Search

Light has been present throughout the history of mankind and even the universe. It is of great significance to human life, contributing to energy, agriculture, communication, and much more. In the biomedical field, light has been developed as a switch to control medical processes with minimal invasion and high spatiotemporal selectivity. During the past three years, near-infrared (NIR) light as long-wavelength light has been applied to more than 3000 achievements in biological applications due to its deep penetration depth and low phototoxicity. Remotely controlled cancer therapy usually involves the conversion of biologically inert NIR light. Thus, various materials, especially nanomaterials that can generate reactive oxygen species (ROS), ultraviolet (UV)/visual light, or thermal energy and so on under NIR illumination achieve great potential for the research of nanomedicine. Here, we offered an overview of recent advances in NIR light-activated nanomedicine for cancer therapeutic applications. NIR-light-conversion nanotechnologies for both directly triggering nanodrugs and smart drug delivery toward tumor therapy were discussed emphatically. The challenges and future trends of the use of NIR light in biomedical applications were also provided as a conclusion. We expect that this review will spark inspiration for biologists, materials scientists, pharmacologists, and chemists to fight against diseases and boost the future clinical-translational applications of NIR technology-based precision nanomedicine.

Nanomedicines (i.e., Au@CoFeB-Rg3) were developed by conjugating multimode nanohybrids with active ingredients of natural herbs using Au@CoFeB nanoparticles as one model of multimode nanohybrids an...

Active substrates are crucial for surface-enhanced Raman scattering (SERS). Among these substrates, large uniform area arrayed nanoporous silver thin films have been developed as active substrates. Arrayed nanoporous silver thin films with unique anisotropic morphologies and nanoporous structures can be fabricated onto the nanoporous anodic aluminum oxide (AAO) of controlled pore size and interspacing by precisely tuning the sputtering parameters. These thin films preserve locally enhanced electromagnetic fields by exciting the surface plasmon resonance, which is beneficial for SERS. In this study, nanoporous silver thin films were transferred into polymethylmethacrylate (PMMA) and polydimethylsiloxane (PDMS) substrates using our recently invented template-assisted sol–gel phase inverse-imprinting process to form two different nanopore thin films. The as-formed Ag nanoporous thin films on PMMA and PDMS exhibited intensively enhanced SERS signals using Rhodamine 6G (R6G) as the model molecule. The two nanopore thin films exhibited opposite pore size-dependent SERS tendencies, which were elucidated by the different enhancement tendencies of the electric field around pores of different diameters. In particular, the Ag nanoporous thin film on PMMA exhibited an R6G detection limit of as low as 10−6 mol L−1, and the SERS enhancement factor (EF) was more than 106. The low detection limit and large EF demonstrated the high sensitivity of the as-prepared SERS substrates for label-free detection of biomolecules. Compared with conventional smooth films, this nanopore structure can facilitate future application in biomolecular sensors, which allows the detection of single molecules via an electronic readout without requirement for amplification or labels.

In this paper, Fe(1-x)Znx@Zn(1-y)FeyOz nanocrystals were successfully synthesized via a simple programmed microfluidic process (SPMP). The sizes, shapes, crystal structures and surface compositions were characterized by transmission electron microscope (TEM), energy dispersion X-ray spectroscopy (EDX), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). It was found that the Fe(1-x)Znx@Zn(1-y)FeyOz nanocrystals (NCs) were mainly composed of iron-rich FeZn alloys and surface coatings are mainly formed by the Fe-doped ZnO. These nanocrystals preserved unique Fe/Zn ratio dependent optical and magnetic properties. A visible green emission at 530 nm and a weak violet emission at 425 nm were observed in the photoluminescence (PL) spectra due to the radiative transition of electrons from antisite defect (OZn) and zinc interstitial defects to the conduction band, respectively, as compared to that in pure ZnO (∼379 nm). The PL intensities of these nanocrystals can be increased significantly with the increase of the Zn contents in nanocrystals. The Fe(1-x)Znx@Zn(1-y)FeyOz nanocrystals with a Fe/Zn atom ratio of 2.6/1 preserved the ferromagnetic property, which can be attributed to the high Fe content, varieties of defects caused by ZnFe2O4 shells and the interaction between the shell and FeZn alloy cores. With the decrease of iron content, the coercivities of nanocrystals decreased distinctly.

