Photo-Curable Lacquer Sap Resin Based on Urushiol-Mimicking, Tyrosine-Containing Additive.

Oriental lacquer sap is attracting considerable attention as a renewable and eco-friendly natural resin with high durability, heat resistance, insulation, insect repellency, and antiseptic and antibacterial properties. However, to ensure excellent coating performance, it is necessary to improve the drying/curing process of lacquer sap with a time-consuming drying time at high humidity [relative humidity (RH), 70-90%] and ambient temperature (20-30 °C). Drawing on an understanding of the polymerization mechanism of urushiol, the main component of the lacquer sap consisted of a water-in-oil (W/O) emulsion, and this study presents an eco-friendly additive that mimics the structure-function of urushiol composed of a polar catechol head group and a nonpolar hydrocarbon tail. A photo-curable lacquer sap was thus developed by adding a tyrosine amino acid-based lipid agent (denoted as Y-ADDA), which allows faster and more effective drying/curing at lower humidity while maintaining the nature-derived properties of lacquer sap. Y-ADDA easily coassembles with urushiol in the W/O emulsion droplets, thereby significantly accelerating the formation of a polymer network along with urushiol during water evaporation leading to fast drying/curing under ultraviolet (UV) light irradiation at low humidity (∼50% RH). The UV-cured lacquer sap resins showed higher performance in terms of film processing and physicochemical properties compared with that of the lacquer containing only tyrosine amino acids without aliphatic tail conjugation, N-(9-fluorenylmethoxycarbonyl)-O-tert-butyl-l-tyrosine Fmoc-Tyr(tBu)-OH. Furthermore, the drying and curing times, film morphology, transmittance, hardness, and adhesion strength of the UV-cured lacquer were markedly superior compared to those of shellac, a general eco-friendly fast-drying primer. The study provides useful strategies and insights to promote the industrial application of lacquer sap resins by employing biocompatible nanoagents developed with an understanding of the curing mechanism of natural resins and from the viewpoint of green and sustainable chemistry perspective.

Preparation of Doxorubicin-Loaded Amphiphilic Poly(D,L-Lactide-Co-Glycolide)-b-Poly(N-Acryloylmorpholine) AB2 Miktoarm Star Block Copolymers for Anticancer Drug Delivery.

Owing to their unique topology and physical properties, micelles based on miktoarm amphiphilic star block copolymers play an important role in the biomedical field for drug delivery. Herein, we developed a series of AB2-type poly(D,L-lactide-co-glycolide)-b-poly(N-acryloyl morpholine) (PLGA-b-PNAM2) miktoarm star block copolymers by reversible addition-fragmentation chain-transfer polymerization and ring-opening copolymerization. The resulting miktoarm star polymers were investigated by 1H NMR spectroscopy and gel permeation chromatography. The critical micellar concentration value of the micelles increases with an increase in PNAM block length. As revealed by transmission electron microscopy and dynamic light scattering, the amphiphilic miktoarm star block copolymers can self-assemble to form spherical micellar aggregates in water. The anticancer drug doxorubicin (DOX) was encapsulated by polymeric micelles; the drug-loading efficiency and drug-loading content of the DOX-loaded micelles were 81.7% and 9.1%, respectively. Acidic environments triggered the dissociation of the polymeric micelles, which led to the more release of DOX in pH 6.4 than pH 7.4. The amphiphilic PLGA-b-PNAM2 miktoarm star block copolymers may have broad application as nanocarriers for controlled drug delivery.

Three-Dimensional Nanoporous Metal Structures from Poly(2-vinylpyridine)-block-Poly(4-vinylpyridine) Copolymer Thin Film.

We fabricated 3D nanoporous metal structures from poly(2-vinylpyridine)-block-poly(4-vinylpyridine) copolymer (P24VP) thin film with vertically oriented lamellar nanodomains by coordinating corresponding metal precursors followed by reduction to metals. Although metal precursors are coordinated with both P2VP and P4VP blocks, the metal coordination power toward P4VP block is much greater than that toward P2VP block. Thus, most of the metal precursors are located in the P4VP block, while a few exist in the P2VP block. After the metal precursors were reduced to corresponding metals by reactive ion etching, metals located in P4VP regions became continuous main frames. However, metals in P2VP regions could not be continuous because of smaller amounts, resulting in nanoporous structures. Using these 3D nanoporous structures, we measured the electrocatalytic activity for hydrogen evolution reaction. 3D nanoporous platinum (Pt) showed enhanced catalytic activity compared with Pt flat film due to the large surface area. Moreover, 3D nanoporous Pt/cobalt bimetallic structures showed better catalytic activity than 3D nanoporous Pt structures.

Targeted delivery of doxorubicin-loaded poly (ε-caprolactone)-b-poly (N-vinylpyrrolidone) micelles enhances antitumor effect in lymphoma.

