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Metal ions play critical roles in chemical, biological, and environmental processes. Various biomolecules have the ability to coordinate with metal ions and form various materials. Nucleobases, nucleosides, and nucleotides, as the essential components of DNA, have emerged as a useful building block for the construction of functional nanomaterials. In recent years, DNA oligonucleotides have also been used for this purpose. We herein review the strategies for the synthesis of soft nanomaterials through the assembly of nucleotides (or DNA) and metal ions to yield various nanoparticles, fibers, and hydrogels. Such coordination methods are simple to operate and can be carried out under ambient conditions. The luminescent, catalytic, and molecular recognition properties of these coordination materials are described with representative recent examples. Their applications ranging from biosensing, enzyme encapsulation, catalysis, templated shell growth to cancer therapy are highlighted. Finally, challenges of this field and future perspectives are discussed.

The sensitive detection of coronavirus is of vital importance for the prevention of its rapid spread. Porcine epidemic diarrhea virus (PEDV) is a highly contagious coronavirus that causes severe diarrhea and death in neonatal piglets. In this work, a novel PCN-224-based electrochemiluminescence (ECL) system was constructed for PEDV detection with high sensitivity. We found that PCN-224 can be employed as an ECL reporter with a strong signal because of its zirconium-based organic porous frame nanomaterial with a large specific surface area and stable structure. TiO2 nanoparticles were used as an accelerator for the first time to promote the reduction of coreactant potassium peroxydisulfate on the cathode; thus, the initial ECL signal of PCN-224 was significantly amplified. In the presence of PEDV, the ECL signal decreased due to the block effect to electron transfer. As a result, the novel "signal off" biosensor achieved a sensitive detection of PEDV ranging from 1 pg/mL to 10 ng/mL, with a detection limit of 0.4 pg/mL (S/N = 3). Importantly, the PCN-224 nanomaterial enriched the ECL system in biological analysis, and the proposed strategy provided a new route for coronavirus detection.

Biological nitrogen fixation is essential to crop production, but it can be inhibited by high concentrations of reactive oxygen species (ROS) due to the irreversible inactivation of the nitrogenase complex, thus posing a threat to food security and sustainable agricultural development. Here, we constructed an antioxidant cobalt ferrite (CoFe2O4) nanozyme as a bridge between nanotechnology and biological nitrogen fixation, which was shown to efficiently regulate the reactive oxygen metabolism and protect nitrogenase, thereby significantly enhancing the symbiotic nitrogen fixation efficiency by 260% in Glycine max (L.) Merr. (soybean). The CoFe2O4 nanozyme was also revealed to effectively reduce the concentration of ROS in the nodule by 56.6%, creating a superior environment for the proliferation of rhizobia and forming more effective nodules (larger nodules for an increase of 45.6% in the number of parasitic rhizobia). Furthermore, the CoFe2O4 nanozyme was shown to act as a synergist of leghemoglobin and increase its accumulation by 45.9%, where the high concentration of leghemoglobin in nodular cells can create a relatively hypoxic environment and protect nitrogenase, thus achieving a quantitative leap in nitrogen fixation capacity and simultaneously increasing the soybean photosynthesis by 67.2%. Our study has demonstrated that the CoFe2O4 nanozyme can efficiently regulate the intracellular ROS metabolism and serve as a promising strategy for enhancing symbiotic nitrogen fixation.

An ultrasensitive electrochemiluminescence (ECL) biosensor was developed based on MIL-53(Al)@CdS QDs and SiO2@AuNPs for trichlorfon detection. Metal–organic frameworks (MOFs) were used as a loading platform that provided a large surface area to load targets and modified materials onto the electrode. At the same time, SiO2@AuNPs loaded plenty of AuNPs which effectively increased the ECL resonance energy transfer between the CdS QDs, so that the ECL signal was strongly quenched and resulted in an amplified response. In the range of 10−11–10−4 M, the ECL response showed a linear relationship with the concentration (logarithm) of trichlorfon, and the detection limit was 5.1 × 10−12 M (S/N = 3). When the biosensor was applied to detect trichlorfon in lettuce, broccoli, cucumber, and chives, the recoveries obtained from the spiked samples were 97%–105%, 102%–104%, 100%–104%, and 98%–104%, respectively. Thus, this novel ECL biosensor has potential applications for the analysis of trichlorfon in food samples.

Nucleic acid lateral flow sensing has drawn great research attention since it has the advantages of being simple, rapid, and cost-effective. However, considering the trace amounts of the nucleic acid targets, its sensitivity is still limited. Although enormous efforts have been devoted to enhancing its sensitivity, developing a simple lateral flow sensing platform with high sensitivity remains challenging. We report a novel lateral flow microRNA-21 biosensing platform based on a portable surface enhanced Raman scattering (SERS) reader coupled with a catalytic hairpin assembly signal amplification strategy. Hairpin DNA probes were anchored on Au@Ag nanotags, and the presence of microRNA-21 triggered the formation of numerous double-stranded DNAs along with the exposure of the biotin groups. By this means, the target was recycled and signal amplification was achieved. The Au@Ag nanoprobes with exposed biotin can be captured on the test line via its interaction with streptavidin. By scanning the strip with a portable SERS reader, the sensitive quantification of microRNA-21 was realized with a detection limit as low as 84 fM. The proposed strategy was employed to detect the target in a serum sample, demonstrating its great potential in amplified point-of-care biosensing for clinical diagnosis.

A short kanamycin-binding aptamer has been widely used for detecting kanamycin. One of the popular signaling methods is based on the color change of gold nanoparticles (AuNPs) to develop label-free colorimetric biosensors. The general perception was that aptamer binding to its target would inhibit aptamer adsorption by the AuNPs. This inhibited adsorption results in the aggregation of the AuNPs and a color change upon addition of salt. However, the potential adsorption of kanamycin was ignored. Herein, we carefully studied the adsorption of kanamycin on AuNPs and performed a comprehensive analysis using two mutated aptamers and a randomly sequenced DNA which were not supposed to bind kanamycin. In addition, a total of six antibiotics were studied over a wide concentration range. As low as 90 nM kanamycin can induce the aggregation of 3 nM citrate-capped AuNPs, indicating very strong adsorption of kanamycin. The color change was independent of DNA sequence, and all the tested sequences showed a similar color response, regardless of aptamer. Among the different antibiotics, kanamycin and streptomycin induced a color change but not the other four. Our results support an alternative mechanism that kanamycin and streptomycin adsorption by the AuNPs was the main reason for the color change instead of aptamer binding.

