Recent Advances in Antibacterial Coatings to Combat Orthopedic Implant-Associated Infections.

Implant-associated infections (IAIs) represent a major health burden due to the complex structural features of biofilms and their inherent tolerance to antimicrobial agents and the immune system. Thus, the viable options to eradicate biofilms embedded on medical implants are surgical operations and long-term and repeated antibiotic courses. Recent years have witnessed a growing interest in the development of robust and reliable strategies for prevention and treatment of IAIs. In particular, it seems promising to develop materials with anti-biofouling and antibacterial properties for combating IAIs on implants. In this contribution, we exclusively focus on recent advances in the development of modified and functionalized implant surfaces for inhibiting bacterial attachment and eventually biofilm formation on orthopedic implants. Further, we highlight recent progress in the development of antibacterial coatings (including self-assembled nanocoatings) for preventing biofilm formation on orthopedic implants. Among the recently introduced approaches for development of efficient and durable antibacterial coatings, we focus on the use of safe and biocompatible materials with excellent antibacterial activities for local delivery of combinatorial antimicrobial agents for preventing and treating IAIs and overcoming antimicrobial resistance.

Investigation of Antibiofilm and Antibacterial Properties of Green Synthesized Silver Nanoparticles from Aqueous Extract of Rumex sp.

The decrease in the effectiveness of conventional drugs as a result of the growth of resistance to antibiotics has increased the need for innovative tools to control the infections. At this point, metallic nanoparticles, in particular silver nanoparticles, have appeared as a promising method. In the current study, the extract of Rumex sp. (Labada, dock) leaves was used as a reducing agent for the formation of silver nanoparticles. Unlike similar studies, in this study the synthesis conditions were optimized by changing the extract ratio and silver nitrate concentration. Morphological investigations of synthesized silver nanoparticles showed that spherical homogeneous particles at size under 100 nm had been produced. SEM/EDS and FTIR analyses showed that plant components are involved in the synthesis of nanoparticles. It was also determined that higher extract ratio reduced nanoparticle size. The antimicrobial effects of the synthesized nanoparticles against Gram-positive and Gram-negative bacteria were tested, and it was determined that all nanoparticles exhibited activity against both groups. Rumex sp. silver nanoparticles (NPs) were revealed to exhibit antibiofilm activity against three different isolates with moderate and strong biofilm-forming ability. The NPs reduced the biofilm-forming capacity of Acinetobacter baumannii and Klebsiella pneumonaie by 2.66-fold and 3.25-fold, whereas they decreased the Escherichia coli biofilm-forming capacity by 1.25-fold. The investigation of microbial biofilm could play an important role in developing new strategies for treatment options. Our results suggest that Rumex sp. silver NPs may have a high potential for use in the treatment of pathogenic strains.

Determination of the Cytotoxicity and Antibiofilm Potential Effect of Equisetum arvense Silver Nanoparticles.

This study aimed to synthesize and characterize silver nanoparticles (AgNPs) by green synthesis from Equisetum arvense (Ea) extracts and to investigate their cytotoxicity, antibiofilm activity, and α-glucosidase enzyme inhibition. Diverse characterization techniques were applied to verify the production of nanoparticles. SEM examination confirmed that the size of nanoparticles is in the range of 40-60 nm. Also, interactions between silver and natural compounds of plant extract were confirmed through FT-IR and EDX analyses. It was determined that Equisetum arvense silver nanoparticles had antibiofilm activity against three different clinical strains with high biofilm-forming ability. AgNPs reduced the biofilm-forming capacity of clinical A. baumannii isolate with strong biofilm-forming capacity by approximately twofold, while the capacity of clinical K.pneumonaie and E.coli isolates decreased by 1.5 and 1.2 fold, respectively. The α-glucosidase enzyme inhibition potential of the AgNPs, which is determined as 93.50%, was higher than the plant extract with, and the α- 30.37%. MTT was performed to assess whether incubation of nanoparticles with A549 and ARPE-19 cell lines affected their viability, and a dramatic reduction in cell growth inhibition of both A549 and ARPE-19 cells was observed. It has been shown that A549 cells treated with 200 and 150 µg/mL nanoparticles had less cell proliferation compared to control cells at 24-h and 48-h incubation time. According to these results, Ea-derived AgNPs appear to have potential anticancer activity against A549 cancer cells. Investigating the effects of green synthesis nanoparticles on microbial biofilm and various tumors may be important for developing new therapies. The outcomes of this study have showed that Ea-AgNPsmay have a high potential both in the treatment of pathogenic strains that form biofilms, as well as in anticancer therapy use.

A novel niosome formulation for encapsulation of anthocyanins and modelling intestinal transport.

The bioavailability of drugs can be improved by regulating the structural properties, particularly lipoid systems, such as niosomes, can increase cellular uptake. Herein, we optimized double emulsion and niosomal formulations for encapsulating anthocyanin-rich black carrot extract. Nanoparticles obtained by selected formulation were characterized in terms of morphology, particle size, drug encapsulation efficiency, in vitro release and cytotoxicity. The optimum conditions for niosomal formulation were elicited as 30 mg of cholesterol, 150 mg of Tween 20 and feeding time of 1 min at a stirring rate of 900 rpm yielding the lowest average particle size of 130 nm. In vitro release data showed the majority of the encapsulated anthocyanins were released at the end of 10 h. A mathematical model was developed to estimate the absorption of anthocyanins released from niosomes and cytotoxicity was assessed against neuroblastoma. Overall, these findings suggest that niosomal vesicles might be suitable delivery systems for anthocyanins.