Carbon supported FePt and FePtSn alloy nanocrystals were synthesized via a hybrid microfluidic-batch process. Their microstructures and compositions were characterized by transmission electron microscopy, high resolution transmission electron microscope, energy dispersive X-ray spectrometer, X-ray powder diffraction and X-ray photoelectric spectroscopy. All the nanocatalysts show a homogeneous distribution of ultra-small alloy nanoparticles (∼2–3 nm) on the surface of carbon black. The electrochemical results indicate that FePtSn/C nanocatalysts have more excellent catalytic activity for methanol oxidation compared with Pt/C catalyst. Chronoamperometry measurements were performed at 0.45 V for 3600 s. At 3600 s, the mass specific activity of FePtSn/C (Sn at% = 14) can retain 103 mA mg Pt −1 , about 10 times higher than that of Pt/C catalyst (10 mA mg Pt −1 ). The CO-stripping tests indicate that FePtSn/C (Sn at% = 14) nanocatalysts preserve a high electrochemical active specific surface and a higher ability to resist poisons, thus making the FePtSn/C (Sn at% = 14) catalyst an excellent electrocatalyst for direct methanol fuel cells.

Semiconductor nanocrystals (NCs) exhibit excellent electronic and optical properties due to their shape-, size-, and defect-dependent quantum-confinement effect. Controlling the formation kinetics for tunable size, shape, and defect has become more and more important for desired optoelectronic properties but is very challenging. In our work, we extend our previous hybrid microfluidic-batch process in the size-, shape-, and crystallinity-controlled synthesis of semiconductor NCs using CdSe NCs as model materials by precisely regulating reaction temperatures from 150 to 300 °C at a flow rate of 0.6 mL/min. Highly crystalline CdSe NCs with controlled shapes (vague angular, tripodia, irregular polygon, and sphere) and sizes (from 2.57 to 4.31 nm) were successfully synthesized, exhibiting unique UV−vis absorbance and photoluminescence.

A methodology by coupling a microfluidic-batch process with in situ carbon-black mixing, successive annealing and de-alloying post-treatment was developed for engineering surface and interface microstructures of FePt/C nanocomposites. Ultra-small angular FePt nanocrystals rich in vertexes/terraces/steps and with Pt contents gradually increasing from the inner to the outer part can be synthesized at certain Fe/Pt atomic ratios (2/1 or 1.1/1), which can directly grow on carbon-black for enhanced nanocrystal–carbon interface interaction by introducing the in situ carbon-black mixing process. Composition and structure characterization suggests that FePt@(Fe1−xPtx)Oy(OH)z/C nanocomposites with FePt alloy cores and surface Pt-doping hydroxyl iron oxide shells are formed after annealing. After controlled de-alloying of Fe in annealed nanocrystals with a Fe/Pt ratio of 2/1, the finally formed nanocatalysts exhibited excellent electrochemical catalytic performance using the methanol oxidation reaction as a model, preserving an activity of 1610 mA mg−1 Pt−1 (12 times the commercial Pt/C catalysts, higher than the best result (7.9 times the commercial Pt/C catalysts) just published in Science (Science, 2016, 354, 1410–1414), enhanced durability and high tolerance to CO poisoning.

