Multifunctional PEG Carrier by Chemoenzymatic Synthesis for Drug Delivery Systems: In Memory of Professor Andrzej Dworak.

This paper describes the synthesis and characterization of new bivalent folate-targeted PEGylated doxorubicin (FA2-dPEG-DOX2) made by modular chemo-enzymatic processes using Candida antarctica lipase B (CALB) as a biocatalyst. Unique features are the use of monodisperse PEG (dPEG) and the synthesis of thiol-functionalized folic acid yielding exclusive γ-conjugation of folic acid (FA) to dPEG. The polymer-based drug conjugate is built up by a series of transesterification and Michael addition reactions all catalyzed be CALB. In comparison with other methods in the literature, the modular approach with enzyme catalysis leads to selectivity, full conversion and high yield, and no transition metal catalyst residues. The intermediate product with four acrylate groups is an excellent platform for Michael-addition-type reactions for a wide variety of biologically active molecules. The chemical structures were confirmed by nuclear magnetic resonance spectroscopy (NMR). Flow cytometry analysis showed that, at 10 µM concentration, both free DOX and FA2-dPEG-DOX2 were taken up by 99.9% of triple-negative breast cancer cells in 2 h. Fluorescence was detected for 5 days after injecting compound IV into mice. Preliminary results showed that intra-tumoral injection seemed to delay tumor growth more than intravenous delivery.

Folate-Targeted Monodisperse PEG-Based Conjugates Made by Chemo-Enzymatic Methods for Cancer Diagnosis and Treatment.

This paper focuses on preliminary in vitro and in vivo testing of new bivalent folate-targeted PEGylated doxorubicin (DOX) made by modular chemo-enzymatic processes (FA2-dPEG-DOX2). A unique feature is the use of monodisperse PEG (dPEG). The modular approach with enzyme catalysis ensures exclusive γ-conjugation of folic acid, full conversion and selectivity, and no metal catalyst residues. Flow cytometry analysis showed that at 10 µM concentration, both free DOX and FA2-dPEG-DOX2 would be taken up by 99.9% of triple-negative breast cancer cells in 2 h. Intratumoral injection to mice seemed to delay tumor growth more than intravenous delivery. The mouse health status, food, water consumption, and behavior remained unchanged during the observation.

Polyisobutylene-New Opportunities for Medical Applications.

This paper presents the results of the first part of testing a novel electrospun fiber mat based on a unique macromolecule: polyisobutylene (PIB). A PIB-based compound containing zinc oxide (ZnO) was electrospun into self-supporting mats of 203.75 and 295.5 g/m2 that were investigated using a variety of techniques. The results show that the hydrophobic mats are not cytotoxic, resist fibroblast cell adhesion and biofilm formation and are comfortable and easy to breathe through for use as a mask. The mats show great promise for personal protective equipment and other applications.

Poly(amino acid) based fibrous membranes with tuneable in vivo biodegradation.

In this work two types of biodegradable polysuccinimide-based, electrospun fibrous membranes are presented. One contains disulfide bonds exhibiting a shorter (3 days) in vivo biodegradation time, while the other one has alkyl crosslinks and a longer biodegradation time (more than 7 days). According to the mechanical measurements, the tensile strength of the membranes is comparable to those of soft the connective tissues and visceral tissues. Furthermore, the suture retention test suggests, that the membranes would withstand surgical handling and in vivo fixation. The in vivo biocompatibility study demonstrates how membranes undergo in vivo hydrolysis and by the 3rd day they become poly(aspartic acid) fibrous membranes, which can be then enzymatically degraded. After one week, the disulfide crosslinked membranes almost completely degrade, while the alkyl-chain crosslinked ones mildly lose their integrity as the surrounding tissue invades them. Histopathology revealed mild acute inflammation, which diminished to a minimal level after seven days.

Investigation of the Cytotoxicity of Electrospun Polysuccinimide-Based Fiber Mats.

This study investigated cell viability in the presence of allylamine-modified and plasma-treated electrospun polysuccinimide fiber mats (PSI-AAmp). Low pressure non-equilibrium plasma was used for crosslinking the PSI-AAm. Comparison of FTIR and XPS analyses demonstrated that crosslinking occurred on the surface of the samples. Cell viability was investigated using the MG-63 osteosarcoma cell line and WST-1 viability reagent. Since PSI hydrolyzes to poly(aspartic acid) (PASP), PASP was used in addition to the regular controls (cells only). Phase contrast showed normal morphology in all cases at 24 h; however, in the presence of PSI-AAmp at 72 h, some rounded, dead cells could also be seen, and proliferation was inhibited. Since proliferation in the presence of PASP alone was not inhibited, the cause of inhibition was not the final product of the hydrolysis. Further investigations will be carried out to pinpoint the cause.