Bacteria Inspired Internal Standard SERS Substrate for Quantitative Detection.

Metal-respiring bacteria are frequently used to recycle metal resources by biosynthesizing nanoparticles on its surface in environment treatment. However, further utilization of biogenetic nanoparticles through combining the advantages of both bacteria and nanoparticles is still limited. Herein, biogenetic Au@Ag nanoislands are utilized as the surface-enhanced Raman spectroscopy (SERS) substrate for quantitative detection. Specifically, Au@Ag nanoislands enhance the Raman signal via surface plasmon resonance, while biomolecules (phospholipid, tyrosine, and phenylalanine, etc.) on bacterium serve as an internal standard to eliminate the discrepancy of the target SERS intensity in different hot spots. Gene-controlled biomolecules in bacteria guarantee the reproducibility of this SERS substrate. The generality of this analytical method is demonstrated by determining rhodamine 6G, malachite green, and uric acid. This discovery solves a pervasive problem in SERS analysis through a simple biogenetic nanosystem, which opens up an avenue to address scientific challenges by using versatile organisms from nature.

Biocompatible and highly luminescent near-infrared CuInS2/ZnS quantum dots embedded silica beads for cancer cell imaging.

Bright and stable CuInS2/ZnS@SiO2 nanoparticles with near-infrared (NIR) emission were competently prepared by incorporating the as-prepared hydrophobic CuInS2/ZnS quantum dots (QDs) directly into lipophilic silane micelles and subsequently an exterior silica shell was formed. The obtained CuInS2/ZnS@SiO2 nanoparticles homogeneously comprised both single-core and multicore remarkable CuInS2/ZnS QDs, while the silica shell thickness could be controlled to within 5-10 nm and their overall size was 17-25 nm. Also, the functionalized CuInS2/ZnS QDs encapsulated in the silica spheres, expedited their bioconjugation with holo-Transferrin (Tf) for further cancer cell imaging. The CuInS2/ZnS@SiO2 nanoparticles not only showed a dominant NIR band-edge luminescence at 650-720 nm with a quantum yield (QY) between 30 and 50%, without a recognized photoluminescence (PL) red shift, but also exhibited excellent PL and colloidal stability in aqueous media. Impressively, the cytotoxicity studies revealed minor suppression on cell viability under both CuInS2/ZnS@SiO2 and CuInS2/ZnS@SiO2@Tf concentrations up to 1 mg/mL. The application in live-cell imaging revealed that the potential of CuInS2/ZnS QDs as biocompatible, robust, cadmium-free, and brilliant NIR emitters is considered promising for fluorescent labels.