Oxygen vacancies enhanced photoelectrochemical aptasensing of 2, 3', 5, 5'-tetrachlorobiphenyl amplified with Ag3VO4 nanoparticle-TiO2 nanotube array heterostructure

This work proposed an enhancing mechanism of both oxygen vacancies (OVs) and the heterostructure for amplifying the photoelectrochemical (PEC) aptasensing signal. The OVs were formed by in situ electrochemical reduction of TiO₂ nanotube arrays (TNTAs), and well-separated Ag₃VO₄ nanoparticles (NPs) were then deposited on the TNTAs. The band gaps and positions of these nanomaterials were evaluated by Tauc equation and Mott-Schottky plots to verify the formation of the heterojunction. The OVs and heterojunction greatly enhanced the visible light absorption and improved the charge separation of TNTAs. The amplified PEC signal could be quenched by the resonance energy transfer between Ag₃VO₄ NPs and gold nanorods (Au NRs), which were labeled on the complementary DNA (cDNA) to the aptamer immobilized on the heterojunction. Upon the recognition of the aptamer to target analyte, the Au NR-cDNA was detached from the sensor, leading to a "signal-on" aptasensing strategy. Under optimal conditions, the PEC aptasensor displayed a detection limit of 0.015 pg mL^-1 and a linear range from 0.02 to 300 ng mL^-1 for 2,3',5,5'-tetrachlorobiphenyl.

Novel Protease-Free Long-Lasting Chemiluminescence System Based on the Dox-ABEI Chimeric Magnetic DNA Hydrogel for Ultrasensitive Immunoassay

Most of chemiluminescence (CL) substrates exhibit the flash-type light emission. Therefore, the long-lasting CL system is always the crown in the field of CL-based analysis methodology. In this work, we constructed a Dox-ABEI chimeric magnetic DNA hydrogel (MDH) as a novel protease-free long-lasting CL reaction system. The functional MDH can transform flash-type ABEI/H₂O₂/CO²⁺ reaction into a glow-type CL system because of its block effect on delaying the diffusion rate of co-reactants, making the CL reaction gradually occur. More importantly, the functional MDH possessed the advantages of biocompatibility and controllability and could be well-designed to incorporate different biosensing strategies. Subsequently, we established a functional MDH-based long-lasting CL immunoassay system for ultrasensitive and highly specific detection of d-dimer and fibrin degradation products (FDPs). The designed CL immunoassay can detect d-dimer and FDP down to 53.7 and 31.6 fg/mL, respectively, with a wide line ranging from 100 fg/mL to 100 ng/mL, which was superior to the previously reported CL biosensing strategies. Moreover, benefiting from the magnetic separation of MDH and excellent CL performance, the developed immunoassaying method was successfully applied in the detection of clinical samples, which showed a close correlation with clinical reference technology. Thus, this functional MDH proved to be an excellent long-lasting CL system and a potential technical platform for clinical bioanalysis applications.

A Near-Infrared Photo-Switched MicroRNA Amplifier for Precise Photodynamic Therapy of Early-Stage Cancers

Stimuli-responsive photodynamic therapy (PDT) is a hot topic in precise medicine, but the low abundance of responsive trigger molecules in early-stage disease limits application. Here we designed an amplifier with multiple upconversion luminances to achieve a near-infrared photo-switched cascade reaction triggered by specific microRNA and precise PDT of early-stage cancers. This amplifier was composed of photo-caged DNA nanocombs and an upconversion nanoparticle (UCNP) sensitized with IRDye 800CW. The nanocomb was prepared by assembling a photozipper-protected hairpin and two kinds of hybridizable hairpin probes on a DNA skeleton. Upon 808-nm light irradiation, the produced UV light cleaved off the photozipper to induce microRNA-responsive cascade hybridization reaction, activating the photosensitizers linked to different hairpins to generate reactive oxygen species (ROS) under the simultaneously emitted blue light for efficient PDT.

Target-Catalyzed Assembly of Pyrene-Labeled Hairpins for Exponentially Amplified Biosensing

Rapid and sensitive detection of nucleic acids is vital for disease diagnosis. This work designed an enzyme-free isothermal strategy for rapid exponential signal amplification through target-triggered catalytic hairpin assembly (CHA) to induce the spatially sensitive fluorescent signal of the pyrene excimer. Functionally, this system consisted of three pyrene labelled hairpins (H1, H2, and H3) and one catalyst DNA C. In the presence of C, the CHA was activated to generate intermediate I, which contained a single-stranded region identical to the C sequence for initiating the second cycle of CHA to obtain 2I and thus achieved the exponential formation of I along with the switching of pyrene excimer. The fluorescent signal of the pyrene excimer could be further enhanced via the inclusion of γ-cyclodextrin and showed a linear increase upon increasing logarithm of C concentration. Through the introduction of a helping hairpin H4-containing C sequence and a region specific to the target, this strategy could be extended to realize the quick and sensitive detection of different analytes. Using dengue virus RNA as an analyte model, the proposed fluorescent method showed a linear range from 0.1 to 50 nM with a limit of detection of 0.048 nM at 3σ and good selectivity. The excellent performance and convenient operation demonstrated its promising application in clinical disease diagnosis.

