Green synthesis of silver nanoparticles and biopolymer nanocomposites: a comparative study on physico-chemical, antimicrobial and anticancer activity

The current report was intended towards comparative study of green-synthesized biogenic Rhubarb silver nanoparticles (RS-AgNPs) and chitosan crosslinked silver nanocomposites (CSHD-AgNCs). The physico-chemical characterization was done by UV-visible, FTIR, scanning electron microscopy (SUM), transmission electron microscopy (TEM), TGA, XRD and zeta potential(zeta). The analysis and spectroscopic characterization was done by SEM and TEM and their results reveal that the nanoparticles are spherical in shape, with average size ranges from 5 to 50 nm, and was gathered by face centered cubic (FCC) structure throughout the polymer matrix and stable without any protecting or capping reagents over 450 days. The antimicrobial property of RS-AgNPs and CSHD-AgNCs (zeta = +29.6 and +32.8 mV) was evaluated against E. coli and S. aureus and showed an effective inhibitory property. The RS-AgNPs and CSHD-AgNCs were assessed for their anticancer activity against HeLa cell line by MTT method, and it reveals a dose response activity, time and cell line-dependent cytotoxicity. Based on the results obtained, the RS-AgNPs exhibited higher toxicity over CSHD-AgNCs after 24 h incubation of HeLa cells with different concentrations and is negligible for the aqueous Rhubarb extract. It was concluded that the changes in anticancer activity towards HeLa cells due to biological activity of silver nanoparticles depend on their method of biosynthesis and their physico-chemical nature.Ministry of Education, Youth and Sports of the Czech Republic-NPU Program I [LO1504]; Slovak Grant Agency VEGA [2/0124/18

Chitosan–silver nanocomposites: New functional biomaterial for health-care applications

Chitosan–silver nanocomposites (CS-HDA-AgNCs) was prepared using chitosan, biogenic silver nanocomposites, and crosslinker, hexamethylene 1,6-di(amino carboxysulfonate) (HDA). The film is flexible and transparent. Its physical, mechanical, thermal, hydrophilicity, and swelling properties were improved by HDA (2.5%). The antimicrobial activity of CS-HDA-AgNCs were not displayed any remarkable zone of inhibition but showed toxic effect in the presence of normal 3T3 fibroblasts and cancer HeLa cells. It decreases to ca. 5–7% for both cell lines. In conclusion, it can be mentioned that the CS-HDA-AgNCs, a kind of new functional biomaterial, could be useful for health-care applications. © 2018 Taylor & Francis.Ministry of Education, Youth and Sports of the Czech Republic - NPU Program I [LO1504]; Slovak Grant Agency VEGA [2/0156/15

Cytotoxicity of 2-oxazines and poly(2-oxazine)s in mouse fibroblast

Poly(2-oxazoline)s are a polymer family that has received much attention in the last decade as biomaterials. In contrast, poly(2-oxazine)s, which can be viewed as their higher backbone homologue, have received much less attention. A first step towards the assessment as potential biomaterials is the evaluation of the cytotoxicity of the polymers. Therefore, a small selection of water soluble poly(2-oxazine)s are evaluated with respect to their cytotoxicity against 3T3 mouse fibroblasts. The polymers were tested at concentrations of up to 100 g/L for 24h. In addition, we studied the cytotoxicity of the monomers, namely 2-methyl-2-oxazine, 2-ethyl-2-oxazine and 2-propyl-2-oxazine in the same cell line. We found that neither monomers nor polymers exhibit a pronounced cytotoxicity. None of the monomers lead to any discernable effect on the cell viability in concentrations of up to 1 g/L with IC50 values ranging from 4 g/L to 20 g/L. Not surprisingly, the polymers poly(2-methyl-2-oxazine) and poly(2-ethyl-2-oxazine) exhibit even lower cytotoxicity with IC50 values ranging from 20 to 70 g/L. These preliminary but positive evaluation of the cytotoxicity of poly(2-methyl-2-oxazine) and poly(2-ethyl-2-oxazine) warrants further investigations on their use as biomaterials

Carbonyl iron coated with a sulfobetaine moiety as a biocompatible system and the magnetorheological performance of its silicone oil suspensions

In this study, surface modification of carbonyl iron (CI) particles with sulfobetaine moieties (SBE) was performed by the silanization of activated CI to form stable CI-SBE particles. The modification led to a significant improvement of the thermo-oxidation stability and a negligible suppression of the magnetization of the particles, as revealed by thermogravimetric analysis and vibrating sample magnetometry, respectively. The effect of a magnetic field and temperature on the magnetorheological performance of particle suspensions was investigated using a rotational rheometer in order to clarify the suitability of these systems for the local embolization of blood veins. The suspension based on CI-SBE exhibited a pseudoplastic behaviour and a tunable yield stress in a range from 0.3-4 kPa at the normal human body temperature. Moreover, cell viability for fibroblasts and macrophages was examined via MTT assay, which revealed their suitability for the intended applications for the local embolization of blood veins. © The Royal Society of Chemistry 2016.NPRP from the Qatar National Research Fund (a member of Qatar Foundation) [NPRP-6-381-1-078]; Ministry of Education, Youth and Sports of the Czech Republic - Program NPU I [LO1504]; Internal Grant Agency of the Czech Republic [IGA/CPS/2016/008]; Slovak Grant Agency, VEGA [2/0156/15

In vitro study of partially hydrolyzed poly(2-ethyl-2-oxazolines) as materials for biomedical applications

