Marcin Sobczak

Polymeric Systems of Antimicrobial Peptides—Strategies and Potential Applications

The past decade has seen growing interest in the investigation of peptides with antimicrobial activity (AMPs). One approach utilized in infection control is incorporation of antimicrobial agents conjugated with the polymers. This review presents the recent developments on polymeric AMP carriers and their potential applications in the biomedical and pharmaceutical fields.

Synthesis and Structural Analysis of Polyester Prodrugs of Norfloxacin

Two-, three- and four-arm, star-shaped poly(ε-caprolactone) and poly(D,L‑lactide) homopolymers, and copolymers of ε-caprolactone with D,L-lactide were synthesized via ring-opening polymerization of cyclic esters in the presence of glycerol, penthaerythritol and poly(ethylene glycol) as initiators and stannous octoate as a catalyst. Thus obtained oligomers were successfully used in the synthesis of novel macromolecular prodrugs of norfloxacin. The structures of the polymers and prodrugs were elucidated by means of MALDI-TOF MS, NMR and IR studies.

Nanocrystalline hydroxyapatite doped with selenium oxyanions: A new material for potential biomedical applications

Selenium-substituted hydroxyapatites containing selenate SeO4(2-) or selenite SeO3(2-) ions were synthesized using a wet precipitation method. The selenium content was determined by atomic absorbance spectrometry. The raw, unsintered powders were also characterized using powder X-ray diffraction, middle-range FT-IR spectroscopy and transmission electron microscopy with energy-dispersive X-ray spectroscopic microanalysis. The synthesized apatites were found to be pure and nanocrystalline with a crystal size similar to that in bone mineral. The incorporation of selenium oxyanions into the crystal lattice was confirmed. The toxicity of hydroxyapatites containing selenite or selenate ions was evaluated with a protozoan assay and bacterial luminescence test.

Polymerization of Cyclic Esters Initiated by Carnitine and Tin (II) Octoate

Low-molecular weight poly(ε-caprolactone), polylactides and copolymers of ε−caprolactone and lactides were obtained by the polymerization of cyclic esters in the presence of a carnitine/SnOct2 system. Their structures were proven by means of MALDI−TOF, IR and NMR studies. Effects of temperature, reaction time and carnitine dosage on the polymerization process were examined.

Enzymatic Polymerization of Cyclic Monomers in Ionic Liquids as a Prospective Synthesis Method for Polyesters Used in Drug Delivery Systems

Biodegradable or bioresorbable polymers are commonly used in various pharmaceutical fields (e.g., as drug delivery systems, therapeutic systems or macromolecular drug conjugates). Polyesters are an important class of polymers widely utilized in pharmacy due to their biodegradability and biocompatibility features. In recent years, there has been increased interest in enzyme-catalyzed ring-opening polymerization (e-ROP) of cyclic esters as an alternative method of preparation of biodegradable or bioresorbable polymers. Ionic liquids (ILs) have been presented as green solvents in enzymatic ring-opening polymerization. The activity, stability, selectivity of enzymes in ILs and the ability to catalyze polyester synthesis under these conditions are discussed. Overall, the review demonstrates that e-ROP of lactones or lactides could be an effective method for the synthesis of useful biomedical polymers.

Synthesis and characterization of polyester conjugates of ciprofloxacin.

Two-, three-, four and six-arm, star-shaped poly(epsilon-caprolactone) and polylactide homopolymers were synthesized via ring-opening polymerization of cyclic esters in the presence of glycerol, penthaerythritol, dipentaerythritol and poly(ethylene glycol) as initiators and stannous octoate as a catalyst. Thus obtained oligomers were successfully used in the synthesis of novel polyester conjugates of ciprofloxacin. The structures of the polymers and conjugates were determined by means of GPC, MALDI-TOF MS, NMR and IR studies. The in vitro release of ciprofloxacin from obtained conjugates was investigated.

NOTE: Polymerization of Cyclic Esters Using Aminoacid Initiators

The low-molecular weight poly(ϵ -caprolactone) and polylactide were obtained by the polymerization of cyclic esters in the presence of amino acid initiators. The polymer structures were elucidated by means of MALDI TOF, NMR and IR studies. Effects of temperature, reaction time and initiator dosage on the polymerization process were examined.

Synthesis and study of controlled release of ofloxacin from polyester conjugates

New polymeric conjugates were prepared coupling ofloxacin to two-, three-, four and six-arm, star-shaped poly(ɛ-caprolactone) and polylactide. The homopolymers were synthesized via ring-opening polymerization of ɛ-caprolactone, l-lactide and rac-lactide in the presence of glycerol, penthaerythritol, dipentaerythritol and poly(ethylene glycol) as initiators and stannous octoate as a catalyst. The conjugates were characterized by GPC, MALDI-TOF MS, NMR, IR and viscosity methods. Content of Sn has been investigated in polymers by electrothermal atomic absorption spectrometry. Toxicity of monomers, initiators and polymers were evaluated with bacterial luminescence test and two protozoan assays. The in vitro release of ofloxacin from obtained conjugates in pH 7 was investigated.

Polylactide Conjugates of Camptothecin with Different Drug Release Abilities

Camptothecin-polylactide conjugates (CMPT-PLA) were synthesized by covalent incorporation of CMPT into PLA of different microstructure, i.e., atactic PLA and atactic-block-isotactically enriched PLA (Pm = 0.79) via urethane bonds. The kinetic release of CPMT from CMPT-PLA conjugates, tested in vitro under different conditions, is possible in both cases and notably, strongly dependent on PLA microstructure. It shows that release properties of drug-PLA conjugates can be tailored by controlled design of the PLA microstructure, and allow in the case of CMPT-PLA conjugates for the development of highly controlled biodegradable CMPT systems—important delivery systems for anti-cancer agents.

A Solid-State NMR Study of Selenium Substitution into Nanocrystalline Hydroxyapatite

The substitution of selenium oxyanions in the hydroxyapatite structure was examined using multinuclear solid-state resonance spectroscopy (ssNMR). The study was supported by powder X-ray diffractometry (PXRD) and wavelength dispersion X-ray fluorescence (WD-XRF). Samples of pure hydroxyapatite (HA300) and selenate (HA300-1.2SeO4) or selenite (HA300-1.2SeO3) substituted hydroxyapatites were synthesized using the standard wet method and heated at 300 °C to remove loosely bonded water. PXRD data showed that all samples are single-phase, nanocrystalline hydroxyapatite. The incorporation of selenite and selenate ions affected the lattice constants. In selenium-containing samples the concentration of Se was very similar and amounted to 9.55% and 9.64%, for HA300-1.2SeO4 and HA300-1.2SeO3, respectively. PXRD and ssNMR data showed that the selenite doping significantly decreases the crystallite size and crystallinity degree. 31P and 1H NMR experiments demonstrated the developed surface hydrated layer in all samples, especially in HA300-1.2SeO3. 1H NMR studies showed the dehydroxylation of HA during the selenium oxyanions substitution and the existence of hydrogen bonding in structural hydroxyl group channels. 1H→77Se cross polarization NMR experiments indicated that selenites and selenates are located in the crystal lattice and on the crystal surface.