Novel fluorescent copolyanhydrides as potential visible matrices for drug delivery

Novel functionalized ternary copolymer fluorescent nanoparticles: synthesis, fluorescent characteristics and protein immobilization

Novel fluorescent poly(styrene-acrylamide-acrylic acid) nanoparticles (FPSAAN) were synthesized by means of soapless emulsion polymerization and being modified with hydrazine hydrate by hydrazinolysis. The azidocarbonyl groups which can be rapidly coupled with proteins under mild condition were introduced onto the fluorescent nanoparticles by azido-reaction. Bovine serum albumin (BSA) was selected as a model protein to be covalently immobilized on the azidocarbonyl FPSAAN. Atom force microscopy (AFM), Transmission electron microscopy (TEM), Ultraviolet-visible (UV/Vis) spectrometer, Fourier transforms infrared spectrometer (FTIR), nanoparticle size analyzer and fluorescence spectrophotometer were used to characterize the FPSAAN. Results showed that FPSAAN had a regular spherical shape, and a dramatic narrow size distribution (polydispersity index 0.046 +/- 0.009). The fluorescence intensity of FPSAAN (lambda(ex)/lambda(em) = 253/306 nm), hydrazide-FPSAAN (lambda(ex/)lambda(em) = 260/326 nm), and protein-immobilized FPSAAN (lambda(ex)/lambda(em) = 258/325 nm) was linearly related to the concentration ranging from 1.0 x 10(-3) g l(-1) to 10.0 x 10(-3) g l(-1). The linear relationship was obtained. The equations are y = 52.808x + 16.465 (R (2) = 0.9927), y = 5.1814x + 4.1535 (R (2) = 0.9935) and y = 5.2227x + 5.2883 (R (2) = 0.9937), respectively. In addition, external factors such as pH and ionic strength exert a slight influence on fluorescent properties. The experiments of the immobilization of BSA indicated that FPSAAN with azidocarbonyl groups could be covalently coupled with BSA at the rate of 41.1%. Meanwhile, hCG antibody immobilized FPSAAN have the similar fluorescence characteristics to BSA immobilized FPSAAN. Only negligible difference of the fluorescence characteristics can be found. Furthermore, the fluorescence characteristics of hCG antibody immobilized FPSAAN have not been obviously affected after mixed with the hCG antigen and human plasma. These novel azidocarbonyl FPSAAN with stable fluorescence and active functional azidocarbonyl groups could be used as a promising fluorescent probe for quantitative detection, protein immobilization, cell labeling research and early rapid clinical diagnostics.

Novel Copolyanhydrides Combining Strong Inherent Fluorescence and a Wide Range of Biodegradability: Synthesis, Characterization and in vitro Degradation

In this work, a novel diacid monomer was synthesized in a very convenient scheme. The monomer is derived from naturally occurring products and emits strong fluorescence when polymerized to polyanhydride. The chemical structure of the monomer dCPS is as follows: HOC(O)ArOC(O)(CH2)2C(O)O--Ar--COOH. Copolyanhydrides composed of dCPS and sebacic acid were further prepared by melt copolycondensation, and characterized by IR, NMR, UV-Vis, DSC and fluorometry. The emission wavelength (lambda(em)) of the copolymers could be tuned by the excitation wavelength (lambda(ex)). Fluorescence intensity increased with the increase of dCPS content. The microspheres fabricated from the copolymer with dCPS content as low as 10% could be clearly visualized with fluorescence microscopy. Either blue or green images of the microspheres could be captured with an excitation of UV and visible light. The degradation rate of the copolyanhydrides decreased as the dCPS fraction increased, and the degradation duration could be modulated from several days to more than three months. In addition, it was found that the copolyanhydrides displayed surface degradation characteristics. In view of the advantages of the novel copolyanhydrides, such as easy preparation, unique inherent luminescent properties, and widely adjustable degradation rate, they might be useful for biomedical engineering.

Polyesters based on diacid monomers

Polymers with ester linkages in their main chain comprise a family of polymers with immense diversity and versatility. This review deals with the preparation of such polymers from dicarboxylic acid monomers, and the result in terms of properties and applicability. Polyesters alone, and their copolymers with amides, anhydrides, urethanes, imides, ethers or other functional groups, offer countless opportunities to tune the properties of the resulting material within a broad range. Of particular interest is the inherent biodegradability of the ester linkage. Biodegradability is sought after in a wide range of applications, above all in the preparation of environmentally friendly polymers and biomedical materials for temporary surgical use and in drug delivery.