Photocatalytic and Antimicrobial Properties of [AgTiO₂]:[Clay] Nanocomposite Prepared with Clay Different Ratios

This work aimed to synthesis a novel material that would be able to efficiently remove both organic and microbiological pollutants from wastewater. Through the hydrothermal process, we first doped titanium dioxide, a semiconductor possessing excellent photocatalytic properties with silver nanoparticles having good antibacterial properties. The obtained material was then associated with clay known for its good adsorbent properties to form [AgTiO2]:[clay] type nanocomposites. The different mass composition of [AgTiO2]:[clay] considered in this work were 1:1;1:0.5;1:0.1;1:0.05 and 1:0.01. The prepared nanocomposites were characterized by means of XRD, FTIR and SEM techniques. Results revealed the presence of TiO2 anatase and Ag on the surface of the clay mainly composed of kaolinite and quartz. The photocatalytic activities of the nanocomposites were tested in the presence of synthetic Orange II (25 mg/L) wastewater under visible light irradiation. The experiments demonstrated that organic pollutants were effectively photodegraded when the proportion of clay in the mixture (AgTiO2)-(Clay) was inferior or equaled to 50%. The use of commercial TiO2, for comparison purpose, showed a lower degradation efficiency of the Orange II solution (η < 30%). The antibacterial properties of the nanocomposites [AgTiO2]:[clay] were also assessed in the presence of two types of bacteria E. coli (Gram negative) and S. aureus (Gram positive). The antibacterial activities of the nanocomposites were characterized with and without UV irradiation. In dark conditions, the antibacterial activities of nanocomposites (AgTiO2)-(Clay) against S. aureus gradually increased with increasing the clay amount. Under visible light irradiation, the nanocomposites showed a significant antimicrobial activity against E. coli and S. aureus.

In silico analysis of a disease-causing mutation in PCDH15 gene in a consanguineous Pakistani family with Usher phenotype

AIM： To map Usher phenotype in a consanguineous Pakistani family and identify disease-associated mutation in a causative gene to establish phenotype-genotype correlation.· METHODS： A consanguineous Pakistani family in which Usher phenotype was segregating as an autosomal recessive trait was ascertained. On the basis of results of clinical investigations of affected members of this family disease was diagnosed as Usher syndrome（USH）. To identify the locus responsible for the Usher phenotype in this family, genomic DNA from blood sample of each individual was genotyped using microsatellite Short Tandem Repeat（STR） markers for the known Usher syndrome loci. Then direct sequencing was performed to find out disease associated mutations in the candidate gene.· RESULTS： By genetic linkage analysis, the USH phenotype of this family was mapped to PCDH15 locus on chromosome 10q21.1. Three different point mutations in exon 11 of PCDH15 were identified and one of them,c.1304AC was found to be segregating with the disease phenotype in Pakistani family with Usher phenotype.This, c.1304 A C transversion mutation predicts an amino-acid substitution of aspartic acid with an alanine at residue number 435（p.D435A） of its protein product.Moreover, in silico analysis revealed conservation of aspartic acid at position 435 and predicated this change as pathogenic.·CONCLUSION：Theidentificationofc.1304ACpathogenic mutation in PCDH15 gene and its association with Usher syndrome in a consanguineous Pakistani family is thefirst example of a missense mutation of PCDH15 causing USH1 phenotype. In previous reports, it was hypothesized that severe mutations such as truncated protein of PCDH15 led to the Usher I phenotype and that missense variants are mainly responsible for non-syndromic hearing impairment.