के लिए यंत्रवत् जाने योग्य पॉलिमर Nanocomposites के पर्यावरण की दृष्टि से नियंत्रित Microtensile परीक्षण<em> पूर्व vivo</em> विशेषता
Summary
एक विधि पर चर्चा की है जिसके द्वारा<em> Vivo में</emउत्तेजनाओं उत्तरदायी सामग्री के> यांत्रिक व्यवहार समय के एक समारोह के रूप में नजर रखी है. नमूने का परीक्षण किया जाता है<em> पूर्व vivo</em> मनोवैज्ञानिक वातावरण अनुकरण करने के लिए पर्यावरण नियंत्रण के साथ एक microtensile परीक्षक का उपयोग कर. इस काम के लिए आगे समझ को बढ़ावा देता है<em> Vivo में</emहमारे सामग्री का> व्यवहार.
Abstract
Implantable microdevices are gaining significant attention for several biomedical applications1-4. Such devices have been made from a range of materials, each offering its own advantages and shortcomings5,6. Most prominently, due to the microscale device dimensions, a high modulus is required to facilitate implantation into living tissue. Conversely, the stiffness of the device should match the surrounding tissue to minimize induced local strain7-9. Therefore, we recently developed a new class of bio-inspired materials to meet these requirements by responding to environmental stimuli with a change in mechanical properties10-14. Specifically, our poly(vinyl acetate)-based nanocomposite (PVAc-NC) displays a reduction in stiffness when exposed to water and elevated temperatures (e.g. body temperature). Unfortunately, few methods exist to quantify the stiffness of materials in vivo15, and mechanical testing outside of the physiological environment often requires large samples inappropriate for implantation. Further, stimuli-responsive materials may quickly recover their initial stiffness after explantation. Therefore, we have developed a method by which the mechanical properties of implanted microsamples can be measured ex vivo, with simulated physiological conditions maintained using moisture and temperature control13,16,17.
To this end, a custom microtensile tester was designed to accommodate microscale samples13,17 with widely-varying Young’s moduli (range of 10 MPa to 5 GPa). As our interests are in the application of PVAc-NC as a biologically-adaptable neural probe substrate, a tool capable of mechanical characterization of samples at the microscale was necessary. This tool was adapted to provide humidity and temperature control, which minimized sample drying and cooling17. As a result, the mechanical characteristics of the explanted sample closely reflect those of the sample just prior to explantation.
The overall goal of this method is to quantitatively assess the in vivo mechanical properties, specifically the Young’s modulus, of stimuli-responsive, mechanically-adaptive polymer-based materials. This is accomplished by first establishing the environmental conditions that will minimize a change in sample mechanical properties after explantation without contributing to a reduction in stiffness independent of that resulting from implantation. Samples are then prepared for implantation, handling, and testing (Figure 1A). Each sample is implanted into the cerebral cortex of rats, which is represented here as an explanted rat brain, for a specified duration (Figure 1B). At this point, the sample is explanted and immediately loaded into the microtensile tester, and then subjected to tensile testing (Figure 1C). Subsequent data analysis provides insight into the mechanical behavior of these innovative materials in the environment of the cerebral cortex.
Protocol
Representative Results
Discussion
जैविक प्रणालियों के साथ बातचीत के लिए प्रत्यारोपण जैव चिकित्सा microelectromechanical सिस्टम (BioMEMS) की उन्नति अत्यधिक सिलवाया गुणों के साथ नई सामग्री के विकास को प्रेरित किया जाता है. इन सामग्रियों के कुछ मनोवैज्ञान?…
Disclosures
The authors have nothing to disclose.
Acknowledgements
इस काम में दोनों प्रयोगशाला शुरू हुआ धन (जे Capadona), और Medtronic ग्रेजुएट फेलोशिप (लालकृष्ण पॉटर) के माध्यम से केस वेस्टर्न रिजर्व विश्वविद्यालय में बायोमेडिकल इंजीनियरिंग विभाग द्वारा समर्थित किया गया था. इस शोध पर अतिरिक्त धन के हिस्से में समर्थन किया था NSF अनुदान ईसीएस-0621984 (सी. Zorman), प्रकरण छात्र संघ (सी. Zorman), एक मेरिट समीक्षा पुरस्कार (B7122R) के माध्यम से दिग्गजों मामलों के विभाग, साथ ही उन्नत प्लेटफार्म प्रौद्योगिकी केंद्र (C3819C).
Materials
| Name of Reagent/Material | Company | Catalogue Number | Comments |
| Silicon wafer | University Wafer | Mechanical grade | |
| Extruded acrylic sheet | Professional Plastics | SACR 062EF | Thickness 0.062″ |
| Razor blade | McMaster-Carr | 3962A3 | |
| Tweezers | McMaster-Carr | 8384A47 | #5 tip |
| Super Glue Gel | Loctite | 130380 | |
| Air Brush | Snap-on Industrial | BF175TA | |
| Air Compressor | Paasche | B002YKN8YO | D500 |
| Thermocouple | Omega | HH12A | |
| Hot plate | Cimarec | SP131325Q | |
| CO2 direct-write laser | VersaLaser | 3.5 | |
| Dessicator | Fisher Scientific | 08-595 | |
| Lamp | custom-built | ||
| Microtensile tester | custom-built |
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