Synthesis of Monodisperse Plasmonic Magnetic Microbeads and Their Application in Ultrasensitive Detection of Biomolecules.

Plasmon-enhanced fluorescence (PEF)-based analytical technology has recently demonstrated its ability in detecting biomarkers with ultrahigh sensitivity. However, the scope of the PEF-based technology has been hindered by its reliance on flat substrates with relatively low binding kinetics and the limited multiplex detection ability. Herein, we reported a simple yet robust method for the fabrication of plasmonic magnetic microbeads (PMMBs)-based suspension array technology (SAT) with fluorescence enhancement of about 60-fold, improving the detection limit of biomarkers by 2-orders of magnitude toward 100 fM. We also demonstrated the performance of this method for the detection of anti-acidic ribosomal phosphoprotein 0 (anti-P0) autoantibody in sera from systemic lupus erythematosus (SLE) patients. Owing to the high sensitivity and efficient magnet-based sample collection, our method can be employed for detection of ultrasmall volumes of samples (e.g., 2 µL), promising for point-of-care detection. Furthermore, a size-encoded PMMBs-based multiplexed suspension array for simultaneous detection of multiple biomarkers is realized, illustrating the great potential of this technology in high-throughput disease diagnosis applications.

Animal Bone Supported SnO2 as Recyclable Photocatalyst for Degradation of Rhodamine B Dye.

SnO2 nanoparticles supported on an animal bone which serves as inexpensive and environment-friendly natural products were developed by a facile hydrothermal approach. As a promising photocatalyst, the novel SnO2/porcine bone material exhibited high photocatalytic activity towards the degradation of rhodamine B (RhB) dye under UV-Vis irradiation. About 97.3% of RhB can be effectively decomposed by the catalysis with the SnO2/porcine bone in 90 min, while only 51.5% of RhB can be degraded by pure SnO2 nanoparticles. Moreover, the photocatalytic activity was incremental with the increase of cycle times in previous five cycles. It is mainly because the photocatalyst which has been used for several times possesses a stronger ability of light absorption and utilization compared to the fresh catalyst according to the results of the characterization and relative experiments. It is noteworthy that the animal bone support can improve the activity for the photocatalyst, which would provide further impetus to alternate synthesis strategies for photocatalysts and make the photocatalysis process faster, less expensive, and more environmentally friendly.

Etched-spiky Au@Ag plasmonic-superstructure monolayer films for triple amplification of surface-enhanced Raman scattering signals.

Generally, a high quality surface-enhanced Raman spectroscopy (SERS) substrate often requires a highly-tailorable electromagnetic (EM) field generated at nanoparticle (NP) surfaces by the regulation of the morphologies, components and roughness of NPs. However, most recent universal approaches are restricted to single components, and integrating these key factors into one system to achieve the theoretically maximum signal amplification is still challenging. Herein, we design a triple SERS signal amplification platform by the coordination of spiky Au NPs with rich-tip nanostructures, controllable silver nanoshell, as well as tailorable surface roughness into one nano-system. As a result, the theoretical electromagnetic field of the interfacial self-assembled 2D substrate can be improved by nearly 5 orders of magnitude, and the ideal tracing capability for the model SERS molecule can be achieved at levels of 5 × 10-11 M. Finally, diverse analytes in pesticide residues, environmental pollutants as well as medically diagnose down to 10-11 M and can be fingerprinted by the proposed SERS nano-platform. Our integrated triple amplification platform not only provides an effective SERS sensing strategy, but also makes it possible to simultaneously achieve high sensitivity, stability as well as universality into one plasmonic-based SERS sensing system.

Titanium carbide nanosheets with defect structure for photothermal-enhanced sonodynamic therapy.