The microneedle (MN), a highly efficient and versatile device, has attracted extensive scientific and industrial interests in the past decades due to prominent properties including painless penetration, low cost, excellent therapeutic efficacy, and relative safety. The robust microneedle enabling transdermal delivery has a paramount potential to create advanced functional devices with superior nature for biomedical applications. In this review, a great effort has been made to summarize the advance of microneedles including their materials and latest fabrication method, such as three-dimensional printing (3DP). Importantly, a variety of representative biomedical applications of microneedles such as disease treatment, immunobiological administration, disease diagnosis and cosmetic field, are highlighted in detail. At last, conclusions and future perspectives for development of advanced microneedles in biomedical fields have been discussed systematically. Taken together, as an emerging tool, microneedles have showed profound promise for biomedical applications. Key words: Microneedle patches, Biomedical applications, Microfabricated device, Drug delivery, Disease treatment, Disease diagnosis, Immunobiological administration, 3D printing

Platinum nanoparticles incorporated volumetric bar-chart chip (PtNPs-V-Chip) is able to be used for point-of-care tests by providing quantitative and visualized readout without any assistance from instruments, data processing, or graphic plotting. To improve the sensitivity of PtNPs-V-Chip, hybridization chain reaction was employed in this quantitation platform for highly sensitive assays that can detect as low as 16 pM Ebola Virus DNA, 0.01ng/mL carcinoembryonic antigen (CEA), and the 10 HER2-expressing cancer cells. Based on this amplified strategy, a 100-fold decrease of detection limit was achieved for DNA by improving the number of platinum nanoparticle catalyst for the captured analyte. This quantitation platform can also distinguish single base mismatch of DNA hybridization and observe the concentration threshold of CEA. The new strategy lays the foundation for this quantitation platform to be applied in forensic analysis, biothreat detection, clinical diagnostics and drug screening.

A new methodology is developed for the fabrication of nanostructures on substrate based on anodized Al2O3(AAO) porous template transfer process. It includes (1) forming amorphous alloy, negative UV-resist resin (i.e., SU-8), or PMMA (polymethylmethacrylate) plate nanorod arrays by hot-press molding amorphous alloy, negative UV-resist resin (i.e., SU-8), or PMMA plate into the anodized Al2O3porous substrates; (2) removing AAO templates by chemical etching process after suitable posttreatment (annealing and/or irradiation) to improve the mechanical strength of the nanorod arrays; (3) reforming nanopore films by hot-embossing the nanorod arrays into a thin layer of polymer film on substrates (e.g., silica); (4) cleaning the bottom residues in pores of the films by oxygen plasmon. The results indicate that the diameters of amorphous alloy (or negative UV-resist resin or PMMA) nanorod arrays can be ranged from 32 nm to 200 nm. The diameters of the imprinted ILR-1050 photoresist nanopores are about 94.5 ± 12.2 nm and the diameters of the imprinted or SU-8 resin on glass slides nanopores are about 207 ± 26.4 nm, which inherit the diameters of AAO templates. This methodology provides a general method to fabricate nanorods arrays and/or thin nanopore films by template transfer nanoimprint process.

Core–shell Sn(1−x)Fex@FeySn(1−y)Oz nanohybrids are synthesized via a simple programmed microfluidic process. Characterization by high resolution transmission electron microscopy, energy dispersion X-ray spectroscopy and X-ray diffraction indicates that their sizes, shapes, compositions and crystal structures can be conveniently tuned by reaction temperatures. Different from the orientated growth to rod shaped Sn(1−x)Fex@FeySn(1−y)Oz nanorods (x ≪ 0.1, y < 0.5) with tin-rich crystalline cores and amorphous shells mixing with tiny Fe@FeOx nanoparticles at a low reaction temperature (e.g., 30 °C), the Sn(1−x)Fex@FeySn(1−y)Oz nanospheres (x < 0.5, 0.5 ＜ y < 1) with crystalline tin-rich FeSn alloy cores and surface oxidized tin ferrite shells can be formed at an elevated reaction temperature (e.g., 90 °C). A blue-shift was found in the photoluminescence spectrum due to the existence of Fe in Sn(1−x)Fex@FeySn(1−y)Oz nanospheres compared with those Sn@SnO2 nanohybrids. The superparamagnetic property observed in the nanospheres can be attributed to the SnFe alloy cores and amorphous tin ferrite shells. As to the portion of Fe doping of Sn@SnO2 nanorods mixed with Fe@FeOx nanoparticles formed at 30 °C, they exhibit paramagnetic properties with increased saturated magnetic fields.

