Công nghệ vật liệu trong y sinh học biom aterials chapter 2 phần 2 2

Chap.2 – 2.2 Silicone Introduction to silicone - 1824: tetrachlorosilane (SiCl4); 1863: tetraethylsilane; 1871:diethyldiethoxysilane 1901- 1931:foundation of organosilicon chemistry 1940s: became commercial - Basic repeating units: siloxane; PDMS (polydimethylsiloxane): most common silicone c om R can be different - Have unique properties, possible use as fluids, emulsions, compounds, resins, elastomer - Widely used in a lot of application In aerospace industry (low- and high temperature performance) In electronic field: Electrical insulator, semi conductor ng In construction: Sealants, adhesives, water proof coatings (due to long-term durability) co Widely used in personal care, pharmaceutical, medical device application (excellent biocompatibility) Advanced Program Biomedical Engineering – HUST, Vietnam ng th an du o Chap.2 – 2.2 Sillicone cu u Silicone Chemistry and nomenclature M: Si connected with oxygen atom D: Si connected with oxygen atoms T: Si connected with oxygen atoms Q: Si connected with oxygen atoms Example: Trimethylsiloxy: most common MDnM CuuDuongThanCong.com Advanced Program Biomedical Engineering – HUST, Vietnam https://fb.com/tailieudientucntt 2.2 Sillicone co ng c om Chap.2 – Advanced Program Biomedical Engineering – HUST, Vietnam ng th an du o Chap.2 – 2.2 Sillicone Synthesis cu u 2.1 Silicone polymer CuuDuongThanCong.com Advanced Program Biomedical Engineering – HUST, Vietnam https://fb.com/tailieudientucntt Chap.2 – 2.2 Sillicone 2.2.Silicone elastomer •Cross-linking with radicals - For high consistency silicone rubber (extrusion or injection) - Initiator: peroxide (radicals forming) •Cross-linking by condensation - Mostly for silicone caulks, sealants, silicone adhesives for medical devices - Catalyst needed - By products •Cross-linking by addition c om - Catalyst: Pt or Rh metal complexes - No by products - For molded parts •Elastomer filler - To enhance the strength and modify several properties of silicone elastomer ng - Fillers: titanium oxide, barium sulphate, pigments, fumed silica (most favorable) but needs surface modification (with silane) co - Processing:: two roll mill, twin-screw extruder, Z-blade mixer Advanced Program Biomedical Engineering – HUST, Vietnam ng th an 2.2 Sillicone cu u du o Chap.2 – CuuDuongThanCong.com Advanced Program Biomedical Engineering – HUST, Vietnam https://fb.com/tailieudientucntt Chap.2 – 2.2 Sillicone Some properties - Unusual combination between high surface tension (of inorganic back bone) with low surface tension of organic side groups: Biocompatible elastomer (surface tension 20-30 mN/m) Capable to wetting themselves Silicone organic copolymers can be prepared with surfactant properties (e.g in silicone glycol copolymer - Have week intermolecular interactions: c om Very low glass temperature Have high permeability to oxygen, nitrogen, water vapor… co ng Viscosity id less dependent on temperature than hydrocarbon Advanced Program Biomedical Engineering – HUST, Vietnam ng th an du o Chap.2 – 2.3 Medical Fibers and Biotextiles Medical textiles: medical products and devices for -Wound dressing, bandages… u -Biotextiles, tissue engineering scaffolds, vascular implants… * Medical fiber can be fabricated from monofilament, multifilament, staple… cu * Materials for medical textiles: synthetic polymers, natural polymers, or genetically engineered polymers and the way to choose suitable fiber configuration and materials: based on the requirements of device design and the manner in which fiber is to be used - Non-absorbable synthetic polymers: PET (polyethylene terephthalate)- (Dacron): for most large-caliber textiles vacular grafts PVC copolymer (Vinyon), acrylic polymers, nylon, PTFE-polytetraflourethylene (Teflon)…: for vascular grafts since 1950s .Today only PTFE & PET are still used for vascular grafts (inert, flexible, resilent, durable and resistant to biological degradation - Absorbable polymers: PVA- poly(vinyl alcohol), PLA- poly(lactic acid), PGA-polyglycolide…: for absorbable sutures… - Biopolymers and modified biopolymers (natural polymers: Collagen, polysacharides (alginates, biomimetic polymer synthesized by generic engineering of peptide sequences from elastin, collagen and spider silk…): for absorbent wound dressing, wound management, scaffolds for cell cultures, surgical hemostats… Cotton has been commonly used for bandages, surgical sponges, drapes, and