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.

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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 − 4 M and the linearity is good, especially at the clinical conventional concentration range ( 2.5 − 6.5 × 10 − 3 M ). In addition, the online Raman detection of creatinine aqueous solution LOD is 10 − 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.

In this paper, we present a microstructured optofluidic in-fiber Raman sensor for the detection of quinolone antibiotic residue in a water environment based on Ag surface-enhanced Raman scattering (SERS) substrate grown on the surface of the suspended core of micro-hollow optical fiber (MHF). Here, MHF has a special structure with a suspended core and a microchannel inside, which can become a natural in-fiber optofluidic device. Meanwhile, the self-assembled Ag SERS substrate can be grown on the suspended core’s surface through chemical bonds, forming a microstructured optofluidic device with a Raman enhancement effect. Therefore, it can effectively detect the Raman signal of unlabeled trace quinolone antibiotic residue (ciprofloxacin and norfloxacin) inside the optical fiber. The results show that the ciprofloxacin and norfloxacin detection limits (LOD) are 10 − 10 M and 10 − 11 M , respectively. Compared with the maximum residue limit ( 3.01 × 10 − 7 m o l / L ) stipulated by the European Union, the results are much lower, and an ideal quantitative relationship can be obtained within the detection range. Significantly, this study provides an in-fiber microstructured optofluidic Raman sensor for the label-free detection of quinolone antibiotic residue, which will have good development prospects in the field of antibiotic water pollution environmental detection.

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