With the rapid development of nanotechnology, molybdenum (Mo)-based nanomaterials have been widely used in various fields, and the ensuing environmental behavior has also raised widespread concern....

Activated doxorubicin (DOX) often has severe systemic toxicity and side effects due to its inability to distinguish tumor cells from normal cells, which seriously affects the prognosis of patients. Here, we synthesized an inactivated a DOX prodrug that could be selectively activated by a light-induced caspase-3 enzyme in the tumor site. In the absence of light, this uniformly dispersed nanoparticle avoided the unnecessary toxicity under physiological conditions. Upon the laser irradiating to the tumor area of interest, the nanoparticles can produce a large amount of reactive oxygen species (ROS) to induce cell apoptosis and activate caspase-3 enzyme to release DOX selectively. Meanwhile, the produced ROS can also combine with activated DOX to cause more potent tumor damage. The experiments demonstrated that the light can effectively activate DOX drug through a series of cascade events and the subsequent synergistic therapy both

A DNA tweezer is a dynamic DNA nanomachine that can reversibly switch its state between open and closed. Here, we employed a DNA tweezer for the first time to dynamically control the distance between plasmonic silver nanoparticles (Ag NPs) for a surface enhanced Raman scattering (SERS) biosensing application. Two DNA and 4-nitrothiophenol (4-NTP) modified Ag NPs were linked to the arms of the DNA tweezer (DNA tweezer-Ag NPs probe) by complementary base pairing. Activation of the Raman intensity was achieved by the state transformation of the DNA tweezer-Ag NPs probe from open to closed. The distances between two Ag NPs in open and closed state were 8.1 ± 2.7 nm and 3.2 ± 0.8 nm, respectively. Furthermore, the two Ag NPs were spatially separated in the open state with a low Raman signal, whereas in the closed state, Raman intensity was enhanced because of the proximity of two Ag NPs. The developed biosensing system exhibited a good linear relationship when the concentration of aflatoxin B1 (AFB1) ranged from 1 ng/mL to 0.01 pg/mL, and the limit of detection (LOD) was 5.07 fg/mL. In addition, spike recovery and certificated real foodstuffs were used to examine the feasibility in a real situation. This protocol provides a potential candidate for SERS detection and can be used as a promising technology for biological and chemical sensors.

An aptasensor based on MIL-53(Al)@CdTe was designed for multiple determination of Hg2+ and Pb2+ by electrochemiluminescence (ECL). Upon the recognition of Hg2+, aptamer 2-AuNPs form hairpin structures and are removed from the electrode. While in the presence of Pb2+, aptamer 1-PtNPs capture the target ions and form G-quadruplexes, and then bring PtNPs close enough to CdTe QDs to produce ECL resonance energy transfer. Upon aptamer interaction with Hg2+ and Pb2+, decreased ECL intensity was observed due to enhanced resonance energy transfer (ERET) and attenuated surface plasmon resonance (SPR). The ECL intensity difference (ΔECL) could therefore be used to detect heavy-metal ions with detection limits of 4.1 × 10−12 M (path 1, Hg2+), 3.7 × 10−11 M (path 2, Pb2+), and 2.4 × 10−11 M (path 3, Pb2+). The aptasensor could also be used for detecting Hg2+ and Pb2+ in fish and shrimp samples with good recoveries.

Metal-respiring bacteria are frequently used to recycle metal resources by biosynthesizing nanoparticles on its surface in environment treatment. However, further utilization of biogenetic nanoparticles through combining the advantages of both bacteria and nanoparticles is still limited. Herein, biogenetic Au@Ag nanoislands are utilized as the surface-enhanced Raman spectroscopy (SERS) substrate for quantitative detection. Specifically, Au@Ag nanoislands enhance the Raman signal

Developing nanomaterials-based antimicrobial agents has shown a widespread promise. In this study, silver nanoparticle-modified graphene oxide (GO-AgNPs) nanocomposites were self-assembled via interfacial electrostatic force. By using the porcine reproductive and respiratory syndrome virus (PRRSV) as a pattern, the antiviral effect of the as-prepared GO-AgNPs nanocomposites on the replication of virus was investigated. The results indicated that exposure with GO-AgNPs nanocomposites could obviously suppress PRRSV infection. It was found that GO-AgNPs nanocomposites exhibited a better inhibitory effect compared with AgNPs and GO. By selecting the porcine epidemic diarrhea virus (PEDV) as a contrast virus, GO-AgNPs nanocomposites were proven to have a broad antiviral activity. Mechanism studies showed that GO-AgNPs nanocomposites might prevent PRRSV from entering the host cells, with 59.2% inhibition efficiency. Meanwhile, GO-AgNPs nanocomposite treatment enhances the production of interferon-α (IFN-α) and IFN-stimulating genes (ISGs), which can directly inhibit the proliferation of virus. Taken together, this study reports a new type of antiviral agent and provides a promising pharmaceutical agent for treating infection by the highly pathogenic PRRSV. Moreover, it may provide novel ideas for the research and development of antiviral formulations based on nanocomposites and extend their applications in biological systems.

