Biomedical modification

Grafting and modification of polymers have been found to have applications in the biomedical field. For example, poly(etherurethane), which has good elastomeric and often mechanical properties and a relatively high compatibility with blood, has been used in the man-... 

Radiation grafting for various biomedical applications remains an extremely active field of development. The grafted side chains can contain functional groups to which bioactive materials can be attached. These include amine, carboxylic, and hydroxyl groups, which can be considered as a center for further modifications. 

ADVANTAGES IN MODIFICATION OF NONDEGRADABLE SILICONE RUBBER FOR BIOMEDICAL APPLICATIONS... 

The resultant tailored interface is often vastly superior for biomedical applications over the native silicone interface. Furthermore, surface modification maintains the low materials cost and favorable bulk properties of the original silicone elastomer. The modification methods can be divided into physical and chemical techniques. 

V. J. Stella, T. J. Mikkelson, and J. D. Pipkin, Pro-drugs The control of drug delivery via bioreversible chemical modification, in Drug Delivery Systems Characteristics and Biomedical Applications (R. L. Ju-liano, ed.), Oxford University Press, New York, 1980,... 

Modification, Antiviral, Biomedical and Other Applications. Mount Prospect, IL ATL Press, 1993 87-100. 

Biagini G, Caudarelia R, Vangelista A. 1977. Renal morphological and functional modification in chronic lead poisoning. In Brown SS, ed. Clinical chemistry and chemical toxicology of metals. Elsevier/North-Holland Biomedical Press, 123-126. 

Apart from modifications in the bulk, also surface modification of PHAs has been reported. Poly(3HB-co-3HV) film surfaces have been subjected to plasma treatments, using various (mixtures of) gases, water or allyl alcohol [112-114]. Compared to the non-treated polymer samples, the wettability of the surface modified poly(3HB-co-3HV) was increased significantly [112-114]. This yielded a material with improved biocompatibility, which is imperative in the development of biomedical devices. 

Gupta, B. and Anjum, N. Plasma and Radiation-Induced Graft Modification of Polymers for Biomedical Applications. Vol. 162, pp. 37-63. 

Bioactive PMMA bone cement prepared by modification with methacryloxypropyltrimethoxy silane and calcium chloride. Journal of Biomedical Materials Research, 67A, 1417-1423. 

Kamensky, V.A., Feldchtein, F.I., Gelikonov, V.M., Snopova, L.B., Muraviov, S.V., Malyshev, A.Y., Bityurin, N.M. and Sergeev, A.M. (1999). In situ monitoring of laser modification process in human cataractous lens and porcine cornea using coherence tomography. Journal of Biomedical Optics 4 137-143. 

Teramura Y, Iwata H (2010) Cell surface modification with polymers for biomedical studies. Soft Matter 6 1081-1091... 

Nanoparticle surface modification is of tremendous importance to prevent nanoparticle aggregation prior to injection, decrease the toxicity, and increase the solubility and the biocompatibility in a living system [20]. Imaging studies in mice clearly show that QD surface coatings alter the disposition and pharmacokinetic properties of the nanoparticles. The key factors in surface modifications include the use of proper solvents and chemicals or biomolecules used for the attachment of the drug, targeting ligands, proteins, peptides, nucleic acids etc. for their site-specific biomedical applications. The functionalized or capped nanoparticles should be preferably dispersible in aqueous media. 

Surface modification is necessary in nanoparticles for various reasons (1) to make them biocompatible and non-immunogenic for biomedical applications,... 

Zalipsky, S., and Lee, C. (1992) Use of functionalized poly(ethylene glycol)s for modification of polypeptides. In Poly(Ethylene Glycol) Chemistry Biotechnical and Biomedical Applications (J.M. Harris, ed.), pp. 347-370. Plenum, New York. 

In recent years, CNTs have been receiving considerable attention because of their potential use in biomedical applications. Solubility of CNTs in aqueous media is a fundamental prerequisite to increase their biocompatibility. For this purpose several methods of dispersion and solubilisation have been developed leading to chemically modified CNTs (see Paragraph 2). The modification of carbon nanotubes also provides multiple sites for the attachment of several kinds of molecules, making functionalised CNTs a promising alternative for the delivery of therapeutic compounds. 

Methoxy poly(ethyleneglycol) (mPEG) was the most frequently used semitelechelic polymer for over 2 decades. It has been successfully used for the modification of various proteins, biomedical surfaces and hydrophobic anticancer drugs (for reviews see References [3,9,10]. Recently, a number of new semitelechelic (ST) polymers, such as ST-poly(A -isopropylacry-lamide) (ST-PNIPAAM) [11-15], ST-poly(4-acryloylmorpholine) (ST-PAcM) [16], ST-poly(A-vinylpyrrolidone) (ST-PVP) [17], and ST-poly[A-(2-hydroxypropyl)methacrylamide] (ST-PHPMA) [18-21] have been prepared and shown to be effective in the modification of proteins or biomedical surfaces. 

HPMA copolymers are water-soluble biocompatible polymers, widely used in anticancer drug delivery (reviewed in Reference [22]). HPMA copolymers containing reactive groups at side-chain termini were previously used for the modification of trypsin [23], chymotrypsin [23,24], and acetylcholinesterase [25]. The modification dramatically increased the acetylcholinesterase survival in the blood stream of mice and the thermostability of modified enzymes when compared to the native proteins. However, the modification involved multipoint attachment of the copolymers to the substrates, which may cause crosslinking. To modify proteins or biomedical surfaces by one point attachment, semitelechelic polymers should be used. 

MODIFICATION OF BIOMEDICAL SURFACES WITH SEMITELECHELIC HPMA POLYMERS... 

The modification of the nanospheres with ST HPMA polymers significantly changed the surface structure and property of the nanospheres, which resulted in substantial changes in the biorecogiuzability and biodistribution of the nanospheres. The biocompatibility of HPMA polymers bodes well for the future application of ST PHPMA in the modification of biomedical surfaces. 

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