A novel magnetic fluorescent molecularly imprinted sensor for highly selective and sensitive detection of 4-nitrophenol in food samples through a dual-recognition mechanism.

In this study, surface imprinting, magnetic separation, and fluorescent detection were integrated to develop a dual-recognition sensor (MF-MIPs), which was used for highly selective and sensitive detection of 4-nitrophenol (4-NP) in food samples. Silane-functionalized carbon dots (Si-CDs) participated in the imprinting process and were uniformly distributed into the MIPs layers. MF-MIPs sensor exhibited a high fluorescence response and selectivity based on the dual-recognition mechanism of imprinting recognition and fluorescence identification. The relative fluorescence intensity of MF-MIPs sensor presented a good linear relationship in the range of 0.08-10 µmol·L-1 with a low limit of detection (23.45 nmol·L1) for 4NP. MF-MIPs sensor showed high anti-interference, as well as excellent stability and reusability. The 4-NP recovery from spiked food samples ranged from 93.20 to 102.15%, and the relative standard deviation was lower than 5.0%. Therefore, MF-MIPs sensor may be a promising method for 4-NP detection in food samples.

A nanowell-based molecularly imprinted electrochemical sensor for highly sensitive and selective detection of 17ß-estradiol in food samples.

A novel electrochemical sensor was developed combination molecularly imprinted polymers (MIPs) with nanowell technology, and which was utilized for sensitive and selective 17ß-estradiol (17ß-E2) detection. A nanowell gold film with a thickness of 120 nm and a pore size of ∼20 nm was immobilized onto gold electrode surface to form a nanowell-based electrode. MIPs was then synthesized onto the nanowell-based electrode using electro-polymerization method, and then the nanowell-based MIP electrochemical sensor was formed. This sensor surface exhibited 3D-nanowell structure with higher surface area and enhanced electron-transport ability, while MIPs afford stronger recognition capability with higher selectivity and specificity. Most importantly, the developed sensor was validated for 17ß-E2 detection in food samples with larger detection range from 1 × 10-12 to 1 × 10-5 and lower detection limit of 1 × 10-13. Therefore, such nanowell-based MIP electrochemical sensor may be a promising candidate electrochemical sensor for trace pollution detection in food samples.

Zipper-like magnetic molecularly imprinted microspheres for on/off-switchable recognition and extraction of 17ß-estradiol from food samples.

Zipper-like on/off-switchable and magnetic molecularly imprinted microspheres (SM-MIMs) were constructed using acrylamide (AAm) and 2-acrylamide-2-methyl propanesulfonic acid (AMPS) as functional monomers for 17ß-estradiol (17ß-E2) recognition and extraction. The imprinted polymer interactions between poly(AAm) (PAAm) and poly(AMPS) (PAMPS) with on/off-switchable property to temperature, exhibited dissociation at relatively higher temperatures (such as 30 °C) and helped 17ß-E2 enter into imprinted sites, leading to higher binding capability. Conversely, the interpolymer complexes between PAAm and PAMPS formed and blocked 17ß-E2 access to imprinted sites at lower temperature (such as 20 °C). SM-MIMs were used as dispersive solid phase extraction (SPE) adsorbent with HPLC for 17ß-E2 pretreatment and detection in food samples, and low limit detection (2.52 µg L-1) and quantification (10.76 µg L-1) with higher recovery were obtained. Therefore, SM-MIMs may be a promising adsorbent for 17ß-E2 pretreatment in food samples owing to its advantages of on/off-switchable recognition, eco-friendly elution, and efficient separation.

Cationic Polystyrene Resolves Nonalcoholic Steatohepatitis, Obesity, and Metabolic Disorders by Promoting Eubiosis of Gut Microbiota and Decreasing Endotoxemia.

A pandemic of metabolic diseases, consisting of type 2 diabetes, nonalcoholic fatty liver disease, and obesity, has imposed critical challenges for societies worldwide, prompting investigation of underlying mechanisms and exploration of low-cost and effective treatment. In this report, we demonstrate that metabolic disorders in mice generated by feeding with a high-fat diet without dietary vitamin D can be prevented by oral administration of polycationic amine resin. Oral administration of cholestyramine, but not the control uncharged polystyrene, was able to sequester negatively charged bacterial endotoxin in the gut, leading to 1) reduced plasma endotoxin levels, 2) resolved systemic inflammation and hepatic steatohepatitis, and 3) improved insulin sensitivity. Gut dysbiosis, characterized as an increase of the phylum Firmicutes and a decrease of Bacteroidetes and Akkermansia muciniphila, was fully corrected by cholestyramine, indicating that the negatively charged components in the gut are critical for the dysbiosis. Furthermore, fecal bacteria transplant, derived from cholestyramine-treated animals, was sufficient to antagonize the metabolic disorders of the recipient mice. These results indicate that the negatively charged components produced by dysbiosis are critical for biogenesis of metabolic disorders and also show a potential application of cationic polystyrene to treat metabolic disorders through promoting gut eubiosis.