Platinum nanoparticles (PtNPs) are able to efficiently catalyze H2O2 to generate oxygen gas. However, due to the lack of an efficient approach or device that is able to measure the produced oxygen gas, the catalytic reaction has never been used for diagnostic applications. Microfluidics technology provides a platform that meets these requirements. The volumetric bar chart chip (V-Chip) volumetrically measures the production of oxygen gas by PtNPs and can be integrated with ELISA technology to provide visible and quantitative readouts without assistance from expensive instrumentation or complicated data processing. Herein we show that PtNPs outperform catalase with respect to stability at high H2O2 concentrations, high temperatures, or long-term reactions, and are resistant to most catalase inhibitors. In addition, we show that the catalase-like activity of PtNPs in concert with the V-Chip can be used to sensitively and specifically detect cancer biomarkers both in serum and on the cell surface.

Molecular diagnostics is crucial for prevention, identification, and treatment of disease. Traditional technologies for molecular diagnostics using blood are limited to laboratory use because they rely on sample purification and sophisticated instruments, are labor and time intensive, expensive, and require highly trained operators. This review discusses the frontiers of point-of-care (POC) diagnostic technologies using a drop of blood obtained from a finger prick. These technologies, including emerging biotechnologies, nanotechnologies, and microfluidics, hold the potential for rapid, accurate, and inexpensive disease diagnostics.

Precisely controlling the microstructure and composition of each component in hybrid nanomaterials is critical for desired properties but very challenging. Herein, we demonstrate a new proof-of-concept method, or microtubing-based simple-programmed microfluidic processes (MT-SPMPs). MT-SPMPs preserve the ability for controlled hybridization by accurately adjusting the detailed microstructures and crystal phases of components using Sn–SnO2 nanoparticles as models, by coupling the synergistic effects of complex surfactants with the precise reaction kinetics control. Consequently, uniform Sn–SnO2 nanospheres with diameters from 2 nm to 14 nm or Sn@SnO2 nanorods with a diameter of 19 nm and length of 66 nm can be achieved. The SnO2 shell thickness can be well controlled at the Bohr exciton radius range. Particularly, the defect type and density in these nanospheres and nanorods can be tuned for unique ultraviolet emission at 347 nm or enhanced blue emission at 475 nm. Analysis on the detailed microstructure and crystal-phase dependent photoluminescences indicates that the quantum mechanical dipole-forbidden rule can be effectively conquered by the formation of Sn–SnO2 nanohybrids with controlled defects (oxygen vacancies or Sn interstitials).

Nanohybrids composed of two or more components exhibit many distinct physicochemical properties and hold great promise for applications in optics, electronics, magnetics, new energy, environment protection, and biomedical engineering. Microfluidic systems exhibit many advantages due to their unique characteristics of narrow channels, variable length, controllable number of channels and multiple integrations. Particularly their spatial-temporarily splitting of the formation stages during nanomaterials formation along the microfluidic channels favors the online control of the reaction kinetic parameters and in situ tuning of the product properties. This Review is focused on the features of the current types of microfluidic devices in the synthesis of different types of nanohybrids based on the classification of the four main kinds of materials: metal, nonmetal inorganic, polymer and composites. Their morphologies, compositions and properties can be adjusted conveniently in these synthesis systems. Synthesis advantages of varieties of microfluidic devices for specific nanohybrids of defined surfaces and interfaces are presented according to their process and microstructure features of devices as compared with conventional methods. A summary is presented, and challenges are put forward for the future development of the microfluidic synthesis of nanohybrids for advanced applications.

