Imitation-mussel fluorescent silicon quantum dots for selective labeling and imaging of bacteria and biofilms

Abstract

Selective labeling of distinct bacteria and biofilm is poised for the fundamental understanding of bacterial activities, interactions, and coupled phenomena occurring at the microscale. However, a simple and effective way to achieve selective bacterial labeling is still lacking. Herein, we report a fluorescence probe with core-shell nanostructure that has polydopamine (PDA) coating on the surface of fluorescent silicon quantum dots (SiQDs@PDA). The surface of the SiQDs@PDA can be functionalized by various molecules (2-mercaptoethylamine hydrochloride, PEG, d-alanine, glucose amide) through different strategies (Michael addition, π-π interaction, and ion–ion interaction). Importantly, the d-alanine (D-Ala)- and gluconamide (Glc)-functionalized SiQDs@PDA fluorescence probes are capable of selectively labeling gram-positive and gram-negative bacteria, as well as their biofilms. The excellent performance in universal functionalization and selective labeling and imaging of bacteria and their biofilms demonstrate that SiQDs@PDA are a promising fluorescence tool in microbe research.

Sialic acid-targeting multi-functionalized silicon quantum dots for synergistic photodynamic and photothermal cancer therapy

“…Firstly, SiQDs were coated with a thin layer of PDA by simply mixing SiQDs with dopamine in weakly basic Tris buffer at room temperature as reported in our previous publication. 45 Subsequently, Ce6 was conjugated to SiQDs@PDA through the amide condensation reaction in the presence of EDC and NHS, followed by the coupling of PBA onto the outer layer of SiQDs via the Michael addition reaction between PDA and SH-PBA. TEM images showed that SiQDs@Ce6/PBA maintained the spherical shape of SiQDs and had an average diameter of ∼10 nm (Fig.…”

“…proteins and DNA) via multiple mechanisms, including hydrogen bonding interactions, covalent bond reconstruction, or π–π stacking. 45 Therefore, by means of the PDA-mediated conjugation method, we hypothesized that a robust PDT/PTT-delivery-system based on SiQDs could be fabricated for enhanced synergistic PDT/PTT cancer therapy. In addition, because PDA can naturally display the photothermal effect upon NIR light irradiation, 46,47 there is no need for adding any other PTAs, which can further simplify the fabrication process.…”

Silicon Compound Nanomaterials: Exploring Emission Mechanisms and Photobiological Applications

“…An example is the work of Jiayi Lin et al, who performed selective labeling of distinct bacteria and biofilms to distinguish between Gram‐positive and Gram‐negative bacteria (Figure 17b). [ 206 ]…”

“…Reproduced under the terms of a Creative Commons Attribution CC‐BY License. [ 206 ] Copyright 2022, The Authors, published by Frontiers.…”

“…An example is the work of Jiayi Lin et al, who performed selective labeling of distinct bacteria and biofilms to distinguish between Gram-positive and Gramnegative bacteria (Figure 17b). [206] Moreover, the convergence of many areas like nanomaterials engineering, microbiology, and biomedicine can provide innovations from a multidisciplinary perspective achieving proof-ofconcept applications. Pathogen and virus detection has gained particular attention derived from the recent SARS-CoV2 pandemic and bacterial resistance, which are public concern issues that affect significantly the global population and must be promptly solved.…”