Nonspecific Sites Research Articles

The Advancement of Gas-Generating Nanoplatforms in Biomedical Fields: Current Frontiers and Future Perspectives.

Diverse gases (NO, CO, H2 S, H2 , etc.) have been widely applied in the medical intervention of various diseases, including cancer, cardiovascular disease, ischemia-reperfusion injury, bacterial infection, etc., attributing to their inherent biomedical activities. Although many gases have many biomedical activities, their clinical use is still limited due to the rapid and free diffusion behavior of these gases molecules, which may cause potential side effects and/or ineffective treatment. Gas-generating nanoplatforms (GGNs) are effective strategies to address the aforementioned challenges of gas therapy by preventing gas production or release at nonspecific sites, enhancing GGNs accumulation at targeted sites, and controlling gas release in response to exogenous (UV, NIR, US, etc.) or endogenous (H2 O2 , GSH, pH, etc.) stimuli at the lesion site, further maintaining gas concentration within the effective range and achieving the purpose of disease treatment. This review comprehensively summarizes the advancements of "state-of-the-art" GGNs in the recent three years, with emphasis on the composition, structure, preparation process, and gas release mechanism of the nanocarriers. Furthermore, the therapeutic effects and limitations of GGNs in preclinical studies using cell/animal models are discussed. Overall, this review enlightens the further development of this field and promotes the clinical transformation of gas therapy.

Triple-color fluorescence co-localization of PD-L1-overexpressing cancer exosomes.

Programed cell death ligand 1 (PD-L1) is a protein biomarker overexpressed on exosomes derived from tumor cells. It plays an important role in tumor diagnosis, screening, evaluation of therapeutic efficacy, and prognosis. In this study, a facile method is presentedto detect PD-L1-overexpressing cancer exosomes with high specificity and sensitivity. First, gold nanospheres (GNSs) were attached to the bottom of an eight-well chambered slide by electrostatic adsorption, forming the detection substrate. Then, Cy5-labeled CD63 aptamers (i.e., the capture probes) were modified on the GNSs by Au-S bond. After adding samples containing target exosomes which were stained by membrane dyes DiI in advance, FAM-labeled PD-L1 aptamers (i.e., the immunoprobes) were added to recognize PD-L1 on the target exosomes. By triple-color fluorescence co-localization (TFC) of the Cy5, DiI, and FAM channels, highly sensitive and reliable detection of the PD-L1-overexpressing exosomes was achieved in the concentration range 7.78 × 101 to 7.78 × 104 particles/mL with a detection limit down to 6 particles/mL. The advantages of the proposeddetection method include the following; first, the detection substrate is easy to prepare and convenient to clean. Second, the TFC strategy can completely exclude nonspecific reaction sites and thus significantly improves the accuracy. Such a facile and reliable detection method holds a great potential in exosome-based cancer theranostics. In this paper, we proposed a triple-color fluorescence co-localization (TFC) strategy to significantly improve the reliability of exosome detection and the detection substrate is easy to prepare and convenient to clean. In addition, the LOD is down to 6 particles/mL, which is quite low compared with other detection methods.

Ferritin: A Promising Nanoreactor and Nanocarrier for Bionanotechnology.