Sonodynamic therapy (SDT) has attracted widespread interest in biomedicine, owing to its novel and noninvasive therapeutic method triggered by ultrasound (US). Herein, the Ti3C2 MXene nanosheets (Ti3C2 NSs) are developed as good sonosensitizers via a two-step method of chemical exfoliation and high-temperature treatment. With the high-temperature treatment, the oxygen defect of Ti3C2 MXene nanosheets (H-Ti3C2 NSs) is greatly increased. Therefore, the electron (e-) and hole (h+) generated by US can be separated faster due to the improved degree of oxidation, and then the recombination of e--h+ can be prevented with the abundant oxygen defect under US irradiation, which induced the sonodynamic efficiency greatly to improve around 3.7-fold compared with Ti3C2 NSs without high-temperature treatment. After PEGylation, the H-Ti3C2-PEG NSs show good stability and biocompatibility. In vitro studies exhibit that the inherent property of mild photothermal effect can promote the endocytosis of H-Ti3C2-PEG NSs, which can improve the SDT efficacy. In vivo studies further display that the increased blood supply by the mild photothermal effect can significantly relieve hypoxia in the tumor microenvironment, showing photothermal therapy (PTT) enhanced SDT. Most importantly, the H-Ti3C2-PEG NSs can be biodegraded and excreted out of the body, showing no significant long-term toxicity. Our work develops the defective H-Ti3C2 NSs as high-efficiency and safe sonosensitizers for photothermal-enhanced SDT of cancer, extending the biomedical application of MXene-based nanoplatforms.

Titanium Sulfide Nanosheets Serve as Cascade Bioreactors for H2 S-Mediated Programmed Gas-Sonodynamic Cancer Therapy.

Gas-mediated sonodynamic therapy (SDT) has the potential to become an effective strategy to improve the therapeutic outcome and survival rate of cancer patients. Herein, titanium sulfide nanosheets (TiSX NSs) are prepared as cascade bioreactors for sequential gas-sonodynamic cancer therapy. TiSX NSs themselves as hydrogen sulfide (H2 S) donors can burst release H2 S gas. Following H2 S generation, TiSX NSs are gradually degraded to become S-defective and partly oxidized into TiOX on their surface, which endows TiSX NSs with high sonodynamic properties under ultrasound (US) irradiation. In vitro and in vivo experiments show the excellent therapeutic effects of TiSX NSs. In detail, large amounts of H2 S gas and reactive oxygen species (ROS) can simultaneously inhibit mitochondrial respiration and ATP synthesis, leading to cancer cell apoptosis. Of note, H2 S gas also plays important roles in modulating and activating the immune system to effectively inhibit pulmonary metastasis. Finally, the metabolizable TiSX NSs are excreted out of the body without inducing any significant long-term toxicity. Collectively, this work establishes a cascade bioreactor of TiSX NSs with satisfactory H2 S release ability and excellent ROS generation properties under US irradiation for programmed gas-sonodynamic cancer therapy.

In situ reduction triggers the highly sensitive detection of pesticide by classic gold nanoparticle and quantum dots nanocomposite.

Fluorescence "turn on" method is always preferable for target detection under the urgent demand to develop point-of-care portable sensors in practical applications due to its higher selectivity and less false positives. However, there is only few reports of pesticide monitoring based on this strategy so far most probably ascribed to its poor hydrophilicity and reactivity. In this work, triggered by reductant tris (2-carboxyethyl) phosphine hydrochloride (TCEP), initially fluorescence-quenched gold nanoparticles (Au NPs)-decorated quantum dots (QDs)-embedded nanobead shows obvious fluorescence "turn on" signal response to thiram with concentration response range of 0.01-20 µM and limit of detection (LOD) of 7 nM due to the target-induced dissociation of Au NPs from the surface of probe nanobead. Moreover, paper sensor has been successfully developed by immersing commercial drainage membrane in probe solution for visual detection of thiram with the ultrahigh LOD (50 nM) by the naked eye. More importantly, this work, for the first time, reported an in situ reduction strategy to improve the interaction between target and nanoprobe and thus bring obvious signal output for pesticide detection with high sensitivity, demonstrating the potential to expand the detection scope of nanomaterials.

Synthesis of polystyrene-based fluorescent quantum dots nanolabel and its performance in H5N1 virus and SARS-CoV-2 antibody sensing.

