Recent developments in high-performance Nafion membranes for hydrogen fuel cells applications

As a promising alternative to petroleum fossil energy,polymer electrolyte membrane fuel cell has drawn considerable attention due to its low pollution emission,high energy density,portability,and long operation times.Proton exchange membrane(PEM)like Nafion plays an essential role as the core of fuel cell.A good PEM must have satisfactory performance such as high proton conductivity,excellent mechanical strength,electrochemical stability,and suitable for making membrane electrode assemblies(MEA).However,performance degradation and high permeability remain the main shortcomings of Nafion.Therefore,the development of a new PEM with better performance in some special conditions is greatly desired.In this review,we aim to summarize the latest achievements in improving the Nafion performance that works well under elevated temperature or methanol-fueled systems.The methods described in this article can be divided into some categories,utilizing hydrophilic inorganic material,metal-organic frameworks,nanocomposites,and ionic liquids.In addition,the mechanism of proton conduction in Nafion membranes is discussed.These composite membranes exhibit some desirable characteristics,but the development is still at an early stage.In the future,revolutionary approaches are needed to accelerate the application of fuel cells and promote the renewal of energy structure.

A Self-assembled Nanoparticle Platform Based on Amphiphilic Oleanolic Acid Polyprodrug for Cancer Therapy

Oleanolic acid(OA)is a pentacyclic triterpenoid compound with extensive biological effects,such as anti-inflammatory and anticancer activities.However,the application of OA in chemotherapy is hampered by its poor solubility and severe adverse effects.To solve the problems,we developed a self-assembled nanoparticle platform based on amphiphilic oleanolic acid polyprodrug,poly[oligo(ethylene glycol)methyl ether methacrylate]-b-poly(oleanolic acid methacrylate)(POEGMA-b-POAMA),encapsulating 10-hydroxycamptothecin(HCPT)to achieve efficient cancer therapy.The polyprodrug was prepared via reversible addition-fragmentation chain transfer polymerization(RAFT),and could selfassemble to prepare POEGMA-b-POAMA/HCPT nanoparticles(NPs).The obtained nanoparticles exhibited appropriate particle size,excellent drug stability,good drug loading capacity,and high drug loading efficiency.In vitro drug release indicated that the drug release was prolonged to 132 h.The POEGMA-b-POAMA/HCPT NPs enhanced cell cytotoxicity in 4T1 cells and MCF-7 cells and could be efficiently uptaken by 4T1 cells.Furthermore,in vivo antitumor efficiency showed that the POEGMA-b-POAMA/HCPT NPs had great antitumor efficiency with considerably low adverse effects in the treatment of the 4T1 mouse breast tumor xenograft tumor.Therefore,POEGMA-b-POAMA/HCPT NPs provide great potential as a platform for drug delivery applications.