Simultaneous photocatalytic degradation and SERS detection of tetracycline with self-sustainable and recyclable ternary PI/TiO_(2)/Ag flexible microfibers

Facile and efficient photocatalysts using sunlight,as well as fast and sensitive surface-enhanced Raman spectroscopy(SERS)substrates,are urgently needed for practical degradation of tetracycline(TC).To meet these requirements,a new paradigm for PI/TiO_(2)/Ag organic‒inorganic ternary flexible microfibers based on semiconducting titanium dioxide(TiO_(2)),the noble metal silver(Ag)and the conjugated polymer polyimide(PI)was developed by engineering a simple method.Under sunlight,the photocatalytic characteristics of the PI/TiO_(2)/Ag flexible microfibers containing varying amounts of Ag quantum dots(QDs)were evaluated with photocatalytic degradation of TC in aqueous solution.The results demonstrated that the amount of Ag affected the photocatalytic activity.Among the tested samples,PI/TiO_(2)/Ag-0.07(93.1%)exhibited a higher photocatalytic degradation rate than PI/TiO_(2)(25.7%),PI/TiO_(2)/Ag-0.05(77.7%),and PI/TiO_(2)/Ag-0.09(63.3%).This observation and evaluation conducted in the present work strongly indicated a charge transfer mechanism.Moreover,the PI/TiO_(2)/Ag-0.07 flexible microfibers exhibited highly sensitive SERS detection,as demonstrated by the observation of the Raman peaks for TC even at an extremely low concentration of 10–10 moles per liter.The excellent photocatalytic performance and SERS detection capability of the PI/TiO_(2)/Ag flexible microfibers arose from the Schottky barrier formed between Ag and TiO_(2)and also from the outstanding plasmonic resonance and visible light absorptivity of Ag,along with immobilization by the PI.The successful synthesis of PI/TiO_(2)/Ag flexible microfibers holds significant promise for sensitive detection and efficient photocatalytic degradation of antibiotics.

Determining antimicrobial resistance profiles and identifying novel mutations of Neisseria gonorrhoeae genomes obtained by multiplexed MinION sequencing

Gonorrhea is one of the most common sexually transmitted diseases worldwide. To cure infection and prevent transmission,timely and appropriate antimicrobial therapy is necessary. Unfortunately, Neisseria gonorrhoeae, the etiological agent of gonorrhea, has acquired nearly all known mechanisms of antimicrobial resistance(AMR), thereby compromising the efficacy of antimicrobial therapy. Treatment failure resulting from AMR has become a global public health concern. Whole-genome sequencing is an effective method to determine the AMR characteristics of N. gonorrhoeae. Compared with next-generation sequencing, the MinION sequencer(Oxford Nanopore Technologies(ONT)) has the advantages of long read length and portability. Based on a pilot study using MinION to sequence the genome of N. gonorrhoeae, we optimized the workflow of sequencing and data analysis in the current study. Here we sequenced nine isolates within one flow cell using a multiplexed sequencing strategy. After hybrid assembly with Illumina reads, nine integral circular chromosomes were obtained. By using the online tool Pathogenwatch and a BLAST-based workflow, we acquired complete AMR profiles related to seven classes of antibiotics. We also evaluated the performance of ONT-only assemblies. Most AMR determinants identified by ONT-only assemblies were the same as those identified by hybrid assemblies. Moreover, one of the nine assemblies indicated a potentially novel antimicrobial-related mutation located in mtrR which results in a frame-shift, premature stop codon, and truncated peptide.In addition, this is the first study using the MinION sequencer to obtain complete genome sequences of N. gonorrhoeae strains which are epidemic in China. This study shows that complete genome sequences and antimicrobial characteristics of N.gonorrhoeae can be obtained using the MinION sequencer in a simple and cost-effective manner, with hardly any knowledge of bioinformatics required. More importantly, this strategy provides us with a potential approach to discover new AMR determinants.