Hybrids of Upconversion Nanoparticles and Silver Nanoclusters Ensure Superior Bactericidal Capability via Combined Sterilization

Abstract

It is highly desired to develop new antibacterial agents with superior bactericidal efficiency for minimizing the damage to biological cells. We developed a combined antibacterial nanohybrid exhibiting a superb bactericidal effect and excellent biocompatibility by integrating upconversion nanoparticles (UCNPs) with silver nanoclusters (AgNCs). UCNPs and methylene blue (MB) molecules were encapsulated with silica microspheres via microemulsion, with MB as the photosensitizer. Silver ions (Ag + ) were reduced by amino groups on the surface of silica spheres, wherein silver nanoclusters (AgNCs) were formed in situ to produce the nanohybrid, UCNPs@SiO 2 (MB)@AgNCs. UCNPs emit visible light at 655 nm under excitation by near-infrared radiation (NIR, 980 nm). MB absorbs the emission from UCNPs to generate toxic singlet oxygen ( 1 O 2 ), which leads to the apoptosis of bacteria cells. Meanwhile, silver ions released from AgNCs destroy the bacteria membrane structure. Upon NIR irradiation at 980 nm for 10 min, 8.33 μg mL −1 nanohybrid results in a 100% killing rate for both Gram-positive S. aureus (+) and Gram-negative E. coli (−).

Enhanced Eradication of Enterococcus faecalis Biofilms by Quaternized Chitosan-Coated Upconversion Nanoparticles for Photodynamic Therapy in Persistent Endodontic Infections

“…The chemical feature of QCh, UCNP@SiO 2 /MB, and UCNP@SiO 2 /MB@QCh was measured by FTIR analysis ( Figures 2C,D ). After salinization, UCNP@SiO 2 /MB showed two strong absorption bands at 1,066 and 800 cm −1 due to asymmetric, symmetric stretching vibrations and bending vibrations of the Si-O-Si bond (Liu et al, 2020 ). This provided an elucidation for the successful synthesis of UCNP@SiO 2 /MB.…”

“…Then, the mixture was incubated in a shaking incubator for an hour (Li et al, 2017 ). Next, 200 μl mixture suspension was illuminated by a 980 nm laser for 10 min (Liu et al, 2020 ). The control group included the solution of 1 ml bacterial strain and 1 ml BHI medium.…”

“…For instance, Liu et al verified the antibacterial effect of UCNP@SiO 2 /MB against Staphylococcus aureus and Escherichia coli . The death rates of these two bacteria were achieved at 37.56 ± 4.00% and 63.97 ± 5.26%, respectively (Liu et al, 2020 ). The antibacterial effect of UCNP@SiO 2 /MB was relatively low for Gram-negative bacteria, as the negatively charged nanoparticles were difficult to contact and interact with negatively charged bacteria rapidly and directly (Yue et al, 2018 ; Ahmed et al, 2020 ).…”

Highly Sensitive Lanthanide-Doped Nanoparticles-Based Point-of-Care Diagnosis of Human Cardiac Troponin I

“…15,16 Furthermore, Ln 3+ ions-doped NPs based LFA can achieve highly sensitive bioanalysis. For example, Liu et al 17 employed near infrared lanthanide-doped NPs modified FLA platform with low interference and low detection limit. Chen et al 18 reported a lanthanide-doped polystyrene NPs based LFA, and the result was consistent with clinical diagnosis.…”

Insight into the antibacterial resistance of graphdiyne functionalized by silver nanoparticles

“…Silver‐based materials have been used as disinfectants empirically for a long history. In the last few decades, various forms of nano‐silver species were widely used as antibacterial components in coatings, 7 wound dressings 8,9 and other products, 10–12 due to their high bactericidal efficiency. Nevertheless, silver is not always effective, for resistance to ionic silver has been acknowledged for years 13–15 .…”