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Bio-Implants Derived from Biocompatible and Biodegradable Biopolymeric Materials
Published in P. Mereena Luke, K. R. Dhanya, Didier Rouxel, Nandakumar Kalarikkal, Sabu Thomas, Advanced Studies in Experimental and Clinical Medicine, 2021
Kumar et al. [16] have developed a green route to pegylated amphiphilic polymers with the use of immobilized enzyme, Candida Antarctica lipase B. The ability of these polymers to form the nano-micelles makes them suitable for application in drug delivery systems and in cancer diagnostics. Gong et al. [17] developed a new highly innovative two-photon activated photodynamic therapy (PDT) which has three-fold level of application, (a) a photosensitizer: a porphyrin substituted on the meso positions by chromophores with large two-photon absorption and activated in the near infra-red region in the tissue transparency window and efficiently producing singlet oxygen as the cytotoxic agent; (b) which can target small molecule also target receptor sites on the tumor; and (c) a imaging agent near IR that can correctly give image of the tumor for treatment. Adronov et al. [14] synthesized carborane functionalized dendronized polymers and found them to be useful as potential boron neutron capture therapy (BNCT) agents. Nederberg and coworkers [18] have developed a series of telechelic biodegradable ionomers based on poly(trimethylene carbonate) carrying zwitterionic, anionic, or cationic functional groups for protein drug delivery. Biodegradable ionomers was utilized for protein loading simply by letting the material swell in an aqueous protein solution. The process can be done either directly after loading or after a drying. Protein activity is maintained suggesting that these ionomers may favorably interact with guest proteins and denaturation is suppressed.
Nanomaterials for Theranostics: Recent Advances and Future Challenges *
Published in Valerio Voliani, Nanomaterials and Neoplasms, 2021
Eun-Kyung Lim, Taekhoon Kim, Soonmyung Paik, Seungjoo Haam, Yong-Min Huh, Kwangyeol Lee
Sandre et al. encapsulated anticancer drug, DOX, and γ-Fe2O3 within the poly(trimethylene carbonate)-b-poly(L-glutamic acid) block copolymer vesicle [784]. The liposome vesicle releases the therapeutic content at a temperature of 37°C, and this could be accomplished by heating iron oxide nanoparticles under an applied external magnetic field. The polymersome successfully released DOX into aqueous solution under a magnetic field; the release rate was twice as fast as magnetic field unapplied polymersome (Fig. 16.29). Facilitated DOX release by magnetic hyperthermia was also reported with Zn-doped iron oxide nanoparticle trapped in mesoporous silica, which contains DOX in the mesopores [107].
Evidence for Mesh Use
Published in Jeff Garner, Dominic Slade, Manual of Complex Abdominal Wall Reconstruction, 2020
The delayed absorbable mesh that has been on the market for the longest time (∼10 years) is Bio A® (WL Gore & Associates, Flagstaff, Arizona), a sheet of a copolymer of polyglycolic acid and trimethylene carbonate which undergoes hydrolysis with complete resorption by 6 months. TIGR Matrix® (Novus Scientific, Uppsala, Sweden) is composed of two fibre types – a fast-resorbing fibre that has disappeared completely at 4 months and a slow-resorbing fibre that maintains high tensile strength for at least 6 months but is fully resorbed by 3 years. The fast-resorbing fibre is a copolymer of glycolide, lactide and trimethylene carbonate whereas the slow-resorbing fibre is a copolymer of lactide and trimethylene carbonate. Phasix™ (CR Bard, Warwick, Rhode Island) is a monofilament mesh composed of poly-4-hydroxybutyrate that degrades by hydrolysis over 12–18 months. The clinical data on these meshes is somewhat limited by their life span on the market but is slowly accruing.
