Unique Fluorescent Imaging Probe for Bacterial Surface Localization and Resistant Enzyme Imaging

Abstract

Emergence of antibiotic bacterial resistance has caused serious clinical issues worldwide due to increasingly difficult treatment. Development of a specific approach for selective visualization of resistant bacteria will be highly significant for clinical investigations to promote timely diagnosis and treatment of bacterial infections. In this article, we present an effective method that not only is able to selectively recognize drug resistant AmpC β-lactamases enzyme but, more importantly, is able to interact with bacterial cell wall components, resulting in a desired localization effect on the bacterial surface. A unique and specific enzyme-responsive cephalosporin probe (DFD-1) has been developed for the selective recognition of resistance bacteria AmpC β-lactamase, by employing fluorescence resonance energy transfer with an "off-on" bioimaging. To achieve the desired localization, a lipid-azide conjugate (LA-12) was utilized to facilitate its penetration into the bacterial surface, followed by copper-free click chemistry. This enables the probe DFD-1 to be anchored onto the cell surface. In the presence of AmpC enzymes, the cephalosporin β-lactam ring on DFD-1 will be hydrolyzed, leading to the quencher release, thus generating fluorescence for real-time resistant bacterial screening. More importantly, the bulky dibenzocyclooctyne group in DFD-1 allowed selective recognition toward the AmpC bacterial enzyme instead of its counterpart ( e.g., TEM-1 β-lactamase). Both live cell imaging and cell cytometry assays showed the great selectivity of DFD-1 to drug resistant bacterial pathogens containing the AmpC enzyme with significant fluorescence enhancement (∼67-fold). This probe presented promising capability to selectively localize and screen for AmpC resistance bacteria, providing great promise for clinical microbiological applications.

Polymer Electrochromism Driven by Metabolic Activity Facilitates Rapid and Facile Bacterial Detection and Susceptibility Evaluation

“…[ 40 ] More recently, metabolic sensing of bacteria through a click reaction has been demonstrated, [ 38a,41 ] but such covalent binding raises concerns in perturbing bacterial structure and functions in living settings. [ 42 ]…”

“…[40] More recently, metabolic sensing of bacteria through a click reaction has been demonstrated, [38a,41] but such covalent binding raises concerns in perturbing bacterial structure and functions in living settings. [42] In this study, we introduced a water-soluble electrochromic ox-PPE, which undergoes extracellular reduction by the metabolites released by live bacteria. Our method avoids the perturbation of bacterial membrane.…”

Fluorogenic Probes/Inhibitors of β‐Lactamase and their Applications in Drug‐Resistant Bacteria

“…Lipid molecule fatty acid is an aturally-expressed cell surface component. [65] In 2018, Xing et al [66] group developed ap robe DFD-1 with fluorescein isothiocyanate as the reporter group and DABCYL as the quenching group (Figure 16 B). After as ynthetic azido-coupled fatty acid as am imic of fatty acid was successfully inserted into bacterial surface,the probe DFD-1 was applied.…”

“…Lipid molecule fatty acid is a naturally‐expressed cell surface component [65] . In 2018, Xing et al [66] . group developed a probe DFD‐1 with fluorescein isothiocyanate as the reporter group and DABCYL as the quenching group (Figure 16 B).…”

Development of small molecule probe for screening of bacterial resistant enzyme and their biomedical applications

“…Bacteria, one of the oldest living organisms on Earth, are unicellular prokaryotic microorganisms that play an essential function in regulating processes in the ecosystem as well as in living organisms. [1][2] In the ecosystem, bacteria play a significant role through cycling of carbon, nitrogen, and sulfur based nutrients; while in living organisms, although some bacteria cause serious diseases, numerous aid regulation of daily activities. To give an example, Escherichia coli in human large intestine synthesize vitamin K2, important for properly facilitated blood coagulation.…”