Peptide-Directed Synthesis of Aggregation-Induced Emission Enhancement-Active Gold Nanoclusters for Single- and Two-Photon Imaging of Lysosome and Expressed αvß3 Integrin Receptors.

This study explores the synthesis and characterization of aggregation-induced emission enhancement (AIEE)-active gold nanoclusters (AuNCs), focusing on their near-infrared luminescence properties and potential applications in biological imaging. These AIEE-active AuNCs were synthesized via the NaBH4-mediated reduction of HAuCl4 in the presence of peptides. We systematically investigated the influence of the peptide sequence on the optical features of the AuNCs, highlighting the role of glutamic acid in enhancing their quantum yield (QY). Among the synthesized peptide-stabilized AuNCs, EECEE-stabilized AuNCs exhibited the maximum QY and a pronounced AIEE effect at pH 5.0, making them suitable for the luminescence imaging of intracellular lysosomes. The AIEE characteristic of the EECEE-stabilized AuNCs was demonstrated through examinations using transmission electron microscopy, dynamic light scattering, zeta potential analysis, and single-particle imaging. The formation of the EECEE-stabilized AuNCs was confirmed by size-exclusion chromatography and mass spectrometry. Spectroscopic and electrochemical examinations uncover the formation process of EECEE-stabilized AuNCs, comprising EECEE-mediated reduction, NaBH4-induced nucleation, complex aggregation, and subsequent cluster growth. Furthermore, we demonstrated the utility of these AuNCs as luminescent probes for intracellular lysosomal imaging, leveraging their pH-responsive AIEE behavior. Additionally, cyclic arginylglycylaspartic acid (RGD)-modified AIEE dots, derived from cyclic RGD-linked peptide-induced aggregation of EECEE-stabilized AuNCs, were developed for single- and two-photon luminescence imaging of αvß3 integrin receptor-positive cancer cells.

Selective and Sensitive Detection of Fe3+ Ions Using a Red-Emissive Fluorescent Probe Based on Triphenylamine and Perylene-Linked Conjugated Microporous Polymer.

The Expansion of modern industry underscores the urgent need to address heavy metal pollution, which is a threat to human-health and environment. Efforts are underwent to develop precise technologies for detecting heavy metal ions (M+-ion). One promising approach involves the use of Conjugated Microporous Polymers (CMPs) modified with Triphenylamine (TPA) anderylene (Peryl), known as TPA-Peryl-CMP, which emits strong refluorescence. Various analytical techniques, such as Brunauer-Emmett-Teller analysis, Fourier transform infrared (FTIR) spectroscopy, nuclear magnetic resonance (NMR) spectroscopy, and thermogravimetric analysis (TGA), are utilized to characterize the synthesized TPA-Peryl-CMP and understand its functional properties. In addition to its remarkable fluorescence behavior, TPA-Peryl-CMP shows promise as a sensor for Fe3+ ions using a turn-off strategy. Due to its exceptional stability and robust π-electron system, this platform demonstrates remarkable sensitivity and selectivity, significantly improving detection capabilities for specific analytes. Detailed procedures related to the mechanism for detecting Fe3+ ions are outlined for sensing Fe3+ ions, revealing a notably strong linear correlation within the concentration range of 0-3 µM, with a correlation coefficient of 0.9936 and the Limit of detection (LOD) 20 nM. It is anticipated that development of such a kind of TPA-Peryl-CMP will observe broader applications in detecting various analytes related to environmental and biological systems.

Process Optimization and Equilibrium, Thermodynamic, and Kinetic Modeling of Toxic Congo Red Dye Adsorption from Aqueous Solutions Using a Copper Ferrite Nanocomposite Adsorbent.

