Microparticles from biodegradable polymers

Abstract

MATERIALSdifference is thus as high as a factor of 3.5. Only when the conversion is higher than 85-90%, does the level of crosslinking agent drastically increase to more than 1 %.If the amount of cross-linking agent is adjusted so that the polymer chains are optimally cross-linked a t low conversions, the cross-linking density may be insufficient, or too high, for the short polymer chains at the end of the reaction. Larger or smaller quantities of cross-linking agent may indeed provide the necessary amount of cross-linker density at higher conversions but at lower conversions the amount is then either too low or too high.The only way to overcome the problem of varying the necessary amount of cross-linker is to use a mixture of a high-and low-reactivity cross-linking agent. The high-reactivity cross-linking agent acts preferentially at a low conversion and the low-reactivity cross-linking agent at higher conversions. By varying the ratio of the two, the cross-linking density can be adjusted over the whole range and network structures with good performance characteristics can be achieved. ~[I] P. K. Chatterjee: Ahsorbencv, Elsevier.

Adjuvanticity Regulation by Biodegradable Polymeric Nano/microparticle Size

“…Polymeric nano/microparticles (NP/MPs) have been extensively investigated, especially biodegradable materials, such as chitosan, poly­(lactic acid) (PLA) and poly­( d , L -lactic- co -glycolic) acid (PLGA). These particles are used in the cosmetics industry, diagnostic imaging, tissue engineering, separations and purification of biological product, drug delivery, and as vaccine adjuvants. − Previous studies by others have shown that biodegradable particles have a high biosafety and biocompatibility and are able to control the release rate and duration of entrapped cargoes. − They can also function as potent vaccine adjuvants, owe to their abilities to improve antigen uptake by antigen-presenting cells (APCs), and further promote the expression of costimulatory molecules and major histocompatibility complex (MHC) molecules. , These excellent properties would be extremely beneficial for various new vaccines, such as protein subunits, recombinant proteins, and synthetic oligopeptides, which have been brought about with the development of biotechnology and genetic engineering . While the antigens we use today have great safety, the weak immunogenicity makes them require adjuvant to elicit powerful humoral and cellular immune response for preventing infectious diseases …”

Synthesis, characterization and biodegradation studies of chain-coupled polyesters based on tartaric acid

“…Tartaric acid is an inexpensive natural resource and a variety of polymers are derived from it such as polyesters, polyamides, poly(ester amide)s and polycarbonates etc. The tartaric acid based polyesters can be potential candidates in controlled drug delivery applications as controlled release agents and drug carriers . More recently, El‐Laboudy et al .…”

Formulation and characterization of dissolvable microneedles for controlled transdermal delivery of ketoprofen encapsulated in polymeric nanoparticles

“…Budući da je period njihove degradacije uglavnom veoma dug, veliki dio istraživačkog interesa je usmjeren ka dobijanju modifikovanih prirodnih polimera. Jedan od načina modifikacije prirodnih polimera je dodavanjem polarnih grupa koje su nestabilnije i pospješuju degradaciju polimera (23).…”