BACKGROUND: The present study was motivated by the need to design a safe nano-carrier for the delivery of doxorubicin which could be tolerant to normal cells. PCL63-b-PNVP90 was loaded with doxorubicin (6 mg/ml), and with 49.8% drug loading efficiency; it offers a unique platform providing selective immune responses against lymphoma. METHODS: In this study, we have used micelles of amphiphilic PCL63-b-PNVP90 block copolymer as nano-carrier for controlled release of doxorubicin (DOX). DOX is physically entrapped and stabilized in the hydrophobic cores of the micelles and biological roles of these micelles were evaluated in lymphoma. RESULTS: DOX loaded PCL63-b-PNVP90 block copolymer micelles (DOX-PCL63-b-PNVP90) shows enhanced growth inhibition and cytotoxicity against human (K-562, JE6.1 and Raji) and mice lymphoma cells (Dalton's lymphoma, DL). DOX-PCL63-b-PNVP90 demonstrates higher levels of tumoricidal effect against DOX-resistant tumor cells compared to free DOX. DOX-PCL63-b-PNVP90 demonstrated effective drug loading and a pH-responsive drug release character besides exhibiting sustained drug release performance in in-vitro and intracellular drug release experiments. CONCLUSION: Unlike free DOX, DOX-PCL63-b-PNVP90 does not show cytotoxicity against normal cells. DOX-PCL63-b-PNVP90 prolonged the survival of tumor (DL) bearing mice by enhancing the apoptosis of the tumor cells in targeted organs like liver and spleen.

Synthesis and study of the properties of stereocontrolled poly(N-isopropylacrylamide) gel and its linear homopolymer prepared in the presence of a Y(OTf)3 Lewis acid: effect of the composition of methanol-water mixtures as synthesis media.

Poly(N-isopropylacrylamide) (PNIPAM) hydrogels and the corresponding linear homopolymers were synthesized in different methanol-water mixtures (x(m) = 0, 0.13, 0.21, 0.31, 0.43, 0.57, and 0.76, where x(m) is the mole fraction of methanol) in the presence of 0.1 M Y(OTf)(3) Lewis acid. The isotacticity (meso dyad (m), %) and cloud-point temperature of these homopolymers were gradually increased and decreased, respectively, with the increase in the x(m) values of the synthesis solvent mixtures. Moreover, the corresponding linear PNIPAM homopolymers prepared in the absence of Y(OTf)(3) showed an almost constant isotacticity of m = 45% and a cloud-point temperature of 33.0 °C. A SEM study revealed that the resulting hydrogels were highly porous except for the gels prepared at x(m) = 0 and 0.76. The swelling ratios of these hydrogels in water at different temperatures and in different methanol-water mixtures at 20 °C and the deswelling rate and the reswelling rate of these hydrogels were studied. All of these swelling results were compared with that of the corresponding gels prepared in the absence of a Lewis acid (Biswas, C. S.; Patel, V. K.; Vishwakarma, N. K.; Mishra, A. K.; Bhimireddi, R.; Rai, R.; Ray, B. J. Appl. Polym. Sci.2012, DOI: 10.1002/app.36318) and explained on the basis of the porosity of the gel, the state of aggregation and isotacticity of the PNIPAM chain segment, and the cononsolvency of the methanol-water mixture toward the PNIPAM chain segment.

Synthesis and characterization of stereocontrolled poly(N-isopropylacrylamide) hydrogel prepared in the presence of Y(OTf)3 Lewis acid.

Macroporous poly(N-isopropylacrylamide) (PNIPAM) hydrogels have been prepared in methanol-water (1:1, v/v) mixture in the presence of 0, 0.05, 0.1, 0.15, and 0.2 M Y(OTf)(3) Lewis acid concentrations. Synthesis of the corresponding linear PNIPAM homopolymers in the absence of a cross-linker keeping all other conditions the same shows that the isotacticity (meso dyad, %) and the cloud point temperature of the resulted in polymers increases and decreases, respectively, with the increase in the concentration of the Lewis acid. SEM micrographs reveal that the resulted hydrogels are highly porous. Swelling ratios of all the hydrogels in water decrease with the increase in the temperature. Moreover, swelling ratios of all the hydrogels in different methanol-water mixtures pass through a minimum in the co-nonsolvency zone, and the co-nonsolvency zone shifts toward the lower methanol-content solvent mixture with gradual increase in the Lewis acid concentration. Deswelling rate of the hydrogel prepared in methanol-water (1:1, v/v) mixture is much faster than that of the conventional hydrogel prepared in water. Moreover, the deswelling rate slightly increases with the hydrogels prepared with the increasing concentrations of Lewis acid. But, the reswelling rate of the hydrogels follows almost the reverse order. All these results have been explained on the basis of the formation of highly porous hydrogels with higher isotactic PNIPAM chain segment owing to the faster polymerization rate in the methanol-water mixture in the presence of Lewis acid and the co-nonsolvency behavior of the methanol-water (1:1, v/v) mixture toward PNIPAM chain segment in the PNIPAM hydrogel.