Bacterial detection with amphiphilic carbon dots

Abstract

New bacterial detection and imaging methods are desirable for diagnostics and healthcare applications, as well as in basic scientific research. We present a simple analytical platform for bacterial detection and imaging based upon attachment of amphiphilic carbon dots (CDs) to bacterial cells. We show that CDs functionalized with hydrocarbon chains readily bind to bacterial cells following short incubation and enable detection of bacteria through both fluorescence spectroscopy and microscopy. Importantly, we demonstrate that the intensity and spectral position of the carbon dots' fluorescence depend upon bacterial species, providing a tool for distinguishing among bacteria even in cases of mixed bacterial populations. Moreover, bacterial labelling with the amphiphilic CDs enables visualization of physiological processes such as cell division.

Single Upconversion Nanoparticle–Bacterium Cotrapping for Single‐Bacterium Labeling and Analysis

“…Regarding bacterium labeling, in addition to the intrinsic advantages of UCNPs such as intense photoluminescence detectable at the single‐particle level, resistance to photoblinking and photobleachng, lack of an autofluorescence background, and minimized photodamage to cells, compared with the previously reported methods for the fluorescent labeling of bacteria, the main advantages of our method are: (1) labeling can be achieved at the single‐bacterium level; (2) the labeling UCNPs are directly optically connected to the bacteria without requiring complex biochemical procedures, and this method can be applied to different kinds of bacteria and cells, not just limited to some specific kinds requiring specific biochemical treatments for the modification of fluorescent nanomaterials; (3) the labeled single bacterium can be moved to designated locations in 3D for further specific analysis; (4) observation, identification, and analysis of the single labeled bacteria can be realized from the emitting green light of UCNPs; (5) the dynamic signal from a labeled bacterium can be detected in real time (which is critical for single‐bacterium analysis), and (6) single‐bacterium sizing can be realized.…”

“…These methods have shown extremely high detection sensitivity of bacteria due to the absence of background noise, because biological samples exhibit virtually no magnetic background . While fluorescent labeling methods use fluorescent nanomaterials, such as fluorescent‐bioconjugated silica nanoparticles, quantum dots, carbon dots, and fluorescent micelles, as labeling probes. These fluorescent nanomaterials show many advantages over common fluorophores.…”

Luminescent assays based on carbon dots for inorganic trace analysis

“…In this sense, CDs have been applied for detection of biological (Cai et al 2015, Mehta et al 2015, Nandi et al 2015, Niu et al 2015, organic Huang et al 2014a, and inorganic (Yin et al 2013, Liu et al 2014b, Zhang and Chen 2014c, Zhao et al 2014a, Cui et al 2015, Gogoi et al 2015 species. Regarding inorganic trace analysis, a dramatic increase in the number of publications describing CD-based systems has occurred in the last 2 years (Figure 1).…”

Carbon-dot–hydrogel for enzyme-mediated bacterial detection

“…31,32 Cdots have been recently used as a platform for bacterial sensing and imaging. 33 Hybrid carbon-dot hydrogel systems were also used for detection of heavy metal ions.…”