Biosynthesis of silver nanoparticles with antibacterial, antioxidant, anti-inflammatory properties and their burn wound healing efficacy.

The current study aims to develop a novel burn wound ointment consisting of sheep's tail ointment loaded with AgNP. The AgNP in the ointment serves as an antibacterial, antioxidant and anti-inflammatory agent. The AgNP was developed via the biological method with the assistance of the medicinal plant Rhodiola rosea. The characterization of AgNP was assessed using UV-Vis spectroscopy, FTIR, Zeta Potential, XRD, PCCS, SEM, and EDX techniques. The formation of AgNP was confirmed by UV-Vis spectrum at the absorbance of ∼430 nm, and the biomolecules responsible for reducing and capping the AgNP were characterized by FTIR analysis. The stability of AgNP was determined with Zeta potential, which revealed a highly stable colloidal solution with a surface charge of -68.38 ± 3.4 mV. The synthesized AgNP had a face-centered cubic structure with a crystallite size of 23 nm and average grain size of 67.5 nm. The SEM image showed a fairly monodisperse 20 nm-sized spherical-shaped AgNP. The synthesized AgNP contained high purity of the silver, and a low concentration of AgNP inhibited both Gram-positive and Gram-negative bacteria. Moreover, the scavenging activity of AgNP was investigated using DPPH and H2O2 scavenging assay, and the results revealed a dose-dependent antioxidant activity with the highest activity at a concentration of 450 µg/ml. Finally, the burn wound healing effect was evaluated by applying the AgNP-loaded ointment to the wound site of BALB/c mice. The in-vivo studies confirmed that AgNP-loaded ointment reduced the wound size, decreased the epidermis layer, and lowered mast cell migration compared to untreated burn wounds. And the synthesized AgNP regulated both pro-inflammatory and anti-inflammatory gene expression, thereby promoting burn wound closure on BALB/c mice. The developed AgNP-loaded ointment has the potential to be applied in the biomedical field.

Antibacterial activity and characteristics of silver nanoparticles biosynthesized from Carduus crispus.

In recent years' synthesis of metal nanoparticle using plants has been extensively studied and recognized as a non-toxic and efficient method applicable in biomedical field. The aim of this study is to investigate the role of different parts of medical plant Carduus crispus on synthesizing silver nanoparticles and characterize the produced nanoparticle. Our study showed that silver nanoparticles (AgNP) synthesized via whole plant extract exhibited a blue shift in absorption spectra with increased optical density, which correlates to a high yield and small size. Also, the results of zeta potential, X-ray diffraction, photon cross-correlation spectroscopy analysis showed the surface charge of - 54.29 ± 4.96 mV (AgNP-S), - 42.64 ± 3.762 mV (AgNP-F), - 46.02 ± 4.17 mV (AgNP-W), the crystallite size of 36 nm (AgNP-S), 13 nm (AgNP-F), 14 nm (AgNP-W) with face-centered cubic structure and average grain sizes of 145.1 nm, 22.5 nm and 99.6 nm. Another important characteristic, such as elemental composition and constituent capping agent has been determined by energy-dispersive X-ray spectroscopy and Fourier transform infrared. The silver nanoparticles were composed of ~ 80% Ag, ~ 15% K, and ~ 7.5% Ca (or ~ 2.8% P) elements. Moreover, the results of the FTIR measurement suggested that the distinct functional groups present in both AgNP-S and AgNP-F were found in AgNP-W. The atomic force microscopy analysis revealed that AgNP-S, AgNP-F and AgNP-W had sizes of 131 nm, 33 nm and 70 nm respectively. In addition, the biosynthesized silver nanoparticles were evaluated for their cytotoxicity and antibacterial activity. At 17 µg/ml concentration, AgNP-S, AgNP-F and AgNP-W showed very low toxicity on HepG2 cell line but also high antibacterial activity. The silver nanoparticles showed antibacterial activity on both gram-negative bacterium Escherichia coli (5.5 ± 0.2 mm to 6.5 ± 0.3 mm) and gram-positive bacterium Micrococcus luteus (7 ± 0.4 mm to 7.7 ± 0.5 mm). Our study is meaningful as a first observation indicating the possibility of using special plant organs to control the characteristics of nanoparticles.

Cellular Membrane Composition Requirement by Antimicrobial and Anticancer Peptide GA-K4.

Naturally occurring antimicrobial peptides important for innate immunity are widely studied for their antimicrobial and anticancer activity. The primary target of these AMPs is believed to be the bacterial cytoplasmic membrane. However, the interaction between cytoplasmic membrane and the antimicrobial peptides remains poorly understood. Therefore to focus on the target membrane composition that is required by AMPs to interact with membranes, we have examined the interaction of the antimicrobial and anticancer active 11-residue GA-K4 (FLKWLFKWAKK) peptide with model and intact cell membranes. Effect on the structural conformational properties of GA-K4 peptide was investigated by means of far-UV CD and fluorescence spectroscopic methods. The different conformation of GA-K4 peptide in large unilamellar vesicles (LUV) bilayer and micelle environment suggest that the curvature has an influence on the secondary structure acquired by the peptide. Furthermore, the leakage experiment result confirmed that GA-K4 induced the leakage of cytoplasmic membrane in Staphylococcus аureus bacterial cells. Fluorescence data revealed the interfacial location of GA-K4 peptide in the model membranes. The blue-shift in emission wavelength by tryptophan residues in fluorescence data indicated the penetration of GA-K4 peptide in micelles and phospholipid bilayers. These results showed that the GA-K4 peptide is a membrane-active peptide and its activity depends on membrane curvature and lipid composition. Although further studies are required to confirm the mechanism of action, the data suggest mechanism of toroidal pore formation for the interaction of GA-K4 peptide with membranes. Our studies will be helpful in better understanding of the membrane requirment of peptides to express their therapeutic effects.

