Sensitive and Selective Near-Infrared Fluorescent Off–On Probe and Its Application to Imaging Different Levels of β-Lactamase in Staphylococcus aureus

Abstract

A highly sensitive and selective near-infrared (NIR) fluorescent probe, (E)-2-(2-(6-((2-carboxy-8-oxo-7-(2-phenylacetamido)-5-thia-1-azabicyclo[4.2.0]oct-2-en-3-yl)methoxy)-2,3-dihydro-1H-xanthen-4-yl)vinyl)-3,3-dimethyl-1-propyl-3H-indol-1-ium (1), is developed for the determination of β-lactamase. The probe is designed and synthesized by incorporating the specific substrate (cephalosporin) of β-lactamase into a stable hemicyanine skeleton. The fluorescence of 1 itself is very weak due to the alkylation of the hydroxyl group of the hemicyanine fluorophore; however, β-lactamase can selectively react with its substrate (β-lactam ring) in the probe, thereby causing a spontaneous fragmentation. This action leads to the release of the fluorophore and a large fluorescence enhancement at 707 nm (λex = 680 nm). Under the optimized conditions, the fluorescence response of probe 1 is directly proportional to the concentration of β-lactamase in the range of 0.05-2 nM, with a detection limit of 0.02 nM. The validity of the probe has been confirmed by determining β-lactamase in human urine samples in comparison with that determined by iodimetry. Moreover, by taking advantage of its high sensitivity and NIR emission feature, the probe has also been utilized to image β-lactamase in three types of Staphylococcus aureus, including methicillin-resistant S. aureus ATCC BAA44, penicillin-resistant strain ATCC 11632, and penicillin-susceptible strain ATCC 29213, which clearly reveals the significantly different expression levels of β-lactamase in these S. aureus.

Sensitive Fluorescence Probe with Long Analytical Wavelengths for γ-Glutamyl Transpeptidase Detection in Human Serum and Living Cells

“…The results obtained from the two methods are in good agreement with each other, and no significant difference is found at the 90% confidence level using a paired t-test. 20,28 Therefore, the proposed method can be satisfactorily applied to the quantitative determination of GGT in clinical samples such as human serum. [a] In both methods, serum samples were 10-fold diluted for measurement, and the values (mean of three determinations ± standard deviation) represent GGT levels in the undiluted samples.…”

Chemiluminescent Carbapenem‐Based Molecular Probe for Detection of Carbapenemase Activity in Live Bacteria

“…Because of these difficulties,c onsiderable efforts have been invested in searching for new improved methods that are sensitive, specific,r apid, and cost-effective. Following the successful development of b-lactamase-responsive chromogenica nd fluorogenic molecular probes for the identification of bacterial pathogens, [20][21][22][23][24][25][26][27][28][29] scientists are now actively seekings imilar methods for the specific detectiono fc arbapenemasea nd CPOs.…”

pH‐Responsive, Light‐Triggered on‐Demand Antibiotic Release from Functional Metal–Organic Framework for Bacterial Infection Combination Therapy

“…In particular, drug release mechanisms with triggers that respond to surrounding factors, such as pH, temperature, illumination, and enzymes are of high practical significance. Toward this goal, various nanomaterials including nanoparticles, microgels, nanotubes,polymeric micelles, and fluorescent probe are or can be designed to be particularly sensitive to environmental factors.…”