Polymers based on 2-oxazoline, such as poly(2-ethyl-2-oxazolines) (PETOx), are considered to be a type of 'pseudopeptide' with the ability to form novel biomaterials. The hydrolysis of PETOx was carried out to evaluate its use in biomedical applications. In the present work, PETOx samples with a range of molar masses were prepared by living cationic polymerization. Hydrolysis was carried out at time intervals ranging from 15 to 180 min to prepare copolymers with different amounts of ethylene imine units. H-1 NMR spectroscopy was used to identify the structure of the hydrolyzed polymers. The dependence of in vitro cell viability on the degree of hydrolysis was determined using three different model cell lines, namely, mouse embryonic 3T3 fibroblasts, pancreatic beta TC3 cells, and mouse lymphoid macrophages P388.D1. It was demonstrated that increasing the degree of hydrolysis decreased cell viability for all cell types. Fibroblast cells displayed the highest tolerance; additionally, the effect of polymer size showed no observable significance. Macrophage cells, immune system representatives, displayed the highest sensitivity to contact with hydrolyzed PETOx. The effect of polymer hydrolysis, polymer concentration and the incubation time on cell viability was experimentally observed. Confocal laser-scanning microscopy provided evidence of cellular uptake of pyrene-labeled (co)polymers.Slovak Grant Agency, VEGA [2/0151/12, 2/0163/12]; Operational Program Education for Competitiveness; European Social Fund (ESF); national budget of the Czech Republic [CZ.1.07/2.3.00/20.0104]; Ministry of Education, Youth and Sports of the Czech Republic [ME-LH14050

Tulips: A Renewable Source of Monomer for Superabsorbent Hydrogels

A new class of superabsorbent hydrogels was synthesized by copolymerization of acrylamide with sodium 4-hydroxy-methylenebutaimate (SHMB). SHMB is obtained by saponification of a-methylene-y-butyrolactone (MBL) which is a renewable monomer from tulips. Radical polymerization of SHMB was studied for the first tin*. The extent of side products through the ring closure depended on the pH used during the polymerization. Reactivity ratios for copolymerization of SHMB with acrylamide were estimated. Prepared hydrogels with various composition were investigated for their swelling, mechanical and thermal properties, and morphology as well as cytotoxicity. The achieved degree of swelling of the hydrogels was up to 82 000% and significantly exceeds the capacity of classical superabsorbent hydrogels made of acrylamide and salts of acrylic acid. The degree of swelling as well as mechanical and thermal properties of the hydrogels could be tuned by SHMB content.European Regional Development Fund through project POLYFRIEND [HUSK 1101/1.2.1/0209]; VEGA grant agency [2/0167/14]; Ministry of Education, Youth and Sports of the Czech Republic-Program NPU I [LO1504

Antibacterial activity of 3D printed thermoplastic elastomers doped with carbon quantum dots for biomedical applications

3D printing provides a lot of varieties for the manufacturing of personalized biomedical devices. Incorporation of the nanoparticles with potential antibacterial activity to the printed materials is another added value. One example of such nanoparticles are hydrophobic carbon quantum dots (hCQDs), which are zero-dimensional redox-active materials with high chemical stability and low production costs. They produce singlet oxygen only when activated by a specific wavelength of visible blue light which allows for controlled antibacterial action and minimizes the chances of bacterial resistance emergence. We prepared and characterized polymer composites based on thermoplastic elastomers (TPE) doped with hCQDs (TPE/hCQDs). The composites were 3D printed using fused deposition modeling method. In the first set of samples, a filament of pure TPE was immersed in a solution of hCQDs (0.5 mg/mL), then 3D printed, and compared with unmodified TPE filament. The mechanical properties, swelling behavior, hardness, and thermal stability of TPE/hCQDs were compared with the pure TPE printed samples. The production of singlet oxygen was confirmed by the electron paramagnetic resonance method. The antibacterial activity of the samples was tested according to ISO 22196 against Staphylococcus aureus and Escherichia coli after one hour of exposure to blue light, which completely inhibited bacterial growth. Besides, the cytotoxicity of samples was evaluated by MTT assay, and no significant effect of the materials on cell viability was observed. 3D printed materials with antibacterial activity represent a perspective for the future, especially in the field of personalized medicine, as well as in products for other industries

Sulfobetaines meet carboxybetaines: Modulation of thermo- and ion-responsivity, water structure, mechanical properties, and cell adhesion

A procedure for the preparation of copolymers bearing sulfobetaine and carboxybetaine methacrylic-based monomers by free-radical polymerization is described and discussed. A combination of monomers affects the upper critical solution temperature (UCST) in water and in the presence of a simple NaCl electrolyte while retaining the zwitterionic character. In addition, hydrogel samples were prepared and showed tunable water structure and mechanical properties. The total nonfreezable water content decreases with the amount of carboxybetaine segment in the hydrogel feed and the compression moduli were in a range of 0.7-1.6 MPa. Responses to external conditions such as temperature and ion strength were investigated and a potential application such as modulated thermal detection is proposed. The presence of the carboxylate group in the carboxybetaine segment enables a small fluorescence probe and peptide bearing RDG motif to be attached to polymer and hydrogel samples, respectively. The hydrogel samples functionalized with the RGD motif exhibit controlled cell adhesion. Such synthetic strategy based on combination of different zwitterionic segments offers a simple pathway for the development of zwitterionic materials with programmable properties. © 2018 American Chemical Society.Qatar University Grant [QUUG-CAM 2017-1]; VEGA Scientific Grant Agency [2/0158/17