(A) Preparation of (GPTS-APTS) modified MWCNT solution/GA-CNT, (B) preparation of sol–gel active and partially cured polymer matrix and (C) preparation of ECB-CNT composite.

This work describes the preparation of an analytical microextraction sorbent using a simple and versatile sol–gel hybrid composite, i.e. , aramid oligomers wrapping multi-walled carbon nanotubes (CNTs) covalently bonded to a porous silica network.

Detecting tissue pH in vivo is extremely vital for medical diagnosis and formulation of treatment decisions. To this end, many investigations have been carried out to develop an accurate and efficient method of in vivo pH measurement. Most of the techniques developed so far suffer from inadequate accuracy, due to poor sensitivity at low concentration of the target or nonspecific interactions within the tissue matrix. To overcome these issues, we describe herein the development of a simple, yet reliable, way to estimate pH with high precision using a Gd(III)-DOTA-silyl-based acid-labile group as a pH-sensitive contrast agent with Magnetic Resonance Imaging (MRI). With this method, a change in ${\mathrm{T}}_1$ weighted image intensity of the newly developed pH-sensitive contrast is directly linked to the proton concentration in the media. As a result, we were able estimate the pH of the target with 95% reliability.

A hybrid sorbent material was developed by modifying nitrogen-doped graphene quantum dots (N-GQDs) with 3-glycidyloxypropyltrimethoxysilane (GPTMS) and 3-aminopropyltriethoxysilane (APTS), producing functionalized GQDs (f-GQDs) with enhanced extraction capabilities. Combining the adsorption properties of GQDs with the functional versatility of silanes, this material effectively serves as a solid-phase extraction sorbent for non-steroidal anti-inflammatory drugs (NSAIDs) from aqueous matrices. The f-GQDs composite was thoroughly characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), atomic force microscopy (AFM), and zeta potential analysis, confirming structural integrity and functional enhancements. The synergistic effects of silanes on the N-GQDs surface provided increased hydrophobicity and additional adsorption sites, resulting in superior extraction efficiency compared to conventional materials. Analytical parameters were optimized to yield maximum extraction performance, with the method showing excellent linearity (r² ≥ 0.99) over a concentration range of 50–500 μg L⁻¹, and low limits of detection (15.72–23.60 μg L⁻¹) and quantification (51.89–70.62 μg L⁻¹). High enrichment factors, recovery rates (95–98.7%), and reproducibility (RSDs < 10%, n = 3) demonstrate the robustness of this approach. Successfully applied to NSAID determination in an acetate buffer solution, this method is both efficient and sustainable, requiring minimal sorbent to achieve high extraction yields, showing strong potential for environmental and pharmaceutical analyses.