surgical apparel, and in surgical gowns CuuDuongThanCong.com Advanced Program Biomedical Engineering – HUST, Vietnam https://fb.com/tailieudientucntt Chap.2 – 2.3 Medical Fibers and Biotextiles co ng c om Important Note! for most synthetic polymers: additive (dyes, stabilizer, antioxidants, delustrants) problems from commercial polymers Advanced Program Biomedical Engineering – HUST, Vietnam ng th an 2.3 Medical Fibers and Biotextiles cu u du o Chap.2 – 10 CuuDuongThanCong.com Advanced Program Biomedical Engineering – HUST, Vietnam https://fb.com/tailieudientucntt 2.3 Medical Fibers and Biotextiles co ng c om Chap.2 – Advanced Program Biomedical Engineering – HUST, Vietnam ng th an 11 cu u du o Chap.2 – 12 CuuDuongThanCong.com Advanced Program Biomedical Engineering – HUST, Vietnam https://fb.com/tailieudientucntt co ng c om Chap.2 – Advanced Program Biomedical Engineering – HUST, Vietnam ng th an 13 cu u du o Chap.2 – 2.3 Medical Fibers and Biotextiles Preparation •Melt Spinning •Wet spinning •Electrospinning Melt spinning: -Typically used with thermoplastics -Yarn can be further processed - Size of spun fiber: 10 µm (multifilaments) 500 µm or more (for monofilament) Electrospinning: - For very fine fiber - Use electrostatic field and high voltage (5-30 kV) - Fiber diameter: µm-100 nm 14 CuuDuongThanCong.com Advanced Program Biomedical Engineering – HUST, Vietnam https://fb.com/tailieudientucntt 2.3 Medical Fibers and Biotextiles c om Chap.2 – Wet spinning Low-temperature process co ng (related to degradation proplems) Advanced Program Biomedical Engineering – HUST, Vietnam ng th an 15 du o Chap.2 – 2.3 Medical Fibers and Biotextiles Construction u •Nonwovens -Is a textile structure produced directly from fibers without the intermediate step of yarn production cu -Fibers: bond or interlocked together by chemical, or thermal action or by using adhesive or solvent; oriented random or in one or more directions •Woven fabrics: -Textile configuration where the primary structural yarns are oriented at 90o to each other - Plain, twill, satin weaves -Water permeability should be controlled (50-350 ml cm-2.min-1) •Knits -Made by interloping yarn in horizontal row and vertical columns of stitches •Braids 16 CuuDuongThanCong.com Advanced Program Biomedical Engineering – HUST, Vietnam https://fb.com/tailieudientucntt 2.3 Medical Fibers and Biotextiles co ng c om Chap.2 – Advanced Program Biomedical Engineering – HUST, Vietnam ng th an 17 2.3 Medical Fibers and Biotextiles cu u du o Chap.2 – 18 CuuDuongThanCong.com Advanced Program Biomedical Engineering – HUST, Vietnam https://fb.com/tailieudientucntt Chap.2 – 2.3 Medical Fibers and Biotextiles co ng c om Finishing Advanced Program Biomedical Engineering – HUST, Vietnam ng th an 19 2.3 Medical Fibers and Biotextiles Testing cu u du o Chap.2 – 20 CuuDuongThanCong.com Advanced Program Biomedical Engineering – HUST, Vietnam https://fb.com/tailieudientucntt Chap.2 – 2.4 Hydrogels Hydrogel: Polymer that can adsorb water 30% or more of its weight - Are water-swollen, cross-linked structure - Containing ether covalent bonds produced by simple reaction of one or more comonomers - Containing physical cross-linked from entanglements, association bond such as hydrogen bonds or strong Van der Waal interaction between chains - Have received significant attention for biomedical applications - Classification: Based on preparation: homopolymer hydrogels, copolymer hydrogels, multipolymer hydrogels, interpenetrating polymeric hydrogels c om Based on ionic charge: neutral, anionic, cationic or ampholytic hydrogels Based on physical structural feature: amorphous (chain are arranged randomly), semicrystalline (charcterized by dense regions of crystallites) hydrogels, hydrogen- bonded or cpmplexation structure (may be responsible for the three-dimetional structure formed) hydrogels -Structure: Connection points of several chains: junction (tetrafunctional cross-linked), multifunctional junction, physical molecular entanglements co ng Possible a junction is an association of polymer chains caused by van der Waal forces Advanced Program Biomedical Engineering – HUST, Vietnam ng th an 21 2.4 Hydrogels cu u du o Chap.2 – 22 CuuDuongThanCong.com Advanced Program Biomedical Engineering – HUST, Vietnam https://fb.com/tailieudientucntt Chap.2 – 2.4 Hydrogels Preparation: swelling cross-linked structure in water or in biological fluids Chemical cross-linking: direct reaction of linear or