Fabrication and characterization of hybrid eco-friendly high methoxyl pectin/gelatin/TiO2/curcumin (PGTC) nanocomposite biofilms for salmon fillet packaging.

Hybrid eco-friendly nanocomposite films were fabricated by blending high-methoxyl pectin, gelatin, TiO2, and curcumin through the solution casting method. Various concentrations (0-5 wt%) of TiO2 nanoparticles (TNPs) and curcumin as an organic filler were added to the blend solutions. A high TNP concentration affected the surface morphology, roughness, and compactness of the films. Additionally, 3D mapping revealed the nanoparticle distribution in the film layers. Moisture content, water solubility, and light transmittance reduced dramatically with increasing TNP content, in accordance with the water vapor and oxygen permeabilities. X-ray diffraction revealed that the films were semicrystalline nanocomposites, and the thermal properties of the films increased when 5 wt% of TNPs was incorporated into the blend solution. Fourier-transform infrared and Raman analyses revealed interactions among biopolymers, nanoparticles, and organic fillers through hydrogen bonding. The shelf life of fresh salmon fillets was prolonged to six days for all groups, revealed by total viable counts and psychrotrophic bacteria counts, and the pH of the salmon fillets could be extended until the sixth day for all groups. Biodegradation assays demonstrated a significant weight loss in the nanocomposite films. Therefore, a nanocomposite film with 5 wt% TNPs could potentially be cytotoxic to NIH 3T3 cells.

Antiblood Cell Adhesion of Mussel-Inspired Chondroitin Sulfate- and Caffeic Acid-Modified Polycarbonate Membranes.

We fabricated a mussel-inspired hemocompatible polycarbonate membrane (PC) modified by the cross-linking of chondroitin sulfate and caffeic acid polymer using CA-CS via a Schiff base and Michael addition reaction and named it CA-CS-PC. The as-fabricated CA-CS-PC membrane shows excellent hydrophilicity with a water contact angle of 0° and a negative surface charge with a zeta potential of -32 mV. The antiadhesion property of the CA-CS-modified PC membrane was investigated by enzyme-linked immunosorbent assay (ELISA), using human plasma protein fibrinogen adsorption studies, and proved to have excellent antiadhesion properties, because of the lower fibrinogen adsorption. In addition, the CA-CS-PC membrane also shows enhanced hemocompatibility. Finally, blood cell attachment tests of the CA-CS-PC membrane were observed by CLSM and SEM, and the obtained results proved that CA-CS-PC effectively resisted cell adhesion, such as platelets and leucocytes. Therefore, this work disclosed a new way to design a simple and versatile modification of the membrane surface by caffeic acid and chondroitin sulfate and apply it for cell adhesion.

Fluorine-Free Superhydrophobic Covalent-Organic-Polymer Nanosheet Coating for Selective Dye and Emulsion Separation.

Covalent organic polymer nanosheets (COPNs) endowed with porous networks and large surface areas in their structures offer great advantages over other materials in addressing environmental problems. In this study, fluorine-free superhydrophobic COPNs were designed and applied to selective dye absorption. Notably, COPNs selectively adsorb dyes with a high hydrophobic index (HI) and reject low HI dyes with maximum adsorption capacities of 361 and 263 mg/g for crystal violet and methylene blue, respectively. The adsorption isotherm model showed that the COPNs follow the Langmuir adsorption isotherm model and pseudo-second-order kinetics. Next, we explored the superhydrophobicity of the COPNs by in situ fabrication with melamine sponge (COPNs-MS), which incorporates the superhydrophobicity of COPNs [water contact angle (WCA) of >150°] with the structure and flexibility of the MS skeleton. The COPNs-MS shows various oil-adsorbing properties with good adsorption capacity (from 60 to 120 g/g) and also effectively separates various surfactant-stabilized emulsions with a separation efficiency of over 99%. The as-fabricated COPNs-MS retains its superhydrophobicity in various solvents and hazardous conditions (WCA ≥ 150°) and exhibits good flame retardancy and excellent compression properties with excellent antifouling property due to the superhydrophobic COPN coating. Furthermore, COPNs-MS also demonstrates excellent recyclability because the strong COPN coating in the MS skeleton retains its hydrophobicity. Therefore, our fluorine-free superhydrophobic COPNs are not only capable of selective dye adsorption but also exhibit very good oil adsorption and surfactant-stabilized emulsion separation performance.

Thioether-terminated triazole-bridged covalent organic framework for dual-sensitive drug delivery application.