In the present investigation of copper ferrite, a CuFe2O4 nanocomposite adsorbent was synthesized using the sol-gel method, and its relevance in the adsorptive elimination of the toxic Congo red (CR) aqueous phase was examined. A variety of structural methods were used to analyze the CuFe2O4 nanocomposite; the as-synthesized nanocomposite had agglomerated clusters with a porous, irregular, rough surface that could be seen using FE-SEM, and it also contained carbon (23.47%), oxygen (44.31%), copper (10.21%), and iron (22.01%) in its elemental composition by weight. Experiments were designed to achieve the most optimized system through the utilization of a central composite design (CCD). The highest uptake of CR dye at equilibrium occurred when the initial pH value was 5.5, the adsorbate concentration was 125 mg/L, and the adsorbent dosage was 3.5 g/L. Kinetic studies were conducted, and they showed that the adsorption process followed a pseudo-second-order (PSO) model (regression coefficient, R2 = 0.9998), suggesting a chemisorption mechanism, and the overall reaction rate was governed by both the film and pore diffusion of adsorbate molecules. The process through which dye molecules were taken up onto the particle surface revealed interactions involving electrostatic forces, hydrogen bonding, and pore filling. According to isotherm studies, the equilibrium data exhibited strong agreement with the Langmuir model (R2 = 0.9989), demonstrating a maximum monolayer adsorption capacity (qmax) of 64.72 mg/g at pH 6 and 302 K. Considering the obtained negative ΔG and positive ΔHads and ΔSads values across all tested temperatures in the thermodynamic investigations, it was confirmed that the adsorption process was characterized as endothermic, spontaneous, and feasible, with an increased level of randomness. The CuFe2O4 adsorbent developed in this study is anticipated to find extensive application in effluent treatment, owing to its excellent reusability and remarkable capability to effectively remove CR in comparison to other adsorbents.

Gold nanocluster-based fluorescent sensors for in vitro and in vivo ratiometric imaging of biomolecules.

Gold nanoclusters (AuNCs) are promising nanomaterials for ratiometric fluorescent probes due to their tunable fluorescence wavelengths dependent on size and structure, as well as their biocompatibility and resistance to photobleaching. By incorporating an additional fluorescence spectral peak, dual-emission AuNC-based fluorescent probes have been developed to enhance the signal output reproducibility. These probes can be fabricated by integrating various luminescent nanomaterials with AuNCs. This review focuses on the preparation methods and applications of ratiometric fluorescent probes derived from AuNCs and other fluorescent nanomaterials or fluorescent dyes for both in vitro and in vivo bioimaging of target analytes. Additionally, the review delves into the sensing mechanisms of AuNC-based ratiometric probes, their synthetic strategies, and the challenges encountered when using AuNCs for ratiometric bioimaging. Moreover, we explore the application of protein-stabilized AuNCs and thiolate-capped AuNC-based ratiometric fluorescent probes for biosensing and bioimaging. Two primary methods for assembling AuNCs and fluorophores into ratiometric fluorescent probes are discussed: triggered assembly and self-assembly. Finally, we address the challenges and issues associated with ratiometric bioimaging using AuNCs and propose future directions for further advancing AuNCs as ratiometric imaging agents.

Directed self-assembly of Ag+-deposited MoS2 quantum dots for colorimetric, fluorescent and fluorescence-lifetime sensing of alkaline phosphatase.

We developed a triple-readout probe for colorimetric, fluorescent, and fluorescence-lifetime sensing of alkaline phosphatase (ALP) through the hydrolyzed ascorbic acid phosphate (AAP)-mediated formation of silver nanoparticles (AgNPs) on Ag+-deposited MoS2 quantum dots (QDs). Ag+ ions were self-assembled on a monolayer MoS2 QD surface through the formation of Ag-S bonds. When ALP hydrolyzed AAP in an alkaline buffer, the resultant ascorbic acid (AA) triggered the reduction of the bound Ag+ ions into AgNPs on the MoS2 QD surface. The resultant AgNPs induced an efficient fluorescence quenching of the MoS2 QDs through simultaneous static and dynamic quenching processes, generated an intense surface plasmon resonance peak, and triggered a reduction in the fluorescence lifetime of the MoS2 QDs. Electron microscopy and spectroscopic techniques revealed the successful fabrication of Ag+-deposited MoS2 QDs and the ALP-mediated formation of AgNPs on the MoS2 QD surface. The linear quantification ranges for ALP were 0.05-2.5, 0.1-4, and 1-4 units L-1 in the fluorescent, colorimetric, and fluorescence-lifetime detection modes, respectively. In addition, the proposed probe integrated with an ALP-linked sandwich immunoassay exhibited high sensitivity and selectivity for the fluorescence sensing of rabbit immunoglobulin G with a detection limit of 8 pg mL-1 and linear range of 25-1000 pg mL-1. The sensitivity of the probe is comparable to those of previously reported immunoassays involving ultrasensitive electrochemical detection, hydrogen evolution reactions, or electron spin resonance. The probe integrated with the sandwich assay serves as a promising platform for the detection of target proteins in clinical samples.

