Expression and radiolabeling of Cas9 protein

As a robust platform for genome editing,CRISPR/Cas9 is currently being explored for engineering biology or therapeutics,yet means for quantitative detection of Cas9 proteins remain to be fully realized.Here,we expressed Cas9 proteins and developed a novel detection method that traced Cas9 based on radiolabeled iodine.Through optimizing the reaction conditions of reaction time,temperature and cycles,we obtained ^(125)I-Cas9 of high labeling yield.The prepared ^(125)I-Cas9 was stable in various media and preserved excellent genome editing efficiency.Thus,our strategy provides a convenient and efficient tool for further tracing biological behaviors of Cas9 proteins in living systems.

Effect of concentration and adsorption time on the formation of a large-scale origami pattern

The arrangement of DNA-based nanostructures into the desired large-scale periodic pattern with the highest possible accuracy and control is essential for the DNA application in functional biomaterials;however, formation of a DNA nanostructure pattern without utilizing the molecular interactions in nanotechnology field remains difficult. In this article, we use the optimal concentration and adsorption time of origami to induce DNA origami in the form of a large-scale 2D pattern on mica without changing the origami itself. DNA origami structures can form a pattern by close packing of symmetric and electrostatic interactions between ions, which was confirmed by the atomic force microscopy images. Furthermore, we identified favorable conditions for the concentration of enable pattern formation with DNA origami. This work provides an insight to understand the adsorption of DNA on mica and guides researches on regular DNA nanostructure pattern, which can serve as templates for pattern formation of proteins or other biomolecules.

Iterative and accurate determination of small angle X-ray scattering background

X-ray scattering is widely used in material structural characterizations.The weak scattering nature,however,makes it susceptible to background noise and can consequently render the final results unreliable.In this paper,we report an iterative method to determine X-ray scattering background and demonstrate its feasibility by small angle X-ray scattering on gold nanoparticles.This method solely relies on the correct structural modeling of the sample to separate scattering signal from background in data fitting processes,which allows them to be immune from experimental uncertainties.The importance of accurate determination of the scaling factor for background subtraction is also illustrated.

Controlling the Coffee Ring Effect on Graphene and Polymer by Cations

Recently,there are great efforts that have been taken to suppressing/controlling the coffee ring effect,but it is of challenge to achieve inexpensive and efficient control with less disturbance,suitable for scalable production and highly enhancing the printing/dyeing color fastness.By only adding trace amounts of salt into the suspensions,here we experimentally achieve the facile and highly efficient control of the coffee ring effect of suspended matter on substrates of graphene,natural graphite,and polyethylene terephthalate surfaces.Notably,friction force measurements show that ion-controlled uniform patterns also greatly enhance color fastness.Molecular dynamics simulations reveal that,due to strong hydrated cation-π interactions between hydrated cations and aromatic rings in the substrate surface,the suspended matters are adsorbed on the surfaces mediated by cations so that the suspended matters are uniformly distributed.These findings will open new avenues for fabricating functional patterns on graphene substrates and will benefit practical applications including printing,coating,and dyeing.

Discrimination of foodborne pathogenic bacteria using synchrotron FTIR microspectroscopy

Traditional Fourier transform infrared(FTIR)spectroscopy has been recognized as a valuable method to characterize and classify kinds of microorganisms.In this study,combined with multivariate statistical analysis,synchrotron radiation-based FTIR(SR-FTIR) microspectroscopy was applied to identify and discriminate ten foodborne bacterial strains.Our results show that the whole spectra(3000-900 cm^(-1)) and three subdivided spectral regions(3000-2800,1800-1500 and 1200-900 cm^(-1),representing lipids,proteins and polysaccharides,respectively) can be used to type bacteria.Either the whole spectra or the three subdivided spectra are good for discriminating the bacteria at levels of species and subspecies,but the whole spectra should be given preference at the genus level.The findings demonstrate that SR-FTIR microspectroscopy is a powerful tool to identify and classify foodborne pathogenic bacteria at the genus,species and subspecies level.

