Synthesis, complex formation and corneal permeation of cyclodextrin-modified, thiolated poly(aspartic acid) as self-gelling formulation of dexamethasone

The present study aimed at developing a potential in situ gellable dexamethasone (DXM) eye drop. Poly(aspartic acid) (PASP) derivatives were synthesized with dual functionality to improve the solubility of DXM, and to achieve in situ gelation. First, amine-modified β-cyclodextrin (CD) was attached to polysuccinimide (PSI), second, thiol functionalities were added by the reaction of cysteamine and succinimide rings. Finally, the PSI derivatives were hydrolysed to the corresponding PASP derivatives to get water-soluble polymers. Phase-solubility studies confirmed the complexation ability of CD-containing PASP derivatives. In situ gelation and the effect of the CD immobilization on this behaviour were characterized by rheological measurements. The solubilizing effect of CD was confirmed by kinetic solubility measurements, whereas in vitro corneal permeability assay (corneal-PAMPA) measurements were performed to determine in vitro permeability and flux values. The effect of the PASP derivatives on permeation strongly depended on chemical composition and polymer concentration.

Magnetic targeted nanoparticles based on β-cyclodextrin and chitosan for hydrophobic drug delivery and a study of their mechanism

Magnetic nanoparticles double coated with β-cyclodextrin and chitosan were prepared for hydrophobic drug delivery, and its related mechanism was discussed.

Multifunctional Environmental Smart Fertilizer Based on l-Aspartic Acid for Sustained Nutrient Release

Fertilizer is one of the most important elements of modern agriculture. However, conventional fertilizer, when applied to crops, is vulnerable to losses through volatilization, leaching, nitrification, or other means. Such a loss limits crop yields and pollutes the environment. In an effort to enhance nutrient use efficiency and reduce environmental pollution, an environmental smart fertilizer was reported in the current study. Poly(aspartic acid) and a degradable macro-cross-linker based on l-aspartic acid were synthesized and introduced into the fertilizer as a superabsorbent to improve the fertilizer degradability and soil moisture-retention capacity. Sustained release behavior of the fertilizer was achieved in soil. Cumulative release of nitrogen and phosphorus was 79.8% and 64.4% after 30 days, respectively. The water-holding and water-retention capacities of soil with the superabsorbent are obviously higher than those of the control soil without superabsorbent. For the sample of 200 g of soil with 1.5 g of superabsorbent, the water-holding capacity is 81.8%, and the water-retention capacity remains 22.6% after 23 days. All of the current results in this study indicated that the as-prepared fertilizer has a promising application in sustainable modern agriculture.

Hollow nanosphere fabricated from β-cyclodextrin-grafted α,β-poly(aspartic acid) as the carrier of camptothecin

This research is aimed to develop a kind of hollow nanosphere based on β-cyclodextrin-grafted α, β-poly(aspartic acid) (β-CD-graft-PAsp) as drug carrier to enhance the stability of camptothecin (CPT) in aqueous media. Firstly, mono(6-(2-aminoethyl) amino-6-deoxy)-β-cyclodextrin (β-CDen) was synthesized by a substitution reaction between mono-6-deoxy-6-(p-tolylsulfonyl)-β-cyclodextrin (6-OTs-β-CD) and ethylenediamine; and then, the five-member rings in poly(L-succinimide) (PSI) were successively opened by β-CDen to obtain β-CD-graft-PAsp. The synthesized β-CD-graft-PAsp was found to form the unique hollow nanosphere with the internal hole of about 17 nm and many β-CD cavities of 0.7 nm interspersed on the shell. The drug-loading behavior of the hollow nanosphere was also evaluated by using CPT as guest molecule of β-CD. It was worth of note that the β-CD-graft-PAsp hollow nanosphere as carrier enhanced the stability of CPT in aqueous media, and the CPT from the β-CD-graft-PAsp hollow nanosphere displayed a sustained release profile and hence resulted in the essential decrease of cytotoxicity to L929 cell line. Furthermore, almost no cytotoxicity of the β-CD-graft-PAsp is desirable for the application of drug carrier. As a result, the β-CD-graft-PAsp hollow nanosphere showed a great potential as the carrier of CPT.

Avoiding spurious correlation in analysis of chemical kinetic data

This communication demonstrates that improperly formulated data analyses can inflate the strength of statistical correlations and result in drawing incorrect conclusions. The widespread misuse of a second-order kinetic model in the recent literature reveals that many chemists are not aware of the dangers of spurious correlation.