Synthesis of gold nanoclusters-loaded lysozyme nanoparticles for ratiometric fluorescent detection of cyanide in tap water, cyanogenic glycoside-containing plants, and soils.

The modification of protein-stabilized gold nanoclusters with fluorophores has been intensively applied for the ratiometric detection of biomolecules, metal ions, and anions. This study developed a straightforward strategy to prepare lysozyme nanoparticle-encapsulated gold nanoclusters (LysNP-AuNCs) as a dual-emission probe for the ratiometric sensing of cyanide through fluorescence resonance energy transfer (FRET) without the conjugation of additional fluorophores. The reduction of gold ion precursors with lysozyme generated lysozyme-stabilized AuNCs under an alkaline pH, which were demonstrated to self-assemble into nanoaggregates during the formation of AuNCs. The aggregated lysozyme molecules on the AuNCs were treated with glutaraldehyde, triggering the conversion of the aggregated lysozymes into blue-emitting lysozyme nanoparticles. As a result, the AuNCs were well distributed inside a single lysozyme nanoparticle, as demonstrated by transmission electron microscopy. The presence of cyanide triggered the etching of the AuNCs in the LysNP-AuNCs, leading to the suppression of FRET from lysozyme nanoparticle to AuNCs. The LysNP-AuNC probe was implemented for FRET detection of cyanide with a linear range of 3-100 µM. Additionally, the selectivity of the LysNP-AuNC probe for cyanide toward other anions was remarkably high. The practicality of the proposed probe was evaluated by quantifying cyanide in tap water and soils and monitoring the liberation of hydrogen cyanide from cyanogenic glycoside-containing foods.

Surgical application of endoscopic-assisted minimally-invasive neurosurgery to traumatic brain injury: Case series and review of literature.

BACKGROUND/PURPOSE: Adequate decompression is the primary goal during surgical management of patients with traumatic brain injury (TBI). Therefore, it may seem counterintuitive to use minimally-invasive strategies to treat these patients. However, recent studies show that endoscopic-assisted minimally-invasive neurosurgery (MIN) can provide both adequate decompression (which is critical for preserving viable brain tissue) and maximize neurological recovery for patients with TBI. Hence, we reviewed the pertinent literature and shared our experiences on the use of MIN. METHODS: This was a retrospective multi-center study. We collected data of 22 TBI patients receiving endoscopic-assisted MIN within 72 hours after the onset, with Glasgow Coma Scale (GCS) scores of 6-14 and whose hemorrhage volume ranging from 30 to 70 mL. RESULTS: We have applied MIN techniques to a group of 22 patients with traumatic ICH (TICH), epidural hematoma (EDH), and subdural hematoma (SDH). The mean pre-operative GCS score was 7.5 (median 7), and mean hemorrhage volume was 57.14 cm3 Surgery time was shortened with MIN approaches to a mean of 59.6 min. At 6-month follow-up, the mean GCS score had improved to 12.3 (median 15). By preserving more normal brain tissue, MIN for patients with TBI can result in beneficial effects on recoveries and neurological outcomes. CONCLUSION: Endoscopic-assisted MIN in TBI is safe and effective in a carefully selected group of patients.

Self-Assembly of Poly(ethyleneimine)-Modified g-C3N4 Nanosheets with Lysozyme Fibrils for Chromium Detoxification.

