely in place by the fully flexible swivel grip. With a built-in lens cover, UV coating, easy thumb operation buttons, and secondary zoom and record buttons you can enjoy its beauty with confidence.
100.00 0.00 0.00
Face Detection AF technology
Unlike conventional camcorders, the VP-MX25/MX20s advanced Face Detection AF technology targets the faces in the screen. With intelligent face detection auto-focus, faces are always focused-on, even if they are not in the center of the screen. Samsungs Face Detection AF enables you to capture clearer, higher quality video.
The most crucial factor in deciding video quality of a camcorder is its lens. Thats why the VP-MX25/MX20 is equipped with a high quality Schneider Kreuznach lens. World famous for premium optics, Schneider Kreuznach lenses provide improved distortion aberration and astigmatic aberration for superior, natural-looking images. With its 34x optical zoom, the VP-MX25/MX20s Schneider Kreuznach lens takes you as close to the action as you could ever want to be.
Built-in Lens Cover
Secondary Zoom / Rec. Buttons
Easy Thumb Operation
Creating home movie magic
Enjoy all the fun of home movie making with the Samsung VP-MX25/MX20. Professional video quality is delivered with a simplicity that enables anyone to feel comfortable. Its easy to use, and packed with intuitive features that allow you to shoot amazing footage with a minimum of fuss. Enjoy all the fun of home movie making with Samsung.
Sensor Lens Image Sensor Gross Pixel Effective Pixel (Movie / Still) Lens Optical Zoom / Digital Zoom F Number Focal Length Filter Diameter Lens Cover Image Stabilizer Minimum Illumination Scene Mode (Program AE) Focus Wind cut LCD Aspect Ratio LCD Enhancer Viewfinder Storage Media 1 Storage Media 2 Storage Media 3 Video Format (Flash Memory) Audio Still Picture Video(PAL) Still Picture Resolution I/O Interface USB IEEE1394 AV S-Video component HDMI External Mic. Input PC camera Model Code Capacity i-check Battery Time Power Consumption GUI Language Accessory Shoe Remote Controller Soft Pouch AV Cable Component Cable USB Cable Cradle Battery Video Editing S/W 1/1.8" CMOS 6.4M 2.1M / 4.0M HD 10x / 100x F.1.8~2.5 f=6.3 ~ 63mm 49mm Built-in(Auto) EIS 1 Lux(Color Nite Mode) AF / MF / Touch O 2.7" / 230K 16:9 Wide O X Built-in Flash (8GB) SDHC / MMC + Slot H.264 AAC JPEG HD : 1920 x 1080 ( 50i / 25p ) SD : 720 x 576 8M (Interpolation) 6M / 4M / 3M / 1.5M / 340K O (USB 2.0) X O (Output only) O (Output only) O (Output only) O (Output only) O (Output only) X IA-BP85ST 7.4V / 850mAh O 80min 4.1W 23 X O O O O O O O Media Show 4.0 66.0 x 67.2 x 139 456g
1/6" CCD 800K 400K Schneider Kreuznach 34x / 1200x F.1.6~4.3 f=2.3 ~ 78.2mm 30mm Built-in Hyper D.I.S. 3 Lux AF / MF O 2.7" / 112K 16:9 Wide O X SDHC / MMC + Slot X H.264 AAC X 720 x 576 / 50i X O (USB 2.0) X O (Output only) X X X X X IA-BP85ST 7.4V / 850mAh O 180min 2.0W 24 X X O O X O X O Media Show 4.0 60.5 x 60 x 125 270g
1/6" CCD 1/6" CCD 800K 800K 400K/480K 400K Schneider Kreuznach Schneider Kreuznach 34x / 1200x 34x / 1200x F.1.6~4.3 F.1.6~4.3 f=2.3 ~ 78.2mm f=2.3 ~ 78.2mm 30mm 30mm Built-in Built-in Hyper D.I.S. Hyper D.I.S. 3 Lux 3 Lux Auto / Daylight / Cloudy / Fluorescent / Tungsten / Custom WB AF / MF AF / MF O O 2.7" / 112K 2.7" / 112K 16:9 Wide 16:9 Wide O O X X Built-in Flash (16GB) Built-in Flash (8GB) SDHC / MMC + Slot SDHC / MMC + Slot H.264 AAC 800x600 JPEG 720 x 576 / 50i 800 x 600 O (USB 2.0) X O (Output only) X X X X X IA-BP85ST 7.4V / 850mAh O 180min 2.0W 24 X X O O X O O O Media Show 4.0 60.5 x 60 x 125 270g H.264 AAC X 720 x 576 / 50i X O (USB 2.0) X O (Output only) X X X X X IA-BP85ST 7.4V / 850mAh O 180min 2.0W 24 X X O O X O O O Media Show 4.0 60.5 x 60 x 125 270g
Free style shooting
The VP-MX25/MX20s multi-positional swivel hand grip offers full flexibility and freedom of movement for the full range of shooting positions. The innovative swivel grip allowing you to seamlessly move the camcorder between regular and low level positions, giving you complete control over how and what you shoot.
