Blood cellular membrane-coated Au/polydopamine nanoparticle-targeted NIR-II antibacterial therapy.

Bacterial infections are the primary causes of infectious diseases in humans. In recent years, the abuse of antibiotics has led to the widespread enhancement of bacterial resistance. Concerns have been raised about the identification of a common treatment platform for bacterial infections. In this study, a composite nanomaterial was used for near-infrared II (NIR-II) photothermal antibacterial treatment. Red blood cell membrane was peeled and coated onto the surface of the Au/polydopamine nanoparticle-containing aptamer. The composite nanomaterials based on Au/polydopamine exhibit highest photothermal conversion capability. Moreover, these assembled nanoparticles can quickly enter the body's circular system with a specific capability to recognise bacteria. In vivo experiments demonstrated that the composites could kill bacteria from infected blood while significantly reducing the level of bacteria in various organs. Such assemblies offer a paradigm for the treatment of bacterial infections caused by the side effects of antibiotics.

Recent Advances in Polyoxometalates with Enzyme-like Characteristics for Analytical Applications.

Artificial enzymes based on inorganic solids with both enzyme-mimetic activities and the special material features has been a promising candidate to overcome many deleterious effects of native enzymes in analytical applications. Polyoxometalates (POMs) are an importance class of molecular metal-oxygen anionic clusters. Their outstanding physicochemical properties, versatility and potential applications in energy conversion, magnetism, catalysis, molecular electronics and biomedicine have long been studied. However, the analytical applications of them is limited. Recently, the intrinsic enzymatic activities of POMs have also been found and become an area of growing interest. In this review, along with other reports, we aimed to classify the enzymatic activity of POMs, summarize the construction of POMs-based enzymes, and survey their recent advances in analytical fields. Finally, the current challenges and trends of the polyoxometalates with enzymatic activity in future chemo-/bio-sensing applications are briefly discussed.

A Multifunctional Janus Electrospun Nanofiber Dressing with Biofluid Draining, Monitoring, and Antibacterial Properties for Wound Healing.

Wound healing greatly affects patients' health and produces medical burden. Therefore, we developed a multifunctional electrospun nanofiber dressing, which can inhibit methicillin-resistant Staphylococcus aureus (MRSA), drain excessive biofluid to promote wound healing, and simultaneously monitor wound pH level. The polyoxometalate (α-K6P2W18O62·14H2O, P2W18) and oxacillin (OXA) are encapsulated in hydrophobic polylactide (PLA) nanofiber to synergistically inhibit MRSA. The phenol red (PSP) is encapsulated in hydrophilic polyacrylonitrile (PAN) nanofiber to sensitively indicate wound pH in situ. The PSP/PAN nanofiber is directly electrospun on the patterning OXA/P2W18/PLA nanofiber layer to form a Janus dressing. By taking advantage of the wettability difference between the two layers, the excess biofluid can be drained away from the wound. In addition, the Janus dressing exhibits good biocompatibility and accelerates wound healing via its antimicrobial activity and skin repairing function. This multifunctional Janus electrospun nanofiber dressing would be beneficial for wound management and treatment.

Multienzymatic Antioxidant Activity of Manganese-Based Nanoparticles for Protection against Oxidative Cell Damage.

Oxidative stress is related to many diseases, but available clinical treatment methods are currently limited. Exploitation of enzyme-mimicking nanomaterials (nanozymes) is a promising way for scavenging reactive oxygen species (ROS) and treatment of ROS-related diseases. Herein, the catalase (CAT), superoxide dismutase (SOD), and glutathione peroxidase (GPx) mimicking activities are expressed by MnO2 nanoparticles (MnO2-BSA NPs) coated with BSA. Effective •OH removal activity is also expressed by MnO2-BSA NPs at neutral pH. Apoptosis inhibition and ROS scavenging capabilities of MnO2-BSA NPs are evident on the H2O2-exposed BEAS-2B cells line. Western blot analysis indicates that MnO2-BSA NPs inhibit H2O2-induced apoptosis by mediating the expression of apoptosis-related proteins.