We disclose a straightforward approach to fabricate nanocomposites for efficient capture of Cr(VI) from an aqueous solution through the self-assembly of poly(ethyleneimine)-modified graphitic carbon nitride nanosheets (PEI-g-C3N4 NSs) and lysozyme fibrils (LFs). The as-made PEI-g-C3N4 NSs@LFs exhibited mesoporous structures with a high specific surface area of 39.6 m2 g-1, a large pore volume of 0.25 cm3 g-1, several functional groups (e.g., -N, -NH, -NH2, and -COOH), and a zero-point charge at pH 9.1. These merits allow the PEI-g-C3N4 NSs@LFs to further enhance their physical adsorption and electrostatic attraction with the negatively charged Cr(VI) species of HCrO4- and CrO42-, which is beneficial for the uptake of Cr(VI), >80%, from an aqueous solution in a wide pH range. Interestingly, X-ray photoelectron spectra indicate that the PEI-g-C3N4 NSs@LFs converted Cr(VI) to Cr(III) through visible-light-induced photoreduction. The adsorption of Cr(VI) on the surface of PEI-g-C3N4 NSs@LFs was found to obey the Freundlich isotherm model, signifying that they have a heterogeneous surface for the multilayer uptake of Cr(VI). In contrast, the PEI-g-C3N4 NSs and LFs as Cr(VI) adsorbents followed the Langmuir isotherm model. Adsorption kinetic studies showed that the uptake of Cr(VI) through the PEI-g-C3N4 NSs@LFs was highly correlated with a pseudo-first-order model, suggesting that physisorption dominates the interaction of Cr(VI) and the PEI-g-C3N4 NSs@LFs. In real-life applications, the PEI-g-C3N4 NSs@LFs were used for the detoxification of the total chromium in the industrial effluent and sludge samples.

An eco-friendly solvent-free reaction based on peptide probes: design an extraction-free method for analysis of acrylamide under microliter volume.

Acrylamide is a group 2A carcinogen and potential endocrine disruptor that can enter the ecosystem by various routes and has recently become a dangerous pollutant. This widely used chemical can enter the human body via air inhalation, food or water consumption, or skin contact. In this study, we developed a peptide probe for the detection of acrylamide by matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) after its micro-tagging with a peptide. Direct detection of acrylamide by MALDI-TOF MS is not feasible due to its poor ionization in the MALDI interface, which hinders its analysis by the technique. After microwave irradiation for 2 min, the formed acrylamide-peptide derivative was detected easily by MALDI-TOF MS without the need for extraction procedures. The procedure does not involve organic solvents and a water-soluble peptide that allows detection of acrylamide in small sample volumes with a limit of detection (LOD) of 0.05 ng/µL. The relative standard deviation (RSD) and relative error (RE) of the measurements were < 6.7% for intra- and inter-day assays. Gel-washing solutions from a polyacrylamide gel experiment were used as a model to study the efficiency of the developed method. Finally, we used the proposed method for the detection of free acrylamide in small volumes of lung epithelial cells (a model to test the air inhalation of acrylamide under a tiny volume of sample) and human urine. The developed method will enable rapid acrylamide detection in environmental and biological samples via a green approach based on microwave-assisted derivatization in water alongside the use of a less toxic derivatization reagent, reusable target plate, and miniaturization protocols.

Identification of significant protein markers by mass spectrometry after co-treatment of cells with different drugs: An in vitro survey platform.

RATIONALE: Understanding drug-drug interactions and predicting the side effects induced by polypharmacy are difficult because there are few suitable platforms that can predict drug-drug interactions and possible side effects. Hence, developing a platform to identify significant protein markers of drug-drug interactions and their associated side effects is necessary to avoid adverse effects. METHODS: Human liver cells were treated with ethosuximide in combination with cimetidine, ketotifen, metformin, metronidazole, or phenytoin. After sample preparation and extraction, mitochondrial proteins from liver cells were isolated and digested with trypsin. Then, peptide solutions were detected using a nano ultra-performance liquid chromatographic system combined with tandem mass spectrometry. The Ingenuity Pathway Analysis tool was used to simulate drug-drug interactions and identify protein markers associated with drug-induced adverse effects. RESULTS: Several protein markers were identified by the proposed method after liver cells were co-treated with ethosuximide and other drugs. Several of these protein markers have previously been reported in the literature, indicating that the proposed platform is workable. CONCLUSIONS: Using the proposed in vitro platform, significant protein markers of drug-drug interactions could be identified by mass spectrometry. This workflow can then help predict indicators of drug-drug interactions and associated adverse effects for increased safety in clinical prescriptions.