Dual Time Zone function
For your convenience the VP-MX25/MX20 is equipped with World Time Setting. This feature allows you to select the city and time zone that you are visiting without having to change your hometown time setting. Simply select the Visit time, select where you are, and when you get home again, just select Home and the time will be reset as if youd never gone away.
Can select home or visit place time City-based time set
Home: 10/20 12:30 AM Visit: 10/21 08:30 AM - 04:00
Home 10/2012:30 AM
Date / Time Set
Date/Time Time Difference
Intelligent scene setting
The iScene function provides you with specialized recording modes for a variety of scenes, making capturing perfect video footage easier than ever before. iScene offers preset recording environments for Sports, Portrait, Spotlight, Beach, Snow, High Speed, Food, and Waterfall scenes by optimizing the White Balance, Exposure, and Shutter time.
By setting time intervals for frame capture, you can take full advantage of the Interval Recording function. This feature, using selective frame capture enables you to record over an extended period of time so that you can see the effects of long term recording condensed into a shorter time frame. Imagine the passage of clouds through the sky or the suns descent over the water.
Color Dimension ( W x H x D)mm Weight
Product designs and specifications are subject to change without prior notice.
Recording Time (Flash Memory)
Memory Size Super fine(5Mbps) Fine (4Mbps) Normal (3Mbps) Web & Mobile (2Mbps)
8GB(min.) 310 460
16GB(min.) 620 920
32GB(min.) 1240 1840
The iCheck function gives you instant access to remaining battery and storage information without having to turn the camcorder on. Simply press the iCheck button the VP-MX25/MX20 displays remaining battery and storage time on the LCD and then turns off automatically.
Bundle Accessory VP-HMX20C
Power Adaptor AV Cable USB Cable Component Cable Remote Controller Battery Pack
Selective Frame Capture
Quick Guide (N.A. only)
Power Adaptor AV Cable USB Cable Battery Pack Cradle S/W CD
ISSN 0006-3509, Biophysics, 2008, Vol. 53, No. 6, pp. 544549. Pleiades Publishing, Inc., 2008. Original Russian Text T.F. Shklyar, A.P. Safronov, I.S. Klyuzhin, G. Pollack, F.A. Blyakhman, 2008, published in Biozika, 2008, Vol. 53, No. 6, pp. 10001007.