One of the main challenges for tumor vascular infarction in combating cancer lies in failing to produce sustained complete thrombosis. Inspired by the capability of vascular infarction in blocking the delivery of oxygen to aggravate tumor hypoxia, we herein present the performance of selective tumor thrombus inducing hypoxia activation therapy to improve the therapeutic index of coagulation-based tumor therapy. By encapsulating coagulation-inducing protease thrombin and a hypoxia-activated prodrug (HAP) tirapazamine into metal-organic framework nanoparticles with a tumor-homing ligand, the obtained nanoplatform selectively activates the platelet aggregation at tumor to induce the thrombosis and vascular obstruction therapy by the exposed thrombin. Meanwhile, the thrombus can cut off the blood oxygen supply and potentiate the hypoxia levels to enhance the HAP therapy. This strategy not only addresses the dissatisfaction of vascular therapy, but also conquers the dilemma of inadequate hypoxia in the HAP treatment. Since clinical operations such as surgery can be used to induce the coagulation, the coagulation based synergistic therapy is promising to be translated into a clinical combination regimen. Agency for Science, Technology and Research (A*STAR) National Research Foundation (NRF) Submitted/Accepted version This work was supported by grants from the National Natural Science Foundation of China (21778020, 31750110464, and 31950410755), the Sci-Tech Innovation Foundation of Huazhong Agricultural University (2662018PY024), the National Key R&D Program of China (2016YFD0500706), and the Science and Technology Major Project of Guangxi (Gui Ke AA18118046). This work was also supported by the Singapore Agency for Science, Technology and Research (A*STAR) AME IRG grant (A20E5c0081), and the Singapore National Research Foundation Investigatorship (NRF-NRFI2018-03).

A sensitive electrochemiluminescence (ECL) aptasensor based on 3D graphene is described for thrombin detection utilizing nitrogen-doped graphene quantum dots doped silica (NGQDs@SiO2) nanocomposite labeling as an enhancer. Ru(bpy)32+-Pt nanoparticles (Ru-PtNPs) with an ECL signal were dropped onto a 3D graphene-modified electrode, and then, a complementary thrombin aptamer (cDNA) was conjugated to the Ru-PtNPs. Finally, NGQDs@SiO2, coupled with the thrombin aptamer as the booster, was attached to the electrode surface by using hybridization with the cDNA, and the ECL intensity was efficiently enhanced. The target thrombin induced the NGQDs@SiO2 nanocomposites labeled with the thrombin (TB) aptamer to be extracted because of their strong binding with thrombin. The immobilization amount of NGQDs@SiO2 on the modified electrode decreased. Thus, the presence of thrombin could result in a decrease in the ECL signal. On the basis of the signal amplification factors, the fabricated ECL aptasensor demonstrated excellent properties with concentrations varying from 2.0 pM to 50 nM and a detection limit of 23.1 fM.

The development of novel antimicrobial agents is a top priority in the fight against drug-resistant bacteria. Here, we synthesized a green nanoantibiotic, nitrogen-doped carbon quantum dots (N-CQDs) from bis-quaternary ammonium salt (BQAS) as carbon and nitrogen sources. The as-obtained N-CQDs possess high antibacterial activity (>99%) against both methicillin-resistant Staphylococcus aureus (MRSA) and Ampicillin-resistant Escherichia coli bacteria in vitro than some known clinical antibiotics (vancomycin and gentamicin). The N-CQDs can kill MRSA pathogens without inducing resistance, prevent biofilm formation and eliminate established biofilm and persister cells. The treatment of N-CQDs can significantly reduce the amount of bacteria on the infected tissue and accelerate wound healing. The N-CQDs are positively charged, thus enabling them to interact with bacterial cell membrane through electrostatic interaction, leading to severe damage and an increased permeability of the cell membrane, which further promotes the penetration of N-CQDs into the membrane and induces the degradation of DNA by N-CQDs generated reactive oxygen species. The N-CQDs also play a role in obstructing the intracellular metabolic pathways of MRSA. The overall data demonstrate the green nanoantibiotic as an excellent eradicator of biofilm and persister cells as well as a promising antibacterial candidate for treating infections induced by drug-resistant bacteria.

Extensive efforts have been devoted to improve electrocatalytic activity of the catalysts in the fuel cells, however, it's still a big challenge to obtain the catalysts with low-cost and high-efficiency. Here we report the branched PdCuCo catalyst coated by amorphous nickel boride membrane displays an effective activity toward oxygen reduction reaction (ORR) and methanol oxidation reaction (MOR). The coating membrane serves as an electron acceptor to tune the surface electronic structure of the catalyst. And the interactional effect of the composite catalysts exhibit a normal distribution trend of mass activity (MA) and specific activity (SA) for the ORR and MOR. The SA of the composite catalysts effectively improves 3.3 times for ORR and 4.1 times for MOR than PdCuCo. Moreover, the proposed cost-effective catalyst can inspire novel design perspective about the focus attention of catalytic activity.

Due to their remarkable antibacterial properties, silver nanoparticles (Ag NPs) and curcumin (CCM) have been widely used in the antimicrobial field. In our study, we have fabricated the uniform and stable silver/curcumin composite nanoparticles by a facile ultrasound treatment process and the synergistic antibacterial activity were evaluated. The curcumin not only played a role of reducing agent but also acted as a capping agent. The antibacterial effects of silver/curcumin (cAgNPs) were studied by measuring the growth curve and surface plate assay based on the E. coli and B. subtilis, which showed concentration dependent bacteriostatic and bactericidal effects of cAgNPs. The presence of CCM enhance the binding of Ag to bacterial membrane and Ag+ release in comparison to that without CCM, so that creating a temporary and local high Ag+ concentration near the surface of the bacterium, meanwhile, generation of more reactive oxygen species, lead to membrane damage, bacterial lipases and induce leakage of intracellular contents followed by bacterial death that lead to growth inhibition of the bacteria. The antibacterial effects were characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM), the effect which were further found to decrease by introducing antioxidant N-acetyl-l-cysteine (NAC) act as a reactive oxygen species (ROS) scavenging agent. These initial data suggest that cAgNPs have a highly antibacterial efficient and might have potential to be developed as an effective antimicrobial nanomaterial.

DNA nanotechnology engineered at the solid-liquid interface has advanced our fundamental understanding of DNA hybridization kinetics and facilitated the design of improved biosensing, bioimaging and therapeutic platforms. Three research branches of DNA nanotechnology exist: (i) structural DNA nanotechnology for the construction of various nanoscale patterns; (ii) dynamic DNA nanotechnology for the operation of nanodevices; and (iii) functional DNA nanotechnology for the exploration of new DNA functions. Although the initial stages of DNA nanotechnology research began in aqueous solution, current research efforts have shifted to solid-liquid interfaces. Based on shape and component features, these interfaces can be classified as flat interfaces, nanoparticle interfaces, and soft interfaces of DNA origami and cell membranes. This review briefly discusses the development of DNA nanotechnology. We then highlight the important roles of structural DNA nanotechnology in tailoring the properties of flat interfaces and modifications of nanoparticle interfaces, and extensively review their successful bioapplications. In addition, engineering advances in DNA nanodevices at interfaces for improved biosensing both in vitro and in vivo are presented. The use of DNA nanotechnology as a tool to engineer cell membranes to reveal protein levels and cell behavior is also discussed. Finally, we present challenges and an outlook for this emerging field.

