Razvoj postupaka polimerizacije L-laktida

To determine the appropriate conditions for the polymerization of (Llactide), to obtain poly(L-lactide) a few different methods were applied: in closed vials under vacuum, in the reactor under high pressure, in the microwave reactor and in a reactor with solvent using the initiator. The molecular masses of prepared samples were determined using GPC method. It was assessed that by microwave synthesis method for the polymerization time less than 30 minutes the resulting polymer have the highest molecular mass, 178.000 g mol-1. It was estimated that the samples synthesized with trifluoromethanesulfonic acid as initiator have the best thermal stability.Za određivanje optimalnih uslova za polimerizacije (L- laktida), za dobijanje poli (L-laktida) (PLLA) primenjene su različite metode polimerizacije: u zatvorenim posudama pod vakumom, u reaktoru pod visokim pritiskom, mikrotalasnom polju i u rastvoru sa inicijatorom. Za određivanje molekulskih masa korišćena je GPC metoda. Ustanovljeno je da je mikrotalasna sinteza postupak sa najkraćim vremenom polimerizacije (manjim od 30 minuta) pri čemu je nastaje polimer koji ima najveću molarnu masu 178.000 g mol-1. Najbolju termičku stabilnost imao je uzorak PLLA sintetisan sa trifluorometansulfonskom kiselinom kao inicijatorom

Postupci recikliranja otpadnih gumenih proizvoda za dobijanje elastomernih hibridnih materijala

Preparation of elastomeric materials based on recycled elastomer powder is huge ecological tasc.The goal of this applicative work was to synthesize hybrid materials based on sulfur cured ternary blends of polyisoprene rubber, polybutadiene rubber, and styrene-butadiene rubber filled with carbon black nano-particles and waste rubber powder (REP). Properties and ageing of prepared materials were assessed as a function of REP content. The stress-strain experiments were measured before and after the aging. It was assessed that the tensile strength of obtained materials decreased as the content of recycled rubber increased.Dobijanje sirovina na osnovu otpadnih gumenih proizvoda predstavlja voma značajan ekološki zadatak. Cilj ovog aplikativnog rada je bio da se sintetišu hibridni elastomerni materijali na osnovu sumporom umrežene ter-blende prirodnog kaučuka, polibutadienskog kaučuka i stiren-butadienskog kaučuka, aktivnog nano-punila i mlevene otpadne gume (REP). Određena su mehanička svojstva dobijenih materijala pre i posle starenja u funkciji sadržaja recikliranog gumenog praha. Ustanovljeno je da se prekidna čvrstoća sintetisanih hibridnih materijala smanjuje sa porastom sadržaja recikliranog elastomernog praha

Emerging glyco-based strategies to steer immune responses

Glycan structures are common posttranslational modifications of proteins, which serve multiple important structural roles (for instance in protein folding), but also are crucial participants in cell-cell communications and in the regulation of immune responses. Through the interaction with glycan-binding receptors, glycans are able to affect the activation status of antigen-presenting cells, leading either to induction of pro-inflammatory responses or to suppression of immunity and instigation of immune tolerance. This unique feature of glycans has attracted the interest and spurred collaborations of glyco-chemists and glyco-immunologists to develop glycan-based tools as potential therapeutic approaches in the fight against diseases such as cancer and autoimmune conditions. In this review, we highlight emerging advances in this field, and in particular, we discuss on how glycan-modified conjugates or glycoengineered cells can be employed as targeting devices to direct tumor antigens to lectin receptors on antigen-presenting cells, like dendritic cells. In addition, we address how glycan-based nanoparticles can act as delivery platforms to enhance immune responses. Finally, we discuss some of the latest developments in glycan-based therapies, including chimeric antigen receptor (CAR)-T cells to achieve targeting of tumor-associated glycan-specific epitopes, as well as the use of glycan moieties to suppress ongoing immune responses, especially in the context of autoimmunity