A photo zipper locked DNA nanomachine with an internal standard for precise miRNA imaging in living cells

DNA nanomachines are capable of converting tiny triggers into autonomous accelerated cascade hybridization reactions and they have been used as a signal amplification strategy for intracellular imaging. However, the "always active" property of most DNA nanomachines with an "absolute intensity-dependent" signal acquisition mode results in "false positive signal amplification" by extracellular analytes and impairs detection accuracy. Here we design a photo zipper locked miRNA responsive DNA nanomachine (PZ-DNA nanomachine) based on upconversion nanoparticles (UCNPs) with a photo-cleavable DNA strand to block the miRNA recognition region, which provided sufficient protection to the DNA nanomachine against nonspecific extracellular activation and allowed satisfactory signal amplification for sensitive miRNA imaging after intracellular photoactivation. Multiple emissions from the UCNPs were also utilized as an internal standard to self-calibrate the intracellular miRNA responsive fluorescence signal. The presented PZ-DNA nanomachine demonstrated the sensitive imaging of intracellular miRNA from different cell lines, which resulted in good accordance with qRT-PCR measurements, providing a universal platform for precise imaging in living cells with high spatial-temporal specificity.

Oxygen Vacancy-Enhanced Electrochemiluminescence Sensing Strategy Using Luminol Thermally Encapsulated in Apoferritin as a Transducer for Biomarker Immunoassay

Oxygen vacancies (OVs) enhanced electrochemiluminescence (ECL) biosensing strategy using luminol thermally encapsulated in apoferritin (Lum@apoFt) as an efficient transducer was investigated for ultrasensitive biomarker detection. By applying the oxygen-defect engineering (ODE) strategy, the OVs enriched cobalt-iron oxide (r-CoFe₂O₄) was fabricated as the sensing substrate to boost the electron mobility and catalyze the generation of superoxide anion radical (O₂^•-) for signal amplification. It should be noted that r-CoFe₂O₄ with higher OVs density dramatically accelerated the ECL reaction between O₂^•- and luminol anionic radicals, achieving 6.5-fold stronger ECL output than CoFe₂O₄ with no or low OVs density. Moreover, facile encapsulation of approximate 412 luminol molecules in a single apoFt cavity was first realized by an efficient thermal-induction method. The obtained Lum@apoFt complexes exhibited well-maintained ECL efficiency and excellent biocompatibility for biological modifications. On this basis, a biosensor was developed for early diagnostics of squamous cell carcinomas by detecting its representative biomarker named cytokeratin 19 fragment 21-1 (CYFRA 21-1), from which excellent linearity was achieved in 0.5 pg/mL to 50 ng/mL with a detection limit of 0.14 pg/mL. This work not only put forward a novel idea of creating OVs enriched sensing interface with excellent signal-amplification function but also proposes a facile and robust methodology to design apoFt-based transducers for developing more practical nanoscale biosensors in early diagnostics of diseases.

Cardiac troponin I photoelectrochemical sensor: {Mo368} as electrode donor for Bi2S3 and Au co-sensitized FeOOH composite

A suitable electron donor, which guarantees the stability of the whole system, is considered as the driving force of the PEC sensor. Nowadays, searching appropriate electron donor is still one of the orientations to explorate in the field of sensor. Na₄₈[H₄₉₆Mo₃₆₈O₁₄₆₄S₄₈]·ca.1000H₂O (abbr. {Mo₃₆₈}), as a type of polyoxometalate, has perfect morphology, definite size and unique electronic property. Due to the prominent water solubility, {Mo₃₆₈} usually releases small cations and exists as large anions in the ultrapure water. The interesting property endows {Mo₃₆₈} with excellent reducibility, which provides great feasibility to become an outstanding electron donor. In addition, FeOOH prepared through a simple operation owns high adsorption capacity, which ensures the fastness of other materials. Subsequently, the narrow band-gap of Bi₂S₃ and the unique noble metal properties of Au nanoparticles are utilized to co-sensitize FeOOH to improve the light-harvesting capability and photoelectric conversion efficiency. Combined with the specificity recognition of antigen and antibody, a novel photoelectrochemical sensor is constructed with a wide detection range of 1.00 pg mL^-1 - 100 ng mL^-1 and low detection limit (0.76 pg mL^-1), which achieves the sensitive detection of cardiac troponin I in early diagnosis of cardiovascular disease.