One-dimension ZnSe and ZnO nanostructures with controlled diameters from 10 to 80 nm and lengths from 30 nm to micrometers were grown via the vapor–liquid–solid growth process using Au nanoparticles as catalysts fabricated by anodic aluminum oxide template assisted vapor deposition. The dependence of the growth on Au nanoparticle (NP) diameters and vapor stoichiometry during growth was investigated. Statistical analysis of the dimensions of nanostructures showed that large Au NPs led to thick and long nanorods (NRs) or nanowires (NWs) within the initial growth phase, but resulted in a slow growth rate as the NRs elongate. The diameter ratio of NRs to Au NPs, or R (Dnanorod/DAu), decreases from 0.45 to 0.32 as the mean length of NRs increases from 30 nm to 230 nm. The composition changes as the NRs elongate, as identified by energy dispersive X-ray analysis, indicate that the stoichiometry of ZnSe NWs can be controlled from Zn-rich to Se-rich; however, for ZnO NRs and NWs, their stoichiometry maintains Zn-rich throughout the growth process. These results are significant for the controlled fabrication of one-dimension nanostructures since their optoelectronic properties are directly determined by their dimensions and composition stoichiometry.

Co@Au core shell nanoparticles (NPs) of different shell thicknesses were fabricated by a combination of the displacement process and the reduction–deposition process in a microfluidic reactor. Changes in the core sizes and the whole sizes of these Co@Au NPs with the shell formation were investigated. Effects of the shell thickness and the size change on the Co–Au interface pinning effects and the interparticle interaction were analyzed and correlated to their magnetic properties and surface plasmon resonance (SPR). Increasing the shell thickness causes an increase of the coercivity at 10 K due to the enhanced interfacial pining effect and decease of the coercivity at 300 K due to the reduced interparticle interaction. The increased core sizes and Co–Au interface pinning effects with the shell formation, and the higher interparticle interaction than that of well-dispersed species, result in significantly enhanced blocking temperature (Tb) for these Co@Au NPs. But the Tb's for these Co@Au NPs slightly decre...

Point-of-care (POC) testing has the potential to enable rapid, low-cost, and large-scale screening. POC detection of a multiplexed biomarker panel can facilitate the early diagnosis of non-small cell lung cancer (NSCLC) and, thus, may allow for more timely surgical intervention for life-saving treatment. Herein, we report the nanoporous glass (NPG) integrated volumetric bar-chart chip (V-Chip) for POC detection of the three NSCLC biomarkers CEA, CYFRA 21-1, and SCCA, by the naked eye. The 3D nanostructures in the NPG membrane efficiently increase the number of binding sites for antibodies and decrease the diffusion distance between antibody and antigen, enabling the low detection limit and rapid analysis time of the NPG-V-Chip. We utilized the NPG-V-Chip to test the NSCLC biomarker panel and found that the limit of detection can reach 50 pg/mL (10-fold improvement over the original V-Chip), and the total assay time can be decreased from 4 to 0.5 h. We then detected CEA in 21 serum samples from patients with common cancers, and the on-chip results showed good correlation with the clinical results. We further assayed 10 lung cancer samples using the device and confirmed the results obtained using conventional ELISA methods. In summary, the NPG-V-Chip platform has the ability of multiplex, low detection limit, low cost, lack of need for accessory equipment, and rapid analysis time, which may render the V-Chip a useful platform for quantitative POC detection in resource-limited settings and personalized diagnostics.

A microfluidic reactor process (MRP) has proved to be a flexible approach in nanoparticle synthesis. A controlled-growth process for nanoparticles (NPs) production, based on a tubular microfluidic reactor, was demonstrated using copper NPs as a model. This process includes continuous mixing of the washing reagent with the preformed NP seed solution for controlled release of the surfactant around the small NP seeds in a Y-mixer. This promotes growth of seeds in a micro-tubing with inner diameter of 127 μm. Nearly monodispersed copper NPs, with critical size 135.6 ± 11.4 nm, can be obtained by this controlled-growth process in the micro-tubing. As a control experiment, NPs grown by the bottle-batched washing process show greatly increased polydispersion, as demonstrated by a dual-peak size distribution with one peak at 6.2 ± 2.6 nm and the other at 36.4 ± 14.4 nm. The two different growth procedures also endow the Cu NPs with distinct differences in their crystallinity and optical properties.