Quantum dots (QDs) based fluorescent nanobeads are considered as promising materials for next generation point-of-care diagnosis systems. In this study, we carried out, for the first time, the synthesis of QDs nanobeads using polystyrene (PS) nanobead as the template. QDs loading on PS nanobead surface in this method can be readily achieved by the use of polyelectrolyte, avoiding the time-consuming and uncontrollable silane reagents-involved functionalization procedure that conventional synthesis of silica-based QDs nanobeads often suffer from. Notably, the application of QDs nanobeads in suspension microarray for H5N1 virus detection leads to a sensitivity lower than 25 PFU/mL. In addition, QDs nanobead was also incorporated into lateral flow assay for SARS-CoV-2 antibody detection, leading to more than one order of magnitude detection sensitivity as compared to that of commercial one based on colloid gold.

A novel gold nanoparticles decorated magnetic microbead-based molecular beacon for DNA multiplexing detection by flow cytometry.

Gold nanoparticles-based molecular beacon (Au NPs-MB), due to its extraordinary highly-quenching efficiency for fluorophores, has been extensively investigated and widely used for bioimaging and bioassay. However, apart from irreversible aggregation during the "aging" step, the preparation of Au NPs-MB often suffers from relatively poor salt stability, limiting its further in vivo application. Herein, Au NPs decorated magnetic microbeads was developed to construct a novel magnetic MB for DNA assay, which not only totally solved the aggregation problem of Au NPs, but also exhibited robust stability in buffer solution. Most importantly, the fluorescence signal of each microbeads could be collected individually, realizing single microbeads-based DNA imaging, and the detection limit for target DNA could reach 0.1 nM with the detection range of 0.2-20 nM. More importantly, because the magnetic microbeads with three sizes could be readily distinguished by flow cytometry, the employed three types of hairpin DNA probes can be labelled with the same dye FITC without fluorescence cross-interference. Therefore, multiplexing detection of tumor-suppressor genes (p16, p21 and p53) could be readily realized by using size-encoded magnetic microbeads pre-functionalized with corresponding probe DNA illustrating the potential of this method in multiplexing bioassay applications.

Multifunctional Two-Dimensional Core-Shell MXene@Gold Nanocomposites for Enhanced Photo-Radio Combined Therapy in the Second Biological Window.

Multifunctional nanoplatforms with special advantages in the diagnosis and treatment of cancer have been widely explored in nanomedicine. Herein, we synthesize two-dimensional core-shell nanocomposites (Ti3C2@Au) via a seed-growth method starting from the titanium carbide (Ti3C2) nanosheets, a classical type of MXene nanostructure. After growing gold on the surface of Ti3C2 nanosheets, the stability and biocompatibility of the nanocomposites are greatly improved by the thiol modification. Also importantly, the optical absorption in the near-infrared region is enhanced. Utilizing the ability of the high optical absorbance and strong X-ray attenuation, the synthesized Ti3C2@Au nanocomposites are used for photoacoustic and computed tomography dual-modal imaging. Importantly, the mild photothermal effect of the Ti3C2@Au nanocomposites could improve the tumor oxygenation, which significantly enhances the radiotherapy. No obvious long-term toxicity of the nanocomposites is found at the injected dose. This work highlights the promise of special properties of MXene-based multifunctional nanostructures for cancer theranostics.

Single microbead-based fluorescence "turn on" detection of biothiols by flow cytometry.