A Correlation between Mechanical and Electrical Properties of the Synthetic Hydrogel Chosen as an Experimental Model of Cytoskeleton
T. F. Shklyar , A. P. Safronov , I. S. Klyuzhin , G. Pollack , and F. A. Blyakhman
a a b b c a
Ural State Medical Academy, ul. Repina 3, Yekaterinburg, 620219 Russia; b e-mail: Tatyana.Shclyar@usu.ru Gorky Ural State University, ul. Lenina c 51, Yekaterinburg, 620083 Russia University of Washington, Seattle, WA, 98195 USA
Received June 28, 2008
AbstractThe correlation between the electrochemical (Donnan) potential and volume swelling was studied for synthetic polyelectrolyte hydrogels considered as models of cytoskeleton gel-forming biopolymers. Hydro-gels involving polyacrylic and polymethacrylic acids with varying network density were synthesized by a radical polymerization in aqueous solution. Electrical charge was introduced into the gel network by partial neutralization of monomer acids with several alkali and alkali earth (hydr)oxides. The electrochemical (Donnan) potential of synthetic gels was determined using conventional microelectrode tools for cell potential determination. It was demonstrated that the negative electrical potential of many anionic gels with various charges and network densities decreased with the degree of equilibrium swelling, i.e., with the decrease in water content in the gel. It was shown that a drastic phase transition in the gel structure from a swollen to a + 2+ compressed state induced by K /Ca exchange is accompanied by an analogous decrease in the absolute Donnan potential of the gels. A kinetic study demonstrated that the gel volume changed ahead of its electrical potential. This suggests that the volume phase transition in gel is the main cause of the electrical response. A similarity between the swelling/compression transition in synthetic gels and the volume changes in the cytoskeleton in the vicinity of the cell membrane was demonstrated. Based on the universal analogy between the properties of synthetic and natural polymer gels, a possible involvement of swelling of the gel-like cytoskeleton structures in electrical regulation in the cell was postulated. Key words: cytoskeleton, polyelectrolyte gel, electrochemical potential, phase transition DOI: 10.1134/S0006350908060146
Abbreviation: PMAA, polymethacrylic acid of ions at different sides of the membrane, i.e., to different concentrations of of a living cell is a three-dimenions inside and outside the cell. The cytoskeleton sional network of protein laments submerged into the The key role in formation of the electrochemical cell potential is ascribed to the membrane channels and liquid phase, cytosol. From a physicochemical standpumps point, the protein ionwater structure of cytoskeleton resembles a synthetic polyelectrolyte gel with a loose However, experimental data demonstrate that synpolymer. network swollen in solution. A typical archi-thetic polyelectrolyte gels have an electrochemical tecture of such gels is a network of cross-linked potential close in its value to the intracellular potential charged polymeric laments. despite the absence of any channels or pumps . In The polyelectrolyte gels are the materials able to addition, it was demonstrated that the propagation of considerably change their volume by absorbing a sol-the wave of changing membrane potential in the cell vent. When inuenced by various physical or chemical (action potential) was accompanied by swelling of gelimpacts, for example, temperature, pH, and change in like cytoskeleton structures located immediately under the ambient ionic composition, gels display consider-the membrane . This suggested the hypothesis on a able structural rearrangements from a swollen to a com-tight correlation between the cell electrical activity and pressed state and vice versa. Such transformations were the properties of intracellular gel, including its phase named the phase transition in gel, analogously to the transitions under special conditions . transitions of water from a liquid to ice or vapor at a The goal of this work was to study the dependence crystallization or a boiling temperature. polyelectro-It is generally accepted that the electrical properties lyte gels of electrochemical potential in synthetic on the degree of their swelling. The degree of of the cell are related to an inhomogeneous distribution gel swelling is the parameter that characterizes the
amount of solvent absorbed by a dry polymer. A change in the degree of swelling reects the mechanical reorganization in the gel, appearing as its compression or swelling due to extrusion or absorption of solvent by polymeric network. In this study, the degree of gel swelling was varied by supplementing the solvent with calcium ions at various concentrations. The electrical potential of the gel was measured under two types of experimental conditions, static and dynamic. Under static conditions, the potential was determined at xed values of the degree of swelling, whereas under dynamic conditions, degree 1 potential was recoded during the change in the the of gel swelling. The resulting data suggest a tight correlation between the mechanical transformations in the gel and its electrical characteristics. MATERIALS AND METHODS The gels of polymethacrylic acid (PMAA) synthesized by a free radical polymerization of a partially neutralized methacrylic acid in aqueous solution with N,N'-methylene diacrylamide as a cross-linking agent were used in the work. The reagents were obtained from Merck Schuchardt (Hohenbrunn, Germany). The aqueous solution of methacrylic acid was supplemented with potassium hydroxide at an amount necessary for neutralizing a specied fraction of methacrylic acid. The total concentration of monomer acid and its salt was 2.7 M. The prepared solution was supplemented with the cross-linking agent at the amount that provided a specied number of monomers in the linear polymer per one unit of the network. Polymerization was initiated with ammonium persulfate and conducted at 70C for 2 h in a special cylindrical mold. Upon completion of the synthesis, gels were taken out of the mold and washed in distilled water for 2 weeks, changing water daily, to remove the low-molecular-weight impurities. In this work, we studied the gels PMAA 200/25 and PMAA 100/50. The gure indicates the average number of monomers in linear regions per one network unit andexperimental conditions. salt groups of potasStatic the second, the percent of Under static consium methacrylate relative toswollen in distilled monoditions, the gel specimens the total number of water mers. placed into the solutions with different concentrawere tions of calcium ions (0.001 to 10 mM CaCl2) for at least 48 h to reach an equilibrium and then used to measure the electrochemical potential and the degree of equilibrium swelling. The electrochemical potential was determined using microelectrode tools conventionally used for determination of electrochemical potentials in living cells. In particular, we used two identical Ag/AgCl electrodes placed into glass micropipettes with a tip diameter of about 1 m lled with 3 M KCl solution. One electrode was dipped into gel and the other, into BIOPHYSICS Vol. 53 No. 6 2008
Fig. 1. An example of the experimental record of electrochemical potential in hydrogel. Arrows denote the time moments when electrode was dipped into the gel and removed from it.
