Biomedical modification drug delivery

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,... 

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. 

Society for Biomaterials. 17,000 Commerce Parkway, Suite C, Mt.Laurel, NJ 08054, U.S.A. Phone + 1 856-439-0826, Fax +1 856-439-0525. E-mail info biomaterials.org. URL http // www.biomaterials.org/. Holds annual conference provides awards to students and researchers in the field and offers networking via special interest groups in many areas, including tissue engineering, drug delivery, surface characterization and modification, and orthopaedic biomaterials. Sponsors publication of Journal of Biomedical Materials Research Part A and Part B and Biomaterials Forum, the official news magazine of the Society. 

Classical polymers have become increasingly used in medicine as components of biomedical devices, but with the development of new techniques for functionaUzalion, more sophisticated polymers have been developed, for instance as constituents of implants and drug delivery. In addition, chemical modification applied to polymers by y-irradiation to create new materials and applications is an effective alternative to reintegrate some polymers whose use has been limited due to problems associated with biocompatibility, toxicity, or bacterial colonization. All monomers and synthetic polymers presented in this chapter and their corresponding abbreviations are given in Table 10.1. 

This chapter focuses on the use of nanotechnology in the development of cellulose and chitin nanoctystals and their novel biomedical applications. It consists of four main sections. The first section is a brief introduction. The second section focuses on cellulose nanocrystals (CNCs) and their preparation procedure, physical properties, and surface modifications. Cationic modification of CNCs is also presented to produce positively charged CNCs. Various bioapplications of CNCs in bionanocomposites, drug delivery, and biosensors are discussed as well. The third section focuses on chitin nanoctystals (CHNCs). Except for a short introduction on chitin and its structure, the methods of isolation and characterization of chitin are discussed and the surface modifications and properties of CHNCs are summarized. The applications of CHNCs as reinforcing fillers in nanocomposites and several biomedical applications are discussed. The fourth section is a summary and perspective highlighting the future directions on the application of these natural nanoctystals in various key industries related to biomedicine. 

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