Biological thiols (biothiols), such as glutathione (GSH), cysteine (Cys) and homocysteine (Hcy), play a vital role in the process of reversible redox reactions in physiological systems. In this work, flow cytometry-based fluorescent sensor is for the first time developed for the detection of biothiols in a fluorescence "turn on" manner. The probe which we name "Polystyrene/Quantum Dots/Gold Nanoparticles" or (PS/QDs/Au) is constructed by immobilizing QDs onto the surface of PS microbeads to obtain fluorescent microbeads. The probe (PS/QDs/Au) is constructed by immobilizing QDs onto the surface of PS microbeads to obtain fluorescent microbeads, followed by gold NPs absorption through electrostatic interaction to quench their fluorescence. In the presence of biothiols, the fluorescence of our probe can be restored in less than 5 min, and the detection limits for GSH, Cys and Hcy are 0.5 µM, 0.1 µM and 0.3 µM, respectively. Most importantly, the fluorescence signal of each of our probe microbeads can be collected individually by flow cytometry, realizing single microbead-based biothiols detection for the first time. Moreover, the probe is successfully applied to imaging of intracellular biothiols in A549 cells, demonstrating its potential in biological application.

Amplifying the signal of localized surface plasmon resonance sensing for the sensitive detection of Escherichia coli O157:H7.

Gold nanorods (Au NRs) based localized surface plasmon resonance (LSPR) sensors have been widely employed in various fields including biology, environment and food safety detection, but their size- and shape-dependent sensitivity limits their practical applications in sensing and biological detection. In our present work, we proposed an approach to maximally amplify the signal of Au NRs based LSPR sensing by coating an optimized thickness of mesoporous silica onto Au NRs. The plasmonic peaks of Au NRs@SiO2 with different shell thickness showed finely linear response to the change of surrounding refractive index. The optimized thickness of mesoporous silica of Au NRs@SiO2 not only provided high stability for LSPR sensor,but also displayed much higher sensitivity (390 nm/RIU) than values of Au NRs from previous reports. The obtained Au NRs@SiO2 based LSPR sensor was further used in practical application for selectively detection of the E. coli O157:H7, and the detection limit achieved 10 CFU, which is much lower than conventional methods such as electrochemical methods and lateral-flow immunochromatography.

High-density, aligned SiO2 nanowire arrays: microscopic imaging of the unique growth style and their ultraviolet light emission properties.

High-density, free-standing SiO2 nanowire arrays were successfully fabricated by a simple chemical vapor deposition method through a controlled pattern of the micrometer-sized alloyed balls on the Si substrate combined with a local balanced and steady-state reaction vapor environment. The direct observation of temporal evolution of the SiO2 nanowire growth process via the microscopic imaging approach offers us amazing pictures related to the unique vapor-liquid-solid (VLS) growth styles. These novel results are beneficial to understanding the formation mechanism of silica nanowire arrays, and at the same time, they extend our knowledge of VLS growth phenomena. The stable and strong ultraviolet emission properties of the as-grown products are of significant interest for their potential applications related to nanoscale optoelectronic device including ultraviolet-light-emitting devices, etc.

Large-scale synthesis of a novel tri(8-hydroxyquioline) aluminum nanostructure.

A novel tri(8-hydroxyquioline) aluminum (AlQ3) nanostructure was prepared on large scale at low cost by low-temperature physical vapor deposition (PVD). The morphologies, the chemical bondings, and photoluminescence of the AlQ3 nanostructure were investigated by environmental scanning electronic microscopy (ESEM), Fourier transform infrared spectrum (FT-IR), and photoluminescence (PL) spectra, respectively. The AlQ3 nanostructure was composed of micro-sphere with nanowire-cluster growing on the surface. The diameter of micro-sphere and nanowire were about 5 microm and 80 nm, respectively. FT-IR results indicated that the AlQ3 molecule had a strong thermal stability under research conditions. The growth mechanism of the novel nanostructure was discussed. The novel organic nanostructure would be believed to attractive building field-emission devices and other optical devices.

Nitrogen and Sulfur Codoped Reduced Graphene Oxide as a General Platform for Rapid and Sensitive Fluorescent Detection of Biological Species.

