Multifunctional Cu-MSN@GCDs Nanocomposites Integrating Environment-Responsive Antibacterial Activity and Real-Time Fluorescence Monitoring

Abstract

In this study, Cu²⁺-doped mesoporous silica nanoparticles(MSNs)(Cu-MSNs)were synthesized via a hydrothermal method, using MSNs as the host matrix. Subsequently, green-emissive carbon dots(GCDs)were covalently grafted onto the surface of Cu-MSNs through an amidation reaction, yielding a nanocomposite denoted as Cu-MSN@GCDs. Cu-MSN@GCDs were designed to combine antibacterial and cellular imaging functions. The GCDs, derived from sodium citrate and formamide, exhibited fluorescence stability in a pH range of 3. 0- 10. 0 and possessed a specific Cu²⁺ fluorescence quenching property, enabling the detection of micromolar Cu²⁺. X-ray diffraction(XRD), Fourier transform infrared(FTIR)spectroscopy, and X-ray photoelectron spectroscopy(XPS)analyses confirmed that Cu-MSN @GCDs nanocomposites were successfully constructed. In vitro experiments showed that Cu-MSN @GCDs underwent significant degradation and released Cu²⁺ under acidic conditions(pH=4. 8), and effectively inhibited the growth of Staphylococcus aureus(S.aureus), with a minimum inhibitory concentration(MIC)of 0. 500 mg / mL. Additionally, the fluorescence imaging test showed a good multichannel color rendering ability in 4T1 cells. The nanocomposite combines environmentresponsive antibacterial activity and real-time fluorescence monitoring function, providing a new strategy for the development of multifunctional nano-drug delivery systems.

Keywords

mesoporous silica nanoparticle(MSN) / carbon dots doping / Cu²⁺ quenching / antibacterial property / cellular imaging

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