Tetrahedral Framework Nucleic Acid-Based Delivery of Resveratrol Alleviates Insulin Resistance:From Innate to Adaptive Immunity

Obesity-induced insulin resistance is the hallmark of metabolic syndrome,and chronic,low-grade tissue inflammation links obesity to insulin resistance through the activation of tissue-infiltrating immune cells.Current therapeutic approaches lack efficacy and immunomodulatory capacity.Thus,a new therapeutic approach is needed to prevent chronic inflammation and alleviate insulin resistance.Here,we synthesized a tetrahedral framework nucleic acid(tFNA)nanoparticle that carried resveratrol(RSV)to inhibit tissue inflammation and improve insulin sensitivity in obese mice.The prepared nanoparticles,namely tFNAs-RSV,possessed the characteristics of simple synthesis,stable properties,good water solubility,and superior biocompatibility.The tFNA-based delivery ameliorated the lability of RSV and enhanced its therapeutic efficacy.In high-fat diet(HFD)-fed mice,the administration of tFNAs-RSV ameliorated insulin resistance by alleviating inflammation status.tFNAs-RSV could reverse M1 phenotype macrophages in tissues to M2 phenotype macrophages.As for adaptive immunity,the prepared nanoparticles could repress the activation of Th1 and Th17 and promote Th2 and Treg,leading to the alleviation of insulin resistance.Furthermore,this study is the first to demonstrate that tFNAs,a nucleic acid material,possess immunomodulatory capacity.Collectively,our findings demonstrate that tFNAs-RSV alleviate insulin resistance and ameliorate inflammation in HFD mice,suggesting that nucleic acid materials or nucleic acid-based delivery systems may be a potential agent for the treatment of insulin resistance and obesity-related metabolic diseases.

Correction to:Tetrahedral Framework Nucleic Acid‑Based Delivery of Resveratrol Alleviates Insulin Resistance:From Innate to Adaptive Immunity

Correction to:Nano‑Micro Lett.(2021)13:86 https://doi.org/10.1007/s40820-021-00614-6 The Nano-Micro Letters(2021)13:86,article by Li et al.,entitled“Tetrahedral Framework Nucleic Acid‐Based Delivery of Resveratrol Alleviates Insulin Resistance:From Innate to Adaptive Immunity”(Nano-Micro Lett.https://doi.org/10.1007/s40820-021-00614-6),was published online 06 March,2020,with errors.

Construction of DNA-based logic gates on nanostructured microelectrodes

Electrochemical logical operations utilizing biological molecules(protein or DNA), which can be used in disease diagnostics and bio-computing, have attracted great research interest. However, the existing logic operations, being realized on macroscopic electrode, are not suitable for implantable logic devices. Here, we demonstrate DNA-based logic gates with electrochemical signal as output combined with gold flower microelectrodes. The designed logic gates are of fast response, enzyme-free, and micrometer scale. They perform well in either pure solution or complex matrices, such as fetal bovine serum,suggesting great potential for in vivo applications.

Real-time label-free analysis of the thermostability of DNA structures using GelRed

In biological systems, conformational transformations of nucleic acids play critical roles in genetic regulation. However, it remains a tricky task to design and optimize specific labeling strategies to track these changes.In this study, we exploited an intercalating fluorescent dye,GelRed, to characterize different DNA structures. We studied the correlation between fluorescence intensity and DNA structural properties. We showed that single-stranded DNAs with predicted self-folded secondary structures show much stronger fluorescence than those without such structures. For double-stranded DNAs, we observed that fluorescence intensity is positively correlated to their GCcontent. We also demonstrated that GelRed can be used to monitor DNA conformational changes upon temperature variations in real time. Based on these findings, we concluded that the fluorescence intensity of a GelRed-stained DNA structure has a good correlation with its thermostability in the form of a change in Gibbs free energy.

Functional Recovery with Electro-Acupuncture Stimulation in an Mecp2-Knockout Rat Model of Rett Syndrome

Rett syndrome is a progressive neurodevelopmental disorder that lacks effective treatments.Although deep-brain stimulation can alleviate some symptoms in Rett model mice,this interventional manipula-tion requires deliberate surgical operations.Here,we report that electro-acupuncture stimulation(EAS)can ameliorate symptoms of an Mecp2-knockout rat model of Rett syndrome from the remote acupoints Baihui(GV 20),Yongquan(KI 1),and Shenmen(HT 7).We find that EAS not only prolongs the survival time of Rett rats,but also improves their behavior ability,including locomotion,motor coordination,and social interaction.Neural activation was observed in the substantia nigra of the midbrain,corpus striatum,and cerebral cortex of wild-type and Rett model rats,as reflected by the increased expression of the c-Fos protein.Hence,EAS provides a potential promising therapeutic tool for treating neurodevel-opmental diseases.