Recent advances on smart glycoconjugate vaccines in infections and cancer

Vaccination is one of the greatest achievements in biomedical research preventing death and morbidity in many infectious diseases through the induction of pathogen-specific humoral and cellular immune responses. Currently, no effective vaccines are available for pathogens with a highly variable antigenic load, such as the human immunodeficiency virus or to induce cellular T-cell immunity in the fight against cancer. The recent SARS-CoV-2 outbreak has reinforced the relevance of designing smart therapeutic vaccine modalities to ensure public health. Indeed, academic and private companies have ongoing joint efforts to develop novel vaccine prototypes for this virus. Many pathogens are covered by a dense glycan-coat, which form an attractive target for vaccine development. Moreover, many tumor types are characterized by altered glycosylation profiles that are known as “tumor-associated carbohydrate antigens”. Unfortunately, glycans do not provoke a vigorous immune response and generally serve as T-cell-independent antigens, not eliciting protective immunoglobulin G responses nor inducing immunological memory. A close and continuous crosstalk between glycochemists and glycoimmunologists is essential for the successful development of efficient immune modulators. It is clear that this is a key point for the discovery of novel approaches, which could significantly improve our understanding of the immune system. In this review, we discuss the latest advancements in development of vaccines against glycan epitopes to gain selective immune responses and to provide an overview on the role of different immunogenic constructs in improving glycovaccine efficacy

The influence of shaped TiO2 nanofillers on thermal properties of polyvinyl alcohol

Poly(vinyl alcohol)-based nanocomposites consisting of shaped TiO2 nanocrystals (nanoparticles, nanotubes or nanorods) were synthesized by direct blending of the polymer and a solution of titania nanocrystals or powder. In order to elucidate the influence of the shape of the titania nanocrystals on thermal stability of the polymer matrix and particles interaction with poly(vinyl alcohol) (PVA) chains, structural and thermal characterizations of PVA/TiO2 nanocomposites were performed. Faceted nanoparticles increased the thermal stability of the PVA matrix. Titania nanotubes and nanorods did not show any stabilizing effect on the polymer matrix under an argon atmosphere. The thermo-oxidative degradation temperature of PVA increased with addition of faceted TiO2 nanoparticles. The thermo-oxidative stability of the PVA matrix was affected more by the presence of titania nanotubes and nanorods in comparison with its thermal stability under an inert atmosphere. The degree crystallinity (X-c=32 %) of the PVA matrix slightly decreased in the presence of the faceted TiO2 nanoparticles in nanocomposite samples

Covalent modification of single wall carbon nanotubes upon gamma irradiation in aqueous media

Single wall carbon nanotubes (SWCNTs) were exposed to gamma radiation, absorbing the doses of 25, 50 and 100 kGy in aqueous environment. After the irradiation treatment, the changes in the structure were studied using Fourier transform Infrared and Raman spectroscopy, thermogravimetric analysis and atomic force microscopy. Fourier Transform Infrared Spectroscopy has shown that the irradiation of SWCNTs in aqueous environment leads to covalent functionalization of SWCNTs. The irradiation of water leads to its radiolysis and the formation of free radical species of different types. These species react with nanotube sidewalls and in such way carboxylic and hydroxylic groups are covalently bonded to the sidewalls of SWCNTs. Thermogravimetric analysis was used to estimate the total amount of covalently bonded groups. The highest ratio of covalently bonded groups appears in nanotubes irradiated with the 100 kGy dose. Raman spectroscopy proved that the increase in irradiation doses leads to an increase of structural disorder of SWCNTs, presumably in the form of defects in carbon nanotube walls. Examination of I-D to I-G ratio shows a three times larger degree of structural disorder after the irradiation treatment with 100 kGy. The analysis of carbon nanotube Raman spectra RBM bands determined the presence of both semiconducting and metallic carbon nanotubes after gamma irradiation treatment. These measurements prove that gamma irradiation treatments have a nonselective effect regarding different chirality and therefore conductance of nanotubes. Atomic force microscopy shows a significant carbon nanotube shortening as the effect of gamma radiation treatment. Nanotubes with length between 500 nm and 1 mu m are predominant

Synthesis, structural characterisation and antibacterial activity of Ag+-doped fluorapatite nanomaterials prepared by neutralization method