the ambient solution. The difference in potentials was measured with the help of an amplier with an INA 129 (Burr-Brown, United States) integrated circuit. An example of the recorded data is shown in Fig. 1, demonstrating a typical potential versus time dependence. The method was detailed earlier . At least 10 measurements were made per each specimen to average the data. Then the gels were removed from solutions, weighed, and dried in a drying cabinet to weigh the dry residue. The degree of swelling was calculated as the ratio of the weight of the specimen swollen in the corresponding solution to the dry weight after a complete drying. Thus, the parameter quantitatively characterized the increase in the weight of gel specimen after swelling in the corresponding solvent. Dynamic experimental conditions. The electrochemical potential for each specimen was measured for 3 h from the moment when the specimen was transferred from distilled water into the solution with the corresponding CaCl2 concentration. The potential was recorded with 10-min interval by repeated (10 times) dipping of the electrode into the specimen to determine the mean value for each time point. To measured the dynamics of gel volume character2+ istics in solutions with various Ca concentrations, an optical device was designed (for the ow chart, see Fig. 2). Cylindrical gel specimens of approximately mm (Fig, 2, right) were used. The data were recorded with a Samsung VP-W80 Hi8 camcorder with a PAL output signal. The camera was coupled with an IBM PC to digitize the specimen images with the help of a Conexant bt878 analog-to-digital converter. An original software in a Delphi environment was used to process the images; the program allowed for quantication of the specimen linear sizes in any direction as well
Fig. 2. Flow chart of the optical video system for measuring the volume of gel specimens; the cylindrical gel specimens are shown to the right.
as the area of the gel visible surface and a complete absolute error of area calculations. The data were statistically processed by the standard tial remains constant in the range of the degree of tools with the Microsoft Excel. swelling from the initial level ( = 115-fold) to ~ 80-fold and then commences shifting towards less RESULTS negative values. The degree of gel swelling and the Measurements under static conditions. Figure 3 electrochemical potential were tightly correlated. The shows the dependences of the degree of PMAA 200/25 correlation coefcient was 0.930 (n = 19, p < 0.001). gel swelling (upper curve) and its electrochemical The minus sign means that the larger the degree of potential (lower curve) on the concentration of calcium swelling, the more negative is the potential. Regression ions in solution. The mean values of eight experiments analysis demonstrated a statistically signicant are given. Horizontal dashed lines show the initial val- logarithmic dependence of the potential 2 on the degree ues of each parameter for the specimens in distilled of swelling: = 35.3ln() 24.8 and R = 0.96. Figure 5 shows the dependences of the relative degree water. of calcium chloride to solution decreased the Addition of swelling /0 and potential /0 on the concentration degree of swelling of gel specimens. This means that of Ca2+ ions in solution. The mean values of the volume of specimen reduced or that the specimen compressed. In particular, if the degree of swelling 2+ Degree of swelling 120 was 115 5fold, its values at Ca concentrations of 0.05, 1.0, and 10 mM were 108 6, 9 3, and fold, respectively. The gel electrochemical potential, , changed from to mV 2+ with the increase in Ca concentration in solution from 0.1 to 5 mM, i.e., the potential became less negative; theisshift towards the positive regiondependences 100 It evident from Fig. 3 that the was about are mV. S-shaped. A drastic twofold decrease in the volume of 2+ specimen took place at the threshold Ca concentration, amounting to 0.50.6 mM. A drastic decrease in the absolute value of electrochemical potential in the 2+ specimens was observed in the Ca concentration range of 1.01.5 mM. The dependence between the degree of swelling and gel electrochemical potential is graphically shown in Fig. 4. Dependence of the electrochemical potential on the degree of swelling of PMAA 200/25 gel. Fig. 4. It is evident that the gel electrochemical potenBIOPHYSICS Vol. 53 No. 6 2008
Fig. 3. Dependences of the degree of PMAA 200/25 gel swelling and its electrochemical potential on the concentration of calcium ions in solution. The abscissa shows the log 2+ arithm of Ca concentration in solution (M); horizontal dashed lines, the initial values of each parameter for specimens in distilled water.
