Efficient elimination of multidrug-resistant bacteria using copper sulfide nanozymes anchored to graphene oxide nanosheets

Antibacterial nanomaterials have attracted growing interest for bacterial infection therapy.However,most nanomaterials eliminate bacteria either physically or chemically,which hampers their efficacy when dealing with multidrug-resistant bacteria.To overcome this,we integrated copper sulfide(CuS)nanoparticles with active graphene oxide nanosheets(GO NSs)to synthesize a superior nanocomposite(CuS/GO NC)that acts both physically and chemically on the bacteria.CuS/GO NC was produced using a facile hydrothermal method,whereby the CuS nanoparticles grew and were uniformly dispersed on the GO NSs in situ.We found that the CuS/GO NC possesses a unique needle-like morphology that physically damages the bacterial cell membrane.CuS/GO NC also exhibits high oxidase-and peroxidase-like activity,ensuring efficient generation of the reactive oxygen species•OH from H2O2,which kills bacteria chemically.These features endow the CuS/GO NC with excellent antibacterial capabilities to kill multidrug-resistant bacteria such as methicillin-resistant Staphylococcus aureus(MRSA)with only a single dose.Additionally,it was found that the CuS/GO NC accelerated the healing of infected wounds in vivo owing to its good biocompatibility as well as facilitation of cell migration and collagen secretion.This study provides a new strategy to combine the physical and chemical antibacterial modes of nanomaterials to develop more effective therapies to combat multidrug-resistant bacterial infections.

Gadolinium-hyaluronic acid nanoparticles as an efficient and safe magnetic resonance imaging contrast agent for articular cartilage injury detection

Accurate detection of cartilage injuries is critical for their proper treatment because these injuries lack the selfhealing ability and lead to joint dysfunction.However,the low longitudinal T1 relaxivity(r1)and non-specificity of contrast agents(such as gadolinium(III)-diethylenetriamine-pentaacetic acid(Gd-DTPA))significantly limit the efficiency of clinical magnetic resonance imaging(MRI)applications.To overcome these drawbacks,we integrated hyaluronic acid(HA)with Gd to synthesize a Gd-DTPA-HA composite,which was subsequently freeze-dried to produce nanoparticles(NPs).The resultant Gd-HA NPs demonstrated a greater r1 value(12.51 mM^-1 s^-1)compared with the bulk Gd-DTPA-HA(8.37 mM^-1 s^-1)and clinically used Gd-DTPA(3.88 mM^-1 s^-1).Moreover,the high affinity of HA to the cartilage allowed these NPs to penetrate deeper beyond the cartilage surface.As a result,Gd-HA NPs considerably increased the quality of cartilage and lesion MR images via their intra-articular injection in vivo.Specifically,2 h after NP administration,the signal-to-noise ratio at the injured cartilage site was 2.3 times greater than the value measured before the injection.In addition,Gd-HA NPs exhibited good biosafety properties due to the absence of adverse effects in the blood or on the main organs.It was also showed that Gd NPs were first metabolized by the kidney and liver and then excreted from the body with urine.Thus,Gd-HA NPs can potentially serve as an efficient MRI contrast agent for improved detection of cartilage injuries.