Tetrodes, consisting of four twisted micro-wires can simultaneously record the number of neurons in the brain. To improve the quality of neuronal activity detection, the tetrode tips should be modified to increase the surface area and lower the impedance properties. In this study, tetrode tips were modified by the electrodeposition of Au nanoparticles (AuNPs) and dextran (Dex) doped poly (3,4-ethylenedioxythiophene) (PEDOT). The electrochemical properties were measured using electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). A decrease in the impedance value from 4.3 MΩ to 13 kΩ at 1 kHz was achieved by the modified tetrodes. The cathodic charge storage capacity (CSCC) of AuNPs-PEDOT deposited tetrodes was 4.5 mC/cm2, as determined by CV measurements. The tetrodes that were electroplated with AuNPs and PEDOT exhibited an increased surface area, which reduced the tetrode impedance. In vivo recording in the ventral posterior medial (VPM) nucleus of the thalamus was performed to investigate the single-unit activity in normal rats. To evaluate the recording performance of modified tetrodes, spontaneous spike signals were recorded. The values of the L-ratio, isolation distance and signal-to-noise (SNR) confirmed that electroplating the tetrode surface with AuNPs and PEDOT improved the recording performance, and these parameters could be used to effectively quantify the spikes of each cluster.

Malassezia species can cause serious dermatologic diseases in humans. Synthetic antifungal drugs, which have been usually utilised as a treatment for Malassezia-associated diseases, are belonged to the azole group. However, the hypersensitivity and resistance to synthetic drugs due to improper use are raising public concerns. Recently, the study of using herbal essential oils in the control of Malassezia fungus has attracted great attention from researchers. This study analysed and identified 19 compounds of Ocimum sanctum L. essential oil, where eugenol is the main composition in O. sanctum L. essential oil, accounting for 42.4%. O. sanctum L. essential oil showed strong activity against 3 strains of human skin fungi M. furfur VNF01, M. furfurATCC14521, and M. globosa VNG02 with a minimum inhibitory concentration (MIC) of 2.5 μl/ml. Using this concentration, 74.66-80.66% of tested yeast strains’ cell numbers were eliminated after a 20-minute treatment. The results suggested that the herbal O. sanctum L. essential oil could be a potential agent to develop cosmetic products including shampoo and cream for the prevention and treatment of Malassezia-associated diseases.

Streptomyces are considered to be one of the actinomycetes genera having potential in the production of agricultural probiotics because they are safe and have strong antagonism to many bacterial and fungal species that cause plant diseases. In this study, 18 strains of actinomycetes were isolated from growing oranges’ soil in Ha Giang province, of which the actinomycete strain XK1 was considered to be strongly resistant to the fungi Penicillium digitatum and Colletotrichum gloeosporioides causing fruit rot and shedding in citrus. Based on morphological characteristics and 16S rRNA sequence, the strain XK1 was determined to belong to the Streptomyces albulus. On MT2 medium with pH=6, after five days of shaking cultivation at 30°C, the liquid cultures of S. albulus XK1 showed the strongest resisting activity to P. digitatum and C. gloeosporioides. At the same time, the broth cultures of S. albulus XK1 showed inhibitory activity against P. digitatum in oranges. The actinomycete strain S. albulus XK1 was selected base on strong antifungal ability against P. digitatum and C. gloeosporioides and had a potential for application in the production of probiotics used to control fruit rot and shedding in citrus.

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