Stereolithography 3D printing technology in pharmaceuticals: a review
Published in Drug Development and Industrial Pharmacy, 2021
Subhash Deshmane, Prakash Kendre, Hitendra Mahajan, Shirish Jain
The choice of photopolymer is of utmost importance in SLA [94,95]. The lack of approval of photosensitive materials by the regulatory authority (the FDA) limits the use of SLA significantly, even though photosensitive materials are used in tissue engineering. During the last decade, a number of photocrosslinkable polymers have been developed. Poly(ethylene glycol) diacrylate (PEGDA) [73,96], poly(2-hydroxyethyl methacrylate) (pHEMA) [97], poly(ethylene glycol) dimethacrylate (PEGDMA) [98,99] and poly(propylene fumarate)/diethyl fumarate (PPF/DEF) [100,101] are examples of photocrosslinkable polymers. Biomedical materials have applications in surgical tools, hearing aids, knee joint appliances and dental appliances [102]. The multiple resins for one build showed patterning with PEG-DMA and PEG-DA with fluorescently labeled dextran, fluorescently labeled bioactive PEG or bioactive PEG in different regions of the scaffold [103]. Complex 3D scaffolds can be fabricated using photocrosslinkable poly(propylene fumarate) (PPF) [104,105], which requires reactive diluents containing significant amounts of non-degradable components. N-vinyl-2-pyrrolidone and diethyl fumarate are used as diluents to reduce the viscosity of the resin during processing [106]. Reconstruction of cranial defects in rabbits is possible because of the ability to produce controlled microstructures [89]. Trimethylene carbonate, polycaprolactone and poly(D,L-lactide) are examples of materials used commonly in tissue engineering [107,108].
Release mechanisms and applications of drug delivery systems for extended-release
Published in Expert Opinion on Drug Delivery, 2020
Shuying Wang, Renhe Liu, Yao Fu, W. John Kao
Also important is to smooth the release profile over an extended period to reduce potential negative side effect. When employing polymers for controlled release, the manipulation of their comonomer ratio, end groups and molecular weight is always useful to modify the degradation rate so as to smooth the release profile. A typical example was reported by Amsden group [66] for the extended delivery of corticosteroid triamcinolone. To prolong the release, triamcinolone diffusivity (highly dependent on glass transition temperature Tg of the polymer [70]) was reduced via adjusting the monomer composition of hydrophobic prepolymer to increase Tg accordingly. Concurrently, a faster secondary release phase, caused by bulk erosion of the matrix with time [71], was eliminated by manipulating polymer degradation rate to achieve mass loss in a nearly linear fashion with time. Thus, the formulation design was based on the incorporation of trimethylene carbonate (TMC) and D,L-lactide (DLLA) into the prepolymer. The data demonstrated that a nearly constant, prolonged release for over 250 days was achieved using a network consisting of a hydrophobic prepolymer (TMC:DLLA 3:1) co-cross-linked with hydrophilic PEGDA, which was completely different from the ‘S’ shaped release pattern when equimolar ratios of TMC with DLLA was used (Figure 4).
Drug-eluting bioresorbable scaffolds in cardiovascular disease, peripheral artery and gastrointestinal fields: a clinical update
Published in Expert Opinion on Drug Delivery, 2020
Hideyuki Kawashima, Masafumi Ono, Norihiro Kogame, Kuniaki Takahashi, Chun-Chin Chang, Hironori Hara, Chao Gao, Rutao Wang, Mariusz Tomaniak, Rodrigo Modolo, Joanna J. Wykrzykowska, Robbert J. De Winter, Faisal Sharif, Patrick W. Serruys, Yoshinobu Onuma
The polymer of the fast degrading stent is made from poly-dioxanone, barium sulfate, and poly-ethylene-glycol (PEG) (Table 2) [89]. The poly-dioxanone is degraded by hydrolysis and has been used in other medical indications such as surgical sutures. Due to the presence of the PEG block which is also used as medical indication, the polymer degrades faster than the pure p-Dioxanone (1,4-dioxan-2-one) (PDO) material. During the degradation process, the device may remain mostly intact and move into the small intestine. While degradation continues in the gastrointestinal system, soluble degradation byproducts are absorbed into the body. The second type of the stent with the medium degradation type is made only from poly-dioxanone and barium sulfate (Table 2). The third iteration of the device with slow degradation consists of poly lactide-co-caprolactone-co-trimethylene carbonate (TMC) and barium sulfate (Table 2). The TMC block acts as a flexible hinge, and lactide provides strength and stability to the polymer. The different degradation profiles are designed for obstructed biliary or pancreatic ducts with various underlying diseases.