Herein, an ultrathin Pt nanozyme has been developed. The Pt nanozyme exhibited both oxidase and peroxidase-mimetic properties, leading to relieved hypoxia and specific oxidative damage in tumor cells in a cascade manner. Meanwhile, hydrophilic Pt2+ was released sustainably under tumor acidity. These properties endow the Pt nanozyme with great potential in killing drug resistant tumor cells while not damaging normal cells.

The strategy that combines photodynamic therapy (PDT) and photothermal therapy (PTT) is widely used to achieve strong antitumor efficiency. Since light in the NIR-II window possesses ideal penetration ability, developing NIR-II PTT and NIR-II light triggered photosensitizer release for combined PDT and PTT is very promising in nanomedicine. Methods: We develop a novel nanocarrier (termed AuHNRs-DTPP) by conjugating photosensitizer contained chimeric peptide (DTPP) to Au hollow nanorods (AuHNRs). AuHNRs was obtained by a Te-templated method with the assistance of L-cysteine. The chimeric peptide PpIX-PEG8-GGK(TPP)GRDEVDGC (DTPP) was obtained through a solid-phase peptide synthesis (SPPS) method. Results: Under the 1064 nm laser irradiation, the nanocarrier can accumulate heat quickly for efficient PTT, and then release activated photosensitizer for real-time apoptosis imaging. Thereafter, supplementary PDT can be conducted to kill tumor cells survived from the PTT, and meanwhile the normal tissue can be protected from photo-toxicity. Conclusion: This designed AuHNRs-DTPP nanocarrier with remarkable therapy effect, real-time apoptosis imaging ability and reduced skin damage is of great potential in nanomedicine application.

Chemodynamic therapy (CDT) destroys cancer cells by converting H2O2 or O2 into reactive oxygen species (ROS), but its therapeutic efficacy is restricted by the antioxidant capacity of tumor. Previous solutions focused on strengthening the nanodrugs with the ability to increase ROS production or weaken the antioxidant capacity of cancer cells. Conversely, we here develop a mild nanodrug with negligible side effects. Specifically, the Au@Pt nanozyme decorated on a bacterial surface (Bac-Au@Pt) is reported to achieve precise CDT. Due to the tumor targeting ability of bacteria and catalytic property of Au@Pt nanozyme under acidic conditions, this nanosystem can release ROS to tumor cells effectively. In addition, the interferon gamma released by T cells specifically decreases the intracellular reductants in tumor cells, while having no obvious effect on normal cells. Therefore, a low dose of Bac-Au@Pt achieves a satisfactory therapeutic efficacy to tumor cells and is nontoxic to normal cells even at their acidic components. This nanosystem enables CDT and immunotherapy to mutually benefit and improve by each other, providing a promising strategy to achieve high anticancer efficacy even with a low dose usage. National Research Foundation (NRF) This work was financially supported by the National Natural Science Foundation of China (21778020 and 31950410755), the Sci-Tech Innovation Foundation of Huazhong Agricultural University (2662018PY024), the Fundamental Research Funds for the Central Universities (2662015QD026), and the Science and Technology Major Project of Guangxi (Gui Ke AA18118046). This work is also supported by the Singapore National Research Foundation Investigatorship (NRF-NRFI2018-03).

Photothermal therapy (PTT) is considered an alternative for oncotherapy because it has less invasive damage to normal tissues than other methods, particularly in second near-infrared (NIR-II) PTT (1000-1350 nm) because of deeper biological tissue penetration, lower photon scattering, and higher maximum permissible exposure (1.0 W cm

The outbreak of rabies virus (RABV) in Asia and Africa has attracted widespread concern due to its 100% mortality rate, and RABV detection is crucial to its diagnosis and treatment. Herein, we report a sensitive and reliable strategy for the dual-modal RABV detection using pomegranate-shaped dendritic silica nanospheres fabricated with densely incorporated quantum dots (QDs) and horseradish peroxidase (HRP)-labeled antibody. The immunoassay involves the specific interaction between virus and nanospheres-conjugated antibody coupled with robust fluorescence signal originating from QDs and naked-eye discernible colorimetric signal on the oxTMB. The ultrahigh loading capacity of QDs enables the detection limit down to 8 pg/mL via fluorescence modality, a 348-fold improvement as compared with conventional enzyme-linked immunosorbent assay (ELISA). In addition, the detection range was from 1.20 × 102 to 2.34 × 104 pg/mL by plotting the absorbance at 652 nm with RABV concentrations with a detection limit of 91 pg/mL, which is nearly 2 order of magnitude lower than that of the conventional ELISA. Validated with 12 brain tissue samples, our immunoassay results are completely consistent with polymerase chain reaction (PCR) results. Compared with the PCR assay, our approach requires no complex sample pretreatments or expensive instruments. This is the first report on RABV diagnosis using nanomaterials for colorimetry-based prescreening and fluorescence-based quantitative detection, which may pave the way for virus-related disease diagnosis and clinical analysis.

Summary Currently, patients receiving cancer treatments routinely suffer from distressing toxic effects, most originating from premature drug leakage, poor biocompatibility, and off-targeting. For tackling this challenge, we construct an intracellular Ca2+ cascade for tumor therapy via photothermal activation of TRPV1 channels. The nanoplatform creates an artificial calcium overloading stress in specific tumor cells, which is responsible for efficient cell death. Notably, this efficient treatment is activated by mild acidity and TRPV1 channels simultaneously, which contributes to precise tumor therapy and is not limited to hypoxic tumor. In addition, Ca2+ possesses inherent unique biological effect and normal cells are more tolerant of the undesirable destructive influence than tumor cells. The Ca2+ overload leads to cell death due to mitochondrial dysfunction (upregulation of Caspase-3, cytochrome c, and downregulation of Bcl-2 and ATP), and in vivo, the released photothermal CuS nanoparticles allow an enhanced 3D photoacoustic imaging and provide instant diagnosis.

