Guangdong Provincial Key Lab of Nano-Micro Materials Research School of Chemical Biology and Biotechnology, Peking University Shenzhen Graduate School, Shenzhen, China
Prof. Dr. Mei Hong
Guangdong Provincial Key Lab of Nano-Micro Materials Research School of Chemical Biology and Biotechnology, Peking University Shenzhen Graduate School, Shenzhen, China
Photodynamic therapy (PDT) is an alternative strategy for treating pancreatic cancer (PC) in clinics. However, the therapeutic efficacy is generally suppressed by inadequate oxygen supply in the hypoxic tumor microenvironment. Herein, hierarchical zeolite nanocarriers with hydrophilic mesoporous nanostructures and excellent biodegradability are synthesized via a one-pot wet chemical method. By co-loading with catalase and methylene blue (MB), a new type of oxygen self-sufficient PDT platform, a zeolite-catalase-MB nanocapsule (ZCM nanocapsule), is developed. After precision implantation of the ZCM nanocapsule into the tumor area under the real-time ultrasound (US) imaging guidance, the nanocapsule with 90% relative activity of equivalent free catalase enzyme efficiently modulates the tumor hypoxia and enhances the intratumoral US contrast by sustained decomposition of endogenous H2O2 and in situ production of O2 gas bubbles. Meanwhile, the MB loading in hierarchical zeolite matrices prevents the rapid leaching of the photosensitizer in tumor tissue, achieving a good sustained photosensitizer release effect. Based on the synchronous mechanisms, upon near-infrared laser irradiation, the local PC cells are completely killed, and no therapy-induced toxicity and recurrence are observed. This highly biocompatible and biodegradable hierarchical nanozeolite would further facilitate the development of catalase-based catalytic nanomedicine for enhancing chemotherapy, radiotherapy and combination therapy.
18 January 2016 in Journal of Materials Chemistry A
Mesoporous LTA zeolites have been hydrothermally synthesized by using amino acids as a mesoporogen. Amino acids of carnitine, lysine, or their salt derivatives were able to generate disordered mesopores of 10–20 nm within single crystalline LTA zeolites. Unlike other mesopore generating templates such as surfactants or polymers, the amino acid templates could be easily removed by washing with water, eliminating the energy-intensive calcination step. A possible crystallization process involving three-dimensional assembly of amino acid templates via hydrogen bonding and electrostatic interaction was proposed, as it was found that hydrogen bonding is crucial in hierarchical structure generation, and that hydroxyl group shielded acetyl carnitine yielded no mesopores. The obtained hierarchically mesoporous LTA zeolites exhibited a remarkably higher adsorption capacity (264 mg g−1) for catalase enzyme, and retained greater enzyme activity (>90%) than did conventional LTA.
4 September 2017 in Journal of Materials Chemistry A
Core–shell zeolite Y containing an ant-nest like hollow interior has been synthesized in the presence of natural amino acids. Time-resolved characterization of zeolite samples revealed the gradual development of three-dimensionally interconnected mesoporous channels via an intermediate stage of spatially aligned cavities in the core, which did not follow either a classical or a reversed crystal growth route. Comparative experiments suggested coordinative construction actions of amino acids, the interpenetration of which into the internal weak points of the aluminosilicate framework takes place simultaneously with zeolite crystallization. At the point of complete zeolite growth, amino acids in aggregated domains begin disassembling the zeolite interior forming a network of channels while maintaining the external zeolite shell thickness of 165 nm and morphologically similar to conventional faujasite. The core–shell zeolite Y samples exhibit superior crystallinity and enhanced catalytic activity for Friedel–Crafts benzylation of toluene.
Cost‐effective non‐noble metal‐based catalysts for selective hydrogenation with excellent activity, selectivity, and durability are still the holy grail. Herein, an oxygen‐doped carbon (OC) chainmail encapsulated dilute Cu–Ni alloy is developed by simple pyrolysis of Cu/Ni‐metal–organic framework. The CuNi 0.05 @OC catalyst displays superior performance for atmospheric pressure transfer hydrogenation of p ‐chloronitrobenzene and p ‐nitrophenol, and for hydrogenation of furfural, all in water and with exceptional durability. Comprehensive characterizations confirm the close interactions between the diluted Ni sites, the base Cu, and optimized three‐layered graphene chainmail. Theoretical calculations demonstrate that the properly tuned lattice strain and Schottky junction can adjust electron density to facilitate specific adsorption on the active centers, thus enhancing the catalytic activity and selectivity, while the OC shell also offers robust protection. This work provides a simple and environmentally friendly strategy for developing practical heterogeneous catalysts that bring the synergistic effect into play between dilute alloy and functional carbon wrapping.