Vancomycin recognition and induced-aggregation of the Au nanoparticles through freeze-thaw for foodborne pathogen Staphylococcus aureus detection.

Infectious diseases caused by foodborne pathogens have become a serious public health problem. It is urgent to develop simple, rapid, and visual methods for pathogen detection. Herein, gold nanoparticles (AuNPs), aptamer and vancomycin (Van) based dual-recognition molecules and magnetic enrichment were combined to realize visual detection of Staphylococcus aureus (S. aureus). Initially, S. aureus was bounded to aptamer coupled Fe3O4 with high affinity and selectivity, which can achieve the separation and enrichment of S. aureus in complex sample matrix. Subsequently, the second recognition molecule, Van, was conjugated to S. aureus -Apt - Fe3O4. Finally, the unbound Van supernatant was dropped in AuNPs solution that induced the aggregation of the AuNPs through freeze-thaw. Firstly, it was found that AuNPs were stable in the presence of Van after a freeze-thaw cycle. A facile visual colorimetric detection of S. aureus was constructed with the linear range from 101 to 104 CFU/mL and the limit of detection (LOD) of 0.2 CFU/mL. By altering the aptamer, this method can be extended to the other Gram-positive bacteria. The proposed method has great potential applications in monitoring food contamination and infectious diseases.

Survival analysis of patients with tuberculosis and risk factors for multidrug-resistant tuberculosis in Monrovia, Liberia.

We reviewed the records of 337 confirmed cases of tuberculosis patients in Monrovia, the capital of Liberia, 2015. The risk factors affecting the survival and multidrug-resistance of tuberculosis patients were examined. Kaplan-Meier analysis and the log-rank test were used to assess the differences in survival among the patients, while Cox regression model was used for multivariate analysis. The qualitative data was tested with chi-square test in the single factor analysis of multidrug-resistant TB. Multivariate analysis was performed using binary logistic regression analysis. The significance level for all the tests were set at 0.05. The mean period of the follow-up of patients was 10 months. In the 337 patients, 33 (9.8%) died, the 21-month survival rate was 90.2%. The results of multivariate Cox regression analysis show that overcrowding (HR = 7.942, 95% CI 3.258-19.356), former smoking (HR = 3.773, 95% CI 1.601-8.889), current smoking (HR = 3.546, 95% CI 1.195-10.521), multidrug-resistance tuberculosis (HR = 4.632, 95% CI 1.913-11.217) were risk factors for death during anti-tuberculosis treatment in TB patients in Liberia. The results of binary logistic regression analysis show that extra-pulmonary (OR = 2.032, 95% CI 1.133-3.644), family history of TB (OR = 2.387, 95% CI 1.186-4.807) and current smoking (OR = 3.436, 95% CI 1.681-7.027) were risk factors for multidrug-resistant tuberculosis. These results can provide insights on local tuberculosis early intervention, increase public health awareness, and strengthen the control of factors that may affect the survival and multidrug-resistance of tuberculosis patients.

A GdW10@PDA-CAT Sensitizer with High-Z Effect and Self-Supplied Oxygen for Hypoxic-Tumor Radiotherapy.

Anticancer treatment is largely affected by the hypoxic tumor microenvironment (TME), which causes the resistance of the tumor to radiotherapy. Combining radiosensitizer compounds and O2 self-enriched moieties is an emerging strategy in hypoxic-tumor treatments. Herein, we engineered GdW10@PDA-CAT (K3Na4H2GdW10O36·2H2O, GdW10, polydopamine, PDA, catalase, CAT) composites as a radiosensitizer for the TME-manipulated enhancement of radiotherapy. In the composites, Gd (Z = 64) and W (Z = 74), as the high Z elements, make X-ray gather in tumor cells, thereby enhancing DNA damage induced by radiation. CAT can convert H2O2 to O2 and H2O to enhance the X-ray effect under hypoxic TME. CAT and PDA modification enhances the biocompatibility of the composites. Our results showed that GdW10@PDA-CAT composites increased the efficiency of radiotherapy in HT29 cells in culture. This polyoxometalates and O2 self-supplement composites provide a promising radiosensitizer for the radiotherapy field.