Amplified electrochemiluminescence signals promoted by the AIE-active moiety of D-A type polymer dots for biosensing

Three-component conjugated polymers of a strong donor-acceptor (D-A) type could be synthesized by Pd-catalyzed Suzuki coupling polymerization reaction of 1,2-bis(4-bromophenyl)-1,2-diphenylethene (M-1) with 9-octyl-3,6-bis(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-9H-carbazole (M-2) and 4,6-bis((E)-4-bromostyryl)-2,2-difluoro-5-phenyl-2H-1l3,3,2l4-dioxaborinine (M-3). Among them, P-1 and P-2 with high TPE ratios at 0.95 and 0.9 showed obvious aggregation-induced emission (AIE) behavior; in contrast P-3 with a low TPE ratio at 0.8 showed an aggregation-caused quenching (ACQ) phenomenon. In particular, the three resulting polymer dots (P-1 to P-3 Pdots) exhibited a 200 mV lower electrochemiluminescence (ECL) potential due to their strong D-A electronic structure. Most importantly, the ECL signals of Pdots could be enhanced as high as 3 times by increasing their AIE-active TPE moiety ratios from 0.8 (P-3) to 0.95 (P-1) via the band gap emission process. Herein, P-1 Pdots with the strongest ECL signal were successfully used as ECL biosensors for the detection of catechol, epinephrine and dopamine with detection limits of 1, 7 and 3 nM, respectively. This work provides a new strategy for developing highly sensitive ECL biosensors by the smart structure design of the AIE-active Pdots.

Activatable Photodynamic Therapy with Therapeutic Effect Prediction Based on a Self-correction Upconversion Nanoprobe

Though emerging as a promising therapeutic approach for cancers, the crucial challenge for photodynamic therapy (PDT) is activatable phototoxicity for selective cancer cell destruction with low "off-target" damage and simultaneous therapeutic effect prediction. Here, we design an upconversion nanoprobe for intracellular cathepsin B (CaB)-responsive PDT with in situ self-corrected therapeutic effect prediction. The upconversion nanoprobe is composed of multishelled upconversion nanoparticles (UCNPs) NaYF₄:Gd@NaYF₄:Er,Yb@NaYF₄:Nd,Yb, which covalently modified with an antenna molecule 800CW for UCNPs luminance enhancement under NIR irradiation, photosensitizer Rose Bengal (RB) for PDT, Cy3 for therapeutic effect prediction, and CaB substrate peptide labeled with a QSY7 quencher. The energy of UCNPs emission at 540 nm is transferred to Cy3/RB and eventually quenched by QSY7 via two continuous luminance resonance energy transfer processes from interior UCNPs to its surface-extended QSY7. The intracellular CaB specifically cleaves peptide to release QSY7, which correspondingly activates RB with reactive oxygen species (ROS) generation for PDT and recovers Cy3 luminance for CaB imaging. UCNPs emission at 540 nm remains unchanged during the peptide cleavage process, which is served as an internal standard for Cy3 luminance correction, and the fluorescence intensity ratio of Cy3 over UCNPs (FI583/FI540) is measured for self-corrected therapeutic effect prediction. The proposed self-corrected upconversion nanoprobe implies significant potential in precise tumor therapy.

Proximity Enzymatic Glyco-Remodeling Enables Direct and Highly Efficient Lipid Raft Imaging on Live Cells

Lipid rafts, highly ordered cell membrane domains mainly composed of cholesterol, sphingolipids, and protein receptors, serve as important functional platforms for regulation of lipid/protein interactions. The major predicament in lipid raft study is the lack of direct and robust visualization tools for in situ tracking raft components. To solve this issue, we herein report a proximity enzymatic glyco-remodeling strategy for direct and highly efficient lipid raft labeling and imaging on live cells. Through cofunctionalization of raft-specific recognition motif and glycan-remodeling enzyme on gold nanoparticles, the fabricated nanoprobe can be specifically guided to the raft domains to perform catalytic remodeling on neighboring glycans. Taking advantage of the abundant glycoconjugates enriched in lipid rafts, this elaborate design achieves the translation of one raft-recognition event to multiple raft-confined labeling operations, thus, significantly increasing the labeling efficiency and imaging sensitivity. The direct covalent labeling also enables in situ and long-term tracking of raft components in live cells. The method possesses broad applicability and potential expansibility, thus, will greatly facilitate the investigations on the complex composition, organization, and dynamics of lipid rafts.

