Redox homeostasis between hypochlorous
acid (HClO/ClO–) and ascorbic acid (AA) significantly
impacts many physiological
and pathological processes. Herein, we report a new electrochemical
sensor for the simultaneous determination of HClO and AA in body fluids.
We first coated a carbon fiber microelectrode (CFME) with a three-dimensional
nanocomposite consisting of graphene oxide (GO) and carbon nanotubes
(CNTs) to fabricate the CFME/GO–CNT electrode. After the electrochemical
reduction of GO (ERGO), we integrated a latent 1-(3,7-bis(dimethylamino)-10H-phenothiazin-10-yl)-2-methylpropan-1-one (MBS) electrochemical
molecular recognition probe to monitor HClO and employed anthraquinone
(AQ) as an internal reference. The compact CFME/ERGO–CNT/AQ
+ MBS sensor enabled the accurate and simultaneous measurement of
HClO and AA with excellent selectivity and sensitivity. Measurements
were highly reproducible, and the sensor was stable and exceptionally
biocompatible. We successfully detected changes in the redox cycles
of HClO and AA in human body fluids. This sensor is a significant
advance for the investigation of reactions involved in cellular redox
regulation. More importantly, we have devised a strategy for the design
and construction of ratiometric electrochemical biosensors for the
simultaneous determination of various bioactive species.
The microbiota is directly involved in the development and modulation of the intestinal immune system. In particular, members of the genus
Bifidobacterium
play a primary role in immune regulation. In the present study,
Bifidobacterium bifidum
H3-R2 was screened from 15 bifidobacterium strains by
in vitro
experiment, showing a positive tolerance to digestive tract conditions, adhesion ability to intestinal epithelial cells and a regulatory effect on immune cell activity. Immunostimulatory activity of
B. bifidum
H3-R2 was also elucidated
in vivo
in cytoxan (CTX)-treated mice. The results showed that the administration of
B. bifidum
H3-R2 ameliorated the CTX-induced bodyweight loss and imbalanced expression of inflammatory cytokines, enhanced the production of secretory immunoglobulin A (SIgA), and promoted splenic lymphocyte proliferation, natural killer (NK) cell activity and phagocytosis of macrophages in immunosuppressed mice. In addition,
B. bifidum
H3-R2 restored injured intestinal mucosal, and increased the villus length and crypt depth in CTX-treated mice. The results could be helpful for understanding the functions of
B. bifidum
H3-R2, supporting its potential as a novel probiotic for immunoregulation.
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