parameters (n = 8) are given. The ratios /0 and /0 were calculated by normalizing the current value by the value of the corresponding parameter in distilled water (0 and 0), taken as unity. These data demonstrate that the phase transition in gel, i.e., the drastic change in the volume due to partial extrusion of solvent from the polymeric network, 2+ occurs at lower Ca concentrations as compared with the changes in its electrochemical potential. In other 2+ words, at any xed Ca concentration, the value of volume (mechanical) transformation in gel is larger than the corresponding electrochemical changes. Measurements under dynamic conditions. The dynamic monitoring of gel compression and changes in the electrochemical potential were performed with the PMAA 100/50 gel in two sets of independent experiments. The specimens were placed into the corresponding CaCl2 solutions to record either their video images or electrochemical potential. Figure 6 shows two images of the same gel specimen: in distilled water and in 1.0 mM CaCl2 solution. It is evident that the gel volume considerably decreased in the CaCl2 solution as compared with that in distilled water. Figure 7 shows the time dependences of the degree of gel swelling for six specimens, each placed in solution 2+ 2+ with particular Ca concentration. The Ca concentrations are shown to the right. It is evident that the 2+ higher the concentration of Ca ions, the faster is the compression of gel specimens. Figure 8 shows the dynamics of electrochemical potential in four gel specimens, each placed in solution 2+ with the corresponding concentration of Ca ions. It is evident that the electrochemical potential of the gel 2+ placed in the solution with a low Ca concentration (0.1 mM) remained practically constant. In the solution 2+ with 1 mM Ca ions, the absolute value of electrochemical potential commenced decreasing after 30 min. 2+ The larger the concentration of Ca ions, the faster were the changes in the absolute value of electrochemical potential. The fastest and most pronounced decrease in the absolute value of electrochemical potential was 2+ observed in the presence of 5 mM Ca ions. For comparison, Fig. 9 demonstrates the dynamics of electrochemical potential and degree of gel compression 2+ at the same concentration of Ca ions (1 mM). It is evident that the volume-changing (mechanical) events in the gel are ahead of the changes in electrochemical potential. In particular, the potential remained close to the initial level for 30 min, whereas the gel volume over the same period almost halved. The rate of the changes in the electrochemical potential and volume of specimens were also different: over 3 h, the potential decreased in its absolute value to 0.8 of the initial level, whereas the volume dropped to 0.15 of the initial value.
BIOPHYSICS Vol. 53 No. 6 2008
1.2 1.0 0.8 0.6 0.4 0.log[C(Ca , M)]
Fig. 5. Relative changes in the degree of swelling and electrochemical potential of PMAA 200/25 gel at various 2+ con centrations of Ca ions in solution. The abscissa shows the 2+ logarithm of Ca concentration in solution (M) and the ordinate, the relative changes in the degree of gel swelling (see text for details).
Fig. 6. Images of gel specimen before (left) and after 2+ (right) its transfer to the solution with 1.0 mM Ca.
Degree of swelling 100
Fig. 7. Change in the volume of gel (PMAA 100/50) speci2+ mens in the solutions with different concentration of Ca ions (see text for details).