The essence of bionanotechnology lies in the application of nanotechnology/nanomaterials to solve the biological problems. Quantum dots and nanoparticles hold potential biomedical applications, but their inherent problems such as low solubility and associated toxicity due to their interactions at nonspecific target sites is a major concern. The self-assembled, thermostable, ferritin protein nanocages possessing natural iron scavenging ability have emerged as a potential solution to all the above-mentioned problems by acting as nanoreactor and nanocarrier. Ferritins, the cellular iron repositories, are hollow, spherical, symmetric multimeric protein nanocages, which sequester the excess of free Fe(II) and synthesize iron biominerals (Fe2O3·H2O) inside their ∼5-8 nm central cavity. The electrostatics and dynamics of the pore residues not only drives the natural substrate Fe2+ inside ferritin nanocages but also uptakes a set of other metals ions/counterions during in vitro synthesis of nanomaterial. The current review aims to report the recent developments/understanding on ferritin structure (self-assembly, surface/pores electrostatics, metal ion binding sites) and chemistry occurring inside these supramolecular protein cages (protein mediated metal ion uptake and mineralization/nanoparticle formation) along with its surface modification to exploit them for various nanobiotechnological applications. Furthermore, a better understanding of ferritin self-assembly would be highly useful for optimizing the incorporation of nanomaterials via the disassembly/reassembly approach. Several studies have reported the successful engineering of these ferritin protein nanocages in order to utilize them as potential nanoreactor for synthesizing/incorporating nanoparticles and as nanocarrier for delivering imaging agents/drugs at cell specific target sites. Therefore, the combination of nanoscience (nanomaterials) and bioscience (ferritin protein) projects several benefits for various applications ranging from electronics to medicine.

The impact of decoys on a genetic oscillator based on coupled positive-negative feedbacks

Within cells, transcription factors (TFs) bind to a wide range of nonspecific genomic sites in addition to their target sites. Binding to such high affinity “decoys” has been shown to qualitatively alter the dynamics of gene regulatory circuits. Analyzing simple gene expression models with decoy binding we derive formulas for the TF response time as a function of the number of decoys, binding affinity, and stability of the decoy-bound TF. Our results show that while on one hand, decoys make the response sluggish whenever decoy binding stabilizes the TF, on the other hand, decoys can accelerate responses by destabilizing the bound TF. We apply these results in the context of a genetic oscillator based on an activator-repressor motif, where sustained oscillations result from a rapid activator-mediated positive feedback working in conjunction with a slow repressor-mediated negative feedback. Consistent with our response time analysis, we find that activator binding to decoy sites can destroy oscillations in the case of a stable decoy-activator complex that functions to slow down the positive feedback. In contrast, an unstable decoy-activator complex can expand the oscillatory parameter regime. In conclusion, our response time analysis provides intuitive insights into the emergence of sustained oscillations.

Enhanced phosphate removal by nano-lanthanum hydroxide embedded silica aerogel composites: Superior performance and insights into specific adsorption mechanism

Removal of phosphate from wastewater is a global crucial goal and grand challenge for resource recovery and eutrophication control. However, it represents a major application bottleneck in the phosphate-selective sorption system to enhance the selectivity towards phosphate and the stability of adsorbents. In this study, nano-lanthanum hydroxide was embedded inside the porous silica aerogel (SA) to synthesize a novel aerogel composite (LSA) for highly efficient and selective phosphate removal. La(OH)3 is expected to offer the specific binding sites toward phosphate, while the porous SA host serves as a “shield” with a protective network structure and supplies abundant non-specific sites. LSA possessed enhanced phosphate uptake even when competing anions coexisted at higher levels. Furthermore, LSA exhibited pH-independency due to its high pHpzc. LSA also performed the characteristics of high adsorption capacity, La utilization efficiency, and reusability. Specifically, the maximum Langmuir adsorption capacity of LSA-1/10 reached up to 153.8 mg P/g at pH 6.0. The exhausted LSA-1/10 could be effectively regenerated after 8 adsorption–desorption cycles. The underlying mechanism for such satisfactory performances of LSAs was revealed by XRD, STEM-EDS and XPS analysis. The predominant pathway for selective phosphate removal was confirmed to be the inner-sphere complexation between P and La, intriguingly, the formation of LaPO4·xH2O was detected. Moreover, LSAs were proved to be stable and exhibit no potential adverse effects on the ecosystem or human health. Overall, results proved LSA to be a promising sorbent for efficient phosphate capture in complex water remediation with the core features of preference and selectivity.