Zinc and Molybdenum Co-Doped BiVO4 Nanoarray for Photoelectrochemical Diethylstilbestrol Analysis Based on the Dual-Competitive System of Manganese Hexacyanoferrate Hydrate Nanocubes

This study proposes a competitive photoelectrochemical (PEC) immunosensor for detecting diethylstilbestrol (DES). The PEC sensing platform uses a zinc and molybdenum codoped BiVO₄ nanoarray ((Zn,Mo):BiVO₄) as the photoactive matrix and manganese hexacyanoferrate hydrate loading silicon dioxide layer composite nanocubes (MHCF@SiO₂ NCs) as the signal quencher. The (Zn,Mo):BiVO₄ nanoarray demonstrated brilliant PEC behavior, by virtue of the local electric field formed by the codoped Zn and Mo. This doping accelerated the electron transfer and improved the photoelectric conversion efficiency in BiVO₄ nanoarray under visible light. Furthermore, the nanoarray structure with its large surface area provided abundant binding sites for the immune response. As the MHCF@SiO₂ NCs-anti-DES competitively bonded with either free DES or bovine serum albumin conjugated DES (BSA-DES), hydrogen peroxide (H₂O₂) as electron donor was competitively consumed and meanwhile steric resistance blocked electrons transfer. For the above reasons, the photocurrent signal was reduced. Thus, the standard sample free DES was accurately detected, and the fabricated PEC immunosensor displayed an outstanding photocurrent response from 0.1 pg/mL to 50 ng/mL with a detection limit of 0.05 pg/mL. Simultaneously, the acceptable stability, selectivity, and reproducibility of the designed dual-competitive sensing platform suggest its applicability to small molecule detection.

Intensive and Persistent Chemiluminescence System Based on Nano-/Bioenzymes with Local Tandem Catalysis and Surface Diffusion

A chemiluminescence (CL) system with long persistent and intensive emission is essential for accurate CL quantitative analysis and imaging assay. However, with most known CL systems being flash-type, it is still a great challenge to develop long-lasting CL systems. Here, by combining an iron porphyrin metal-organic frameworks (FePorMOFs) based peroxidase mimic with natural glucose oxidase (GOx), an intensive and persistent CL system is presented on the basis of local tandem catalysis and surface diffusion of the nano-/bioenzymes (FePorMOF/GOx). FePorMOF synthesized by iron porphyrin linker and zirconium ion node possesses high peroxidase catalytic activity and stability. Using luminol and glucose as substrate, the FePorMOF/GOx CL system can produce intensive CL emission containing a plateau period of 7.5 h. The strong CL signal is due to the local tandem generation and reaction of H₂O₂ by GOx and FePorMOF, which avoids the diffusion-limited kinetics and leads to a high catalytic efficiency of the nano-/bioenzymes. On the other hand, the long persistent CL emission is attributed mainly to the enzymatic reaction-controlled H₂O₂ supply and surface diffusion-controlled CL reaction. The proposed CL system is explored for CL imaging sensing of glucose and homogeneous immunoassay of α-fetoprotein. The nano-/bioenzymes CL system exhibits intensive and long constant CL emission in physiological condition, showing promising applications in real-time bioassay and bioimaging.

A Filter Supported Surface-Enhanced Raman Scattering "Nose" for Point-of-Care Monitoring of Gaseous Metabolites of Bacteria

This work designs a convenient method for fabrication of surface-enhanced Raman scattering (SERS) devices by loading gold nanostars (AuNSs) on a flat filter support with vacuum filtration. The dense accumulation of AuNSs results in a strong sensitization to SERS signal and shows sensitive response to gaseous metabolites of bacteria, which produces a SERS "nose" for rapid point-of-care monitoring of these metabolites. The "nose" shows good reproducibility and stability and can be used for SERS quantitation of a gaseous target with Raman signal. The impressive performance of the proposed SERS "nose" for detecting gaseous metabolites of common foodborne bacteria like Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa from inoculated samples demonstrates its much higher sensitivity than that of human sense and application in distinguishing spoiled food at an early stage and real-time tracing of food spoilage degree. The strong point-of-care testing ability of the designed SERS "nose" and the miniaturization of whole equipment extend greatly the analytical application of SERS technology in food safety and public health.

Quench-Type Electrochemiluminescence Immunosensor Based on Resonance Energy Transfer from Carbon Nanotubes and Au-Nanoparticles-Enhanced g-C3N4 to CuO@Polydopamine for Procalcitonin Detection