Potential, mV 1.0 0.8 0.6 0.4 0.2
180 Time, min
Fig. 8. Change in the chemical potential of gel (PMAA 2+ 100/50) with time depending on the concentration of Ca ions in solution: (1) 0.1 mM, (2) 1.0 mM; (3) 2.5 mM, and (4) 5.0 mM.
150 Time, min 200
Fig. 9. Dynamics of the relative values of electrochemical potential and volume of gel (PMAA 100/50) specimens in 1 mM CaCl2 solution. The ordinate shows the relative changes in the corresponding parameter (see text for details).
Thus, addition of Ca ions to the solvent reduces the gel volume and decreases the absolute value of its 2+ electrochemical potential; moreover, the larger the Ca concentration, the more pronounced and fast are the changes in mechanical and electrical properties of gel specimens. DISCUSSION Cross-linked synthetic polymers are able to swell in solvent (water), forming a hydrogel. The main characteristic of a gel is the degree of its swelling, i.e., the ratio of gel volume (weight) to the volume (weight) of dry polymer. The degree of swelling or the amount of absorbed solvent depends on manifold factors. In particular, both the specic features of the polymer network internal structure (chemical nature and the number of cross-links) and the external factors (temperature, pH, and molecular and ionic compositions of ambient medium) inuence the degree of swelling . Due to the dependence on external parameters, the degree of gel swelling is a dynamic characteristic It has been demonstrated changeable in a wide range. that the mobile low-molec 2 ular-weight counterions are inhomogeneously distributed in the hydrogels of synthetic polyelectrolytes as well as in the ambient medium, thereby inducing the Donnan potential [2, 7]. Upon establishing of the Don-nan equilibrium, the anionic gels (the gels with predominance of negatively charged acid groups in the chain) display a negative electric potential relative to the ambient solvent [2, 7, 8]. The value of this potential depends on the internal structure of hydrogel, in particular, on the degree of cross-linking between the polymer chains. For example, it has been demonstrated that dense gels display a less negative value of this potential as compared with the loose gels .
It has been shown that this potential shifts with the change in the concentration of cations and anions in solvents as well as when hydrogel is exposed to a constant electric eld ; this suggests that the degree of gel swelling and its electrochemical potential are correlated. The behavior of an anionic gel was studied both by numerical modeling and experimentally [9, 10]. Use of modied microelectrode tools for recording the prole of electrical potential in gel made it possible to demonstrate that the compression/swelling of gel were accompanied by a shift in the Donnan potential. The gel compression in electric eld shifted the potential towards less negative region (depolarization), whereas swelling had an opposite effect (hyperpolarization) .results t well the already known facts. We have Our found that the change in electrochemical potential in gel is tightly correlated with its compression caused by the presence of calcium ions in the solvent. Moreover, the higher the degree of gel compression (increase in the degree of swelling), the less negative was the potential of the specimen. In addition, unlike the known studies, we succeeded in demonstrating that the rate of both gel compression and change in its potential directly depends on the concentration of calcium ions the solvent. Of fundamental importance is the discovered fact that the electrical changes in gel are behind the mechanical transformations occurring in it. This result directly follows from the experiments under dynamic conditions (see Fig. 9) and is indirectly conrmed by the observations under static conditions (see Fig. 5). In the latter case, it was demonstrated that the drastic rearrangements in the gel volume parameters appeared at lower calcium concentrations as compared with the electrostatic changes in the polymer.