Poly(ethyleneoxide-block-methylmethacrylate) derived recessed nanodisc electrode array as an ultrasensitive electrochemical sensing platform for immunosensor

In this work, we present the synthesis of amphiphilic diblock copolymer poly(ethylene oxide-block-methylmethacrylate) (PEO-b-PMMA) using atom transfer radical polymerization and demonstrate its application for the fabrication of recessed nanodisk-array electrode (RNE) as a platform for protein detection. For the fabrication of thin-film, PEO-b-PMMA was spin-coated on the silicon wafer and the phase separation was achieved by a unique direct immersion annealing technique followed by washing with the water/methanol solution to remove the PEO phase. The microphase separation and comprehensive porosity characterizations were done using AFM and electron microscopy. Later, the thin film was loaded on the surface of the glassy carbon electrode by wedge transfer technique and the RNE property of the mesoporous thin film was confirmed using cyclic voltammetry (CV). For the protein sensing application, the thin film-coated electrode was biotinylated using EDC-NHS chemistry, followed by the blocking of the non-specific sites using bovine serum albumin (BSA). The reduction in the CV current and the increase in the channel resistance in EIS at each stage of fabrication confirmed the successful immobilization. For the streptavidin detection, the RNE displayed an ultra-low detection limit of 0.15 fg/ml with enhanced selectivity which confirms the potential of PEO-b-PMMA based RNE as an ultrasensitive immunosensor platform for any biomarker detection.

Enhanced stability and controlled release of menthol using a β-cyclodextrin metal-organic framework

Menthol inclusion complexes (ICs) have addressed a range of opportunities in food applications due to their volatile resistance. However, previous protocols used for their synthesis give low yields and high industrial application costs. In the present investigation, metal–organic frameworks based on β-cyclodextrin (β-CD-MOF) have been prepared for the molecular encapsulation of menthol. Menthol/β-CD-MOF-IC was synthesized under the optimized parameters, after which release behavior was studied. In this optimized manner, a higher menthol capacity was obtained in which the menthol content and encapsulation efficiency were 27.1 and 30.6%, respectively. Compared with menthol/β-CD-IC, menthol/β-CD-MOF-IC is resistant to high temperature, but sensitive to moisture. In a simulated oral release experiment, the rate of menthol release from different samples followed the order of: pure menthol > β-CD > β-CD-MOF, which can be attributed to two mechanisms: non-specific binding and site preference. We propose that β-CD-MOF can be used as a promising delivery system for aroma compounds.

The critical role of mobile phase pH in the performance of oligonucleotide ion-pair liquid chromatography-mass spectrometry methods.

The critical role of mobile phase pH in the performance of oligonucleotide ion-pair liquid chromatography-mass spectrometry methods.

Prostate Magnetic Resonance Imaging Analyses, Clinical Parameters, and Preoperative Nomograms in the Prediction of Extraprostatic Extension.

Introduction: Proper planning of laparoscopic radical prostatectomy (RP) in patients with prostate cancer (PCa) is crucial to achieving good oncological results with the possibility of preserving potency and continence. Aim: The aim of this study was to identify the radiological and clinical parameters that can predict the risk of extraprostatic extension (EPE) for a specific site of the prostate. Predictive models and multiparametric magnetic resonance imaging (mpMRI) data from patients qualified for RP were compared. Material and methods: The study included 61 patients who underwent laparoscopic RP. mpMRI preceded transrectal systematic and cognitive fusion biopsy. Martini, Memorial Sloan-Kettering Cancer Center (MSKCC), and Partin Tables nomograms were used to assess the risk of EPE. The area under the curve (AUC) was calculated for the models and compared. Univariate and multivariate logistic regression analyses were used to determine the combination of variables that best predicted EPE risk based on final histopathology. Results: The combination of mpMRI indicating or suspecting EPE (odds ratio (OR) = 7.49 (2.31–24.27), p < 0.001) and PSA ≥ 20 ng/mL (OR = 12.06 (1.1–132.15), p = 0.04) best predicted the risk of EPE for a specific side of the prostate. For the prediction of ipsilateral EPE risk, the AUC for Martini’s nomogram vs. mpMRI was 0.73 (p < 0.001) vs. 0.63 (p = 0.005), respectively (p = 0.131). The assessment of a non-specific site of EPE by MSKCC vs. Partin Tables showed AUC values of 0.71 (p = 0.007) vs. 0.63 (p = 0.074), respectively (p = 0.211). Conclusions: The combined use of mpMRI, the results of the systematic and targeted biopsy, and prostate-specific antigen baseline can effectively predict ipsilateral EPE (pT3 stage).