Combined effect of pulsed electromagnetic field and sound wave on In vitro and In vivo neural differentiation of human mesenchymal stem cells.

Biophysical wave stimulus has been used as an effective tool to promote cellular maturation and differentiation in the construction of engineered tissue. Pulsed electromagnetic fields (PEMFs) and sound waves have been selected as effective stimuli that can promote neural differentiation. The aim of this study was to investigate the synergistic effect of PEMFs and sound waves on the neural differentiation potential in vitro and in vivo using human bone marrow mesenchymal stem cells (hBM-MSCs). In vitro, neural-related genes in hBM-MSCs were accelerated by the combined exposure to both waves more than by individual exposure to PEMFs or sound waves. The combined wave also up-regulated the expression of neural and synaptic-related proteins in a three-dimensional (3-D) culture system through the phosphorylation of extracellular signal-related kinase. In a mouse model of photochemically induced ischemia, exposure to the combined wave reduced the infarction volume and improved post-injury behavioral activity. These results indicate that a combined stimulus of biophysical waves, PEMFs and sound can enhance and possibly affect the differentiation of MSCs into neural cells. Our study is meaningful for highlighting the potential of combined wave for neurogenic effects and providing new therapeutic approaches for neural cell therapy. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 33:201-211, 2017.

Neuroprotective Effect of Low Frequency-Pulsed Electromagnetic Fields in Ischemic Stroke.

Low frequency-pulsed electromagnetic fields (LF-PEMFs) affect many biological processes; however, the fundamental mechanisms responsible for these effects remain unclear. Our study aimed to investigate the effect of LF-PEMFs on neuroprotection after ischemic stroke. C57B6 mice were exposed to LF-PEMF (F = 60 Hz, Bm = 10 mT) after photothrombotic occlusion. We measured the BDNF/TrkB/Akt signaling pathway, pro-apoptotic and pro-survival protein and gene expressions, and the expression of inflammatory mediators and performed behavioral tests in both LF-PEMF-treated and untreated ischemic stroke mice. Our results showed that LF-PEMF treatment promotes activation of the BDNF/TrkB/Akt signaling pathway. Subsequently, pro-survival proteins were significantly increased, while pro-apoptotic proteins and inflammatory mediators were decreased in ischemic stroke mice after LF-PEMF treatment. The results demonstrated that LF-PEMF exposure has a neuroprotective effect after ischemic stroke in mice during the recovery process.

Effect of human mesenchymal stem cell transplantation on cerebral ischemic volume-controlled photothrombotic mouse model.

Various animal models of stroke have been developed to simulate the human stroke with the development of the ischemic method facilitates preclinical stroke research. The photothrombotic ischemia model, based on the intravascular photochemical reaction, is widely used for in vivo studies. However, this study has limitations, which generated a relatively small-sized infarction model on superficial cortex compared to that of the MCAO stroke model. In this study, the photothorombosis mouse model is adapted and the optimum conditions for generation of cell death and deficits with high reproducibility is determined. The extent of damage within the cortex was assessed by infarct volume and cellular/behavioral analyses. In this model, the neural cell death and inflammatory responses is detected; moreover, the degree of behavioral impairment is correlated with the brain infarct volume. Further, to enhance the understanding of neural repair, the effect of neural differentiation by transplantation of human bone marrow-derived mesenchymal stem cells (BM-MSCs) is analyzed. The authors demonstrated that transplantation of BM-MSCs promoted the neural differentiation and behavioral performance in their photothrombosis model. Therefore, this research was meaningful to provide a stable animal model of stroke with low variability. Moreover, this model will facilitate development of novel MSC-based therapeutics for stroke.

Pulsed electromagnetic fields promote survival and neuronal differentiation of human BM-MSCs.

Pulsed electromagnetic fields (PEMF) are known to affect biological properties such as differentiation, regulation of transcription factor and cell proliferation. However, the cell-protective effect of PEMF exposure is largely unknown. The aim of this study is to understand the mechanisms underlying PEMF-mediated suppression of apoptosis and promotion of survival, including PEMF-induced neuronal differentiation. Treatment of induced human BM-MSCs with PEMF increased the expression of neural markers such as NF-L, NeuroD1 and Tau. Moreover, treatment of induced human BM-MSCs with PEMF greatly decreased cell death in a dose- and time-dependent manner. There is evidence that Akt and Ras are involved in neuronal survival and protection. Activation of Akt and Ras results in the regulation of survival proteins such as Bad and Bcl-xL. Thus, the Akt/Ras signaling pathway may be a desirable target for enhancing cell survival and treatment of neurological disease. Our analyses indicated that PEMF exposure dramatically increased the activity of Akt, Rsk, Creb, Erk, Bcl-xL and Bad via phosphorylation. PEMF-dependent cell protection was reversed by pretreatment with LY294002, a specific inhibitor of phosphatidylinositol 3-kinase (PI3K). Our data suggest that the PI3K/Akt/Bad signaling pathway may be a possible mechanism for the cell-protective effects of PEMF.