Zhihao Li

Near-Infrared-Light Mediated Ratiometric Luminescent Sensor for Multimode Visualized Assays of Explosives

The development of a portable and easy-to-use device for the detection of explosives with high sensitivity and selectivity is in high demand for homeland security and public safety. In this study, we demonstrate miniaturized devices depending on the upconversion ratiometric luminescent probe for point-of-care (POC) assay of explosives with the naked-eye. When the PEI-coated upconversion nanoparticles (UCNPs) selectively bonded to 2,4,6-trinitrotoluene (TNT) explosives by the formation of Meisenheimer complex, the formed of UCNP-Meisenheimer complexes show turned visible multicolor upconversion luminescence (UCL) on account of TNT-modulating Förster resonance energy transfer process under near-infrared excitation. With UCL emission at 808 nm as internal standard and ratiometric UCL at 477 nm to that at 808 nm (I477/I808) as output signal, the probe can simultaneously meet the accuracy for TNT explosives quantitative analysis. In addition, this easy-to-use visual technique provides a powerful tool for convenient POC assay of rapid explosives identification.

A Targeted “Capture” and “Removal” Scavenger toward Multiple Pollutants for Water Remediation based on Molecular Recognition

For the water remediation techniques based on adsorption, the long‐standing contradictories between selectivity and multiple adsorbability, as well as between affinity and recyclability, have put it on weak defense amid more and more severe environment crisis. Here, a pollutant‐targeting hydrogel scavenger is reported for water remediation with both high selectivity and multiple adsorbability for several pollutants, and with strong affinity and good recyclability through rationally integrating the advantages of multiple functional materials. In the scavenger, aptamers fold into binding pockets to accommodate the molecular structure of pollutants to afford perfect selectivity, and Janus nanoparticles with antibacterial function as well as anisotropic surfaces to immobilize multiple aptamers allow for simultaneously handling different kinds of pollutants. The scavenger exhibits high efficiencies in removing pollutants from water and it can be easily recycled for many times without significant loss of loading capacities. Moreover, the residual concentrations of each contaminant are well below the drinking water standards. Thermodynamic behavior of the adsorption process is investigated and the rate‐controlling process is determined. Furthermore, a point of use device is constructed and it displays high efficiency in removing pollutants from environmental water. The scavenger exhibits great promise to be applied in the next generation of water purification systems.

Treatment of municipal wastewater using a contact oxidation filtration separation integrated bioreactor

A new contact oxidation filtration separation integrated bioreactor (CFBR) was used to treat municipal wastewater. The CFBR was made up of a biofilm reactor (the upper part of the CFBR) and a gravitational filtration bed (the lower part of the CFBR). Polyacrylonitrile balls (50mm diameter, 237 m(2)/m(3) specific surface, 90% porosity, and 50.2% packing rate) were filled into the biofilm reactor as biofilm attaching materials and anthracite coal (particle size 1-2mm, packing density 0.947 g/cm(3), non-uniform coefficient (K(80)=d(80)/d(10))<2.0) was placed into the gravitational filtration bed as filter media. At an organic volumetric loading rate of 2.4 kg COD/(m(3)d) and an initial filtration velocity of 5m/h in the CFBR, the average removal efficiencies of COD, ammonia nitrogen, total nitrogen and turbidity were 90.6%, 81.4%, 64.6% and 96.7% respectively, but the treatment process seemed not to be effective in phosphorus removal. The average removal efficiency of total phosphorus was 60.1%. Additionally, the power consumption of the CFBR was less than 0.15 kWh/m(3) of wastewater treated, and less than 1.5 kWh/kg BOD(5) removal.

