In-situ grafting temperature-responsive hydrogel as a bifunctional solid-phase microextraction coating for tunable extraction of biomacromolecules

Aptamer-functionalized stir bar sorptive extraction for selective isolation, identification, and determination of concanavalin A in food by MALDI-TOF-MS

An aptamer-functionalized stir bar sorptive extraction (SBSE) coating is described for the first time devoted to selective isolation and preconcentration of an allergenic food protein, concavanalin A (Con A), followed by matrix-assisted laser desorption/ionization mass spectrometry (MALDI-TOF-MS) determination. For this purpose, the polytetrafluoroethylene surface of commercial magnetic stir bars was properly modified and vinylized to immobilize a thiol-modified aptamer against Con A via straightforward "thiol-ene" click chemistry. The aptamer-functionalized stir bar was employed as SBSE sorbent to isolate Con A, and several parameters that can affect the extraction efficiency were investigated. Under the optimized conditions, Con A was extracted and desorbed during 30 and 45 min, respectively, at 25 °C and 600 rpm. The SBSE MALDI-TOF-MS method provided limits of detection of 0.5 μg mL^-1 for Con A. Furthermore, the SBSE coating was highly selective to Con A compared to other lectins. The developed method was successfully applied to the determination of low levels of Con A in several food matrices (i.e., white beans as well as chickpea, lentils, and wheat flours). Recoveries ranged from 81 to 97% with relative standard deviations below 7%. The aptamer-based stir bars presented suitable physical and chemical long-term stability (1 month) and a reusability of 10 and 5 extraction cycles with standards and food extracts, respectively. The developed aptamer-affinity extraction devices open up the possibility of developing novel highly selective SBSE coatings for the extraction of proteins and peptides from complex samples.

Local delivery of gambogic acid to improve anti-tumor immunity against oral squamous cell carcinoma

Oral squamous cell carcinoma (OSCC) accounts for nearly 90% of oral cavity malignancies. However, despite significant advances in the last four decades, little improvement has been achieved in the overall survival rates for OSCC patients. While gambogic acid (GA) is a potential candidate compound for treating a variety of malignancies, its anti-cancer impact on OSCC has not to be completely investigated. The tumor immune microenvironment (TIME) has been proven to play a crucial role in the prognosis of cancer patients. Although there are few reports on the T cell activation effect of GA, the regulation of GA on the TIME of OSCC has barely been studied yet. In this study, GA was applied to treat OSCC-bearing mice through in situ controlled release. First, GA-loaded mPEG₂₀₀₀-PCL micelles (GA-MIC) were prepared by the thin-film hydration method to improve the aqueous dispersibility of GA. Second, poly(D, l-lactide)-poly(ethylene glycol)-poly(D, l-lactide) (PLEL) was synthesized for thermosensitive hydrogel preparation. Third, GA-MIC was mixed with PLEL to form an injectable therapeutic hydrogel (GA-MIC-GEL). The anti-tumor and TIME regulation effects of GA-MIC-GEL on tumor-bearing mice were further examined. The results showed that the thermosensitive GA-MIC-GEL with sensitive sol-gel transition characteristics could form hydrogel at 37 °C within 24 s, facilitating the local delivery and sustained GA release. Biochemical, hematological, and pathological analysis proved that GA-MIC-GEL has good biological safety. Moreover, GA-MIC-GEL promoted an obvious regression of both primary and distant tumors on the OSCC mouse models. Mechanically, GA-MIC-GEL down-regulated the expression of PD-1, increased the frequency of cytotoxic T cells and reduced the immunosuppressive cellular components, which boosted the anti-tumor immunity of OSCC-bearing mice. The constructed thermosensitive hydrogel for local delivery of GA has provided a safe and effective strategy with great potential for OSCC therapy.