Metal-organic frameworks (MOFs) as porous materials have attracted much attention in various fields such as gas storage, catalysis, separation, and nanomedical engineering. However, their applications in electrochemiluminescence (ECL) biosensing are limited due to the poor conductivity, lack of modification sites, low stability and specificity, and weak biocompatibility. Integrating the functional materials into MOF structures endows MOF composites with improved conductivity and stability and facilitates the design of ECL sensors with multifunctional MOFs, which are potentially advantageous over their individual components. This review summarizes the strategies for designing ECL-active MOF composites including using luminophore as a ligand, in situ encapsulation of luminophore within the framework, and post-synthetic modification. As-prepared MOF composites can serve as innovative emitters, luminophore carriers, electrode modification materials and co-reaction accelerators in ECL biosensors. The sensing applications of ECl-active MOF composites in the past five years are highlighted including immunoassays, genosensors, and small molecule detection. Finally, the prospects and challenges associated with MOF composites and their related materials for ECL biosensing are tentatively proposed.

Cyanide (C≡N) can lead to blood, cardiovascular system, and nervous system disorders owing to the acute and chronic toxicity; thus, aiming at the group or individual poisoning incidents, it is necessary to develop the sensitive and credible method for rapid on-site detection of poisons cyanide. Surface-enhanced Raman spectroscopy (SERS) with the advantages of providing fingerprint information of target molecules and single-molecules sensitivity has been widely used in on-site analysis; however, the SERS measurements always suffer from the problem of the stability of substrates. Here, the polyvinylpyrrolidone (PVP)-stabilized Au NPs (PVP-Au NPs) have been assembled through the simple, convenient evaporation-induced strategy with the large-scale hotspots substrates. The presence of PVP can not only facilitate the assembly of Au NPs but also prevent the corrosion of CN− towards the Au NPs with the formation of [Au (CN)2]−1, providing high stable and reproducible SERS signals. Moreover, the PVP-Au NPs have been assembled on the Si wafer to fabricate the portable SERS chip for rapid on-site detection of CN− with an RSD of 5.8% and limitation of 100 ppb. Furthermore, by coupling a portable Raman spectrometer, the SERS spectra of CN− spiked into different specimens to simulate the poison samples have been collected and analyzed on SERS chips with the recovery of 89–103% and RSD not higher than 11.3%. Consequently, the fabricated SERS chip with assembled PVP-Au NPs can provide sensitive and credible detection for CN− in different specimens, and then would satisfy the rapid on-site evaluation of CN− in poisoning incidents with the portable Raman spectrometer.

Currently, patients receiving cancer treatments routinely suffer from distressing toxic effects, most originating from premature drug leakage, poor biocompatibility and off-targeting. For tackling this challenge, we construct an intracellular Ca2+ cascade for tumor therapy via photothermal activation of TRPV1 channels. The nanoplatform creates an artificial calcium overloading stress in specific tumor cells, which is responsible for efficient cell death. Notably, this efficient treatment is activated by mild acidity and TRPV1 channels simultaneously, which contributes to precise tumor therapy and is not limited to hypoxic tumor. In addition, Ca2+ possesses inherent unique biological effect and normal cells are more tolerant of the undesirable destructive influence of NPs than tumor cells. The Ca2+ overload leads to cell death due to mitochondrial dysfunction (upregulation of Caspase-3, cytochrome c, and downregulation of Bcl-2 and ATP) and in vivo, the release photothermal CuS NPs allows an enhanced 3D photoacoustic (PA) imaging and provide instant diagnosis.

Although considerable progress has been made in nanomedicine, it is still of great significance for nanomedicine machines with natural targeting, diverse functions, maximum drug utilization, and outstanding performance. In this work, a simple small molecule chimeric peptide with the capability of sequential two-step self-assembly was developed. This chimeric peptide could be self-assembled into larger nanoparticles from smaller nanoparticles at tumor extracellular acidic microenvironment and further aggregated in apoptotic tumor cells mediated by photodynamic therapy. In addition to the nanostructure changes, the increasing of size could accelerate cell internalization and tumor accumulation of chimeric peptide for better photodynamic therapy. And the aggregation in the apoptotic cell could enhance the photothermal effect and photoacoustic signal of chimeric peptide for further photothermal therapy and photoacoustic imaging of tumor apoptosis. Both in vitro and in vivo studies demonstrated that these self-assembly behaviors endowed chimeric peptide with well tumor accumulation, preferable tumor suppression, and precise therapeutic evaluation, which should provide a new way for the construction of efficient theranostic agent based on chimeric peptides.

Combating bacterial pathogens has become a global concern, especially the emergence of drug-resistant bacteria have made conventional antibiotics lose their efficiency. This grim situation suggests the necessity to explore novel antibacterial agents with favorable safety and strong antibacterial activity. Here, we took the advantage of quaternary ammonium compounds and synthesized a long-chain high-molecular organic bis-quaternary ammonium salt (BQAS) with a broad-spectrum bactericidal activity through a facile one-pot reaction. The bactericidal effect of BQAS was evaluated by two bacterial human pathogens: Escherichia coli (Gram-negative) and Staphylococcus aureus (Gram-positive), which are the major cause of diarrheal infections in children and adults. Our experimental results indicate that the bactericidal activity of BQAS is linked to the strong contact between the positively charged quaternary ammonium groups and the bacterial cells, thus leading to a temporary and locally high concentration of reactive oxygen species, which subsequently triggers oxidative stress and membrane damage in the bacteria. This mechanism was further confirmed by several assays, such as the membrane permeabilization assay, fluorescent-based cell live/dead test, scanning electron microscopy, transmission electron microscopy, together with the lactate dehydrogenase release assay, which all indicated that BQAS induced damage to the cytoplasmic membrane and the leakage of intracellular fluid containing essential molecules. The excellent bactericidal activity of BQAS suggests its great application potential as a promising candidate against the rapid emergence of drug-resistant bacterial pathogens.