Rational Design of Hierarchical Carbon/Mesoporous Silicon Composite Sponges as High-Performance Flexible Energy Storage Electrodes

Nanostructuring silicon (Si) and combining Si with carbon shells have been studied in recent Li-ion battery electrodes, yet it remains a grand challenge to overcome the low electrical conductivity and associated volume change of Si. Here, by first coating a mesoporous SiO2 (meso-SiO2) onto carbon nanotube (CNT) networks and then converting it into a meso-Si layer covered by carbon, we obtained a freestanding, highly porous composite sponge electrode consisting of three-dimensionally interconnected sandwiched carbon-Si-CNT skeletons. In this hierarchical structure, the macropores among the sponge connect to mesopores in the meso-Si layer so that Li+ diffusion is facilitated, whereas the underlying CNT networks serve as conductive paths for electrons transport. Meanwhile, the outer carbon coating on meso-Si could buffer the volume expansion and prevent material shedding. As a result, our sandwiched carbon-Si-CNT electrodes exhibit large specific capacity, high rate capability and long cycle life. The combination of carbon-wrapped meso-Si and CNT sponges might be a potential strategy for developing efficient electrodes in various energy storage systems.

Simultaneous Visualization and Quantitation of Multiple Steroid Hormones Based on Signal-amplified Biosensing with Duplex Molecular Recognition

The simultaneous quantitation of multiple steroid hormones in real time is of great importance in medical diagnosis. In this study, a portable hormone biosensor based on duplex molecular recognition coupled with a signal-amplified substrate was successfully developed for the simultaneous visualization and quantitation of multiple steroid hormones. Aptamer-functionalized upconversion nanoparticles (UCNPs) with different emission peaks are immobilized on the photonic crystal (PC) substrate as the nanoprobes, leading to the specific and simultaneous assay of multiple steroid hormones. Coupled with the luminescence-enhanced effect of the PC substrate, nanomolar quantification limits of multiple hormones are achieved. This well-designed biosensor is also promising in the quantification of multiple hormones in serum samples. The amplified luminescence signals can be visualized with the naked eye and captured by an unmodified phone camera. This hormone quantitation biosensor exhibits the advantages of multi-detection, visualization, high sensitivity, and selectivity for potential applications in clinical disease diagnosis.

Self-assembled DNA nanomaterials with highly programmed structures and functions

Long admired as the repository of genetic information, DNA has more recently been exploited as a powerful material for self-assembly. Taking advantage of the specificity and programmability of the Watson–Crick base-pairing principle, DNA is able to form diversiform nanostructures and nanomaterials. More importantly, the assembled DNA nanomaterials can be modulated at nanometer spatial resolution with designable structures and functions. Such nanoscale precision endows DNA nanomaterials with well-defined orientations, spacings, stereo-relationships, and even optimized interactions with biomolecules, contributing to a revolution in the development of materials sophistication. Benefiting from these structural and functional properties, DNA nanomaterials have found a wide range of applications in materials science, analytical science, and biomedicine. Here, we summarize the recent progress in the design and applications of DNA nanomaterials which possess intriguing structures and functions, with a highlight on three kinds of important DNA nanomaterials including DNA tetrahedrons, DNA hydrogels and functional DNA nanomaterials. Finally, some of the current challenges are proposed in the design and applications of DNA nanomaterials, and we also provide our understandings of the prospects of several DNA nanomaterials, aiming to motivate future multidisciplinary and interdisciplinary research.

Recent progress in background-free latent fingerprint imaging

Owing to their unique pattern and abundant chemical composition, latent fingerprints (LFPs) can serve as “ID cards” and “information banks” of donors and therefore are valuable for forensic investigation, access control, and even medical diagnosis. LFP imaging has attracted considerable attention, and a great variety of contrast agents has been developed. In LFP imaging, background signals such as background fluorescence from the underlying surface can seriously blur the LFP images and decrease imaging sensitivity; thus, great efforts have been made to eliminate background interference. Here, we stratify the recent progress in background-free LFP imaging by making use of the difference in properties between contrast agents and background compounds. For example, near-infrared (NIR) light-activatable contrast agents can efficiently remove background signals in LFP imaging because the background compounds cannot be excited by NIR light, showing that the difference in excitation properties between contrast agents and background compounds can be employed to eliminate background interference. This review is organized around background-free LFP imaging based on the difference in optical properties between contrast agents and background compounds: (i) different excitation wavelengths, (ii) different emission wavelengths, (iii) different luminescence lifetime values, (iv) different plasmonic properties, (v) different photothermal properties, and (vi) different electrochemiluminescence properties.