Silver doped fluorapatite nanopowders were synthesised by neutralization method, which consists of dissolving Ag2O in solution of HF and H3PO4 and addition to suspension of Ca(OH)(2). The powder XRD, SEM and FTIR studies indicated the formation of a fluorapatite nanomaterials with average length of the particles is about 80 nm and a width of about 15 nm. The FUR studies show that carbonate content in samples is very small and carbonte ions substitute both phosphate and hydroxyl groups in the crystal structure of samples, forming AB-type fluorapatite. Antibacterial studies have demonstrated that all Ag+-doped fluorapatite samples exhibit bactericidal effect against pathogens: Staphylococcus aureus, Micrococcus luteus and Kllebsiela pneumoniae. Antibacterial activity increased with the increase of Ag+ in the samples. The atomic force microscopy studies revealed extensive damage to the bacterial cell envelops in the presence of AW-doped fluorapatite particles which may lead to their death. The synthesized Ag+-doped fluorapatite nanomaterials are promising as antibacterial biomaterials in orthopedics and dentistry. (C) 2015 Elsevier B.V. All rights reserved

Hydrothermal carbonization of spent mushroom substrate: Physicochemical characterization, combustion behavior, kinetic and thermodynamic study

Hydrothermal carbonization (HTC) was employed for the conversion of the spent mushroom substrate (SMS) into a carbonaceous hydrochar. The effect of operating temperature (180, 200, 220, 240, and 260 ?C) on the physicochemical, structural, and combustion properties of the obtained hydrochars was analyzed. The HTC treatment caused the increase of the higher heating value (HHV) and the lower heating value (LHV) of hydrochars for 58 % and 65 % in comparison with SMS, respectively. Analysis of morphology and functional groups showed the formation of microspheres and cracks on the hydrochar surface, which are predominantly dominated by aromatic and oxygen-rich functional groups. Thermal and kinetics analysis showed that HTC treatment improves the combustion behavior of the obtained solids. Combustion kinetic parameters of SMS and hydrochars were determined by the methods of Kissenger-Akahira-Sunose (KAS) and Flynn-Wall-Ozawa (FWO). The thermodynamic parameters and pre-exponential factors reveal a complex mechanism of SMS and hydrochars decomposition process

Recent advances on smart glycoconjugate vaccines in infections and cancer

Vaccination is one of the greatest achievements in biomedical research preventing death and morbidity in many infectious diseases through the induction of pathogen-specific humoral and cellular immune responses. Currently, no effective vaccines are available for pathogens with a highly variable antigenic load, such as the human immunodeficiency virus or to induce cellular T-cell immunity in the fight against cancer. The recent SARS-CoV-2 outbreak has reinforced the relevance of designing smart therapeutic vaccine modalities to ensure public health. Indeed, academic and private companies have ongoing joint efforts to develop novel vaccine prototypes for this virus. Many pathogens are covered by a dense glycan-coat, which form an attractive target for vaccine development. Moreover, many tumor types are characterized by altered glycosylation profiles that are known as "tumor-associated carbohydrate antigens". Unfortunately, glycans do not provoke a vigorous immune response and generally serve as T-cell-independent antigens, not eliciting protective immunoglobulin G responses nor inducing immunological memory. A close and continuous crosstalk between glycochemists and glycoimmunologists is essential for the successful development of efficient immune modulators. It is clear that this is a key point for the discovery of novel approaches, which could significantly improve our understanding of the immune system. In this review, we discuss the latest advancements in development of vaccines against glycan epitopes to gain selective immune responses and to provide an overview on the role of different immunogenic constructs in improving glycovaccine efficacy

Emerging glyco‐based strategies to steer immune responses

Glycan structures are common posttranslational modifications of proteins, which serve multiple important structural roles (for instance in protein folding), but also are crucial participants in cell-cell communications and in the regulation of immune responses. Through the interaction with glycan-binding receptors, glycans are able to affect the activation status of antigen-presenting cells, leading either to induction of pro-inflammatory responses or to suppression of immunity and instigation of immune tolerance. This unique feature of glycans has attracted the interest and spurred collaborations of glyco-chemists and glyco-immunologists to develop glycan-based tools as potential therapeutic approaches in the fight against diseases such as cancer and autoimmune conditions. In this review, we highlight emerging advances in this field, and in particular, we discuss on how glycan-modified conjugates or glycoengineered cells can be employed as targeting devices to direct tumor antigens to lectin receptors on antigen-presenting cells, like dendritic cells. In addition, we address how glycan-based nanoparticles can act as delivery platforms to enhance immune responses. Finally, we discuss some of the latest developments in glycan-based therapies, including chimeric antigen receptor (CAR)-T cells to achieve targeting of tumor-associated glycan-specific epitopes, as well as the use of glycan moieties to suppress ongoing immune responses, especially in the context of autoimmunity