Tracking of Intestinal Probiotics In Vivo by NIR-IIb Fluorescence Imaging.

The ability to accurately characterize microorganism distribution in the intestinal tract is helpful for understanding intrinsic mechanisms. Within the intestine, traditional optical probes used for microorganism labeling commonly suffer from a low imaging penetration depth and poor resolution. We report a novel observation tool useful for microbial research by labeling near-infrared-IIb (NIR-IIb, 1500-1700 nm) lanthanide nanomaterials NaGdF4:Yb3+,Er3+@NaGdF4,Nd3+ (Er@Nd NPs) onto the surface of Lactobacillus bulgaricus (L. bulgaricus) via EDC-NHS chemistry. We monitor microorganisms in tissue by two-photon excitation (TPE) microscopy and in vivo with NIR-IIb imaging. This dual-technique approach offers great potential for determining the distribution of transplanted bacteria in the intestinal tract with a higher spatiotemporal resolution.

An Ag2S@ZIF-Van nanosystem for NIR-II imaging of bacterial-induced inflammation and treatment of wound bacterial infection.

Bacterial diseases pose a serious threat to human health. Continued development of precise diagnostic methods and synergistic therapy techniques for combating bacteria are needed. Herein a hybrid nanosystem (Ag2S@ZIF-Van NS) was constructed by one-step self-assembly of Zn2+, vancomycin (Van) and Ag2S quantum dots (QDs). The nanosystem possesses excellent second near-infrared transparency window (NIR-II) fluorescence properties (∼1200 nm emission wavelength), good photothermal conversion properties, and biocompatibility. The material system enables precise, targeted NIR-II fluorescent imaging of bacterial inflammation in vivo as well as promoting anti-bacterial and wound healing effects.

Preparation of a CaTiO3/Al3+/Pr3+/Sm3+ nanocomposite for enrichment of exosomes in human serum.

Exosomes (30-200 nm) play important roles in intercellular communication. Because their contents differ between healthy individuals and subjects diagnosed with various diseases, exosomes have been regarded as potential sources of biomarkers for clinical diagnosis. However, the accuracy of diagnosis by exosomal biomarkers is highly dependent on the extraction efficiency, yield, and the quality of exosomes. Hence, inexpensive, convenient, and fast exosome separation methods are required. In the present study, the CaTiO3/Al3+/Pr3+/Sm3+ nanocomposite was synthesized and applied in highly selective and efficient separation of exosomes. Notably, the developed material exhibited higher specificity and efficiency than commercially available TiO2. Moreover, CaTiO3/Al3+/Pr3+/Sm3+ could be reused at least three times without any significant decrease in efficiency. The synthesized material was also used for the extraction of exosomes from the serums of patients with Alzheimer's disease (AD) and healthy controls. The exosomes were subjected to two-dimensional gel electrophoresis (2-DE) separation and matrix-assisted laser desorption/ionization-time of flight (MALDI TOF/TOF) mass spectrometry analysis. It was found that five proteins in the exosomes were evidently upregulated, while one protein was downregulated. Among the detected proteins, serum amyloid P-component (SAP) has been reported to be closely related to pathogenesis of AD. The obtained results indicated that the developed method involving separation and analysis of serum exosomes could be used for disease diagnosis or postoperative clinical monitoring.

ZnCuInSe/Au/TiO2 sandwich nanowires-based photoelectrochemical biosensor for ultrasensitive detection of kanamycin.

A highly selective and sensitive photoelectrochemical (PEC) sensing platform was developed for kanamycin assay based on the aptamer modified sandwich-structured ZnCuInSe/Au/TiO2 nanowires. Sandwiched between the TiO2 nanowires and the ZnCuInSe quantum dot (QDs) layer, the Au nanoparticles (Au NPs) serves as a plasmonic photosensitizer and an electron relay, which expand the light absorption range and facilitates the charge transfer. Also, ZnCuInSe QDs, a broad spectrum photosensitizer can capture visible light, which enhance the photocurrent density response. Through the Au-S bond and Cu-S bond, the HS-aptamer were immobilized on the ZnCuInSe/Au/TiO2 nanowires as a recognition unit for kanamycin. The proposed sensing platform showed excellent assay performance for kanamycin with a linear response range from 0.2 to 250 nM, and high selectivity. By changing the recognizers, the proposed sensing platform could be easily extended to detect other biomolecules, and may have a promising application in bioanalysis.

