Green and eco-friendly biosynthesis of zinc oxide nanoparticles using Calendula officinalis flower extract: Wound healing potential and antioxidant activity.

This study aimed to produce zinc oxide nanoparticles with Calendula officinalis flower extract (Co-ZnO NPs) using the green synthesis method. In addition, the antioxidant and wound healing potential of synthesized ZnO NPs were evaluated. The absorbance band at 355 nm, which is typical for ZnO NPs, was determined from the UV-Vis absorbance spectrum. The energy-dispersive X-ray spectroscopy (EDS) measurements revealed a high zinc content of 42.90%. The x-ray diffractometer data showed Co-ZnO NPs with an average crystallite size of 17.66 nm. The Co-ZnO NPs did not have apparent cytotoxicity up to 10 µg/mL (IC50 25.96 µg/mL). C. officinalis ZnO NPs showed partial cell migration and percent wound closure (69.1%) compared with control (64.8%). In addition, antioxidant activities of Co-ZnO NPs with 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and 2,2 diphenyl-1 picrylhydrazil (DPPH) were evaluated and radical scavenging activity of 33.49% and 46.63%, respectively, was determined. These results suggest that C. officinalis extract is an effective reducing agent for the green synthesis of ZnO NPs with significant antioxidant and wound healing potential.

Electrochemical nucleic acid hybridization biosensor based on poly(L-Aspartic acid)-modified electrode for the detection of short oligonucleotide sequences related to hepatitis C virus 1a.

This work describes, for the first time, the fabrication of poly(L-aspartic acid) (PAA) film modified pencil graphite electrode (PGE) for the detection of hepatitis C Virus 1a (HCV1a). The presence of PAA on the electrode surface can provide free carboxyl groups for covalent binding of biomolecules. The PGE surface was first coated with PAA via electropolymerization of the L-aspartic acid, and avidin was subsequently attached to the PAA modified electrode by covalent attachment. Biotinylated HCV1a probes were immobilized on avidin/PAA/PGE via avidin-biotin interaction. The morphology of PAA/PGE was examined using a scanning electron microscope. The hybridization events were monitored with square wave voltammetry using Meldola's blue (MDB). Compared to non-complementary oligonucleotide sequences, when hybridization was carried out between the probe and its synthetic targets or the synthetic polymerase chain reaction analog of HCV1a, the highest MDB signal was observed. The linear range of the biosensor was 12.5 to 100 nM and limit of detection was calculated as 8.7 nM. The biosensor exhibited favorable stability over relatively long-term storage. All these results suggest that PAA-modified electrode can be used to nucleic acid biosensor application and electropolymerization of L-aspartic acid can be considered as a good candidate for the immobilization of biomolecules.