A new type of sandwich electrochemiluminescence (ECL) immunosensor dependent on ECL resonance energy transfer (ECL-RET) to achieve sensitive detection of procalcitonin (PCT) has been designed. In brief, carbon nanotubes (CNT) and Au-nanoparticles-functionalized graphitic carbon nitride (g-C₃N₄-CNT@Au) and CuO nanospheres covered with polydopamine (PDA) layer (CuO@PDA) were synthesized and applied as ECL donor and receptor, respectively. g-C₃N₄-CNT nanomaterials were in situ prepared on the basis of π-π conjugation, and the CNT content in the composite were optimized to achieve a strong and stable ECL signal. At the same time, Au nanoparticles were used to functionalize g-C₃N₄-CNT to further increase the ECL intensity and the loading amount of primary antibody (Ab₁). Moreover, CuO@PDA was first used to successfully quench the ECL signal of g-C₃N₄-CNT@Au. Under the optimum experimental conditions, the linear detection range for PCT concentration was within 0.0001-10 ng mL^-1 and the detection limit was 25.7 fg mL^-1 (S/N = 3). Considering prominent specificity, reproducibility, and stability, the prepared immunosensor was used to assess recovery rate of PCT in human serum according to the standard addition method and the result was satisfactory. In addition, it is worth mentioning that a novel ECL-RET pair of g-C₃N₄-CNT@Au (donor)/CuO@PDA (acceptor) was first developed, which offered an effective analytical tool for sensitive detection of biomarkers in early disease diagnostics.

An oxidatively damaged G-quadruplex/hemin DNAzyme

Oxidative damage of guanine to 8-oxoguanine triggers a partial and variable loss of G-quadruplex/hemin DNAzyme activity and provides clues to the mechanistic origins of DNAzyme deactivation, which originates from an interplay between decreased G-quadruplex stability, lower hemin affinity and a modification of the nature of hemin binding sites.

An anchored monopodial DNA walker triggered by proximity hybridization for amplified amperometric biosensing of nucleic acid and protein

This work designed an anchored monopodial DNA walker to amplify amperometric biosensing signal for sensitive detection of nucleic acid and protein. The biosensing surface was constructed by self-assembling hairpin DNA1 (H1) and small amount of P1-W (probe DNA1 hybridized with walking DNA) on a gold electrode. In the presence of target molecule, the walker could be triggered by the surface proximity hybridization product of P1, target and P2 to induce the cyclic hybridization of H1 with ferrocene modified hairpin DNA2 (H2-Fc), which took electroactive Fc to the electrode surface for amplified amperometric detection of the target. By linking P1 and P2 with dual specific DNA strands, aptamers or antibodies to recognize the target for proximity hybridization of P1 and P2, the walker amplified amperometric strategy could be used for highly sensitive biosensing of different targets. Using DNA and thrombin as the target models, the proposed biosensing methods achieved the linear range from 0.2 pM to 2 nM with a detection limit of 0.11 pM and 1.0 pM to 10 nM with a detection limit of 0.61 pM, respectively. The specific recognition process endowed the strategy with high selectivity and potential applications.

A localized molecular automaton for in situ visualization of proteins with specific chemical modifications

A localized DNA automaton is reported for in situ visualization of a specific protein subtype with dual chemical modifications on the cell surface, which executes protein-confined computation according to an anticoding–coding propagation algorithm.

Given the powerful regulation roles of chemical modification networks in protein structures and functions, it is of vital importance to acquire the spatiotemporal chemical modification pattern information in a protein-specific fashion, which is by far a highly challenging task. Herein, we design a localized DNA automaton, equipped with an anticoding–coding sequential propagation algorithm, for in situ visualization of a given protein subtype with two chemical modifications of interest on the cell surface. The automaton is composed of three probes respectively for the protein and two types of modifications. Once anchored on the cell surface and triggered, the automaton performs sequential protein-localized, DNA hybridization-based computations on the proximity status of each modification type with the protein and contracts the set of close proximity information into a single fluorescence signal turn-on using the designed algorithm. The modular and scalable features of the automaton enable its operation in scaled-down versions for protein-specific identification of one given modification. Thus, this work opens up the possibility of using automata for revealing complex regulation mechanisms of protein posttranslational modifications.

A procalcitonin photoelectrochemical immunosensor: NCQDs and Sb2S3 co-sensitized hydrangea-shaped WO3 as a matrix through a layer-by-layer assembly

Electron-transfer mechanism of a PEC immunosensor based on WO₃/NCQDs/Sb₂S₃ composites in PBS electrolytes containing AA.

A novel approach to photoelectrochemical immunoassay for procalcitonin on the basis of SnS2/CdS

A label-free photoelectrochemical (PEC) immunoassay system based on the one-step synthesis of SnS₂/CdS nanocomposites is successfully constructed for sensitively analyzing procalcitonin (PCT).

One-step electrodeposition of the MOF@CCQDs/NiF electrode for chiral recognition of tyrosine isomers

Electrochemical enantiorecognition of tyrosine (Tyr) isomers using a MOF@CCQDs/NiF electrode prepared by electrodepositing a metal-organic framework (MOF) and chiral carbon quantum dots (CCQDs) on Ni foil is reported. MOF@CCQDs/NiF not only shows highly selective, sensitive and quantitative analysis towards Tyr enantiomers but also presents the ability to determine l-Tyr% in racemic mixtures. This proposed that chiral sensors could be considered for practical applications in the field of Tyr related medical recognition.