Impact of nanoceria shape on degradation of diethyl paraoxon: Synthesis, catalytic mechanism, and water remediation application.

A series of nanomaterials have been demonstrated to be powerful for direct degradation of diethyl paraoxon (EP) to diethyl phosphate and 4-nitrophenol in aqueous solution. However, comparison of catalytic activity of different nanomaterials toward EP is rarely explored. In the present study, four different morphological nanoceria (cubes, rods, polyhedral, and spheres) were synthesized, characterized, and evaluated as a catalyst for the degradation of EP in comparison to other commercially available nanomaterials. Among the tested nanoceria, the cerium dioxide (CeO2) nanopolyhedra possess the best catalytic activity toward the hydrolysis of EP owing to their abundant oxygen vacancy sites, optimal ratio of Ce(III) to Ce(IV), and specific exposed facets. Under the conditions of 0.2 M NH3/NH4Cl buffer and 25 °C, the CeO2 nanopolyhedra catalyzed the reduction of EP to 4-nitrophenol with a >99% conversion at pH 8.0 for 50 h, at pH 10.0 for 12 h, and at pH 12.0 for 2.5 h. The catalytic degradation of nearly 100% EP in NH3/NH4Cl buffer (pH 10.0) at 25 °C is in the decreasing order of CeO2 nanopolyhedra > CeO2 nanorods > ZnO nanospheres (NSs) > CeO2 nanocubes > TiO2 NSs > CeO2 NSs > Fe3O4 NSs ~ Co3O4 NSs ~ control experiment. The mechanism for the degradation of EP was confirmed by monitoring catalytic kinetics of the CeO2 nanopolyhedra in the presence of EP, dimethyl paraoxon, 4-nitrophenyl phosphate, and parathion. The nanocomposites were simply fabricated by electrostatic self-assembly of the CeO2 nanopolyhedra and poly(diallyldimethylammonium chloride)-capped gold nanoparticles (PDDA-AuNPs). The resultant nanocomposites still efficiently catalyzed NaBH4-mediated reduction of 4-nitrophenol to 4-aminophenol with a normalized rate constant of 6.68 ± 0.72 s-1 g-1 and a chemoselectivity of >99%. In confirmation of the robustness and applicability of the as-prepared nanocomposites, they were further used to catalyze the degradation of EP to 4-amionphenol in river water and seawater.

Microextraction combined with microderivatization for drug monitoring and protein modification analysis from limited blood volume using mass spectrometry.

In the clinic, ethosuximide is commonly used to treat generalized absence seizures but has recently been repurposed for other diseases. Because of adverse effects and drug interactions, high-throughput therapeutic drug monitoring of ethosuximide is necessary. Microextraction is a simple, effective, rapid, and low consumption of organic solvents method for sample preparation. In this study, microderivatization-increased detection (MDID)-combined microextraction was used to detect ethosuximide by mass spectrometry. Ethosuximide is a difficult to retain and ionize compound in the C18 nano-flow column and ionization interface, respectively. Hence, we developed a fast method for detecting ethosuximide in human plasma by using the MDID strategy (within 2 min). Chemical microderivatization parameters were studied and optimized to increase the sensitivity of ethosuximide detection at trace levels. The linear range for the analysis of ethosuximide in 10 µL plasma was 5-500 µg/mL with a coefficient of determination (r2) ≥ 0.995. The precision and accuracy of intraday and interday analyses of ethosuximide were below 13.0%. Furthermore, modifications of major proteins in plasma and blood cells, induced by ethosuximide, were identified. The proposed method effectively utilizes microliter samples to detect drug plasma concentrations under suitable microextraction procedures toward the eco-friendly goal of low consumption of organic solvents. Graphical abstract ᅟ.

Local hemostatic matrix for endoscope-assisted removal of intracerebral hemorrhage is safe and effective.