The physicochemical properties of nanomaterials significantly depend on their three-dimensional (3D) morphologies (sizes, shapes and surface topography), the surrounding media, and their spatial arrangement. Systematically and precisely correlating these parameters with the related physicochemical properties of specific single nanoparticles (NPs) is a fundamental requirement for the discovery of their novel properties and applications, as well as for advancing the fundamental and practical knowledge required for the design and fabrication of new materials. In this article, the progress in the identification of the specific individual NP is summarized, including the in situ methods and the spatial-localization methods based on plasmonic NPs as model. Identification of single NPs based on local surface plasmon resonance observed by fluorescent inverted optical microscopy, dark-field microscopy, scanning near-field optical microscopy, atomic force microscopy, and transmission electron microscope are reviewed. Recent progress in the investigation of 3D morphology-dependent optical properties by these methods is described. Experimental and theoretical developments in single-NP identification for the purpose of understanding the physicochemical properties are discussed.

We have developed a modified nanosphere lithography (NSL) process to fabricate surface-confined Ag nanoparticles (NPs) with controlled shapes. NPs with different shapes, such as triangular, quadrilateral, pentagon or trapezoidal with rounded tips or edges, can be fabricated by this process. These Ag NPs can be dislodged into water forming NPs in an aqueous environment. The developed process results in better NP shape retaining than those obtained using the routine NSL process. The UV–vis absorption of the surface-confined Ag NPs show distinct blue shift and reduced intensity after surface modification. The NPs produced by the modified NSL and dislodged in water have significantly less density of debris as observed by transmission electron microscopy and UV–vis absorption spectrum.

We demonstrate a room temperature microfluidic reactor (MFR) process for the synthesis of worm-like and chain-like shaped metallic nanoparticles (NPs). These high aspect ratio NPs are in geometrically metastable states, which can be further transformed into ellipsoidal, spherical, or short rod-like species with enhanced crystallinity after their solutions are stirred for several hours and/or undergo sonication for more than half an hour, evidenced by their transmission electron microscope (TEM) images, selected area electron diffraction (SAED), and X-ray Diffraction (XRD). Analysis on the relative stronger shape control ability by the microfluidic process than by the batch process suggests that the attachment and merging of pre-formed nanoclusters along the flow orientation in the microchannel slits may be the main reason for the formation of non-spherical shaped NPs. The result indicates that the room temperature microfluidic process has the potential to assemble primary nanoclusters into two-dimension architectures (i.e., chain-like networks).

Hybrid multilayer films system permits a lot of realization methods of tailoring of the magnetic properties. In this work, nanoporous hybrid multilayer system Ag was fabricated from anodic aluminum oxide (AAO) by a magnetron sputtering methods of room temperature. It is demonstrated that the magnetic properties can be flexibly manipulated by the substrate, noble metal (i.e. silver), the thickness of the ferromagnetic magnetic material (CoFeB) and the indium tin oxide (ITO).

Single-walled carbon nanotubes (SWNTs) can selectively induce human telomeric i-motif DNA formation at pH 7.0. Based on this property, we design a DNA nanomachine induced by SWNTs on gold surface. The motor DNA is human telomeric G-quadruplex DNA. The reversible hybridization between the motor DNA and its complementary human telomeric i-motif DNA can be modulated by SWNTs without changing solution pH. Up to now, to our knowledge, there is no report to show that a DNA nanomachine is induced by SWNTs or a DNA nanomachine can detect i-motif formation at pH 7.0. Our work may provide a new concept for designing an SWNT-induced DNA nanomachine and for the detection of i-motif DNA structure at pH 7.0. DNA hybridization, conformational transition and i-motif formation have been characterized on surface or in solution by fluorescence confocal microscopy, circular dichroism, DNA melting and gel electrophoresis. The folding and unfolding kinetics of the DNA nanomachine on gold surface were studied by Fourier transform-surface plasmon resonance (FT-SPR). All these results indicate that SWNTs can induce the DNA nanomachine to work efficiently and reversibly. Therefore our work will provide new insights into the design and application of SWNT-induced DNA nanodevice under physiological conditions.