Effects of miR-223 on colorectal cancer cell proliferation and apoptosis through regulating FoxO3a/BIM

OBJECTIVE

Colorectal cancer is a common malignant tumor of the digestive tract. It frequently occurs at the junction of the rectum and sigmoid colon. It is characterized by high mortality and poor prognosis. Bcl-2 interacting mediator of cell death (BIM) plays a role in the regulation of cell proliferation and apoptosis, and involves in the pathogenesis of colorectal cancer. The transcription factor forkhead, transcription factor O subfamily 3a (FoxO3a) plays a role in the regulation of BIM expression and is associated to the pathogenesis of colorectal cancer. Bioinformatics analysis suggests that there is a targeted relationship between FoxO3a and microRNA-223 (miR-223). This study aims to investigate effects of miR-223 on the regulation of FoxO3a/BIM signaling pathway and colorectal cancer cell proliferation and apoptosis.

MATERIALS AND METHODS

Colorectal cancer cell line SW620 and normal colorectal epithelial cell line NCM460 were cultured in vitro. Dual luciferase reporter assay was used to validate the relationship between miR-223 and FoxO3a. Flow cytometry was adopted to detect apoptosis. EdU staining was applied to test cell proliferation. Western blot was selected to determine FoxO3a and BIM protein expressions.

RESULTS

There was targeted regulatory relationship between miR-223 and FoxO3a. MiRa-223 up-regulated, FoxO3a and BIM expressions reduced, and cell proliferation was enhanced in SW620 cells compared with NCM460 cells. MiR-223 inhibitor or pIRES2-FoxO3a transfection significantly increased FoxO3a and BIM expressions, attenuated cell proliferation, and enhanced cell apoptosis.

CONCLUSIONS

MiR-223 targeted inhibited expression of FoxO3. Down-regulating the expression of miR-223, it increased the expressions of FoxO3a and BIM, weakened SW620 cells proliferation and induced apoptosis.

Electrochemiluminescence Double Quenching System Based on Novel Emitter GdPO4:Eu with Low-Excited Positive Potential for Ultrasensitive Procalcitonin Detection

Nowadays, the electrochemiluminescence (ECL) immunosensor with the unique superiority of tunable luminescence and ultrahigh sensitivity has become one of the most promising immunoassay techniques, especially for low-abundance biomarkers analysis. However, the use of signal probes with high excited potential and applied emitters which owned good intensity but biotoxicity limited its application. Herein, an ECL resonance energy transfer strategy was developed based on protein bioactivity protection utilizing europium-doped phosphoric acid gadolinium (GdPO₄:Eu) as novel low-potential luminophor (donor) and Pd@Cu₂O as the quenching probe (acceptor). Specifically, GdPO₄:Eu was first prepared by using the hydrothermal synthesis method to apply in ECL, and when it coexisted with K₂S₂O₈, cathode, a strong ECL signal would be generated at a low potential of -1.15 V (vs Ag/AgCl), where the immunocompetence of antigens and antibodies can be maintained well. Electrical pair Eu³⁺/Eu²⁺, as the coreactant promoter, produced by potential excitation could produce more SO₄^•- to accelerate the oxidation process of GdPO₄:Eu. Meanwhile, Cu₂O coated onto Pd (Pd@Cu₂O), as a dual-quencher, enhanced the quenching effect of Pd alone and controlled the ECL intensity of the "signal on" state within a reasonable range. As a result, the proposed biosensor for detection of trace procalcitonin, a biomarker of systemic inflammatory response syndrome, exhibited a far low detection limit, 0.402 fg/mL (S/N = 3). Importantly, this work not only utilized a promising ECL emitter for biosensing platform construction but also had momentous potential in biomarker detection of disease diagnosis and clinical analysis.

A DNA-Azobenzene Nanopump Fueled by Upconversion Luminescence for Controllable Intracellular Drug Release

Stimulus-responsive drug release possesses considerable significance in cancer therapy. This work reports an upconversion-luminescence-fueled DNA-azobenzene nanopump for rapid and efficient drug release. The nanopump is constructed by assembling the azobenzene-functionalized DNA strands on upconversion nanoparticles (UCNPs). Doxorubicin (DOX) is loaded in the nanopump by intercalation in the DNA helix. Under NIR light, the UCNPs emit both UV and visible photons to fuel the continuous photoisomerization of azo, which acts as an impeller pump to trigger cyclic DNA hybridization and dehybridization for controllable DOX release. In a relatively short period, this system demonstrates 86.7 % DOX release. By assembling HIV-1 TAT peptide and hyaluronic acid on the system, targeting of the cancer-cell nucleus is achieved for perinuclear aggregation of DOX and enhanced anticancer therapy. This highly effective drug delivery nanopump could contribute to chemotherapy development.

