Molecular level structure of biodegradable poly(delta-valerolactone) obtained in the presence of boric acid

In this study, low molecular weight poly(δ-valerolactone) (PVL) was synthesized through bulk-ring openings polymerization of δ-valerolactone with boric acid (B(OH)₃) as a catalyst and benzyl alcohol (BnOH) as an initiator. The resulting homopolymer was characterized with the aid of nuclear magnetic resonance (NMR) and mass spectrometry (MS) techniques to gain further understanding of its molecular structure. The electrospray ionization mass spectrometry (ESI-MS) spectra of poly(δ-valerolactone) showed the presence of two types of homopolyester chains-one terminated by benzyl ester and hydroxyl end groups and one with carboxyl and hydroxyl end groups. Additionally, a small amount of cyclic PVL oligomers was identified. To confirm the structure of PVL oligomers obtained, fragmentation of sodium adducts of individual polyester molecules terminated by various end groups was explored in ESI-MSn by using collision induced dissociation (CID) techniques. The ESI-MSn analyses were conducted both in positive- and negative ion mode. The comparison of the fragmentation spectra obtained with proposed respective theoretical fragmentation pathways allowed the structure of the obtained oligomers to be established at the molecular level. Additionally, using matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS), it was proven that regardless of the degree of oligomerization, the resulting PVL samples were a mixture of two types of linear PVL oligomers differing in end groups and containing just a small amount of cyclic oligomers that tended to be not visible at higher molar masses

Environmental cleaning mission Bioconversion of oxidatively fragmented polyethylene plastic waste to value-added copolyesters

The innovative recycling method, we are proposing, relies upon the controlled oxidative fragmentation of waste LDPE plastic to the inexpensive substrates for future sustainable production of PHAs with the aid of Cupriavidus necator. LDPE oxidized fragments (PE-F) were obtained from the re-engineering LDPE film by means of pro-oxidant/pro-degradant additives, followed by treatment under natural UV light. Cupriavidus necator was grown in either tryptone soya broth (TSB) or basal salt medium (BSM) supplemented with PE-F for 48 h. PHA production was higher in TSB supplemented with PE-F (29%) than in TSB alone (only 0.6%). No PHA was detected in either BSM alone or BSM supplemented with PE-F. The recovered PHA was characterized using GPC, NMR, and electrospray ionization tandem mass spectrometry (ESI-MS/MS). These analytical tools applied confirmed that the resulting PHA was a terpolymer having an average molar mass of 624 kg/mol and consisting of 3-hydroxybutyrate (HB), 3-hydroxyvalerates (HV) and 3-hydroxyhexanoate (HH) co-monomer units randomly distributed along the chain backbone

Mass spectrometry reveals molecular structure of polyhydroxyalkanoates attained by bioconversion of oxidized polypropylene waste fragments

This study investigated the molecular structure of the polyhydroxyalkanoate (PHA) produced via a microbiological shake flask experiment utilizing oxidized polypropylene (PP) waste as an additional carbon source. The bacterial strain Cupriavidus necator H16 was selected as it is non-pathogenic, genetically stable, robust, and one of the best known producers of PHA. Making use of PHA oligomers, formed by controlled moderate-temperature degradation induced by carboxylate moieties, by examination of both the parent and fragmentation ions, the ESI-MS/MS analysis revealed the 3-hydroxybutyrate and randomly distributed 3-hydroxyvalerate as well as 3-hydroxyhexanoate repeat units. Thus, the bioconversion of PP solid waste to a value-added product such as PHA tert-polymer was demonstrated.This research was funded by the Research Investment Fund, University of Wolverhampton, Faculty of Science and Engineering, UK. This work was also partially supported the European Regional Development Fund Project EnTRESS No 01R16P00718 and the PELARGODONT Project UM0-2016/22/Z/STS/00692 financed under the M-ERA.NET 2 Program of Horizon 2020.Published onlin

Surface modification of PHBV fibrous scaffold via lithium borohydride reduction

In this study, lithium borohydride (LiBH(4)) reduction was used to modify the surface chemistry of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) fibers. Although the most common reaction employed in the surface treatment of polyester materials is hydrolysis, it is not suitable for fiber modification of bacterial polyesters, which are highly resistant to this type of reaction. The use of LiBH(4) allowed the formation of surface hydroxyl groups under very mild conditions, which was crucial for maintaining the fibers’ integrity. The presence of these groups resulted in a noticeable improvement in the surface hydrophilicity of PHBV, as revealed by contact angle measurements. After the treatment with a LiBH(4) solution, the electrospun PHBV fibrous mat had a significantly greater number of viable osteoblast-like cells (SaOS-2 cell line) than the untreated mat. Moreover, the results of the cell proliferation measurements correlated well with the observed cell morphology. The most flattened SaOS-2 cells were found on the surface that supported the best cell attachment. Most importantly, the results of our study indicated that the degree of surface modification could be controlled by changing the degradation time and concentration of the borohydride solution. This was of great importance since it allowed optimization of the surface properties to achieve the highest cell-proliferation capacity

Polymeric Carriers for Delivery Systems in the Treatment of Chronic Periodontal Disease