Peroxidase‐Mimicking Nanozyme with Enhanced Activity and High Stability Based on Metal–Support Interactions

Peroxidase-mimicking nanozymes offer unique advantages in terms of high stability and low cost over natural peroxidase for applications in bioanalysis, biomedicine, and the treatment of pollution. However, the design of high-efficiency peroxidase-mimicking nanozymes remains a great challenge. In this study, we adopted a structural-design approach through hybridization of cube-CeO2 and Pt nanoparticles to create a new peroxidase-mimicking nanozyme with high efficiency and excellent stability. Relative to pure cube-CeO2 and Pt nanoparticles, the as-hybridized Pt/cube-CeO2 nanocomposites display much improved activities because of the strong metal-support interaction. Meanwhile, the nanocomposites also maintain high catalytic activity after long-term storage and multiple recycling. Based on their excellent properties, Pt/cube-CeO2 nanocomposites were used to construct high-performance colorimetric biosensors for the sensitive detection of metabolites, including H2 O2 and glucose. Our findings highlight opportunities for the development of high-efficiency peroxidase-mimicking nanozymes with potential applications such as diagnostics, biomedicine, and the treatment of pollution.

Emerging Biomimetic Applications of DNA Nanotechnology

Re-engineering cellular components and biological processes has received great interest and promised compelling advantages in applications ranging from basic cell biology to biomedicine. With the advent of DNA nanotechnology, the programmable self-assembly ability makes DNA an appealing candidate for rational design of artificial components with different structures and functions. This Forum Article summarizes recent developments of DNA nanotechnology in mimicking the structures and functions of existing cellular components. We highlight key successes in the achievements of DNA-based biomimetic membrane proteins and discuss the assembly behavior of these artificial proteins. Then, we focus on the construction of higher-order structures by DNA nanotechnology to recreate cell-like structures. Finally, we explore the current challenges and speculate on future directions of DNA nanotechnology in biomimetics.

Background-free latent fingerprint imaging based on nanocrystals with long-lived luminescence and pH-guided recognition

Latent fingerprints (LFPs) are highly specific to individuals, and LFP imaging has played an important role in areas such as forensic investigation and law enforcement. Presently, LFP imaging still faces considerable problems, including background interference and destructive and complex operations. Herein, we have designed a background-free, nondestructive, and easy-to-perform method for LFP imaging based on pH-mediated recognition of LFPs by carboxyl group-functionalized Zn2GeO4:Mn (ZGO:Mn-COOH) persistent luminescence nanorods (PLNRs). By simply adjusting the pH of the ZGO:Mn-COOH colloid dispersion to a certain acidic range, the negatively charged ZGO:Mn-COOH readily binds to protonated fingerprint ridges via electrostatic attraction. The ZGO:Mn-COOH colloid dispersion can be stored in portable commercial spray bottles, and the LFPs have been easily detected in situ by simply dropping the colloid dispersion on the LFPs. Moreover, since the ZGO:Mn-COOH can remain luminescent after excitation ceases, background color and background fluorescence interference were efficiently removed by simply capturing the luminescent LFP images after the excitation ceased. The entire LFP imaging process can be easily conducted without any destructive or complex operations. Due to the great versatility of the developed method for LFP imaging, clear LFP images with well-resolved ridge patterns were obtained. The designed background-free, nondestructive, and easy-to-perform LFP imaging strategy has great potential for future applications, such as forensic investigations and law enforcement.