Unexpectedly Strong Diamagnetism of Self-Assembled Aromatic Peptides

There is a considerable amount of work that shows the biomagnetism of organic components without ferromagnetic components at the molecular level,but it is of great challenge to cover the giant gap of biomagnetism between their experimental and theoretical results.Here we show that the diamagnetism of aromatic peptides is greatly enhanced for about 11 times by self-assembling,reaching two orders of magnitude higher than the mass susceptibility of pure water.The self-assembly of aromatic rings in the peptide molecules plays the key role in such a strong diamagnetism.

Size-dependent cellular uptake and sustained drug release of PLGA particles

Poly(lactic-co-glycolic)acid(PLGA)particles have become a commonly used drug delivery strategy in the pharmaceutical industry.In this work,we aim to investigate the size-dependent cellular internalization of PLGA particles and its effects on sustained drug release.We prepared three different-sized particles using PLGA(200,500 and 2000 nm)ranging from submicrometer to micrometer.Dexamethasone(DEX)with excellent anti-inflammatory properties was used as a model drug to prepare DEX-loaded PLGA particles(DPs).We comprehensively investigated the encapsulation efficiency,cellular uptake and in vitro drug release profile.Pharmacodynamic assessment revealed that,in the lipopolysaccharide(LPS)-induced RAW 264.7 cells model,500 nm DPs showed sustained anti-inflammatory efficacy.This work provides important information for designing PLGA-based drug delivery systems for biomedical applications.

Synchrotron infrared spectral regions as signatures for foodborne bacterial typing

Fourier-transform infrared(FTIR) spectroscopy has emerged as a viable alternative to biochemical and molecular biology techniques for bacterial typing with advantages such as short analysis time, low cost and laboratorial simplicity. In this study, synchrotron radiationbased FTIR(SR-FTIR) spectroscopy with higher spectral quality was successfully applied to type 16 foodborne pathogenic bacterial strains. Combined with principal component analysis(PCA) and hierarchical cluster analysis(HCA), we found that the specific spectral region1300-1000 cm^(-1), which reflects the information of phosphate compounds and polysaccharides, can be used as the signature region to cluster the strains into groups similar with genetic taxonomic method. These findings demonstrated that FTIR spectra combined with HCA have a great potential in quickly typing bacteria depending on their biochemical signatures.

Synchrotron FTIR spectroscopy reveals molecular changes in Escherichia coli upon Cu^2＋ exposure

Copper ions(e.g.,Cu^(2+)) have outstanding antibacterial properties,but the exact mechanism is rather complex and not fully understood.In this work,synchrotron Fourier transform infrared(FTIR) spectroscopy was used as an analytical tool to investigate the CuCl_2-induced biochemical changes in Escherichia coli.Our spectral measurements indicated that this technique is sensitive enough to detect changes in membrane lipids,nucleic acids,peptidoglycans and proteins of Cu^(2+)-treated bacteria.Interestingly,for short-time treated cells,the effects on phospholipid composition were clearly shown,while no significant alterations of proteins,nucleic acids and peptidoglycans were found.PeakForce quantitative nano-mechanics mode atomic force microscopy(AFM)confirmed the changes in the topography and mechanical properties of bacteria upon the Cu^(2+) exposure.This study demonstrated that FTIR spectroscopy combined with AFM can provide more comprehensive evaluation on the biochemical and mechanical responses of bacteria to copper.