Periodontitis (PD) is a chronic inflammatory disease of periodontal tissues caused by pathogenic microorganisms and characterized by disruption of the tooth-supporting structures. Conventional drug administration pathways in periodontal disease treatment have many drawbacks such as poor biodistribution, low selectivity of the therapeutic effect, burst release of the drug, and damage to healthy cells. To overcome this limitation, controlled drug delivery systems have been developed as a potential method to address oral infectious disease ailments. The use of drug delivery devices proves to be an excellent auxiliary method in improving the quality and effectiveness in periodontitis treatment, which includes inaccessible periodontal pockets. This review explores the current state of knowledge regarding the applications of various polymer-based delivery systems such as hydrogels, liposomes, micro-, and nanoparticles in the treatment of chronic periodontal disease. Furthermore, to present a more comprehensive understanding of the difficulties concerning the treatment of PD, a brief description of the mechanism and development of the disease is outlined

A Preliminary Study of FTIR Spectroscopy as a Potential Non-Invasive Screening Tool for Pediatric Precursor B Lymphoblastic Leukemia

Early detection of the most common pediatric neoplasm, B-cell precursor lymphoblastic leukemia (BCP-ALL), is challenging and requires invasive bone marrow biopsies. The purpose of this study was to establish new biomarkers for early screening to detect pediatric leukemia. In this small cohort study, Fourier transform infrared (FTIR) spectra were obtained from blood sera of 10 patients with BCP-ALL and were compared with the control samples from 10 children with some conditions other than neoplasm. Using various analytical approaches, including a new physical model, some significant differences were observable. The most important include: the different peak area ratio 2965/1645 cm−1 (p = 0.002); the lower average percentage of both β-sheet and β-turn protein structures in the sera of BCP-ALL patients (p = 0.03); an AdaBoost-based predictive model for classifying healthy vs. BCP-ALL patients with 85% accuracy; and the phase shift of the first derivative in the spectral range 1050–1042 cm−1 correlating with white blood cell (WBC) and blast cell count in BCP-ALL patients contrary to the samples obtained from healthy controls. Although verification in larger groups of patients will be necessary, these promising results suggest that FTIR spectroscopy may have future potential for the early screening of BCP-ALL

Hounsfield units and fractal dimension (test HUFRA) for determining PET positive/negative lymph nodes in pediatric Hodgkin's lymphoma patients.

OBJECTIVES:We had developed a method that can help detect and identify lymph nodes affected by the neoplastic process. Our group evaluated the fractal dimension (FD) and X-ray attenuation (XRA) of lymph nodes in HL and compared to their metabolic activity as measured by 18F-FDG-PET examination. METHODS:The training set included 72 lymph nodes from 31 consecutive patients, and the tested set of 71 lymph nodes from next 19 patients. The measurement of FD of each lymph node was performed before the start of therapy using original software. X-ray attenuation (XRA) expressed in HU (Hounsfield Units) from CT scans was compared with the metabolic activity of the lymphatic nodes, measured by 18F-FDG-PET examination. RESULTS:Significant differences were observed between XRAmax and FDmax values in assessing the PET(+) and PET(-) nodes. All nodes were scored from 0 to 2. The HUFRA test properly qualified 95% with a score of 2 and 0 points as PET(+) or PET(-). CONCLUSION:The HUFRA test can differentiate about 70-80% of lymph nodes as PET(+) or PET(-) based solely on the CT examination. It can be useful in patients who were not subjected to 18FFDG-PET/CT examination before the treatment, or who had an unreliable result of 18F-FDG-PET/CT with further research requirements

Bioresorbable electrospun mats of poly(D, L)-lactide / poly[(R, S)-3-hydroxybutyrate] blends for potential use in the treatment of difficult-to-heal skin wounds

This is an accepted manuscript of an article published by Elsevier in European Polymer Journal, available online: https://doi.org/10.1016/j.eurpolymj.2021.110334 The accepted version of the publication may differ from the final published version.This study describes the preparation, physicochemical characterization and the biological studies of the polymeric delivery systems of proanthocyanidins (PCAN) extracted from Pelargonium sidoides for the potential use as wound dressings. In this study 20 wt% PCAN demonstrated good antimicrobial activity against Staphylococcus aures, a gram-positive wound pathogen. Poly(D,L-lactide) and atactic poly[(R,S)-3-hydroxybutyrate] biopolymers were used to construct biodegradable dressings. A series of polylactide/poly[(R,S)-3-hydroxybutyrate] (P(D,L)LA/a-PHB) blends, containing 10, 20, and 30 wt% of a-PHB were prepared and characterized by means of NMR, GPC, FT-IR, and DSC. Based on the findings, the P(D,L)LA/a-PHB [70/30 wt%] blend with the best thermomechanical properties (Tg value equal 37 °C) was chosen for the preparation of two kinds of electrospun mats, both with and without PCAN. About 50 % of PCAN was released from the tested mats during the first 10-12 days of incubation. The electrospun mats with elastic properties, ensuring compatibility with the wound topology, were obtained. The studies of hydrolytic degradation of the constructed mats allowed us to gain complete knowledge of their hydrolysis process, and examine the PCAN release profile as well as identify and characterize the molecular structure of the degradation products of the developed delivery system. Furthermore, preliminary cytotoxicity MTT tests (in vitro) results support the potential application of PCAN-loaded (P(D,L)LA/a-PHB) electrospun mats in wound dressings.Published versio