Luminescence regulation of Sb^(3+)in 0D hybrid metal halides by hydrogen bond network for optical anti-counterfeiting

The Sb^(3+) doping strategy has been proven to be an effective way to regulate the band gap and improve the photophysical properties of organic-inorganic hybrid metal halides(OIHMHs).However,the emission of Sb^(3+) ions in OIHMHs is primarily confined to the low energy region,resulting in yellow or red emissions.To date,there are few reports about green emission of Sb^(3+)-doped OIHMHs.Here,we present a novel approach for regulating the luminescence of Sb^(3+) ions in 0D C_(10)H_(2)_(2)N_(6)InCl_(7)·H_(2)O via hydrogen bond network,in which water molecules act as agents for hydrogen bonding.Sb^(3+)-doped C_(10)H_(2)2N_(6)InCl_(7)·H_(2)O shows a broadband green emission peaking at 540 nm and a high photoluminescence quantum yield(PLQY)of 80%.It is found that the intense green emission stems from the radiative recombination of the self-trapped excitons(STEs).Upon removal of water molecules with heat,C_(10)H_(2)_(2)N_(6)In_(1-x)Sb_(x)Cl_(7) generates yellow emis-sion,attributed to the breaking of the hydrogen bond network and large structural distortions of excited state.Once water molecules are adsorbed by C_(10)H_(2)_(2)N_(6)In_(1-x)Sb_(x)Cl_(7),it can subsequently emit green light.This water-induced reversible emission switching is successfully used for optical security and information encryption.Our findings expand the under-standing of how the local coordination structure influences the photophysical mechanism in Sb^(3+)-doped metal halides and provide a novel method to control the STEs emission.

Near-unity quantum yield in zero-dimensional lead-free manganese-based halides for flexible X-ray imaging with high spatial resolution

Low-dimensional luminescent lead-free metal halides have received substantial attention due to their unique optoelectronic properties.Among them,zero-dimensional(0D)manganese(II)-based metal halides with negligible self-absorption have emerged as potential candidates in X-ray scintillators.Herein,we for the first time report a novel lead-free(TBA)_(2)MnBr_(4) single crystal synthesized via a facile solvent evaporation method.In this crystal,[MnBr_(4)]^(2-)units are isolated by large TBA^(+)organic cations,resulting in a unique 0D structure.The prepared manganese-based crystals exhibit a bright-green emission centered at 512 nm with a high photoluminescence quantum yield(PLQY)of 93.76%at room temperature,originating from the ^(4)T_(1)–^(6)A_(1) transition of Mn^(2+).Apart from their outstanding optical performance,the crystals also show excellent stability and can maintain 94.4%of the initial PLQY even after being stored in air for 90 days.Flexible(TBA)_(2)MnBr4 films prepared as X-ray imaging scintillators exhibit a low detection limit of 63.3 nGyair/s,a high light yield of 68000 ph/MeV,and a high spatial resolution of 15.4 lp/mm.Thus,this work not only enriches the family of lead-free metal halides but also expands the application of manganese(II)-based halides in flexible X-ray scintillators.

Shear-responsive peptide/siRNA complexes as lung-targeting gene vectors

Particles administrated intravenously will pass through the pulmonary capillary network before being distributed to the body.Therefore,fabrication of vectors sensitive to blood shear and active with blood components should be a practical approach to develop lung-targe ting gene carriers self-regulated by circulatory system.In this work,we designed a series of cationic peptides with the same charge density but varying hydrophobicity and capacity to form hydrogen bonds,and investigated their ability to form co mplexes with siRNA,the behaviours of peptide/siRNA complexes in the presence of serum under shear,and the lung-targeting efficacy of the complexes regulated by blood.The hydrophobic interaction co ntrols the complexation between peptide and siRNA,while the hydrogen bonds are responsible for the binding of peptides to the serum components in blood.In vivo tests show that all the peptide/siRNA complexes can accumulate in lung.However,only the complexes that exhibit weak interaction with serum components and can be broken down by shear avoid the inflammation and death caused by pulmonary embolism.Moreover,the peptide with strong hydrophobicity can retain siRNA in lung without early release of the cargo.Our study provides a step toward the development of adaptive gene carriers under the regulation of circulatory system.