All messenger-RNA (mRNA) molecules in eukaryotic cells have a polyadenylic acid [poly(rA)] tail at the 3'-end and human poly(rA) polymerase (PAP) has been considered as a tumor-specific target. A ligand that is capable of recognizing and binding to the poly(rA) tail of mRNA might interfere with the full processing of mRNA by PAP and can be a potential therapeutic agent. We report here for the first time that single-walled carbon nanotubes (SWNTs) can cause single-stranded poly(rA) to self-structure and form a duplex structure, which is studied by UV melting, atomic force microscopy, circular dichroism spectroscopy, and NMR spectrometry. SWNTs have shown potential applications that range from nanodevices, gene therapy, and drug delivery to membrane separations. Our studies may provide new insights into the application of SWNTs under physiological conditions, possibly being used as probes that target specific gene sequences.

This article has been retracted at the request of the Editor-in-Chief and author. Please see Elsevier Policy on Article Withdrawal ( http://www.elsevier.com/locate/withdrawalpolicy ). Reason: The results reported in the paper were taken from a partially completed study carried out at the Old Dominion University without the explicit knowledge or approval of other co-researchers involved in the study.

Quantitative assays are of great importance for point-of-care (POC) diagnostics because they can offer accurate information on the analytes. However, current POC devices often require an accessory instrument to give quantitative readouts for protein biomarkers, especially for those at very low concentration levels. Here, we report a microfluidic platform, the digital volumetric bar-chart chip (DV-chip), for quantitative POC diagnostics with ultra-low detection limits that are readable with the naked eye. Requiring no calibration, the DV-chip presents a digital ink bar chart (representing multiple bits composed of 0 and 1) for the target biomarker based on direct competition between O2 generated by the experimental and control samples. The bar chart clearly and accurately defines target concentration, allowing identification of disease status. For the standard PtNP solutions, the detection limit of the platform is approximately 0.1 pM and the dynamic range covers four orders of magnitude from 0.1 to 1000 pM. CEA samples with concentrations of 1 ng mL(-1) and 1.5 ng mL(-1) could be differentiated by the device. We also performed the ELISA assay for B-type natriuretic peptide (BNP) in 20 plasma samples from heart failure patients and the obtained on-chip data were in agreement with the clinical results. In addition, BNP was detectable at concentrations of less than 5 pM, which is three orders of magnitude lower than the detection limit of the previously reported readerless digital methods. By the integration of gas competition, volumetric bar chart, and digital readout, the DV-chip possesses merits of portability, visible readout, and ultra-low detection limit, which should offer a powerful platform for quantitative POC diagnostics in clinical settings and personalized detection.

A continuous flow polymeric microfluidic reactor utilizing SU-8 as a photoresist on a PEEK (polyetheretherketone) substrate was fabricated by standard UV lithography. Embedded multilayer structures were fabricated between the substrate and the inlets and outlet of the microfluidic reactor that facilitated fabrication of the entire microfluidics using SU-8, resulting in improved bonding between the substrate and the pattern. A 'flexible semi-solid transfer' (FST) process, based on a reduced exposure dosage, was developed to seal the microfluidic channels. Scanning electron microscopy (SEM) images and photographs revealed no trace of blockages in channels due to the sealing process. The maximum pressure drop without any leakage was found to be 2.1 MPa. The microfluidic reactor withstood temperatures as high as 150 °C and was found to be suitable for carrying out wet chemical synthesis.