Zinc trafficking 1. Probing the roles of proteome, metallothionein, and glutathione.

The cellular trafficking pathways that conduct zinc to its sites of binding in functional proteins remain largely unspecified. In this study, the hypothesis was investigated that nonspecific proteomic binding sites serve as intermediates in zinc trafficking. Proteome from pig kidney LLC-PK1 cells contains a large concentration of such sites, displaying an average conditional stability constant of 1010-11, that are dependent on sulfhydryl ligands to achieve high-affinity binding of zinc. As a result, the proteome competes effectively with induced metallothionein for Zn2+ upon exposure of cells to extracellular Zn2+ or during in vitro direct competition. The reaction of added Zn2+ bound to proteome with apo-carbonic anhydrase was examined as a potential model for intracellular zinc trafficking. The extent of this reaction was inversely dependent upon proteome concentration and under cellular conditions thought to be negligible. The rate of reaction was strictly first order in both Zn2+ and apo-carbonic anhydrase, and also considered to be insignificant in cells. Adding the low molecular weight fraction of cell supernatant to the proteome markedly enhanced the speed of this reaction, a phenomenon dependent on the presence of glutathione (GSH). In agreement, inclusion of GSH accelerated the reaction in a concentration-dependent manner. The implications of abundant high-affinity binding sites for Zn2+ within the proteome are considered in relation to their interaction with GSH in the efficient delivery of Zn2+ to functional binding sites and in the operation of fluorescent zinc sensors as a tool to observe zinc trafficking.

Sorption Isotherm Analysis of Trace Metals on a Sandy Textured Coconut Growing Soil

The nature of adsorption of trace metallic plant nutrients, Cu, Mn and Zn, on a coconut growing sandy textured soil (Madampe series) was investigated in 0.050 M KNO₃ medium. Different adsorption parameters, <em>viz </em>contact time, soil mass, initial concentration and pH were optimized for the study. Variation of the mass of each metal ion sorbed on soil and the initial concentration at constant pH was investigated to understand the nature of adsorption. Further, the data at adsorption equilibrium were fitted to two commonly used isotherm models, namely, Langmuir and Freundlich. The optimum parameters were determined as, shaking time: 3 hours; settling time: 30 minutes; soil mass: 1 g; pH: 5-7; and initial concentrations for Mn(II) and Zn(II): 20 mg/L and 15 mg/L, respectively. The experimental data of Mn(II) and Zn(II) lead to regression coefficients (R2) of 0.957 to 0.970, respectively, for the Langmuir model and 0.812 to 0.925, respectively, for the Freundlich model. Although the Langmuir model fitted better with respect to R2 values, both Langmuir and Freundlich models could be used to illustrate the trace metal sorption on the soil. Initially, trace metal ions probably interacted with specific sites where soil surface is homogeneous; this was followed by iteration at nonspecific sites leading to multilayers or through the different modes of mass transfer fulfilling the conditions of the Freundlich model. The adsorption capacity of soil for the three trace metal ions varied in the order of Cu (II) &gt; Zn(II) &gt; Mn(II).

Magnetic Nanoparticles with Surface Nanopockets for Highly Selective Antibody Isolation.