The research of carbon-based antivirals is still in its infancy, and their development into safe and effective carbon dots (CDs) with antiviral activity at multiple points in the life cycle of the virus remains to be explored. Here, we report a one-step method to apply curcumin in order to prepare of uniform and stable cationic carbon dots (CCM-CDs) with antiviral properties. The inhibitory effect of CCM-CDs on viral replication was studied by using porcine epidemic diarrhea virus (PEDV) as a coronavirus model. PEDV is applied as a coronavirus model to study the antiviral effect of as-prepared CCM-CDs on its replication. The cationic CCM-CDs treatment is found obviously to inhibit the proliferation of PEDV compared with the common CDs (EDA-CDs). The CCM-CDs treatment can change the structure of surface protein in viruses, thereby inhibiting viral entry. It can also suppresses the synthesis of negative-strand RNA of the virus, the budding of the virus, and the accumulation of reactive oxygen species by PED...

Ignored damage in adjacent normal tissue is fatal especially in some specific tumor therapy such as brain tumors, but it remains a great challenge to conquer due to random drug diffusion and tumor complexity. Herein, we show that hyperthermia in mitochondria, an interparticle plasmonic coupling effect activated nanoevent, selectively strikes tumor tissues without damaging adjacent normal tissues. Spherical gold nanoparticles with a mitochondria-targeting moiety, triphenyl phosphonium, preferentially accumulated inside tumor mitochondria and reached the threshold to activate interparticle plasmonic coupling effect among gold nanoparticles, realizing selective light-thermal conversion and mitochondrial dysfunction in tumor, whereas little hyperthermia and mitochondrial dysfunction were observed in adjacent normal tissues. In vivo study revealed that the temperature increment in tumor tissue with irradiation was nearly 4-fold that in adjacent normal tissue. This subcellular organelle-templated accumulation strategy provides a therapeutic model for highly selective tumor therapy with negligible local side effects.

In this work, the feasibility of a novel sensitive electrochemiluminescence aptasensor for the detection of lysozyme using Ru(bpy)32+-Silica@Poly-L-lysine-Au (RuSiNPs@PLL-Au) nanocomposites labeling as an indicator was demonstrated. The substrate electrode of the aptasensor was prepared by depositing gold nanoparticles (AuNPs) on 3D graphene-modified electrode. The lysozyme binding aptamer (LBA) was attached to the 3D graphene/AuNPs electrode through gold-thiol affinity, hybridized with a complementary single-strand DNA (CDNA) of the lysozyme aptamer labeled by RuSiNPs@PLL-Au as an electrochemiluminescence intensity amplifier. Thanks to the synergistic amplification of the 3D graphene, the AuNPs and RuSiNPs@PLL-Au NPs linked to Ru(bpy)32+-ECL further enhanced the ECL intensity of the aptasensor. In presence of lysozyme, the CDNA segment of the self-assembled duplex was displaced by the lysozyme, resulting in decreased electrochemiluminescence signal. Under the optimized conditions, the decrease in electrochemiluminescence intensity varied proportionally with the logarithmic concentration of the lysozyme from 2.25 × 10-12 to 5.0 × 10-8 mol L-1, and the detection limit was estimated to 7.5 × 10-13 mol L-1. The aptasensor was further tested in real samples and found reliable for the detection of lysozyme, thus holding great potential application in food safety researches and bioassay analysis.

Development of novel antiviral reagents is of great importance for the control of virus spread. Here, Ag2S nanoclusters (NCs) were proved for the first time to possess highly efficient antiviral activity by using porcine epidemic diarrhea virus (PEDV) as a model of coronavirus. Analyses of virus titers showed that Ag2S NCs significantly suppressed the infection of PEDV by about 3 orders of magnitude at the noncytotoxic concentration at 12 h postinfection, which was further confirmed by the expression of viral proteins. Mechanism investigations indicated that Ag2S NCs treatment inhibits the synthesis of viral negative-strand RNA and viral budding. Ag2S NCs treatment was also found to positively regulate the generation of IFN-stimulating genes (ISGs) and the expression of proinflammation cytokines, which might prevent PEDV infection. This study suggest the novel underlying of Ag2S NCs as a promising therapeutic drug for coronavirus.

Improving the accuracy and sensitivity of fluorescence analysis is of great importance in clinical diagnosis, environmental and food monitoring. Herein, based on fluorescence resonance energy transfer (FRET), a facile and effective ratiometric fluorescence sensor was constructed for the detection of Bacillus thuringiensis (Bt) special gene fragment. In this work, green quantum dots (gQDs) decorated Fe3O4 magnetic beads (MBs) with streptavidin (SA) were acted as donor, and gold nanoparticles (GN) modified red quantum dots (rQDs@SiO2) with hairpin DNA as receptor. When the target sequences exist, the hairpin DNA were unfolded and subsequently captured by MBs@SiO2@gQD-SA via biotin–SA specific interaction. By using the magnetic separation method, the hybridized composites could be easily purified for florescence tests. By this means, rQDs@SiO2@GN could enhance the fluorescence intensity of rQDs (I620) and simultaneously quench the fluorescence response of gQDs (I540) via FRET. Under optimal conditions, the ratio of fluorescence intensity at 620 nm and 540 nm (I620/I540) showed that Bt transgene fragment detection owning a good linearity from 5.0 pM to 10 nM with a detection limit of 0.10 pM (S/N = 3). The high selectivity of the probes was also demonstrated using the single-base and three-base mismatch method.

Photodynamic therapy as a non-invasive approach has obtained great research attention during the last decade. However, photodynamic therapy still suffers from low tumor selectivity and therapeutic inefficacy due to the unspecific distribution of photosensitizers in normal tissues/cells. To overcome these hurdles, functional peptides have been introduced in photodynamic therapy systems due to their advantages of functional diversity, bioactivity, high biocompatibility and biodegradability. Herein, we review various peptide-based self-assemblies or hybrid nanoparticles that have already been reported to achieve tumor tissue, cell or subcellular organelle targeted photodynamic therapy. The role of tumor microenvironments, cellular/subcellular location, and physical/chemical properties of peptide-based nanoparticles in facilitating the photodynamic therapy efficiency are discussed in-depth. The novel development of peptide-based nanoparticles described here should offer great potential to achieve better photodynamic therapy in tumors.