Synthesis and Application of CeO2/SnS2 Heterostructures as a Highly Efficient Coreaction Accelerator in the Luminol-Dissolved O2 System for Ultrasensitive Biomarkers Immunoassay

Electrocheluminescence (ECL) immunoassay amplified by coreaction accelerators has experienced major breakthroughs in ultrasensitive detection of biomarkers. Herein, CeO₂/SnS₂ heterostructures were synthesized and applied as a novel coreaction accelerator to enhance the ECL efficiency of the luminol-dissolved O₂ system for the first time. Benefiting from the well-matched lattice spacing, ultrafine CeO₂ nanoparticles (NPs) were grown in situ on layered SnS₂ nanosheets (NSs) with improved dispersion. CeO₂/SnS₂ as an electroactive substrate can remarkably accelerate the generation of abundant superoxide anion radicals (O₂^•-) to react with luminol anion radical (L^•-), achieving about 2-fold stronger ECL intensity than that of pure CeO₂ NPs. To avoid harsh chemical synthesis of conventional ECL labels and simplify the antibody conjugation process, ferritin (Ft) was served as a natural nanocarrier to immobilize luminol molecules (Lum@Ft) via a one-step linkage, whose protein nanocage can easily connect with the detection antibody. Moreover, a robust site-oriented immobilization strategy using HWRGWVC heptapeptide as specific capturer was further adopted to maintain the bioactivity of the capture antibody on the amine-functionalized CeO₂/SnS₂ surface, which promoted the incubation efficiency markedly. On account of this advanced sensing strategy, a brand new biosensor was constructed for the accurate detection of heart failure biomarkers, which performed with favorable linearity in the range of 0.0001-50 ng/mL and achieved the detection limit of 36 fg/mL.

Controlled assembly of AIEgens based on a super-quadruplex scaffold for detection of plasma membrane proteins

Quantification of plasma membrane proteins (PMPs) is crucial for understanding the fundamentals of cellular signaling systems and their related diseases. In this work, a super-quadruplex scaffold was designed to regulate assembly of oligonucleotide-grafted AIEgens for detection of PMPs. The nonfluorescence oligonucleotide-grafted AIEgen (Oligo-AIEgen) was firstly synthesized by attaching the AIEgen to 3'-terminus of the oligonucleotide through click chemistry. Meanwhile, the tetramolecular hairpin-conjugated super-quadruplex (THP-G4) as cleavage element and signal enhancement scaffold composited of three elements: a substrate sequence of DNAzyme in the loop region, partial hybridization region in the stem, and six guanine nucleotides to form G-quadruplex. Once the DNAzyme was anchored on the specific PMPs through aptamer-protein recognition, the substrate sequence on the loop of THP-G4 was cleaved by DNAzyme with the aid of cofactor Mn^II, resulting in the conformation switch of THP-G4 to the activated G-quadruplex scaffold. The latter could assemble Oligo-AIEgens to generate aggregation-induced emission (AIE) enhancement, resulting in a simple and sensitive strategy for detection of membrane proteins. Moreover, the DNAzyme continuously cut the next THP-G4 to achieve recycling amplification. Under the optimized conditions, this AIE-based strategy exhibited good linear relationship with the logarithm of MUC1 concentration from 0.01 to 10 μg mL^-1 with the limit of detection down to 4.3 ng mL^-1. The G4-assembled AIEgens provides a universal platform for detecting various biomolecules and a proof-of concept for AIE biosensing.

"Three-in-One" SERS Adhesive Tape for Rapid Sampling, Release, and Detection of Wound Infectious Pathogens

The traditional colony culture method for detection of pathogens is subjected to the laborious and tedious experimental procedure, which limits its application in point-of-care (POC) testing and quick diagnosis. This work designs an intelligent adhesive tape as a "three-in-one" platform for rapid sampling, photocontrolled release, and surface-enhanced Raman scattering (SERS) detection of pathogens from infected wounds. This tape is constructed by encapsulating densely packed gold nanostars as SERS substrates between two pieces of graphene and modified with a synthetic o-nitrobenzyl derivative molecule to form an artificial biointerface for highly efficient pathogen capture via electrostatic interaction. The captured targets can be conveniently released onto a solid culture medium by UV cleavage of o-nitrobenzyl moiety for pathogen growth and in situ SERS detection. As a proof of strategy, this "three-in-one" platform has been used for detecting the concurrent infection of Pseudomonas aeruginosa and Staphylococcus aureus by pasting the tape on a skin burn wound. The impressive detection performance with an analytical time of only several hours for these pathogens at an early growth stage demonstrates its great potential as a POC testing device for health care.