Water-soluble ZnCuInSe quantum dots for bacterial classification, detection, and imaging.

Bacteria are everywhere and pose severe threats to human health and safety. The rapid classification and sensitive detection of bacteria are vital steps of bacterial community research and the treatment of infection. Herein, we developed optical property-superior and heavy metal-free ZnCuInSe quantum dots (QDs) for achieving rapid discrimination of Gram-positive/Gram-negative bacteria by the naked eye; driven by the structural differences of bacteria, ZnCuInSe QDs are effective in binding to Gram-positive bacteria, especially Staphylococcus aureus (S. aureus), in comparison with Gram-negative bacteria and give discernable color viewed by the naked eye. Meanwhile, based on its distinctive fluorescence response, the accurate quantification of S. aureus was investigated with a photoluminescence system in the concentration ranges of 1 × 103 to 1 × 1011 CFU/mL, with a limit of detection of 1 × 103 CFU/mL. Furthermore, we demonstrated the feasibility of ZnCuInSe QDs as a fluorescence probe for imaging S. aureus. This simple strategy based on ZnCuInSe QDs provides an unprecedented step for rapid and effective bacterial discrimination, detection, and imaging.

Efficient photocatalytic inactivation of E. coli by Mn-CdS/ZnCuInSe/CuInS2 quantum dots-sensitized TiO2 nanowires.

A novel visible light-driven photocatalyst (represented as Mn-CdS/ZCISe/CIS/TiO2) for the passivation of E. coli was prepared with TiO2 nanowires as support and using CuInS2 (CIS) and ZnCuInSe (ZCISe) quantum dots (QDs), as well as Mn-doped CdS (Mn-CdS) nanoparticles (NPs) as sensitizers. The use of CIS and ZCISe QDs and Mn-CdS NPs extends the light harvest region to visible light. The photoelectric conversion efficiency was consequently improved, with a photocurrent density of 12.5 mA cm-2, about 60 times that of pure TiO2 nanowires. The germicidal efficiency of the photocatalyst was assessed by passivation of E. coli, 96% bacteria in 50 ml 105 colony forming units (CFU) ml-1 solution were killed within 50 min. Besides the high efficiency, the composite has good stability and satisfactory recycling performance. The antibiotic mechanism was also performed by using photoluminescence and a scavenging agent of different active matter, revealing that the photo-generated holes play a major role in the sterilization process.

Cobalt-doped nanoporous carbon as SALDI-TOF-MS adsorbent and matrix for quantification of cetyltrimethylammonium bromide, Rhodamine B and Malachite Green at sub-ppt levels.

Cobalt-doped nanoporous carbon (Co-NPC) with dodecahedral shape was pyrolytically synthesized and applied as a sorbent and matrix for the enrichment and analysis of small molecules by surface-assisted laser desorption/ionization time-of-flight mass spectrometry (SALDI-TOF MS). Extremely low detection limits were accomplished for cetyltrimethylammonium bromide (1 fg·mL-1), and Rhodamine B (1 fg·mL-1) in water, and Malachite Green and its metabolite in fish blood and fish extracts (pg·mL-1 concentrations). Graphical abstract Schematic representation of cobalt-doped nanoporous carbons (Co-NPCs) applied as SALDI matrix for analysis of toxic contaminants in fish and receipt papers. The Co-NPCs have a high desorption/ionization efficiency and low limit of detection.

Photoelectrocatalytic Hydrogen Generation Enabled by CdS Passivated ZnCuInSe Quantum Dot-Sensitized TiO2 Decorated with Ag Nanoparticles.

Here we present the photoelectrocatalytic hydrogen generation properties of CdS passivated ZnCuInSe (ZCISe) quantum dots (QDs) supported by TiO2 nanowires decorated with Ag nanoparticles. In this configuration, Ag nanoparticles were sandwiched between the photo-electrons collector (TiO2) and photo-sensitizers (ZCISe), and acted as an electron relay speeding up the charge carrier transport. ZCISe and CdS enabled the optical absorption of the photoelectrode ranging from ultraviolet to near infrared region, which significantly enhanced the solar-to-chemical energy conversion efficiency. A photocurrent of 10.5 mA/cm² and a hydrogen production rate of about 52.9 µmol/h were achieved under simulated sunlight (1.5 AG).