An injectable alginate-based hydrogel for microfluidic applications.

The objective of this study was to develop an injectable alginate based formulation for immobilizing enzymes into microfluidic systems. The gelation was induced upon lowering the pH by addition of d-glucono-δ-lactone (GDL) and release of Ca+ ions from solid CaCO3. The effects of GDL concentration on enzymatic activity and gelation time were investigated. The results indicated that increasing the GDL concentration increased both surface area and enzymatic activity. Also, chitosan was added to the formulation at different ratios to enhance the stability of enzyme during immobilization. For microfluidic application, 100µl spiral coil single channel microchip was fabricated and alginate GDL mixture containing ß-glucosidase was injected to the microchannel prior to gelation. Enzymatic conversion was performed by pumping substrate (pNPG) through the microchannel. The results indicated that the entire substrate was converted continuously during 24h without any leakage or deactivation of immobilized enzyme.

Formulation of organic and inorganic hydrogel matrices for immobilization of ß-glucosidase in microfluidic platform.

The aim of this study was to formulate silica and alginate hydrogels for immobilization of ß-glucosidase. For this purpose, enzyme kinetics in hydrogels were determined, activity of immobilized enzymes was compared with that of free enzyme, and structures of silica and alginate hydrogels were characterized in terms of surface area and pore size. The addition of polyethylene oxide improved the mechanical strength of the silica gels and 68% of the initial activity of the enzyme was preserved after immobilizing into tetraethyl orthosilicate-polyethylene oxide matrix where the relative activity in alginate beads was 87%. The immobilized ß-glucosidase was loaded into glass-silicon-glass microreactors and catalysis of 4-nitrophenyl ß-d-glucopyranoside was carried out at various retention times (5, 10, and 15 min) to compare the performance of silica and alginate hydrogels as immobilization matrices. The results indicated that alginate hydrogels exhibited slightly better properties than silica, which can be utilized for biocatalysis in microfluidic platforms.

Extracts from black carrot tissue culture as potent anticancer agents.

Black carrots contain anthocyanins possessing enhanced physiological activities. Explants of young black carrot shoots were cultured in Murashige and Skoog (MS) medium for callus initiation and were transferred to new MS medium supplemented with four different combinations of 2,4-dichlorophenoxyacetic acid and kinetin. Subsequently, the lyophilized calli and black carrot harvested from fields were subjected to ultrasound extraction with ethanol at a ratio of 1:15 (w:v). Obtained extracts were applied to various human cancer cell lines including MCF-7 SK-BR-3 and MDA-MB-231 (human breast adenocarcinomas), HT-29 (human colon adenocarcinoma), PC-3 (human prostate adenocarcinoma), Neuro 2A (Musmusculus neuroblastoma) cancer cell lines and VERO (African green monkey kidney) normal cell line by MTT assay. The highest cytotoxic activity was achieved against Neuro-2A cell lines exhibiting viability of 38-46% at 6.25 µg/ml concentration for all calli and natural extracts. However, a significantly high IC50 value of 170.13 µg/ml was attained in normal cell line VERO indicating that its natural counterpart is an ideal candidate for treatment of brain cancer without causing negative effects to normal healthy cells.

An analytical approach based on ESI-MS, LC-MS and PCA for the quali-quantitative analysis of cycloartane derivatives in Astragalus spp.

Astragalus species are widely used as health foods and dietary supplements, as well as drugs in traditional medicine. To rapidly evaluate metabolite similarities and differences among the EtOH extracts of the roots of eight commercial Astragalus spp., an approach based on direct analyses by ESI-MS followed by PCA of ESI-MS data, was carried out. Successively, quali-quantitative analyses of cycloartane derivatives in the eight Astragalus spp. by LC-ESI-MS(n) and PCA of LC-ESI-MS data were performed. This approach allowed to promptly highlighting metabolite similarities and differences among the various Astragalus spp. PCA results from LC-ESI-MS data of Astragalus samples were in reasonable agreement with both PCA results of ESI-MS data and quantitative results. This study affords an analytical method for the quali-quantitative determination of cycloartane derivatives in herbal preparations used as health and food supplements.

Effects of process parameters on supercritical CO2 extraction of total phenols from strawberry (Arbutus unedo L.) fruits: An optimization study.

The aim of this work was to optimize total phenolic yield of Arbutus unedo fruits using supercritical fluid extraction. A Box-Behnken statistical design was used to evaluate the effect of various values of pressure (50-300 bar), temperature (30-80°C) and concentration of ethanol as co-solvent (0-20%) by CO2 flow rate of 15 g/min for 60 min. The most effective variable was co-solvent ratio (p<0.005). Evaluative criteria for both dependent variables (total phenols and radical scavenging activity) in the model were assigned maximum. Optimum extraction conditions were elicited as 60 bar, 48°C and 19.7% yielding 25.72 mg gallic acid equivalent (GAE) total phenols/g extract and 99.9% radical scavenging capacity, which were higher than the values obtained by conventional water (24.89 mg/g; 83.8%) and ethanol (15.12 mg/g; 95.8%) extractions demonstrating challenges as a green separation process with improved product properties for industrial applications.