Monoclonal antibodies (mAbs) are key components of revolutionary disease immunotherapies and are also essential for medical diagnostics and imaging. The impact of cost is illustrated by a price >$200,000 per year per patient for mAb-based cancer therapy. Purification represents a major issue in the final cost of these immunotherapy drugs. Protein A (PrA) resins are widely used to purify antibodies, but resin cost, separation efficiency, reuse, and stability are major issues. This paper explores a synthesis strategy for low-cost, reusable, stable PrA-like nanopockets on core-shell silica-coated magnetic nanoparticles (NPs) for IgG antibody isolation. Mouse IgG2a, a strong PrA binder, was used as a template protein, first attaching it stem-down onto the NP surface. The stem-down orientation of IgG2a on the NP surface before polymerization is critical for designing the films to bind IgGs. Following this, 1-tetraethoxysilane and four organosilane monomers with functional groups capable of mimicking binding interactions of proteins with IgG antibody stems were reacted to form a thin polymer coating on the NPs. After blocking nonspecific binding sites, removal of the mouse IgG2a provided nanopockets on the core-shell NPs that showed binding characteristics for antibodies remarkably similar to PrA. Both smooth and rough core-shell NPs were used, with the latter providing much larger binding capacities for IgGs, with an excellent selectivity slightly better than that of commercial PrA magnetic beads. This paper is the first report of IgG-binding NPs that mimic PrA selectivity. These nanopocket NPs can be used for at least 15 regeneration cycles, and cost/use was 57-fold less than a high-quality commercial PrA resin.

Modeling the Effect of Binding Kinetics in Spatial Drug Distribution in the Brain.

A 3-dimensional mathematical model is developed to determine the effect of drug binding kinetics on the spatial distribution of a drug within the brain. The key components, namely, transport across the blood-brain barrier (BBB), drug distribution in the brain extracellular fluid (ECF), and drug binding kinetics are coupled with the bidirectional bulk flow of the brain ECF to enhance the visualization of drug concentration in the brain. The model is developed based on the cubical volume of a brain unit, which is a union of three subdomains: the brain ECF, the BBB, and the blood plasma. The model is a set of partial differential equations and the associated initial and boundary conditions through which the drug distribution process in the mentioned subdomains is described. Effects of drug binding kinetics are investigated by varying the binding parameter values for both nonspecific and specific binding sites. All variations of binding parameter values are discussed, and the results show the improved visualization of the effect of binding kinetics in the drug distribution within the brain. For more realistic visualization, we suggest incorporating more brain components that make up the large volume of the brain tissue.

Controlled antibody orientation on Fe3O4 nanoparticles and CdTe quantum dots enhanced sensitivity of a sandwich-structured electrogenerated chemiluminescence immunosensor for the determination of human serum albumin

• Impact of antibody orientation in the performance of ECL is firstly investigated. • Protein G results antibody orientation and blocks nonspecific binding sites simultaneously. • Photoluminescence intensity was 11.8 times higher with full antibody orientation than without. • ECL intensity was almost nine times higher with full antibody orientation than without. In the present study, the sensitivity of an electrochemiluminescence (ECL) immunosensor was enhanced by controlled antibody orientation, developed by modification of both Fe 3 O 4 nanoparticles (FNs) and CdTe quantum dots (QDs) as nanocarriers and luminance labels, respectively. Magnetic FNs were selected as nanocarriers for easy magnetic separation and were coated with SiO 2 layer for immobilization of primary antibodies (Ab1). Protein G on the FN surface could support Ab1 with a high degree of controlled orientation and could block nonspecific binding sites to enhance the sensitivity and selectivity of the ECL immunosensor. Moreover, CdTe QDs with protein G coatings were selected as signal labels and were conjugated with secondary antibodies with a high degree of orientation. The sandwich-structured immunosensor exhibited remarkable stability according to cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Photoluminescence and ECL intensities of the developed immunosensor were 11.8 and 9 times higher with controlled antibody orientation than without it. The developed immunosensor, used to quantify human serum albumin (HSA), exhibited a wide linear range (20–680 ng/mL), and a detection limit of 12 ng/mL. Furthermore, HSA-spiked serum samples were used to evaluate the accuracy and reliability of the immunosensor. The results indicate that antibody orientation substantially improves the sensitivity of sandwich-structured ECL immunosensors for clinical bioassay.

