Multi-Stimulus Responsive Multilayer Coating for Treatment of Device-Associated Infections.

Antibacterial coating with antibiotics is highly effective in avoiding device-associated infections (DAIs) which is an unsolved healthcare problem that causes significant morbidity and mortality rates. However, bacterial drug resistance caused by uncontrolled release of antibiotics seriously restricts clinical efficacy of antibacterial coating. Hence, a local and controlled-release system which can release antibiotics in response to bacterial infected signals is necessary in antibacterial coating. Herein, a multi-stimulus responsive multilayer antibacterial coating was prepared through layer-by-layer (LbL) self-assembly of montmorillonite (MMT), chlorhexidine acetate (CHA) and Poly(protocatechuic acid-polyethylene glycol 1000-bis(phenylboronic acid carbamoyl) cystamine) (PPPB). The coating can be covered on various substrates such as cellulose acetate membrane, polyacrylonitrile membrane, polyvinyl chloride membrane, and polyurethane membrane, proving it is a versatile coating. Under the stimulation of acids, glucose or dithiothreitol, this coating was able to achieve controlled release of CHA and kill more than 99% of Staphylococcus aureus and Escherichia coli (4 × 108 CFU/mL) within 4 h. In the mouse infection model, CHA releasing of the coating was triggered by infected microenvironment to completely kill bacteria, achieving wounds healing within 14 days.

Nanoliquid Dressing with Enhancing Anti-Infection Performance under the Moderate Photothermal Effect for Wound Treatment.

Nonhealing wounds have become a major healthcare burden worldwide. Chronic wound healing is universally hampered by the presence of bacterial infections that form biofilms. Therefore, in this study, a novel nanoliquid dressing based on a mild photothermal heating strategy was designed to provide safe healing of biofilm-infected wounds. Dilute nitric acid (HNO3) solution was employed to induce a redox process triggered by copper sulfide (CuS) nanoplates in the nanoliquid dressing. This redox process was further promoted by the mild photothermal effect (≤47.5 °C) that generated a sufficient amount of reactive oxygen species, resulting in less thermal injury to normal tissues. Correspondingly, with the safe concentration of CuS nanoplates (0.4 mg/mL), excellent bactericidal efficiencies up to 98.3 and 99.3% against ampicillin-resistant Escherichia coli (Ampr E. coli) and Staphylococcus aureus (S. aureus) were achieved, respectively. Moreover, the nanoliquid dressing exhibited a near-infrared enhanced destructive effect on mature biofilms. According to in vivo wound healing experiments in mice, the nanoliquid dressing increased the healing rate and reduced the inflammatory response. This study provides a novel insight into treating the biofilm-infected chronic wounds in the "post-antibiotic era".

Upconversion nanoparticle and gold nanocage satellite assemblies for sensitive ctDNA detection in serum.

A rapid molecular diagnostic technique targeting circulating tumor DNA (ctDNA) has become one of the most clinically significant liquid biopsy methods for non-invasive and timely diagnosis of cancer. Herein, a sensitive detection system of ctDNA based on a fluorescence resonance energy transfer (FRET) system using upconversion nanoparticles (UCNPs) and gold nanocages (AuNCs) was constructed. Through the doping of Yb and Tm ions, the excitation and emission wavelengths of UCNPs were adjusted to 980 nm and 806 nm, respectively. Subsequently, UCNPs and AuNCs with the corresponding wavelength absorption were linked by complementary pairing of surface-modified DNA to form near-infrared fluorescent nanoprobes (NIR probes). Targeting DNA mutation recognition and signal transduction were realized by using NIR probes through the toehold-mediated strand displacement reaction. This method could detect a single point mutation of the KRAS gene with a wide detection range from 5 pM to 1000 pM and the limit of detection reached 6.30 pM. More importantly, the stable and highly specific NIR probes could be directly used in the serum environment without complicated pretreatment and amplification processes in advance. It could be envisioned that this specific and sensitive ctDNA detection strategy has great potential in clinical diagnosis and monitoring of diverse malignant tumors.