Encapsulation of RNA by negatively charged human serum albumin via physical interactions

Human serum albumin(HSA)is the most abundant plasma protein and has an inherent ability to target tumor cells.It is an excellent candidate for drug delivery.However,HSA cannot form complex with DNA or RNA,because it is negatively charged under physiological conditions.In this work,we reported a simple method to prepare HSA/RNA nanoparticles mainly by physical interaction.Firstly,the solution p H is adjusted to 4.0,under which condition HSA is positively charged.It forms complex with RNA via electrostatic interaction.The solution is then heated at 75 oC for 15 min to stabilize the structure and the size of the formed complex.The HSA/RNA nanoparticle prepared by this method has a diameter about 110 nm and a narrow distribution.It is also stable for days under physiological conditions.Cellular essays demonstrate that these particles exhibit a high cellular uptake efficiency and non-toxicity to He La cells.

Interaction between human serum albumin and cholesterol-grafted polyglutamate as the potential carriers of protein drugs

Currently there is no successful platform technology for the sustained release of protein drugs.It seems inevitable to specifically develop new materials for such purpose, and hence the understanding of protein–material interactions is highly desirable. In this study, we synthesized cholesterol-grafted polyglutamate(PGA-g-Chol) as a hydrophobically-modified polypeptide, and thoroughly characterized its interaction with a model protein(human serum albumin) in the aqueous solution by using circular dichroism, fluorescence methods, and light scattering. With the protein concentration fixed at 5 μmol/L,adding PGA-g-Chol polymers into the solution resulted in continuous blue shift of the protein fluorescence(from 339 to 332 nm), until the polymer molar concentration reached the same value as the protein. In contrast, the un-modified polyglutamate polymers apparently neither affected the protein microenvironment nor formed aggregates. Based on the experimental data, we proposed a physical picture for such protein–polymer systems, where the polymer first bind with the protein in a 1:1 molar ratio via a fraction of their hydrophobic pendant cholesterol resides along the polymer chain. In this protein/polymer complex, there are excess unbound cholesterol residues. As the polymer concentration increases, the polymers form multi-polymer aggregates around 200 nm in diameter via the same hydrophobic cholesterol residues. The protein/polymer complex also participate in the aggregation via their excess cholesterol residues, and consequently the proteins are encapsulated into the nanoparticles. The encapsulation was also found to increase the thermal stability of the model protein.

Effects of chain length and hydrophobicity/charge ratio of AMP on its antimicrobial activity

Using two series of de novo designed antimicrobial peptides,we studied the effects of peptide length and hydrophobicity/charge(H/C) ratio on the antimicrobial activities.For these peptides,a correlation was established between their antimicrobial efficacy and the leakage,aggregation,and fusion activities on artificial membrane.The results showed that peptides with an H/C ratio of 1.3,and a length of about half of the membrane thickness caused most potent membrane leakage,and negligible membrane aggregation and fusion.In addition,such peptide also exhibited the highest antimicrobial activity.Analysis of the hydrophobic and electrostatic interactions showed that the strength,the order and the position of these interactions determined the activities of the peptides on the artificial membrane and thus the antimicrobial efficacy.Further analyses on the tilt angle of the peptides on the membrane surface indicated that the peptides distorted the membrane in a dynamic mode,instead of being fixed in the membrane at a constant angle.

High-performance CsPbBr_(3)@Cs_(4)PbBr_(6)/SiO_(2) nanocrystals via double coating layers for white light emission and visible light communication

Owing to their outstanding optoelectronic properties,all-inorganic CsPbBr_(3) perovskite nanocrystals(NCs)are regarded as excellent materials for various optoelectronic applications.Unfortunately,their practical applications are limited by poor stability against water,heat,and polar solvents.Here,we propose a facile synthesis strategy for CsPbBr_(3)@Cs_(4)PbBr_(6) NCs via tetraoctylammonium bromide ligand induction at room temperature.The resulting CsPbBr_(3)@Cs_(4)PbBr_(6) NCs show a high photoluminescence quantum yield of 94%.In order to prevent Cs4PbBr6 from being converted back to CsPbBr_(3) NCs when exposed to water,a second coating layer of SiO2 is formed on the surface of the CsPbBr_(3)@Cs_(4)PbBr_(6) NCs by the facile hydrolysis of tetramethoxysilane.The resulting CsPbBr_(3)@Cs_(4)PbBr_(6)/SiO_(2) NCs with their double coating structure have outstanding stability against not only a polar solvent(ethanol)but also water and heat.The as-prepared CsPbBr_(3)@Cs_(4)PbBr_(6)/SiO_(2) NCs serve as green emitters in efficient white light-emitting diodes(WLEDs)with a high color rendering index(CRI)of 91 and a high power efficiency 59.87 lm W−1.Furthermore,the use of these WLEDs in visible light communication(VLC)results in a maximum rate of 44.53 Mbps,suggesting the great potential of the reported methods and materials for solid-state illumination and VLC.