New Insight into the Interactions of Arbutin with Mushroom Tyrosinase.

As a safe substitute for hydroquinone, β-arbutin, a natural plant substance, and its synthetic counterpart, α-arbutin, are used in depigmentation formulations. However, there are debatable points regarding the impact of arbutin on tyrosinase and the pigmentation process. To shed light on this issue, the effects of Pyrus biossieriana leaves extract (PbLE) and β-arbutin, extracted from PbLE, on mushroom tyrosinase (MT) were comprehensively examined. The study was focused on cresolase activity as the characteristic reaction of a tyrosinase. Kinetics studies disclosed that β-arbutin can modulate MT monophenolase activity from inhibition to activation or vice versa. β-Arbutin inhibited L-tyrosine (LTy) oxidation at concentrations < 0.3mM but it increased (more than 400%) the enzymatic oxidation of L-tyrosine at the concentrations > 0.3mM. An opposite pattern (activation then inhibition) was observed when a synthetic substrate was used instead of LTy. Computational studies, focused on the heavy chain of MT, indicated that β-arbutin effect could be overruled by the enzyme's ability to provide the ligand with a non-specific binding site (MTPc). A plausible mechanism was presented to show the influence of MTPc on the substrate pose in the active site. The possible determinant correlation between the findings of this research and the current studies on human tyrosinase role in the pigmentation process has been presented.

The needle and the haystack: single molecule tracking to probe the transcription factor search in eukaryotes.

Transcription factors (TFs) regulate transcription of their target genes by identifying and binding to regulatory regions of the genome among billions of potential non-specific decoy sites, a task that is often presented as a ‘needle in the haystack’ challenge. The TF search process is now well understood in bacteria, but its characterization in eukaryotes needs to account for the complex organization of the nuclear environment. Here we review how live-cell single molecule tracking is starting to shed light on the TF search mechanism in the eukaryotic cell and we outline the future challenges to tackle in order to understand how nuclear organization modulates the TF search process in physiological and pathological conditions.

TALEN outperforms Cas9 in editing heterochromatin target sites

Genome editing critically relies on selective recognition of target sites. However, despite recent progress, the underlying search mechanism of genome-editing proteins is not fully understood in the context of cellular chromatin environments. Here, we use single-molecule imaging in live cells to directly study the behavior of CRISPR/Cas9 and TALEN. Our single-molecule imaging of genome-editing proteins reveals that Cas9 is less efficient in heterochromatin than TALEN because Cas9 becomes encumbered by local searches on non-specific sites in these regions. We find up to a fivefold increase in editing efficiency for TALEN compared to Cas9 in heterochromatin regions. Overall, our results show that Cas9 and TALEN use a combination of 3-D and local searches to identify target sites, and the nanoscopic granularity of local search determines the editing outcomes of the genome-editing proteins. Taken together, our results suggest that TALEN is a more efficient gene-editing tool than Cas9 for applications in heterochromatin.

Nanostructured graphitic carbon nitride based ultrasensing electrochemical biosensor for food toxin detection

We report results of the studies related to the fabrication of thionine functionalized graphitic carbon nitride nanosheets based ultrasensing platform for food toxin (Aflatoxin B1, AfB1) detection. The synthesis of graphitic carbon nitride nanosheets (g-C3N4) was carried out by polycondensation of melamine followed by chemical exfoliation. Further, thionine was used for the functionalization of g-C3N4 (Thn/g-C3N4) and deposited electrophoretically onto the indium tin oxide (ITO) coated glass electrode. The fabricated Thn/g-C3N4/ITO electrode was covalently immobilized by EDC-NHS chemistry with anti-aflatoxin B1 (anti-AfB1) followed by blocking of non-specific sites using BSA molecules. For structural, morphological, functional and electrochemical properties analysis of synthesized nanomaterials and fabricated electrodes X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, atomic force microscopy and cyclic voltammetry techniques were used. The electrochemical response studies of the fabricated biosensing platform (BSA/anti-AfB1/Thn/g-C3N4/ITO) were carried out towards detection of AfB1 antigen using cyclic voltammetry technique. The obtained electrochemical results indicate that the fabricated biosensing electrode having ability to detect AfB1 with lower limit of detection of 0.328 fg mL−1, linear detection range in between 1 fg mL−1 to 1 ng mL−1, sensitivity of 4.85 μA log [ng−1 mL] cm−2 with stability upto 7 weeks.