A novel thioether-terminated triazole bridge-containing covalent organic framework (TCOF) was constructed via a simple click chemistry between alkyne and azide monomers for dual-sensitive [pH and glutathione (GSH)] anticancer drug delivery systems. The synthesized TCOFs were crystalline in nature with a pore size of approximately 10-30 nm, as confirmed by powder X-ray diffraction spectroscopy and Brunauer-Emmett-Teller technique. Owing to the flexible nature of the synthesized COF, polyethylene glycol (PEG) modification was easily performed to yield a stable TCOF (TCOF-PEG) colloidal solution. Doxorubicin (DOX)-loaded TCOF-PEG (TCOF-DOX-PEG) exhibited sensitivity to lysosomal pH 5 and GSH environments. DOX release was four times higher under GSH environment (relative to pH 7.4) and three times higher under pH 5 condition because of the dynamic nature of triazole. In contrast, DOX-loaded COF without the triazole ring (I-COF) did not show any significant drug release in pH 7.4 and acidic pH; however, drug release was observed in GSH environment. MTT drug internalization data demonstrated sustained release of DOX from TCOF-DOX-PEGs. Finally, we demonstrated the utility of TCOF-PEG as an in vitro drug delivery system in HeLa cells. TCOF-DOX-PEG exhibited time-dependent release of DOX followed by internalization. Thus, the novel TCOF system reported here opens a new window in COF research for sensitive drug carrier systems.

PAMAM G4.5 dendrimers for targeted delivery of ferulic acid and paclitaxel to overcome P-glycoprotein-mediated multidrug resistance.

In this study, we prepared ferulic acid (FA) and paclitaxel (PTX) co-loaded polyamidoamine (PAMAM) dendrimers conjugated with arginyl-glycyl-aspartic acid (RGD) to overcome P-glycoprotein (P-gp)-mediated multidrug resistance (MDR). FA was released in greater extent (80%) from the outer layer of the dendrimers compared with PTX (70%) from the interior of the dendrimers. FA improved intracellular availability of PTX via P-gp modulation in drug-resistant cells. In vitro drug uptake data show higher PTX delivery with RGD-PAMAM-FP than with PAMAM-FP in drug resistant KB CH-R 8-5 cell lines. This indicates that RGD facilitates intracellular PTX accumulation through active targeting in multidrug-resistant KB CH-R 8-5 cells. The terminal deoxynucleotidyl transferase 2'-deoxyuridine 5'-triphosphate nick-end labeling assay data and membrane potential analysis in mitochondria confirm the enhanced anticancer potential of RGD-PAMAM-FP nanoaggregates in drug-resistant cells. We also confirmed by the increased protein levels of proapoptotic factors such as caspase 3, caspase 9, p53, and Bax after treatment with RGD-PAMAM-FP nanoaggregates and also downregulates antiapoptotic factors. Hence, FA-PTX co-loaded, RGD-functionalized PAMAM G4.5 dendrimers may be considered as an effective therapeutic strategy to induce apoptosis in P-gp-overexpressing, multidrug-resistant cells.

Electroactive polypyrrole-molybdenum disulfide nanocomposite for ultrasensitive detection of berberine in rat plasma.

Electroactive polypyrrole-molybdenum disulfide (MoP) nanocomposites were synthesized and used for modifying screen-printed carbon electrodes (SPCEs) for ultrasensitive detection of berberine, an anticancer drug, in rat plasma. The electroactive nanocomposites were fabricated by exfoliating MoS2 followed by pyrrole polymerization. The effect of polypyrrole in the MoP nanocomposite was evaluated by varying the pyrrole concentration during polymerization, and the resulting nanocomposites prepared with pyrrole concentrations of 10, 20, 30 µL were named as MoP-1, MoP-2, and MoP-3, respectively. The electrochemical characterization of the three MoP nanocomposite sensors revealed that MoP-2/SPCE exhibited the highest electroactivity. The detection of berberine by the three MoP-coated SPCEs revealed that MoP-2/SPCE exhibited the highest activity against berberine due to a two-electron transfer mechanism on the MoP-2/SPCE electrode surface. The detection limit of berberine using the MoP-2/SPCE sensor was found to be about 0.05 µM, which is remarkably lower than the reported detection limits. The interference study proved the selectivity of the MoP-2/SPCE sensor toward berberine in the presence of other bioactive molecules and metal ions. The designed MoP-2/SPCE sensor retained 92% of its initial activity after 15 days of storage at room temperature, with RSD values of about 2.95% and 3.68% for the repeatability and reproducibility studies. Finally, the detection limit of berberine in a rat plasma sample determined using the MoP-2/SPCE sensor was found to be about 5 µM.