BACKGROUND/PURPOSE: Minimally invasive endoscope-assisted (MIE) evacuation of spontaneous intracerebral hemorrhage (ICH) is simple and effective, but the limited working space may hinder meticulous hemostasis and might lead to rebleeding. Management of intraoperative hemorrhage is therefore a critical issue of this study. This study presents experience in the treatment of patients with various types of ICH by MIE evacuation followed by direct local injection of FloSeal Hemostatic Matrix (Baxter Healthcare Corp, Fremont, CA, USA) for hemostasis. METHODS: The retrospective nonrandomized clinical and radiology-based analysis enrolled 42 patients treated with MIE evacuation of ICH followed by direct local injection of FloSeal Hemostatic Matrix. Rebleeding, morbidity, and mortality were the primary endpoints. The percentage of hematoma evacuated was calculated from the pre- and postoperative brain computed tomography (CT) scans. Extended Glasgow Outcome Scale (GOSE) was evaluated at 6 months postoperatively. RESULTS: Forty-two ICH patients were included in this study, among these, 23 patients were putaminal hemorrhage, 16 were thalamic ICH, and the other three were subcortical type. Surgery-related mortality was 2.4%. The average percentage of hematoma evacuated was 80.8%, and the rebleeding rate was 4.8%. The mean operative time was 102.7 minutes and the average blood loss was 84.9 mL. The mean postoperative GOSE score was 4.55 at 6-months' follow-up. CONCLUSION: This study shows that local application of FloSeal Hemostatic Matrix is safe and effective for hemostasis during MIE evacuation of ICH. In our experience, this shortens the operation time, especially in cases with intraoperative bleeding. A large, prospective, randomized trial is needed to confirm the findings.

Self-Assembly of Monodisperse Carbon Dots into High-Brightness Nanoaggregates for Cellular Uptake Imaging and Iron(III) Sensing.

This study describes a bottom-up assembly route for monodisperse carbon dots (CDs) into different sizes of CD aggregates through the control of the concentration of fatty acids. The highly monodisperse CDs were prepared via solvent-thermal treatment of edible soybean oil, which generated glycerol-based polymer as a carbon source and fatty acid as a surface capping in the synthetic process. The as-synthesized CDs exhibited small particle size variation (2.7 ± 0.2 nm) and narrow emission bands (full width at half-maximum <20 nm). The monodisperse CDs can self-assemble into blue-, green-, yellow-, and red-emitting CD aggregates by tuning the concentration of fatty acids. Compared to commercially available organic dyes and semiconductor quantum dots, the CD aggregates provided a 10-7000-fold improvement in brightness. Additionally, their emission wavelength was tunable across the entire visible spectrum by tuning the excitation wavelength. Because of their high brightness, fluorescence imaging of a single carbon dot and CD aggregate was simply achieved using filter-free dark-field fluorescence microscopy (DFM). We also demonstrate the use of filter-free DFM to dynamically image cellular uptake of the monodisperse CDs in MCF-7 cells and Huh-7 liver cancer cells. Without the conjugation of the fluorophore to the CDs, the particle aggregation-induced red-shifted emission enables the development of the CD-based ratiometric sensor for FeIII ions and pyrophosphate based on FeIII-induced aggregation of the monodisperse CDs.

Design of Peptide-Based Probes for the Microscale Detection of Reactive Oxygen Species.

Reactive oxygen species (ROS) can induce oxidative stress and are associated with cell death and chronic diseases in organisms. In the treatment of disease, drugs that induce ROS are associated with many side effects and unpleasant symptoms. Therefore, during the assessment of new drugs and candidate compounds, ROS generation is an issue of concern, because ROS can modify proteins, lipids, and nucleic acids within organisms and alter their biological functions. In this work, we designed a peptide-based probe for the rapid (<10 min) high-throughput survey of oxidative stress induced by clinical drugs at the microliter level. Using menadione and H2O2 as positive controls, just 100 µg/mL of the test compound and 100 µg/mL of the probe were sufficient to effectively monitor the generation of ROS, which is important as many active compounds are rare and difficult to isolate or purify. This in vitro evaluation could be used to effectively generate preliminary data before pharmacologically active candidate compounds are processed in cell-line or animal tests. Furthermore, we demonstrated that this peptide probe successfully detects ROS in biological samples.

