High Viability of Cells Encapsulated in Degradable Poly(carboxybetaine) Hydrogels

In this study, we report a degradable poly­(carboxybetaine) (pCB) hydrogel, produced via a thiol–disulfide exchange reaction for cell encapsulation. A pCB dithiol was synthesized as a cross-linker and reacted with a pyridyl dithiol-containing CB copolymer to form a hydrogel. We evaluated the biocompatibility of the pCB-based hydrogel via encapsulation of three cell types, including NIH3T3 fibroblasts, MG63 osteoblast-like cells, and HepG2 hepatocarcinoma cells. Up to 90% of cells retained their viability in the pCB hydrogel even at low cell-seeding densities under serum-free conditions after a 9-day culture. Results are compared with a degradable poly­(ethylene glycol) methacrylate (PEGMA) hydrogel, which showed very low cell viability under serum-free condition after a 3-day culture. We incorporated an RGD peptide into the CB hydrogel using a cysteine-terminated cross-linker, which was shown to promote cell proliferation

Protecting Enzymatic Activity via Zwitterionic Nanocapsulation for the Removal of Phenol Compound from Wastewater

Horseradish peroxidase (HRP) holds great potential in wastewater treatment. However, its instability in harsh environments remains a major issue. Various immobilization technologies were developed to retain enzyme stability at the cost of its effectiveness. We demonstrate that zwitterionic encapsulation of HRP retained both protein stability and activity to a large degree. In a water treatment study, encapsulating HRP into a zwitterionic nanogel resulted in a three-fold increase in the catalytic oxidation efficiency of phenol molecules. In addition, zwitterionic nanocapsules exhibited the best performance when compared with nanocapsules made from other hydrophilic polymers. These results indicated that zwitterionic HRP nanocapsules hold great potential in the decontamination of organic pollutants from wastewater

Quorum sensing inhibitors from marine bacteria <i>Oceanobacillus</i> sp. XC22919

<p>In this study, three active compounds isolated from <i>Oceanobacillus</i> sp. XC22919 were identified as 2-methyl-<i>N</i>-(2′-phenylethyl) butyramide (<b>1</b>), 3-methyl-<i>N</i>-(2′-phenylethyl)-butyramide (<b>2</b>) and benzyl benzoate (<b>3</b>), and were first reported to exhibit the apparent quorum sensing inhibitory activities against <i>C.</i> <i>violaceum</i> 026 and <i>P.</i> <i>aeruginosa</i>. Compounds <b>1</b>–<b>3</b> inhibited violacein production of <i>C. violaceum</i> 026 by 10.5–55.7, 11.2–55.7, and 27.2%–95.7%, respectively, and inhibited pyocyanin production of <i>P. aeruginosa</i> by 1.7–50.8, 39.1–90.7, and 57.2%–98.7%, respectively. The azocasein-degrading proteolytic rates of <i>P. aeruginosa</i> were observed by 13.4–31.5, 13.4–28.8, and 11.3%–21.1%, respectively. With respect to elastase, the range of inhibition of activity of compounds <b>1</b>–<b>3</b> was 2.1–30.3, 4.2–18.2, and 8.9%–15.7%, respectively. Compounds <b>1</b> and <b>3</b> also showed a concentration-dependent attenuation in biofilm formation, with the maximum of 50.6% inhibition, and 37.7% inhibition at 100 μg/mL, respectively.</p

A Robust Graft-to Strategy To Form Multifunctional and Stealth Zwitterionic Polymer-Coated Mesoporous Silica Nanoparticles

Mesoporous silica nanoparticles (MSNs) are a new class of carrier materials promising for drug/gene delivery and many other important applications. Stealth coatings are necessary to maintain their stability in complex media. Herein, a biomimetic polymer conjugate containing one ultralow fouling poly­(carboxybetaine) (pCBMA) chain and one surface-adhesive catechol (DOPA) residue group was efficiently grafted to the outer surface of SBA-15 type MSNs using a convenient and robust method. The cytotoxicity of SBA-15-DOPA-pCBMAs was evaluated by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Results showed no significant decrease in cell viability at the tested concentration range. Macrophage cell uptake studies revealed that the uptake ratios of SBA-15-DOPA-pCBMAs were much lower than that of parent MSNs. Furthermore, inductively coupled plasma mass spectrometry (ICP-MS) analysis results showed that after SBA-15-DOPA-pCBMAs were conjugated with a targeting cyclo-[Arg-Gly-Asp-d-Tyr-Lys] (cRGD) peptide, uptake by bovine aortic endothelial cells (BAECs) was notably increased. Results indicated that cRGD-functionalized MSNs were able to selectively interact with cells expressing αvβ3 integrin. Thus, MSNs with DOPA-pCBMAs are promising as stealth multifunctional biocarriers for targeted drug delivery or diagnostics

Cellulose Paper Sensors Modified with Zwitterionic Poly(carboxybetaine) for Sensing and Detection in Complex Media

Poly­(carboxybetaine) (PCB) functionalized cellulose paper was used as a paper-based microfluidic device. The results showed that the PCB modified paper sensor was able to achieve (a) more rapid and sensitive glucose detection from undiluted human serum compared to bare cellulose and (b) specific antigen detection via covalently immobilized antibodies