Stimuli-responsive piezoelectricity in electrospun polycaprolactone (PCL)/Polyvinylidene fluoride (PVDF) fibrous scaffolds for bone regeneration

Polymeric scaffolds are a determinant part of modern tissue engineering owing to their great diversity, adaptability, and processability. Interestingly, the physical properties of these scaffolds, e.g., porosity, mechanical properties, and biocompatibility, can be tuned to make them smart and stimuli-responsive. In this regard, piezoelectric materials can be applied to stimulate bone regeneration by converting mechanical impulses to electrical signals. In the present research, fibers made of various blend ratios of polyvinylidene fluoride (PVDF)/polycaprolactone (PCL) were fabricated, investigated and optimized to promote bone regeneration. Uniform fibers containing β-phase PVDF were obtained due to the simultaneous stretching and high voltage applied during electrospinning. Furthermore, components interaction, crystallinity, and piezoelectric behavior were estimated through fourier-transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), and piezometery, respectively. The samples showed improved wettability and controlled biodegradability, and the piezoelectric charge output reached up to 7.5 pC/N in the sample containing 70 wt% PVDF. At the same time, these scaffolds could provide mechanical properties close to the native bone tissue relying on the PVDF component. In vitro assessments demonstrated that the composite scaffolds were biocompatible and could support cell attachment and proliferation. Moreover, their piezoelectric behavior promoted stem cell differentiation into osteoblasts. Considering the obtained results, the potential of piezoelectric PVDF/PCL blend fibers for bone scaffolds is indisputable

Phytochemical Screening and In vitro Evaluation of Free Radical Scavenging Activity of Dionysia revoluta L.

Dionysia revoluta L., a plant of Primulaceae family is used for treating ulcers and relieving pain in Iranian traditional system of medicine. The present study was aimed at preliminary phytochemical investigation and evaluation of antioxidant characteristics of D. revolute L. ethanol extract and its various fractions. Total phenolic content was determined by Folin–Ciocalteu method. Evaluation of total flavonoid was carried out by the use of an aluminium chloride/sodium carbonate colorimetric procedure. Lipid peroxidation inhibitory effect of ethanol extract was studied and compared with that of butylated hydroxytoluene (BHT). Radical scavenging properties of ethanolic extract and various fractions were determined by 2,2-diphenyl-l-picrylhydrazyl (DPPH) and nitric oxide methods. High phenolic and flavonoid contents and significant radical scavenging properties were detected for the ethyl, acetate and n-butanol fractions. Comparisons were made with known reference antioxidant compounds ascorbic acid, quercetin, and gallic acid. The radical scavenging effect of n-butanol fraction was the highest among all fractions. Acid hydrolysis of n-butanol fraction led to a significant enhancement in its phenolic and flavonoid contents and DPPH scavenging efficacy. The total phenolic content showed a good correlation with radical scavenging activity. The antioxidant activity found in the ethyl acetate and n-butanol fractions of D. revoluta L. may be attributed to the presence of flavonoids and other phenolic compounds. Among various chemical constituents of this plant, the concentration of flavonoids seems to prevail remarkably as indicated by thin layer chromatography of various fractions and diagnostic colour reactions. The results suggest that D. revoluta bears a remarkable radical scavenging and antioxidant activity and is worthy of further detailed phytochemical and antioxidant studies

Novel Combination of Silver Nanoparticles and Carbon Nanotubes for Plasmonic Photo Thermal Therapy in Melanoma Cancer Model

Purpose: Plasmonic photo thermal therapy (PPTT) is a therapeutic method in which the photon energy is rapidly transformed into heat via a series of radiative and non-radiative phenomena to ablate cancer. Plasmonic NPs, such as silver NPs (Ag NPs), have considerable properties in optical absorbance. Furthermore, good thermal conductivity and cell penetration ability of carbon nanotubes (CNTs) could improve the efficacy of Ag NPs for PPTT. Decoration of the multi-walled carbon nanotubes (MWCNTs) with silver has been developed to enhance thermal conductivity of the MWCNT particles. Methods: The Ag NPs were decorated on the CNTs and the ability of these particles (CNT/Ag NPs) in reduction of melanoma tumor size after PTT was evaluated experimentally. For comparison, the PTT of silver nanorods (Ag NRs) and CNTs were investigated. The melanoma tumor was induced by injection of B16/F10 cell line to the inbred mice. Different NPs were injected into the tumors and then irradiated via laser diode (λ=670 nm, P=500 mW, and I= 3.5 W/cm 2 ) at scheduled time. Results: Monitoring of tumor sizes showed that integration of CNTs with silver could enhance the optical absorption of CNTs and improve tumor destruction in PPTT technique. Conclusion: The CNT/Ag NPs could act as a potent agent in PPTT method in curing solid tumors