Enhanced ambient ammonia photosynthesis by Mo-doped Bi_(5)O_(7)Br nanosheets with light-switchable oxygen vacancies

The fabrication of efficient catalysts to reduce nitrogen(N_(2))to ammonia(NH3)is a significant challenge for artificial N_(2) fixation under mild conditions.In this work,we demonstrated that the simultaneous introduction of oxygen vacancies(OVs)and Mo dopants into Bi_(5)O_(7)Br nanosheets can significantly increase the activity for photocatalytic N_(2) fixation.The 1 mol% Mo-doped Bi_(5)O_(7)Br nanosheets exhibited an optimal NH_(3) generation rate of 122.9μmol g^(-1) h^(-1) and durable stability,which is attributed to their optimized conduction band position,suitable absorption edge,large number of light-switchable OVs,and improved charge carrier separation.This work provides a promising approach to design photocatalysts with light-switchable OVs for N_(2) reduction to NH_(3) under mild conditions,highlighting the wide application scope of nanostructured BiOBr-based photocatalysts as effective N_(2) fixation systems.

A combination of Light On gene expression system and tumor microenvironment-responsive nanoparticle delivery system for targeted breast cancer therapy

A light-switchable transgene system called LightOn gene expression system could regulate gene expression with a high on/off ratio under blue light,and have great potential for spatiotemporally controllable gene expression.We developed a nanoparticle drug delivery system(NDDS)to achieve tumor microenvironment-responsive and targeted delivery of diphtheria toxin A(DTA)fragment-encoded plasmids to tumor sites.The expression of DTA was induced by exposure to blue light.Nanoparticles composed of polyethylenimine and vitamin E succinate linked by a disulfide bond,and PEGylated hyaluronic acid modified with RGD peptide,accumulated in tumor tissues and were actively internalized into 4 T1 cells via dual targeting to CD44 andαvβ3 receptors.The LightOn gene expression system was able to control target protein expression through regulation of the intensity or duration of blue light exposure.In vitro studies showed that lisht-induced DTA expression reduced 4 T1 cell viability and induced apoptosis.Furthermore,the LightOn gene expression system enabled spatiotemporal control of the expression of DTA in a mouse 4 T1 tumor xenogratt model,which resulted in excellent antitumor effects,reduced tumor angiogenesis,and no systemic toxicity.The combination of the LightOn gene expression system and NDDS may be an effective strategy for treatment of breast cancer.

A LexA-based yeast two-hybrid system for studying light- switchable interactions of phytochromes with their interacting partners

Phytochromes are a family of photoreceptors in plants that perceive the red(R)and far-red(FR)components of their light environment.Phytochromes exist in vivo in two forms,the inactive Pr form and the active Pfr form,that are interconvertible by treatments with R or FR light.It is believed that phytochromes transduce light signals by interacting with their signaling partners.A GAL4-based lightswitchable yeast two-hybrid(Y2H)system was developed two decades ago and has been successfully employed in many studies to determine phytochrome interactions with their signaling components.However,several pairs of interactions between phytochromes and their interactors,such as the phyACOP1 and phyA-TZP interactions,were demonstrated by other assay systems but were not detected by this GAL4 Y2H system.Here,we report a modified LexA Y2H system,in which the LexA DNA-binding domain is fused to the C-terminus of a phytochrome protein.The conformational changes of phytochromes in response to R and FR light are achieved in yeast cells by exogenously supplying phycocyanobilin(PCB)extracted from Spirulina.The well-defined interaction pairs,including phyA-FHY1 and phyB-PIFs,are well reproducible in this system.Moreover,we show that our system is successful in detecting the phyA-COP1 and phyA-TZP interactions.Together,our study provides an alternative Y2H system that is highly sensitive and reproducible for detecting light-switchable interactions of phytochromes with their interacting partners.