1,4-Benzenediboronic-Acid-Induced Aggregation of Gold Nanoparticles: Application to Hydrogen Peroxide Detection and Biotin-Avidin-Mediated Immunoassay with Naked-Eye Detection.

Hydrogen-peroxide (H2O2)-induced growth of small-sized gold nanoparticles (AuNPs) is often implemented for H2O2 sensing and plasmonic immunoassay. In contrast, there is little-to-no information in the literature regarding the application of H2O2-inhibited aggregation of citrate-capped AuNPs. This study discloses that benzene-1,4-diboronic acid (BDBA) was effective in driving the aggregation of citrate-capped AuNPs through an interaction between α-hydroxycarboxylate of citrate and boronic acids of BDBA. The H2O2-mediated oxidation of BDBA resulted in the conversion of boronic acid groups to phenol groups. The oxidized BDBA was incapable of triggering the aggregation of citrate-capped AuNPs. Thus, the presence of H2O2 prohibited BDBA-induced aggregation of citrate-capped AuNPs. The BDBA-induced aggregation of citrate-capped AuNPs can be paired with the glucose oxidase (GOx)-glucose system to design a colorimetric probe for glucose. Moreover, a H2O2·BDBA·AuNP probe was integrated with sandwich immunoassay, biotinylated antibody, and avidin-conjugated GOx for the selective naked-eye detection of rabbit immunoglobulin G (IgG) and human-prostate-specific antigen (PSA). The lowest detectable concentrations of rabbit IgG and human PSA by the naked eye were down to 0.1 and 4 ng/mL, respectively. More importantly, the proposed plasmonic immunoassay allowed the naked-eye quantification of 0-10 ng/mL PSA at an interval of 2 ng/mL in plasma samples.

Molecular Beacon-Based Fluorescent Assay for Specific Detection of Oversulfated Chondroitin Sulfate Contaminants in Heparin without Enzyme Treatment.

Oversulfated chondroitin sulfate (OSCS) is a harmful contaminant in the pharmaceutical heparin. The development of a rapid, convenient, sensitive, and selective method is required for routine analysis of OSCS in pharmaceutical heparin. Here we report a simple, rapid, sensitive, and enzyme-free method for detecting OSCS in heparin based on the competitive binding between OSCS and the adenosine-repeated molecular beacon (MB) stem to coralyne in the presence of Ca(2+) ions. The MB (A8-MB-A8) contains a 22-mer loop, a stem of a pair of 8-mer adenosine (A) bases, a fluorophore unit at the 5'-end, and a quencher at the 3'-end. The presence of coralyne promotes these A-A mismatches to form a hairpin-shaped MB. However, this kind of MB is incapable of differentiating between heparin and OSCS because they both exhibit strong electrostatic attraction with coralyne. This study found that while Ca(2+) ions can efficiently suppress the negative charges of heparin, they do not neutralize the negative charge of OSCS. Thus, in the presence of Ca(2+) ions, OSCS can remove coralyne from the MB stem, initiating fluorescence of the MB. Under optimal conditions (10 nM A8-MB-A8, 800 nM coralyne, and 0.5 mM Ca(2+) ions), the proposed system can detect 0.01% w/w OSCS in heparin in under 5 min without enzyme treatment. This study also validates the practicality of the proposed system to determine 0.01% w/w OSCS in the pharmaceutical heparin.

Formation of fluorescent polydopamine dots from hydroxyl radical-induced degradation of polydopamine nanoparticles.

This study describes the synthesis of fluorescent polydopamine dots (PDs) through hydroxyl radical-induced degradation of polydopamine nanoparticles. The decomposition of polydopamine nanoparticles to fluorescent PDs was confirmed using transmission electron microscopy and dark-field microscopy. The analysis of PDs by using laser desorption/ionization time-of-flight mass spectrometry revealed that the PDs consisted of dopamine, 5,6-dihydroxyindole, and trihydroxyindole units. Oligomerization and self-assembly of these units produced a broad adsorption band, resulting in an excitation-wavelength-dependent emission behavior. The maximal fluorescence of PDs appeared at 440 nm with a quantum yield of 1.2%. The coordination between the catechol groups of PDs and ferric ions (Fe(3+)) quenched the fluorescence of PDs; the limit of detection at a signal-to-noise ratio of 3 for Fe(3+) was determined to be 0.3 µM. The presence of pyrophosphate switched on the fluorescence of the PD-Fe(3+) complexes. Compared to the other reported methods for sensing Fe(3+), PDs provided simple, low-cost, and reusable detection of Fe(3+).

