In this work, a self-assembled surface-enhanced Raman scattering (SERS) sensor based on an optofluidic microstructured hollow fiber (MHF) integrated composites of graphene oxide (GO), silver nanoparticles (Ag NPs), and 4mercaptophenylboronic acid (4-MPBA) as a glucose detection device was proposed. This SERS substrate is specific to glucose and grows on the outside of the core of MHF. Here, the MHF has a microchannel, where a suspended core was attached. In the microchannel, the trace sample solution was interacted with the SERS substrate, realizing the Raman online sensing detection of trace cerebrospinal fluid glucose. In the range of 0.5−10 mmol/L, the results present that detection of the glucose concentration shows good linearity without external interference. Meanwhile, this type of rapid, online, and label-free SERS sensor of glucose shows the ability to detect excessive glucose content in the actual cerebrospinal fluid environment of the Sprague−Dawley rats, providing a simple detection method for meningitis, meningeal multiple malignant tumor metastasis, and related diseases caused by abnormal glucose content in cerebrospinal fluid.
Particle size significantly affects the brightness of luminescent nanocrystals. Herein we firstly adopt a 1530 nm CW laser as the optical heating source to increase the particle size of Er3+ heavily doped nanocrystals, leading to giant enhancement of the luminescent intensity. The advantages of this method are mainly feature along the facile route, with an ultrafast process, and low threshold of the laser power density. The detailed mechanisms of the laser annealing are carefully investigated. In addition, fluorescence intensity ratio behaviours using different emission bands are comparatively investigated.
In this Letter, we propose a microstructured in-fiber optofluidic surface-enhanced Raman spectroscopy (SERS) sensor for the initial inspection of uremia through the detection of unlabeled urea and creatinine. As a natural microfluidic device, microstructured hollow fiber has a special structure inside. Through chemical bonds, the SERS substrate can be modified and grown on the surface of the suspended core. Here, the silver nanoparticles (Ag NPs) are embedded on the poly diallyl dimethyl ammonium chloride–modified graphene oxide sheet to achieve the self-assembled SERS substrate. The reduced distance between Ag NPs can increase the strong hot spots that generate enhanced Raman signals. Therefore, it can effectively detect the Raman signal of unlabeled trace uremic toxin analytes (urea, creatinine) inside the optical fiber. The results show that under simulated biophysical conditions, the limit detection (LOD) for urea is
10
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4
M
and the linearity is good, especially at the clinical conventional concentration range (
2.5
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6.5
×
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3
M
). In addition, the online Raman detection of creatinine aqueous solution LOD is
10
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6
M
, which also has good linearity. Significantly, this Letter provides a microstructured optofluidic in-fiber Raman sensor for the preliminary detection of uremia, which will have good development prospects in the field of clinical biomedicine.
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