Aflatoxin B1 (AFB1) is one of the most abundant and carcinogenic food-contaminating mycotoxins around the world. In this study, we proposed a surface enhanced Raman scattering (SERS) sensing strategy for the determination of AFB1. An aptamer for AFB1 partially hybridized with complementary-DNA, which was released after the recognition of AFB1 and immediately hybridized with hairpin DNA on the surface of sputtering Au film. Exonuclease III hydrolyzed the double-stranded DNA, leaving short single-stranded DNA on the Au surface and releasing complementary-DNA for next ring opening and digestion. SERS tag was captured on Au surface by DNA hybridization. Agarose gel electrophoresis and dynamic light scattering showed that SERS tag was successfully prepared. The detection principle was validated by electrochemical impedance spectroscopy and SERS at each step. High sensitivity and good selectivity for AFB1 detection were observed. The results showed that there was a good linear relation when the AFB1 concentration was from 1×10-6 to 1ng/mL, and the limit of detection (LOD) was 0.4 fg/mL. This sensor was also applied for quantifying AFB1 levels in spiked peanuts samples, the recoveries was in the range of 89-121%.

Owing to the excellent molecular accessibility and self-supported architectures, three-dimensional (3D) porous nanostructures can promote the catalytic property of Pt-based catalysts. In this work, by using ammonia as the structure-director in the synthetic process, a facile method was developed to synthesize bimetallic 3D porous PtxCu100–x nanochain networks (3D p-PtxCu100–x NCNs) with tunable compositions. The 3D p-Pt46Cu54 NCNs achieve a mass activity of 8.38 A mgPt–1 for ethylene glycol oxidation reaction (EGOR) and 4.01 A mgPt–1 for glycerol oxidation reaction (GOR) in alkaline solution, which is 3.58-fold and 4.01-fold that of commercial Pt/C, respectively. The result demonstrated that the bimetallic 3D nanochain network structures facilitated the effective utilization of Pt. The ammonia mediated one-step synthetic strategy has the potential to prepare other promising 3D porous Pt-based nanomaterials in electrocatalytic applications.

It is attractive but remains challenging to develop nanomaterials-based methods to realize the colorimetric detection of ultratrace biological analytes. In this work, an HAuCl 4 -H 2 O 2 system was developed for the visual detection of intracellular hydrogen peroxide (H 2 O 2 ) based on the Au-Pt/SiO 2 sensing platform. Owing to their excellent intrinsic peroxidase-like activity, Au-Pt/SiO 2 nanospheres were introduced to catalyze the decomposition of H 2 O 2 and then directly reduce HAuCl 4 into gold nanoparticles (Au NPs) for the naked-eye detection. The produced Au NPs behaved color variations from light purple to wine red as H 2 O 2 concentration increased. Under the optimal conditions, this strategy showed excellent sensitivity for H 2 O 2 with a detection limit of 0.1 nM by naked-eye readout and 0.1 pM by UV–vis spectrometer (S/N = 3), as well as acceptable selectivity for H 2 O 2 , which could meet the demand for the detection of H 2 O 2 in biological systems. The method was further validated by the determination of H 2 O 2 in HeLa cells with low cellular cytotoxicity. Thus, this strategy would provide simple and sensitive detection of H 2 O 2 in biological systems, revealing the potential application in clinical, biological and environmental researches.

Carbon-based nanomaterials have been widely developed into innovative antimicrobial agents due to their advantages of high surface-to-volume ratio, extremely high mechanical strength, and distinct physicochemical properties. Here, the nanocomposite of graphene oxide/graphitic carbon nitride (GO/g-C3N4), a free-metal photocatalyst, was fabricated through sonication at room temperature and its antibacterial activity against Escherichia coli (E. coli) was investigated. The 100 μg/mL GO/g-C3N4 composite was found to kill 97.9% of E. coli after 120 min visible light irradiation, which was further confirmed by fluorescent-based cell membrane integrity assay. Additionally, the holes produced by photocatalysis were confirmed by electron spin resonance (ESR) spectra and trapping experiments to participate in photocatalytic sterilization as principal active species and were further verified by transmission electron microscopy (TEM) and scanning electron microscope (SEM) to lead to the distortion and rupture of cell...

Highly sensitive and selective detection of specific DNA sequences is of great importance in clinical diagnosis, environmental and food monitoring, but it still remains challenges to develop a facile method for real sample detection in aqueous solution. Here, a simple and recyclable surface enhanced Raman scattering (SERS) sensor was constructed for Bacillus thuringiensis (Bt) special gene fragment detection by Fe3O4 magnetic beads (MBs) and Au-Ag core-shell nanorods (Au@Ag NRs). A hairpin DNA with sulfhydryl and biotin was attached to Au@Ag NRs as indicator, and MBs with streptavidin (SA) were acted as the capture probe. On the basis of the biotin-SA specific interaction, target sequences were first hybridized with the hairpin DNA and exposed the biotin. Subsequently, the Au@Ag NRs were captured by the streptavidin modified MBs, which reduced the suspended NRs and led to the change of Raman intensity. Under the optimal conditions, the SERS intensity revealed a good linearity with Bt transgene fragment ranging from 0.1pM to 1nM with a detection limit of 0.14pM (S/N=3). To demonstrate the specificity of the strategy, the single-base mismatch in DNA was discussed in the SERS assay. The results showed that the sensitivity and accuracy of the proposed method was acceptable in DNA detection, revealing a great potential in special gene detection.