ALD-coated ultrathin Al_2O_3 film on BiVO_4 nanoparticles for efficient PEC water splitting

Bismuth vanadate(BiVO_4) is a promising semiconductor material for solar energy conversion via photoelectrochemical(PEC) water splitting,whereas its performance is limited by surface recombination due to trapping states.Herein,we developed a new method to passivate the trapping states on BiVO_4 surface using ultrathin aluminum oxide(Al_2O_3) overlayer by atomic layer deposition.The coated ultrathin Al_2O_3 film on BiVO_4 significantly enhanced photocurrent densities of the BiVO_4 anodes under standard illumination of AM1.5 G(100 mW/cm2).The electrochemical impedances and photoluminescence spectra were studied to confirm that the improved PEC water splitting performance of BiVO_4 was due to the decreased surface recombination state on BiVO_4,which effectively enhanced the charge separation.

Quantum dots protect against MPP＋-induced neurotoxicity in a cell model of Parkinson＇s disease through autophagy induction

Autophagy is a basic cellular process that decomposes damaged organelles and aberrant proteins. Dysregulation of autophagy is implicated in pathogenesis of neurodegenerative disorders, including Parkinson's disease(PD). Pharmacological compounds that stimulate autophagy can provide neuroprotection in models of PD. Nanoparticles have emerged as regulators of autophagy and have been tested in adjuvant therapy for diseases. In this present study, we explore the effects of quantum dots(QDs) that can induce autophagy in a cellular model of Parkinson's disease. Cd Te/Cd S/Zn S QDs protect differentiated rat pheochromocytoma PC12 cells from MPP+-induced cell damage, including reduced viability, apoptosis and accumulation of α-Synuclein, a characteristic protein of PD. The protective function of QDs is autophagy-dependent. In addition, we investigate the interaction between quantum dots and autophagic pathways and identify beclin1 as an essential factor for QDs-induced autophagy. Our results reveal new promise of QDs in the theranostic of neurodegenerative diseases.

Superresolution imaging of telomeres with continuous wave stimulated emission depletion (STED) microscope

The significant role of telomeres in cells has attracted much attention since they were discovered.Fluorescence imaging is an effective method to study subcellular structures like telomeres.However,the diffraction limit of traditional optical microscope hampers further investigation on them.Recent progress on superresolution fluorescence microscopy has broken this limit.In this work,we used stimulated emission depletion(STED) microscope to observe fluorescence-labeled telomeres in interphase cell nuclei.The results showed that the size of fluorescent puncta representing telomeres under the STED microscope was much smaller than that under the confocal microscope.Two adjacent telomeres were clearly separated via STED imaging,which could hardly be discriminated by confocal microscopy due to the diffraction limit.We conclude that STED microscope is a more powerful tool that enable us to obtain detailed information about telomeres.

Construction of pH-Triggered DNA Hydrogels Based on Hybridization Chain Reactions

As a novel type of bio-functional material,DNA hydrogels have attracted more and more attention due to their successful applications in 3D cell culturing and tissue engineering for the designable and programmable responsiveness.Herein,we have developed a pH-triggered DNA hydrogel based on a clamped hybridization chain reaction(C-HCR).In this system,a DNA switch was designed,which can release the initiator strand in a controllable way via the formation of the C-G-C4 triplex under the pH stimuli.While the pre-gelation solution is stable in neutral environment,the C-HCR will trigger the sol-gel transition as the pH decreased to 5.0.This strategy has endowed the DNA hydrogel with good controllability for triggering,which also shows potential in intellectual responsiveness to certain stimuli.

Phase transferring luminescent gold nanoclusters via single-stranded DNA

Atomically precise gold nanoclusters(Au NCs) are an emerging class of quantum-sized nanomaterials with discrete electronic energy levels, which has led to a range of attractive electronic and optical applications. Nevertheless, the lack of general methods to transfer Au NCs protected with hydrophobic ligands to an aqueous solution hampers their use in physiological settings. Here,we developed a single-stranded DNA-based approach that could transfer ~90% hydrophobic Au NCs into an aqueous solution.We experimentally and theoretically established that multivalent electrostatic and hydrophobic interactions between DNA strands and the hydrophobic ligand layer on Au NCs resulted in monodispersed DNA-coated Au NCs with high physical integrity in an aqueous solution. The fluorescence quantum yield of Au NCs was increased by ~13 fold, and surface-constrained DNA retained the specific recognition ability for biosensing. We further demonstrated the versatility of this phase-transfer approach, which thus holds great potential to advance biological and medical applications of Au NCs.