Amphiphilic chitosan derivatives-based liposomes: synthesis, development, and properties as a carrier for sustained release of salidroside.

A novel amphiphilic chitosan derivative of N,N-dimethylhexadecyl carboxymethyl chitosan (DCMCs) was synthesized. The structure of DCMCs was confirmed via FT-IR and (1)H NMR, and the critical micelle concentration (CMC) was investigated by fluorescence spectroscopy. The results indicated that DCMCs has hydrophilic carboxyl and hydrophobic methylene groups and the CMC value was 23.00 mg·L(-1). The polymeric liposomes (DCMCs/cholesterol liposomes, DC-Ls) were developed, and its properties were evaluated. The DC-Ls exhibited multilamellar spheres with positive charge (+73.30 mV), narrow size distribution (PDI = 0.277), and good crystal properties. Salidroside was first to encapsulate into DC-Ls. Compared with traditional liposomes (phosphatidylcholine/cholesterol liposome, PC-Ls), DC-Ls showed higher encapsulation efficiency (82.46%) and slower sustained release rate. The in vitro salidroside release from DC-Ls was governed by two distinct stages (i.e., burst release and sustained release) and was dependent on the pH of the release medium. The case II transport and case I Fichian diffusion were the main release mechanisms for the entire release procedure. These results indicated that DC-Ls may be a potential carrier system for the production of functional foods that contain salidroside or other bioactive food ingredients.

A pH-responsive nano-carrier with mesoporous silica nanoparticles cores and poly(acrylic acid) shell-layers: fabrication, characterization and properties for controlled release of salidroside.

A novel pH-responsive nano-carrier MSNs-PAA, possessing mesoporous silica nanoparticles (MSNs) cores and poly(acrylic acid) (PAA) shell-layers, was developed for controlled release of salidroside. The vinyl double bonds modified MSNs were synthesized by using cetyltrimethylammonium bromide (CTAB) as templates, tetraethyl orthosilicate (TEOS) as silicon source, and 3-(trimethoxylsilyl) propyl methacrylate (MPS) as surface modification functionalities. The pH-responsive layers of PAA were grafted onto the vinyl double bonds of the MSNs via precipitation polymerization, producing the MSNs-PAA with a hollow cubic core and mesoporous shell with penetrating pore channels. The characteristic results also showed that PAA was successfully grafted onto the surface of the MSNs. The MSNs-PAA was investigated as carriers for loading and regulating the release of salidroside in different pH solutions for the first time. The results demonstrated that the PAA layers on the surface of MSNs-PAA exhibited opened and closed states at different pH values, and thus could regulate the uptake and release of salidroside. The application of such pH-responsive nano-carrier might offer a potential platform for controlled delivery and increasing the bioavailability of drugs.

Responsiveness of voltage-gated calcium channels in SH-SY5Y human neuroblastoma cells on quasi-three-dimensional micropatterns formed with poly (l-lactic acid).

INTRODUCTION: In this study, quasi-three-dimensional (3D) microwell patterns were fabricated with poly (l-lactic acid) for the development of cell-based assays, targeting voltage-gated calcium channels (VGCCs). METHODS AND MATERIALS: SH-SY5Y human neuroblastoma cells were interfaced with the microwell patterns and found to grow as two dimensional (2D), 3D, and near two dimensional (N2D), categorized on the basis of the cells' location in the pattern. The capability of the microwell patterns to support 3D cell growth was evaluated in terms of the percentage of the cells in each growth category. Cell spreading was analyzed in terms of projection areas under light microscopy. SH-SY5Y cells' VGCC responsiveness was evaluated with confocal microscopy and a calcium fluorescent indicator, Calcium Green™-1. The expression of L-type calcium channels was evaluated using immunofluorescence staining with DM-BODIPY. RESULTS: It was found that cells within the microwells, either N2D or 3D, showed more rounded shapes and less projection areas than 2D cells on flat poly (l-lactic acid) substrates. Also, cells in microwells showed a significantly lower VGCC responsiveness than cells on flat substrates, in terms of both response magnitudes and percentages of responsive cells, upon depolarization with 50 mM K(+). This lower VGCC responsiveness could not be explained by the difference in L-type calcium channel expression. For the two patterns addressed in this study, N2D cells consistently exhibited an intermediate value of either projection areas or VGCC responsiveness between those for 2D and 3D cells, suggesting a correlative relation between cell morphology and VGCC responsiveness. CONCLUSION: These results suggest that the pattern structure and therefore the cell growth characteristics were critical factors in determining cell VGCC responsiveness and thus provide an approach for engineering cell functionality in cell-based assay systems and tissue engineering scaffolds.