By using graphene oxide (GO) as the stabilizing and dispersing agent in aqueous solution at room temperature, Pd-based (PdTe, PdPtTe, and PdAuTe) nanotubes (NTs)/GO nanocomposites were readily prepared. The obtained GO-supported one-dimensional (1D) Pd-based NTs have relatively uniform morphology and good dispersity. The catalytical properties of PdAuTe NTs/reduced GO (rGO) nanocomposites with different metal ratios were systematically investigated after electrochemical reduction process. Pd47Au33Te20 nanotubes/rGO nanocomposites possess the optimal mass activity (5.31 mA ug–1Pd), which is 5.16-fold that of commercial Pd/C catalyst. The study provides a new strategy for clean synthesis of Pd-based NTs/GO nanocomposites, which are efficient catalysts for ethanol electrooxidation. It will probably inspire more appropriate utilization of graphene to design new hybrid materials with better properties applied in fuel cells or other related fields.

Self-supported one-dimensional nanocatalysts with better electrical transport and less vulnerable to dissolution and aggregation than zero-dimensional nanocrystals have aroused particular attention in mimic-enzyme catalysis. Herein, the porous Au/PtAu bimetallic heterojunction nanotube (PtAu BNT) as a remarkable catalyst was firstly introduced into the near–infrared electrochemiluminesence (NIR ECL) immunoassay for enhancing detection sensitivity of porcine reproductive and respiratory syndrome virus (PRRSV). Meanwhile, the unique and strong host-guest recognition between β-cyclodextrin and adamantine was chose as the linker to assemble the PtAu BNTs catalysts onto PRRSV antibody, which clearly surpassed the unstable electrostatic assembly between cationic surfactant and biosamples. The formed supramolecular “bridge” could extend the space to accommodate more PtAu BNTs catalysts and reduce the blocking effect. The fabricated sandwich immunosensor exhibited excellent analytical performance for PRRSV with a better linear detection range from 1:103 to 1:106 (dilution ratio) and a sensitive detection limit (10.8 pg/mL). Good stability, acceptable reproducibility and accuracy of the immunosensor suggested its potential applications in clinical diagnostics.

Rapid sampling and multicomponent detection are crucial for monitoring of pesticide residues analysis. Here, a gecko-inspired nanotentacle surface-enhanced Raman spectroscopy (G-SERS) platform is proposed for the first time for the simultaneous detection of three kinds of pesticides via a simple and intuitive “press and peeled-off” approach. The G-SERS platform obtained from seeding deposition of silver nanoparticles (Ag NPs) on 3D PDMS nanotentacle array is flexible and free-standing. Compared with other substrates, this G-SERS substrate can simultaneously provide outstanding SERS activity (enhancement factor = 1.2 × 107), superior reproducibility (RSD = 5.8%) and countless flexible nanoscale “tentacles” (∼6.7 × 108/cm2). Moreover, the high density of “tentacles” can freely approach the microarea and enable efficient target collection, which were confirmed by SEM and HPLC. By direct sampling from cucumber, apple, and grape surfaces, thiram (TMTD), methyl parathion (MPT), malachite green (MG), and their m...

Carbon dots (CDs) have been widely used for the preparation of multifunctional probes by conjugation with organic fluorescent dyes. However, the effect of organic fluorescent dyes on CDs still remains poorly understood. Herein, the effect of fluorescein isothiocyanate (FITC) on CDs was explored by spectroscopic techniques at pH5.1, 7.0 and 9.0. The fluorescent intensity of CDs was found to be quenched gradually after mixing directly with different concentrations of FITC, but the fluorescent lifetime of CDs remained unchanged. According to the results of UV-vis absorption spectra and fluorescent lifetime measurements, a pH-dependent inner filter effect (IFE) between CDs and FITC was proposed. However, the fluorescent lifetime of CDs deceased after their conjugation with FITC, implying the fluorescence resonance energy transfer (FRET) between CDs and FITC. This study has revealed two different effects of FITC on CDs with varying pH values and provided useful theoretical guidelines for further research on the interaction between other nanoparticles and fluorophores.

A facile method for the synthesis of Au-pearl/Pd-wire heterostructured nanonecklaces (APHNs) was developed for the first time, in which regular Au pearls with controllable size and interval distance were interlinked into a string by an ultrathin and ultralong Pd nanowire. The distribution density of Au nanopearls was regulated by the concentration of the reducing agent, while their size was controlled by the amount of the Au precursor. In the study of degradation of 4-nitrophenol (4-NP), the catalytic properties of several typical APHNs are proved to be inherently related to their morphology. By comparison with other nanostructures and commercial Pd/C, the APHNs show superior catalytic activities and better stability in general. The study demonstrated that novel heterostructures have superior catalytic properties in the degradation of 4-NP. Moreover, the nanostructures have the potential to be used as a high-efficiency catalyst in other catalytic reactions.

The rhizobium-legume symbiosis system is critical for nitrogen-cycle balance in agriculture. However, the potential effects of carbon nanomaterials (CNMs) on this system remain largely unknown. Herein, we studied the effects of four carbon-based materials (activated carbon (AC), single-walled carbon nanotubes (SWCNTs), multi-walled carbon nanotubes (MWCNTs) and graphene oxide (GO)) on the rhizobium-legume symbiosis system consisting of Lotus japonicus and Mesorhizobium loti MAFF303099. Under non-symbiotic conditions, the bacterial growth and root development of plants were both clearly inhibited by SWCNTs and GO, while the elongation of plant stems was enhanced by MWCNTs to a certain degree. More importantly, only MWCNTs could increase the number of nodules and enhance the activity of nitrogenase in the rhizobium-plant interaction. Further analyses showed that the average number of nodules in plants treated with 100 μg mL-1 MWCNTs was significantly increased by 39% at 14 days post inoculation (dpi) and by 41% at 28 dpi. Meanwhile, the biological nitrogen fixation of the nodules was promoted by more than 10% under 100 μg mL-1 MWCNT treatment, which enhanced the above- and below-ground fresh biomass by 14% and 25% respectively at 28 dpi. Transmission electron microscopy images further indicated that MWCNTs penetrated the cell wall, and pierced through the cell membrane to be transmitted into the cytoplasm. In addition, gene expression analysis showed that the promotion of nodulation by MWCNTs was correlated with the up-regulation of certain genes involved in this signaling pathway. In particular, the expression of NIN, a crucial gene regulating the development of nodules, was significantly elevated 2-fold by MWCNTs at an early stage of nodulation. These findings are expected to facilitate the understanding and future utilization of MWCNTs in agriculture.