Photoelectrochemical competitive immunosensor for 17β-estradiol detection based on ZnIn2S4@NH2-MIL-125(Ti) amplified by PDA NS/Mn:ZnCdS

A competitive-type PEC immunosensor for 17β-estradiol (E₂) detection was successfully fabricated using ZnIn₂S₄@NH₂-MIL-125(Ti) composite as matrix. The excellent PEC behavior of ZnIn₂S₄@NH₂-MIL-125(Ti) composite could be attributed to that the Ti⁴⁺-Ti³⁺ intervalence cycles in the titanium oxo-cluster of NH₂-MIL-125(Ti) as well as the matching energy level between ZnIn₂S₄ and NH₂-MIL-125(Ti) promote the migration and separation of photocarrier. Besides, polydopamine (PDA) with abundant amino- and quinone-groups was selected to further improve the PEC signals and capture antibody, which implement through the covalent bonding of PDA and BSA-E₂ or carboxyl-group functionalized Mn:ZnCdS QDs in the competitive-type strategy. Concretely, the quinone functional groups in PDA film was applied to immobilize BSA-E₂ through Michael reactions, and the PDA nanosphere loaded Mn:ZnCdS quantum dot (PDA NS/Mn:ZnCdS QDs) was used as antibodies' labels to amplify PEC signals. After PDA NS/Mn:ZnCdS-anti-E₂ immobilized on the modified electrode, a remarkable increase of photocurrent signal was observed owing to the specific bonding of antigen and antibody. Based on the competitive binding of PDA NS/Mn:ZnCdS-anti-E₂ with either free E₂ or bovine serum albumin (BSA)-E₂ causing the change of the photocurrent signal, the standard sample free E₂ could be accuracy detect. Under optimal conditions, the competitive-type PEC immunosensor exhibited the linear range from 0.0005 ng/mL to 20 ng/mL and a limit detection of 0.3 pg/mL (S/N = 3). Meanwhile, the acceptable stability, selectivity and reproducibility of the proposed PEC immunosensing platform indicating the promising detection of small molecular environmental pollutants.

Near-infrared boosted ROS responsive siRNA delivery and cancer therapy with sequentially peeled upconversion nano-onions

RNA interference (RNAi) therapy has become an appealing approach for cancer treatment, while the specificity and efficiency of controlled small interference RNA (siRNA) release remain challenging due to the heterogeneity of tumor environment. Herein, upconversion nano-onions (UCNOs) with stacked polymer coating layers are constructed to decompose sequentially in response to extracellular environment and NIR stimulation. The UCNOs (UCNPs-PEIRB-PEISeSe/siRNA-R8-HA) are composed of upconversion nanoparticles (UCNPs) core functionalized with inner coating layer of photosensitizer rose bengal (RB) conjugated PEI 600, middle coating layer of singlet oxygen (¹O₂) sensitive diselenide linked PEI 600 with therapeutic siRNA loading and cell-penetrating peptide R8 modification, and outer coating layer of negatively charged hyaluronic acid (HA). HA prevents siRNA leakage during delivery process and specifically targets tumor cells with overexpressed CD44 membrane receptors, and digested by cell secreted hyaluronidase (HAase). Upon the subsequent irradiation at 808 nm, UCNPs core generates emissions around 540 nm, which activate RB to boost ROS generation for complete PEI-SeSe decompose. The NIR boosted decompose of UCNOs induces a fast and efficient siRNA release, which effectively improves the gene silencing efficiency in vitro and suppresses tumor growth in vivo. The proposed sequentially responsive UCNOs have promising potential application in precision medicine.

Selenium-isotopic signature toward mass spectrometric identification and enzyme activity assay

The unraveling of enzymatic reactions, especially identification of enzymatic substrates or products, is important to elucidate biological processes. Here a selenium-isotopic signature for mass spectrometric identification of enzymatic-related species is demonstrated by using selenium-containing peptides (SePeps) as substrates. Thus a strategy is proposed for rapid and precise assay of multiple enzyme activity. These SePeps can be synthesized by introduction of one selenomethionine residue in the sequence and simply identified in the full-scan mode with the feature of distinctive selenium-isotopic distribution without MS/MS verifications, which proposes a novel solution to the specific identification of enzyme-related species, allows to exclude the interferences of species with tiny mass differences in bio-samples, and meanwhile can offer a judgement on data accuracy for the analysis of enzyme activities. As a proof-of-concept, a method for multiple analysis of two representative enzymes in MCF-7 cell lysate has been developed with the isotopic peak areas of either SePep substrates or enzymatic products with the top intensities. These results could be the foundation to extend the method for more complicated enzyme systems. The selenium-isotopic signature provides a powerful protocol for high-throughput assays of peptide-metabolizing enzymes with enhanced confidence and can be extended to screen enzymatic reaction-related substrates.