Design of two and three input molecular logic gates using non-Watson-Crick base pairing-based molecular beacons.

This study presents a single, resettable, and sensitive molecular beacon (MB) used to operate molecular-scale logic gates. The MB consists of a random DNA sequence, a fluorophore at the 5'-end, and a quencher at the 3'-end. The presence of Hg(2+), Ag(+), and coralyne promoted the formation of stable T-Hg(2+)-T, C-Ag(+)-C, and A2-coralyne-A2 coordination in the MB probe, respectively, thereby driving its conformational change. The metal ion or small molecule-mediated coordination of mismatched DNA brought the fluorophore and the quencher into close proximity, resulting in collisional quenching of fluorescence between the two organic dyes. Because thiol can bind Hg(2+) and remove it from the T-Hg(2+)-T-based MB, adding thiol to a solution of the T-Hg(2+)-T-based MB allowed the fluorophore and the quencher to be widely separated. A similar phenomenon was observed when replacing Hg(2+) with Ag(+). Because Ag(+) strongly binds to iodide, cyanide, and cysteine, they were capable of removing Ag(+) from the C-Ag(+)-C-based MB, restoring the fluorescence of the MB. Moreover, the fluorescence of the A2-coralyne-A2-based MB could be switched on by adding polyadenosine. Using these analytes as inputs and the MB as a signal transducer, we successfully developed a series of two-input, three-input, and set-reset logic gates at the molecular level.

Fine-Tuned Graphene Oxide Nanocomposite: Harnessing Copper(II)-Imidazole Complex for Enhanced Biological Responses and Balanced Photocatalytic Functionality.

In this study, the synthesis of biologically active copper(II) complex [Cu(im)2]Cl2 was achieved using a reported method. Subsequently, this copper(II) complex was strategically grafted onto graphene oxide, resulting in the formation of a nanocomposite denoted as copper(II)-complex-grafted graphene oxide (Cu-GO). The comprehensive characterization of Cu-GO was conducted through various techniques, including X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), UV-visible spectroscopy, emission spectra analysis, X-ray photoelectron spectroscopy (XPS), and Copper K-edge X-ray Absorption Near Edge Structure (XANES) spectroscopy. The antibacterial efficacy of Cu-GO compounds was assessed using disk diffusion and microbroth dilution methods. Notably, the copper complex exhibited the highest effectiveness, showcasing a Minimal Inhibitory Concentration (MIC) value of 500 µL against Klebsiella bacteria. The antibacterial activities of all compounds were systematically screened, revealing the superior performance of the copper complex compared to standalone copper compounds. Expanding the scope of the investigation, we explored the antioxidant and anti-obesity activities of the copper complexes against Klebsiella organisms. The results underscore promising directions for the further exploration of the diverse health-related applications of these compounds. Moreover, the photocatalytic performance of the Cu-GO nanocomposite was evaluated under sunlight irradiation. Notably, the antioxidant and anti-obesity activities of Cu-GO, assessed in terms of percentage inhibition at a concentration of 200 mg/mL, exhibited values of 41% and 45%, respectively. Additionally, the Cu-GO composite exhibited exceptional efficacy, achieving a degradation efficiency of 74% for RhB under sunlight irradiation, surpassing both graphite and GO. These findings not only demonstrate enhanced biological activity, but also highlight a notable level of moderate photocatalytic performance. Such dual functionality underscores the potential versatility of Cu-GO nanocomposites across various applications, blending heightened biological efficacy with controlled photocatalysis. Our study offers valuable insights into the multifunctional attributes of copper(II)-complex-grafted graphene oxide nanocomposites, thereby paving the way for their broader utilization in diverse fields.