Nitrogen (N) and sulfur (S) codoped reduced graphene oxide (N,S-rGO) was synthesized through a facile solvothermal process. The introduction of N and S heteroatoms into GO effectively activated the sp(2)-hybridized carbon lattice and made the material an ideal electron/energy acceptor. Such unique properties enable this material to perform as a general platform for rapid and sensitive detection of various biological species through simple fluorescence quenching and recovering. When quantum dot (QD)-labeled HBV (human being disease-related gene hepatitis B virus DNA) and HIV (human being disease-related gene human immunodeficiency virus DNA) molecular beacon probes were mixed with N,S-rGO, QD fluorescence was quenched; when target HBV and HIV DNA were added, QD fluorescence was recovered. By the recovered fluorescence intensity, the target virus DNA detection limits were reduced to 2.4 nM for HBV and 3.0 nM for HIV with detection time of less than 5 min. It must be stressed out that different viruses in the same homogeneous aqueous media could be discriminated and quantified simultaneously through choosing diverse QD probes with different colors. Moreover, even one mismatched target DNA could be distinguished using this method. When altering the molecular beacon loop domain to protein aptamers, this sensing strategy was also able to detect thrombin and IgE in 5 min with detection limits of 0.17 ng mL(-1) and 0.19 ng mL(-1), respectively, which was far more rapid and sensitive than bare GO-based fluorescence detection strategy.

Flower-like porous hematite nanoarchitectures achieved by complexation-mediated oxidation-hydrolysis reaction.

Flower-like porous hematite (α-Fe(2)O(3)) nanoarchitectures composed of ultra-thin nanoflakes were prepared by annealing the iron oxide precursor formed via the oxidation-hydrolysis reaction between Fe(II) ions and Tris(hydroxymethyl)aminomethane (abbreviated as Tris). The microstructure of the prepared FeOOH and hematite samples were fully characterized by field-emission scanning electron microscopy, transmission electron microscopy, X-ray diffraction analysis, Fourier-transforming infrared spectra, thermogravimetric analysis, and nitrogen adsorption-desorption isotherm. Based on the influences of reactant concentrations, reaction time and reaction temperature on the morphologies of the resultant samples, a formation mechanism of etching was proposed, Fe(II)-Tris complexes were self-assembled via hydrogen bonds into brick-like building blocks, which then aggregated into rudimentary nanoparticles, and the synergistic effect between the crystallization of FeOOH and dissociation of Fe(II)-Tris complexes make the rudimentary nanoparticles evolve into the flower-like products. The as-prepared flower-like α-Fe(2)O(3) nanostructures possessed a Brunauer-Emmett-Teller specific surface area of 191.63 m(2)g(-1), hierarchical pore distribution ranging from micropores to macropores, and good crystallinity, and excellent visible photocatalysis in terms of removing chemical oxygen demand of dimethyl sulfoxide industrial wastewater. The current work provides a reliable approach for building functional hierarchical nanoarchitectures and the prepared iron oxide nanomaterials demonstrate an excellent ability to remove toxic pollutants in industrial wastewater.

Transdermal delivery of praziquantel: effects of solvents on permeation across rabbit skin.

To explore a new method for the transdermal delivery of praziquantel (PZQ), the effects of solvents on permeation across rabbit skin were investigated. The solubility of PZQ in five different solvents, ethylene glycol monophenyl ether (EGPE), 1,4-dioxane, tetrahydrofuran, dimethyl sulfoxide, and oleic acid, were measured with a UV-Vis spectrophotometer. The determination of the n-octanol/water partition coefficient of PZQ in the five different solutions and assay of serum concentration following PZQ transdermal administration in rabbits were performed using HPLC. The results indicated that the transdermal absorption of the drug was related to the partition coefficient and lipophilic characteristics of the solvent. The optimal solvent for PZQ transdermal delivery was EGPE in our protocol. The solubility of PZQ in EGPE is >400 mg/ml, and the apparent partition coefficient of PZQ in the solution is 0.895 (log P value). After transdermal administration of PZQ in EGPE solution, the bioavailability is 2.85-fold that after oral administration. The serum drug concentration was maintained at 4.0 mug/ml over 4 h, which is sufficient for the treatment of schistosomiasis. At the same time, no apparent side effects were found on the skin. EGPE may thus be a promising vehicle for the transdermal delivery of PZQ in the future.