Conformational Plasticity and DNA-Binding Specificity of the Eukaryotic Transcription Factor Pax5.

The eukaryotic transcription factor Pax5 has a DNA-binding Paired domain composed of two independent helical bundle subdomains joined by a flexible linker. Previously, we showed distinct biophysical properties of the N-terminal (NTD) and C-terminal (CTD) subdomains, with implications for how these two regions cooperate to distinguish nonspecific and cognate DNA sites [Perez-Borrajero, C., et al. (2016) J. Mol. Biol. 428, 2372-2391]. In this study, we combined experimental methods and molecular dynamics (MD) simulations to dissect the mechanisms underlying the functional differences between the Pax5 subdomains. Both subdomains showed a similar dependence of DNA-binding affinity on ionic strength. However, due to a greater contribution of non-ionic interactions, the NTD bound its cognate DNA half-site with an affinity approximately 10-fold higher than that of the CTD with its half-site. These interactions involve base-mediated contacts as evidenced by nuclear magnetic resonance spectroscopy-monitored chemical shift perturbations. Isothermal titration calorimetry revealed that favorable enthalpic and compensating unfavorable entropic changes were substantially larger for DNA binding by the NTD than by the CTD. Complementary MD simulations indicated that the DNA recognition helix H3 of the NTD is particularly flexible in the absence of DNA and undergoes the largest changes in conformational dynamics upon binding. Overall, these data suggest that the differences observed for the subdomains of Pax5 are due to the coupling of DNA binding with dampening of motions in the NTD required for specific base contacts. Thus, the conformational plasticity of the Pax5 Paired domain underpins the differing roles of its subdomains in association with nonspecific versus cognate DNA sites.

Efficient Curing Sacrificial Agent-Induced Dual-Heterojunction Photoelectrochemical System for Highly Sensitive Immunoassay.

A photoelectrochemical (PEC) biosensor is a very efficient and sensitive detection technology for the quick and effective conversion of light to electrical signals. However, the sensitivity and stability of the sensors are still unsatisfactory based on single-phase semiconductors or in the absence of sacrificial agents in the test solution. Herein, we present an efficient curing sacrificial agent-induced dual-heterojunction PEC system, which can detect the prostate-specific antigen (PSA) with high sensitivity. This PEC immune system was initially fabricated using single-walled carbon nanohorns (SWCNHs), p-type MoS2, and n-type Ag2S successively through a Schottky junction and p-n heterojunction on a glassy carbon electrode with electrodeposited gold nanoparticles. Then, the capture antibody (Ab1) was modified and the nonspecific binding sites were sealed off. Meanwhile, the ferrocene (Fc) solidified with hollow nanospheres of zinc ferrite (ZnFe2O4) served as a curing electronic sacrificial agent (Fc-ZnFe2O4). Next, the detection antibody labeled with Fc-ZnFe2O4 (Ab2-Fc-ZnFe2O4) was used as a bio-nanoprobe and captured by PSA and Ab1 via sandwich immunorecognition. Under white light, PEC signal amplification could be driven by the curing electronic sacrificial agent-induced dual-heterojunction to achieve the highly sensitive detection of the target. This proposed system exhibited excellent photocurrent performance within the working range from 1 fg·mL-1 to 100 ng·mL-1 at a low detection limit of 0.44 fg·mL-1 (S/N = 3). The proposed strategy features high sensitivity, selectivity, and stability that provides a new opportunity for the development of biosensors in the PEC field.