The negative Donnan potential of anionic gel is determined by a higher concentration of positive counterions inside the gel as compared with the ambient medium [2, 7]. Therefore, a decrease in the potential 2+ upon addition of Ca ions to the medium can result from a leveling of positive counterion concentrations inside and outside the gel. However, in this case, the change in potential must occur ahead of the gel com2+ pression, which will appear with the diffusion of Ca ions into the gel. According to our data, the structural changes in the gel precede the changes in its potential, A vice versa. notparticular mechanism of the effect of gel structural changes on its potential is still vague. It can be connected with a redistribution of mobile counterions caused by compression of the polymer network as well as result from a decrease in the interlament distances, changing the density of the network charge. Independently of a particular mechanism, we consider important the mere fact that the structural changes lead to an electrostatic response. gels are an adequate model of Assuming that synthetic the intracellular polyelectrolyte protein network, we can infer that, rst, a mechanical transformation of the cytoskeleton entails a change in the electrochemical cell potential and, second, the cytoskeleton, at least in part, is responsible for the cell potential or controls it. The well-known phenomenon of a mechanoelectrical feedback in the contractile cells favors the above assumptions. In particular, it has been demonstrated that the extension of a cardiomyocytes by 10% of its 3 initial length depolarizes the membrane by 68 mV . Qualitatively analogous data have been also obtained by other researchers . A mechanically induced depolarization inuences the cell electrophysiology, causing the changes in excitability, rate of pulse conduction, duration of action potential, and so on [15, is assumed that the mechanosensitive ion channels It 16]. activated by cell extension are responsible for the mechanoelectrical feedback [17, 18]. The molecular mechanism of channel activation during cell extension is yet vague, although it is known that this requires the presence of cytoskeleton in the cell . It has been hypothesized that the mechanosensitive channels can be activated as a result of the tension in the membrane lipid bilayer or in the cytoskeleton structures connected with channel hand, according to our results, the pheOn the other proteins . nomenon of mechanoelectrical feedback, at least in
part, can be determined by the physicochemical properties of the cell cytoskeleton. In addition, mechanosensitive channels can be activated as a result of the initial shift in the cell cytoskeleton potential, triggering, in its turn, the chain of subsequent well-known events, provided that the properties of biological and synthetic polymers are similar enough. REFERENCES
1. B. Alberts, D. Bray, J. Lewis, et al., Molecular Biology of the Cell, 3rd ed. (Garland, New York, 1994). 2. A. Safronov, T. Shklyar, V. Borodin, et al., in Water in Biology, Ed. by G. Pollack, I. Cameron, and D. Wheatley (Springer, New York, 2006), pp. 273284. 3. I. Tasaki, Jpn. J. Physiol. 49, 125 (1999). 4. I. Tasaki, Ferroelectrics 220, 305 (1999). 5. I. Tasaki, J. Theor. Biol. 218, 497 (2002). 6. O. E. Filippova, Vysokomolekul. Soedinen. 42 (12), 2328 (2000). 7. R. W. Guelch, J. Holdenried, A. Weible, et al, in Proceedings of the SPIE Smart Structures and Materials 2000: Electroactive Polymer Actuators and Devices 6/2000, Vol. 3987. pp. 193202. 8. F. Gao, F. B. Reitz, and G. H. Pollack, J. Appl. Polym. Sci. 89, 1319 (2003). 9. T. Wallmersperger, B. Kroplin, J. Holdenried, and R. W. Gulch, in Proceedings of the SPIE Smart Structures and Materials 2001: Electroactive Polymer Actuators and Devices, 7/2001, Vol. 4329. pp. 10. T. Wallmersperger, B. Kroplin, and R. W. Gulch, Mech. 264275. Mater. 36, 411 (2004). 11. A. G. Kamkin, I. S. Kisileva, and V. N. Yarygin, Usp. Fiz. Nauk, 32 (2), 58 (2001). 12. M. J. Lab, Circ. Res. 42, 519 (1978). 13. D. E. Hansen, C. S. Craig, and L. M. Hondeghem, Circulation 81, 1094 (1990). 14. M. R. Franz, R. Cima, D. Wang, et al. Circulation 86, 968 (1992). 15. R. H. Kaufmann, M. J. Lab, and R. Hennekes, Pug. Arch. 324, 100 (1971). 16. R. Hennekes, R. H. Kaufmann, M. J. Lab, and R. J. Mol. Cell. Cardiol. 9, 699 (1977). Steiner, 17. H. Hu and F. Sachs, J. Mol. Cell. Cardiol. 29, 1511 (1997). 18. F. Sachs and C. E. Morris, Rev. Physiol. Biochem. Pharmacol. 132, 1 (1998). 19. M. Sokabe, F. Sachs, and Z. Jing, Biophys. J. 59, 722 (1991). 20. P. A. Watson, FASEB J. 5, 2013 (1991).
SPELL: 1. recoded, 2. inhomogeneously, 3. depolarizes
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