A near-infrared light-triggered nano-domino system for efficient biofilm eradication: Activation of dispersing and killing functions by generating nitric oxide and peroxynitrite via cascade reactions.

One of the serious threats to global public health is the bacterial biofilm, which results in numerous persistent and recurrent infections. Herein, we proposed a near-infrared (NIR) light-triggered "nano-domino" system with "dispersing and killing" functionality for biofilm eradication. The nanoplatform was fabricated by the self-assembly of chitosan conjugated with L-arginine (L-Arg, a natural nitric oxide (NO) donor) and indocyanine green (ICG, a phototherapy agent). Using an NIR irradiation "trigger", a series of reactive oxygen species (ROS) including singlet oxygen (1O2), hydrogen peroxide (H2O2), and superoxide anions (·O2-), as well as heat were generated from ICG aggregates. Subsequently, 1O2 and H2O2 catalyzed L-Arg to produce NO, which dispersed the biofilm and reacted with ·O2- to form peroxynitrite to kill bacteria with ROS collaboratively. Meanwhile, the generated heat increased the permeability of bacterial membranes, aggravating the damage to biofilm bacteria. The experiments on biofilm eradication demonstrated that this "nano-domino" system was capable to eradicate over 99.99% of biofilms formed by Methicillin-resistant Staphylococcus aureus (MRSA) and Pseudomonas aeruginosa under 5-min NIR irradiation. Notably, these integrated benefits allowed the system to promote the healing of MRSA biofilm-infected wounds in vivo with negligible toxicity. Overall, this reported NIR-triggered "nano-domino" system holds great promise for addressing the difficulties associated with bacterial biofilm eradication. STATEMENT OF SIGNIFICANCE: Novel agents for biofilm eradication are urgently needed due to the alarming rise in antimicrobial resistance to conventional antibiotics and the critical shortage of new drugs. In this study, we created a nano-domino system that uses near-infrared (NIR) light as a trigger to eradicate mature biofilms. In response to a short-term NIR irradiation, the proposed nanoplatform could generate nitric oxide and peroxynitrite to disperse the biofilm and kill the bacteria inside, respectively, leading to efficient eradication of Methicillin-resistant Staphylococcus aureus and Pseudomonas aeruginosa biofilms with minimal cytotoxicity. The findings, therefore, indicate that this nanoplatform with enhanced antibiofilm performance might provide a reliable and promising solution to biofilm-related problems.

Recent Advances in Dual-Function Superhydrophobic Antibacterial Surfaces.

Bacterial adhesion and subsequent biofilm formation on the surfaces of synthetic materials imposes a significant burden in various fields, which can lead to infections in patients or reduce the service life of industrial devices. Therefore, there is increasing interest in imbuing surfaces with antibacterial properties. Bioinspired superhydrophobic surfaces with high water contact angles (>150°) exhibit excellent surface repellency against contaminations, thereby preventing initial bacterial adhesion and inhibiting biofilm formation. However, conventional superhydrophobic surfaces typically lack long-term durability and are incapable of achieving persistent efficacy against bacterial adhesion. To overcome these limitations, in recent decades, dual-function superhydrophobic antibacterial surfaces with both bacteria-repelling and bacteria-killing properties have been developed by introducing bactericidal components. These surfaces have demonstrated improved long-term antibacterial performance in addressing the issues associated with surface-attached bacteria. This review summarizes the recent advancements of these dual-function superhydrophobic antibacterial surfaces. First, a brief overview of the fabrication strategies and bacteria-repelling mechanism of superhydrophobic surfaces is provided and then the dual-function superhydrophobic antibacterial surfaces are classified into three types based on the bacteria-killing mechanism: i) mechanotherapy, ii) chemotherapy, and iii) phototherapy. Finally, the limitations and challenges of current research are discussed and future perspectives in this promising area are proposed.

Studies on the regulatory effect of Peony-Glycyrrhiza Decoction on prolactin hyperactivity and underlying mechanism in hyperprolactinemia rat model.

Clinical trials have demonstrated the beneficial effects of Peony-Glycyrrhiza Decoction (PGD) in alleviating antipsychotic-induced hyperprolactinemia (hyperPRL) in schizophrenic patients. In previous experiment, PGD suppressed prolactin (PRL) level in MMQ cells, involving modulating the expression of D2 receptor (DRD2) and dopamine transporter (DAT). In the present study, hyperPRL female rat model induced by dopamine blocker metoclopramide (MCP) was applied to further confirm the anti-hyperpPRL activity of PGD and underlying mechanism. In MCP-induced hyperPRL rats, the elevated serum PRL level was significantly suppressed by either PGD (2.5-10 g/kg) or bromocriptine (BMT) (0.6 mg/kg) administration for 14 days. However, in MCP-induced rats, only PGD restored the under-expressed serum progesterone (P) to control level. Both PGD and BMT administration restore the under-expression of DRD2, DAT and TH resulted from MCP in pituitary gland and hypothalamus. Compared to untreated group, hyperPRL animals had a marked reduction on DRD2 and DAT expression in the arcuate nucleus. PGD (10 g/kg) and BMT (0.6 mg/kg) treatment significant reversed the expression of DRD2 and DAT. Collectively, the anti-hyperPRL activity of PGD associates with the modulation of dopaminergic neuronal system and the restoration of serum progesterone level. Our finding supports PGD as an effective agent against hyperPRL.