Biosynthesis and physico-chemical characterization of high performing peptide hydrogels@graphene oxide composites

Hydrogels based on short peptide molecules are interesting biomaterials with wide present and prospective use in biotechnologies. A well-known possible drawback of these materials can be their limited mechanical performance. In order to overcome this problem, we prepared Fmoc-Phe3self-assembling peptides by a biocatalytic approach, and we reinforced the hydrogel with graphene oxide nanosheets. The formulation here proposed confers to the hydrogel additional physicochemical properties without hampering peptide self-assembly. We investigated in depth the effect of nanocarbon morphology on hydrogel properties (i.e. morphology, viscoelastic properties, stiffness, resistance to an applied stress). In view of further developments towards possible clinical applications, we have preliminarily tested the biocompatibility of the composites. Our results showed that the innovative hydrogel composite formulation based on FmocPhe3 and GO is a biomaterial with improved mechanical properties that appears suitable for the development of biotechnological applications

A modular microfluidic platform for the synthesis of biopolymeric nanoparticles entrapping organic actives

By using a novel and versatile capillary microfluidic flow-focusing device we fabricated monodisperse drug-loaded nanoparticles from biodegradable polymers. A model amphiphilic drug (dexamethasone) was incorporated within the biodegradable matrix of the particles. The effects of flow rate ratio, polymer concentration and microreactor focusing channel dimensions on nanoparticles size and drug loading have been investigated. The presented data demonstrate that the microfluidic approach resulted in the production of colloidal nanoparticles with a narrow size distribution and useful morphological characteristics.This approach allows the rapid, easy, low cost and automated synthesis of polymeric nanoparticles, thus it may become a useful approach in the progression from laboratory scale to pilot-line scale processes

Different aspects of solvent engineering in lipase catalysed esterifications

A microbial lipase from Pseudomonas sp., immobilized on an ACR-silica gel, has been used as catalyst for esterification reactions in organic solvents which were largely different in some fundamental physico-chemical characteristics. The results obtained were compared with the same reactions carried out in supercritical carbon dioxide. Significant variations in conversion values as function of log Pmow of the solvent (dielectric constants and Hildebrand solubility parameters not providing consistent results) seem to demonstrate the importance of the enzyme-water content on the mechanism of action as in terms of conformations arrangements as well as in terms of substrates partition equilibrium with the polar matrix. Differently, the conversions and enantioselectivity of the reactions in the supercritical fluid, always higher than in organic solvents, could be attributed to the specific properties of the medium in terms of low viscosity and surface pressure values and higher diffusivity of substrates in the supercritical phase

Macrolide antibiotic intermediate preparation through Pseudomonas cepacia lipase biocatalyzed reactions

A lipase form Pseudomonas sp. has been employed as enantioselective catalyst in transesterification reaction using a substrate bicyclo[2.2.1]heptene derivatives and acetic esters with different substitution in organic moieties in organic solvent. The influence of hte chemical structure of the acyl donors has been studied

Enzymatic preparation of chiral intermediates for macrolide antibiotics

A Pseudomonas sp. lipase has been employed as enantioselective catalyst in transesterification reactions using as substrates bicyclo[2.2.1]heptene derivatives and acetic esters in organic solvents. The influence of the reaction medium on the activity and enantioselectivity of the lipase in transesterification reactions was investigated

Lipase-catalyzed regioselective acylation of tritylglycosides in supercritical carbon dioxide

Candida rugosa lipase (CRL) was used to catalyze the regioselective acylation of methyl 6-O-trityl -d-glucopyranoside in supercritical CO2 (SCCO2), using vinyl acetate as the acyl donor and obtained final conversion values up to 91.4%. The effect of pressure, temperature, enzyme quantity and sugar/ester molar ratio on the catalytic efficiency and regioselectivity of CRL was evaluated. The regioselectivity of the reaction was shifted towards the synthesis of 3-O-acetyl 6-O-trityl -d-glucopyranoside and this is a function of the chemico-physical parameters of the supercritical medium employed. In fact, by varying the CO2 pressure used in the process up to 20MPa at constant temperature, we were able to obtain the formation of the sole 3-O-acetyl 6-O-trityl -d-glucopyranoside regioisomer. A kinetic study was also performed and the relative kinetic parameters calculated