Bacterial determination, emerging as a critical step in the understanding of increasingly serious bacterial contaminations, remains a major challenge. Herein, a novel chemiluminescence biosensor was exploited for the ultrasensitive determination of nuclease activity and bacteria, in which, hemin, the chemiluminescent (CL) tag molecule was encapsulated into ordered mesopores of mesoporous silica nanoparticles with a specific DNA gate. The capped DNA could be specifically switched upon exposure to the DNA nuclease or bacterial lysate and allowed for an increased release of the encapsulated hemin, which therefore resulted in an obviously enhanced CL signal for the luminol−H 2 O 2 system. Attributed to this unique behavior with the linear or sigmoidal relationship between CL intensity and DNA nuclease or bacterial concentration, the as-prepared CL biosensor could detect S1 nuclease activity in the concentration range 0.01−10.0 U with a detection limit of 0.1 mU, and Escherichia coli O157:H7 (E. coli) or Staphylococcus aureus (S. aureus) in the concentration ranges 10 1 to 10 9 cfu mL −1 . The detection limit of E. coli and S. aureus was calculated to be 3.0 and 2.5 cfu mL −1 , respectively, which was comparable or even better than that of previous studies. Thus, this detection method could achieve detectable levels without cell enrichment overnight. Moreover, the proposed biosensing system could be conducted in the homogeneous solution without separation and washing, greatly improving the reaction efficiency and simplifying the procedure. As expected, the novel CL biosensor promised a great potential for simple and convenient detection of nuclease and bacteria in fields such as food bacterial contamination, pharmaceuticals, and clinical analysis.
Fibroblast
activation protein-alpha (FAPα) is a key modulator
of the microenvironment in multiple pathologies and is becoming the
next pan-cancer target for cancer diagnostics and therapeutics. Chemiluminescence
(CL) luminophores are considered as one of the most sensitive families
of probes for detection and imaging applications due to their high
signal-to-noise ratio. Until now, however, no such effective CL probe
was reported for FAPα detection. Herein, we developed a novel
CL probe for the detection of endogenous FAPα activity by incorporating
FAPα-specific dipeptide substrates (glycine-proline) to the
improved Schaap’s adamantylidene-dioxetane. In this manner,
we designed three CL probes (CFCL, BFCL,
and QFCL) with the dipeptide substrate blocked by N-terminal
benzyloxycarbonyl, N-tert-butoxycarbonyl
or N-quinoline-4-carboxylic acid, respectively, which
was used as the masking group to restrain the chemiexcitation energy.
Probe CFCL exhibited the optimal specificity for the
discrimination of FAPα from dipeptidase IV and prolyl oligopeptidase,
which was elucidated by molecular docking simulation. Upon FAPα
cleavage, CFCL was turned on for the highly selective
and sensitive detection of FAPα with a limit of detection of
0.785 ng/mL. Furthermore, the ability of CFCL to image
FAPα was effectively demonstrated in vitro, including various
biological samples (plasma and tissue preparations), and in living
systems (tumor cells and tumor-bearing mice). Furthermore, this newly
established probe could be easily extended to evaluate FAPα
inhibitors. Overall, we anticipate that probe CFCL will
offer a facile and cost-effective alternative in the early detection
of pathologies, individual tailoring of drug therapy, and drug screening.
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