branched polymer with at least one crss-linking agents (difunctional, small molecular weight) or copolymerization cross-linking reaction, or cross-linking a combination of monomer and linear polymeric chains by interlinking agents Photopolymerization or irradiation cross-linking Important biomedical hydrogels - PHEMA (poly(2-hydroxylethyl methacrylate): most widely used, inert to normal biological processes, resistant to degradation, not absorb by the body, biocompatible, withstand heat sterilization wothour damage, can easily prepared in several shapes and forms, used for blood-compatible applications, artifical tendon materials c om -Polyacryamide -MAA (methacrylic acid), MMA, MAH (maleic anhydride): useful monomer for preparation of hydrogels -PVA:hydrophilic, nontoxic, good mucoadhesive properties -PEO and PEG Applications: ng -Used for blood-compatible applications, artificial tendon materials, wound healing bioadhesive, artificial kidney membranes, artificial skin, articular cartilage (PHEMA, PVA, Polyacryamide) co -Very popular in pharmaceutical application: swelling-controlled release system (for bioactive agents), such as drug release system (PHEMA, PVA Advanced Program Biomedical Engineering – HUST, Vietnam ng th an 23 du o Chap.2 – 2.5 Smart polymers Smart polymers (Stimulus-responsive, interlligent polymers) u -Are polymers that respond with sharp, large property change to small change in physical or chemical conditions cu -Other names: environmentally sensitive polymer -Can take many forms -May be dissolved in aqueous solution (convert from solution to a gel): polymers with alcohol groups: poly(hydropropyl acrylate), PVA derivates… - May be absorbed or grafted on aqueous-solid interfaces (converting interface fron hydrophilic to hydrophobic):PNIPAAm - May be cross-linked in the form of hydrogels: PNIPAAm 24 CuuDuongThanCong.com Advanced Program Biomedical Engineering – HUST, Vietnam https://fb.com/tailieudientucntt 2.5 Smart polymers co ng c om Chap.2 – Advanced Program Biomedical Engineering – HUST, Vietnam ng th an 25 2.5 Smart polymers cu u du o Chap.2 – 26 CuuDuongThanCong.com Advanced Program Biomedical Engineering – HUST, Vietnam https://fb.com/tailieudientucntt Chap.2 – 2.6 Biodegradable polymers co ng c om Examples of Biodegradable Polymers Advanced Program Biomedical Engineering – HUST, Vietnam ng th an 27 2.5 Smart polymers cu u du o Chap.2 – 28 CuuDuongThanCong.com Advanced Program Biomedical Engineering – HUST, Vietnam https://fb.com/tailieudientucntt 2.6 Biodegradable polymers co ng c om Chap.2 – Advanced Program Biomedical Engineering – HUST, Vietnam ng th an 29 du o Chap.2 – 2.6 Biodegradable polymers cu u Mechanism of chemical degradation 30 CuuDuongThanCong.com Advanced Program Biomedical Engineering – HUST, Vietnam https://fb.com/tailieudientucntt Chap.2 – 2.7 Natural polymers co ng c om Examples of natural polymers Advanced Program Biomedical Engineering – HUST, Vietnam ng th an 31 du o Chap.2 – 2.7 Natural materials cu u Structure of protein 32 CuuDuongThanCong.com Advanced Program Biomedical Engineering – HUST, Vietnam https://fb.com/tailieudientucntt Chap.2 – 2.7 Natural materials co ng c om Collagen Advanced Program Biomedical Engineering – HUST, Vietnam ng th an 33 2.7 Natural materials cu u du o Chap.2 – 34 CuuDuongThanCong.com Advanced Program Biomedical Engineering – HUST, Vietnam https://fb.com/tailieudientucntt Chap.2 – 2.7 Natural materials co ng c om Elastin Advanced Program Biomedical Engineering – HUST, Vietnam ng th an 35 du o Chap.2 – 2.7 Natural materials cu u Glucosaminoglycans 36 CuuDuongThanCong.com Advanced Program Biomedical Engineering – HUST, Vietnam https://fb.com/tailieudientucntt 2.7 Natural materials co ng c om Chap.2 – Advanced Program Biomedical Engineering – HUST, Vietnam cu u du o ng th an 37 CuuDuongThanCong.com https://fb.com/tailieudientucntt ... Non-absorbable synthetic polymers: PET (polyethylene terephthalate)- (Dacron): for most large-caliber textiles vacular grafts PVC copolymer (Vinyon), acrylic polymers, nylon, PTFE-polytetraflourethylene... homopolymer hydrogels, copolymer hydrogels, multipolymer hydrogels, interpenetrating polymeric hydrogels c om Based on ionic charge: neutral, anionic, cationic or ampholytic hydrogels Based on physical... polymeric chains by interlinking agents Photopolymerization or irradiation cross-linking Important biomedical hydrogels - PHEMA (poly (2- hydroxylethyl methacrylate): most widely used, inert to