Graphene oxide (GO)/graphene (GN) nanosheets were coated onto the poly(glycidyl methacrylate-ethylene dimethacrylate) monolithic bed synthesized inside the capillary in order to prepare a promising polymer monolith microextraction (PMME) material (GO/GN@poly(GMA-EDMA)). Various techniques, including Fourier transform infrared spectroscopy, atomic force microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, and scanning electron microscopy, were employed to characterize the synthesized GO/GN@poly(GMA-EDMA) monoliths, confirming that GO/GN was effectively functionalized on the poly(GMA-EDMA) monolithic materials. Furthermore, a new method was developed for the analysis of sarcosine (identified as a potential prostate cancer biomarker) using PMME coupled with liquid chromatography-tandem mass spectrometry (LC-MS/MS). Under the preoptimized conditions, the monolithic column afforded satisfactory enhancement factor (32-fold) and low limits of detection (1.0 ng mL(-1)) were obtained. In comparison to several other commercialized solid phase extraction adsorbents, GN@poly(GMA-EDMA) monoliths exhibited excellent performance with recoveries of sarcosine approaching 93% with relative standard deviations less than 11.5%.
An inverse opal photonic crystal sensor that could specifically detect chloramphenicol (CAP) in a label-free way was introduced in the current research. A colloidal crystal template was first prepared from monodisperse SiO(2) nanospheres. Precursors with different compositions were infused into the void spaces of the respective templates and aggregated. The template and the imprinted CAP were removed, and a molecularly imprinted photonic polymer (MIPP) with numerous nanocavities derived from the SiO(2) template was prepared. The MIPP could specifically recognize the target CAP. The results showed that the embedding and transporting of CAP could change the reflection peak intensity of the MIPP. The MIPP exhibited good responsiveness, with a detection range from 1 ng mL(-1) to 1 μg mL(-1) of CAP. The MIPP response time was 8 min upon its addition to CAP at a concentration of 10 ng mL(-1), which is shorter than that of other methods. After repeated use, the MIPP maintained a good performance and detection capacity. Thus, the results prove that the novel sensor could specifically detect CAP in a simple, time-saving, and low-cost manner.
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