In Vitro Antifungal Activity and Mechanism of Ag3PW12O40 Composites against Candida Species.

Fungal infections pose a serious threat to human health. Polyoxometalates (POMs) are metal-oxygen clusters with potential application in the control of microbial infections. Herein, the Ag3PW12O40 composites have been synthesized and verified by Fourier transform infrared (FT-IR) spectrum, transmission electron microscopy (TEM), scanning electron microscope (SEM), elemental analysis, and X-ray diffraction (XRD). The antifungal activities of Ag3PW12O40 were screened in 19 Candida species strains through the determination of minimum inhibitory concentration (MIC) by the microdilution checkerboard technique. The minimum inhibitory concentration (MIC50) values of Ag3PW12O40 are 2~32 µg/mL to the Candida species. The MIC80 value of Ag3PW12O40 to resistant clinical isolates C. albicans HL963 is 8 µg/mL, which is lower than the positive control, fluconazole (FLC). The mechanism against C. albicans HL963 results show that Ag3PW12O40 can decrease the ergosterol content. The expressions of ERG1, ERG7, and ERG11, which impact on the synthesis of ergosterol, are all prominently upregulated by Ag3PW12O40. It indicates that Ag3PW12O40 is a candidate in the development of new antifungal agents.

Fluorometric Detection of Thiamine Based on Hemoglobin-Cu3(PO4)2 Nanoflowers (NFs) with Peroxidase Mimetic Activity.

Component analysis plays an important role in food production, pharmaceutics and agriculture. Nanozymes have attracted wide attention in analytical applications for their enzyme-like properties. In this work, a fluorometric method is described for the determination of thiamine (TH) (vitamin B1) based on hemoglobin-Cu3(PO4)2 nanoflowers (Hb-Cu3(PO4)2 NFs) with peroxidase-like properties. The Hb-Cu3(PO4)2 NFs catalyzed the decomposition of H2O2 into ·OH radicals in an alkaline solution that could efficiently react with nonfluorescent thiamine to fluoresce thiochrome. The fluorescence of thiochrome was further enhanced with a nonionic surfactant, Tween 80. Under optimal reaction conditions, the linear range for thiamine was from 5 × 10-8 to 5 × 10-5 mol/L. The correlation coefficient for the calibration curve and the limit of detection (LOD) were 0.9972 and 4.8 × 10-8 mol/L, respectively. The other vitamins did not bring about any obvious changes in fluorescence. The developed method based on hybrid nanoflowers is specific, pragmatically simple and sensitive, and has potential for application in thiamine detection.

An enhanced antibacterial nanoflowers AgPW@PDA@Nisin constructed from polyoxometalate and nisin.

A new composite, AgPW@PDA@Nisin, with shell-core structure was successfully synthesized by a polydopamine (PDA) surfaced conjugated nisin (an antibacterial 34 amino acid polycyclic peptide) as shell and polyoxometalates (Ag3PW12O40 = AgPW) as core. The composite was characterized by the zeta potential, scanning electron microscopy (SEM), transmission electron microscope (TEM), X-ray diffraction analysis (XRD), fourier transform infrared (FT-IR). The AgPW@PDA@Nisin showed flower hierarchical structure and potential antibacterial activity against S. aureus ATCC29213. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of it were 4 and 32 µg/mL. AgPW@PDA@Nisin nanoflowers-induced bacterial death bears the characteristic of cell morphology, membrane integrity and permeability changing, nucleotide leakage. It indicated that the AgPW@PDA@Nisin interfere with the cell membrane, resulting in antibacterial activity against S. aureus. The cytotoxicity of the nanoflowers was low on HDF-a (human dermal fibroblasts) cells. A new class of hybrid inorganic-organic nanoflowers based on polyoxometalates and nisin with enhanced antibacterial properties can be developed for food preservation.