Drug delivery biocompatible gels

As mentioned above, the preparation of nanogels by addition reactions of functional macromolecular precursors is mainly used for biomedical applications. Thus, the choice of synthetic precursors for microgel formation is restricted to biocompatible materials. Moreover, as most applications are in drug delivery, the molecular weight of the gel precursors should be below the threshold for renal clearance, a value that depends on the molecular architecture and chemical nature of the polymer but that is usually smaller than 30kDa, which is set as the limit for linear PEG [97], Polymers that are mostly used and thus presented in more detail here are PEG, poly(glycidol) (PG), and polyethylene imine) (PEI). 

Used to render surfaces biocompatible and resistant to protein adhesion copolymers with poly(propylene oxide) form thermoreversible gels for drug delivery... 

Chitosan and chitosan derivatives have been extensively studied for drug delivery and other biomedical applications due to (1) their biocompatibility and low toxicity, (2) their possible formulation in nanoparticles or in gels, and (3) their cationic properties. An overview of their use in biomedical applications will be given for... 

Intriguingly, some of the properties of LMWGs, such as biodegradabihty, biocompatibility, and gende physical and chemical profiles, represent considerable potential in the fields of biomedicinal applications and drug delivery [58-62]. For this purpose, amphiphilic 3,4,5-trihydroxybenzoic derivatives with linkers of different lengths (26a, 26b, Fig. 3.23) were developed by us [63]. The compounds 26a and 26b with two naked -COOH are able to gel in aqueous ethanol, meanwhile, they can trap a great amount of tetracycline hydrochloride (TH) in gel tissue. In the presence of BSA or amino acids, TH could be controUably released into water solution. 

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