We demonstrate a simple and clean physical methodology for fabricating such nanoparticle assemblies (dense arrays and/or dendrites) related to the interfacial interaction between the constructed materials and the anodized aluminum oxide (AAO) porous templates. The interfacial interaction can be regulated by the surface tension of the constructed materials and the AAO membrane, and the AAO-template structure, such as pore size, membrane thickness and surface morphologies. Depending on the interfacial interaction between the constructed materials and the AAO templates, NP arrays with mean particle diameters from 3.8 ± 1.0 nm to 12.5 ± 2.9 nm, mean inter-edge spacings from 3.5 ± 1.4 nm to 7.9 ± 3.4 nm and areal densities from 5.6 × 10(11) NPs per cm(2) to 1.5 × 10(12) NPs per cm(2) are fabricated over large areas (currently ~2 cm × 3 cm). The fabrication process includes firstly thermal evaporation of metal layers no more than 10 nm thick on the pre-coated Si wafer by AAO templates with a thickness of less than 150 nm and mean pore sizes no more than 12 nm, and then removal of the AAO templates. The NP arrays can be stable for hours at a temperature slightly below the melting point of the constructed materials (e.g., ~800 °C for Au NPs for 4 hours) with little change in size and inter-particle separation. Using one of them (e.g., 11.8 nm Au NPs) as growth-oriented catalysts, ultra-thin (12.1 ± 2.3 nm) dense nanowires can be conveniently obtained. Furthermore, dendrite superstructures can be generated easily from eutectic alloy NPs with diameters of ~10 nm pre-formed by thermal evaporation of metal layers more than 20 nm thick on surface-patterned thick AAO templates (e.g., 500 nm). The resulting dendrites, dense arrays and other superstructures (i.e., nanorods and nanowires) formed using NP arrays as catalysts, should have broad applications in catalysis, information technology, photovoltaics and biomedical engineering.

Microfluidics have become an enabling technology for point-of-care and personalized diagnostics. Desirable capabilities of microfluidics-based diagnostic devices include simplicity, portability, low cost and the performance of multiplexed and quantitative measurements, ideally in a high-throughput format. Here we present the multiplexed volumetric bar-chart chip (V-Chip), which integrates all these capabilities in one device. A key feature of the V-Chip is that quantitative results are displayed as bar charts directly on the device—without the need for optical instruments or any data processing or plotting steps. This is achieved by directly linking oxygen production by catalase, which is proportional to the concentration of the analyte, with the displacement of ink along channels on the device. We demonstrate the rapid quantification of protein biomarkers in diverse clinical samples with the V-Chip. The development of the V-Chip thus opens up the possibility of greatly simplified point-of-care and personalized diagnostics., Diagnostic microfluidic devices often require complicated optical systems and computers to quantify results. Here, Qin and colleagues link enzymatic biomarker detection with the displacement of ink, resulting in a device that displays quantitative results as bar graphs directly on the device.

Since ancient time, noble metal has been used to make ornaments, jewelry, high-value tableware, utensils, currency coins and medicines due to its brilliant metallic luster, stability in air and water and anti-bacteria and anti-fungi properties (Jain, Huang et al. 2007) (Erhardt 2003; Daniel and Astruc 2004; Brayner 2008; Maneerung, Tokura et al. 2008). In fact, noble metal is also valuable due to its unique physicochemical properties, the highest electrical and thermal conductivity, the lowest contact resistance, and the highest optical reflectivity (particularly in ultra-violet region) of all metals(Edwards and Petersen 1936 ; Hammond 2000). Its d-electron configuration endows them with active chemical properties, for example, 3 variable oxidation states for silver, the most common of which is the +1 state, as in AgNO3, the +2 state as in silver(II) fluoride AgF2, and the +3 state as in compounds such as potassium tetrafluoroargentate K[AgF4], and suitability as catalysts by losing one or two more 4d electrons (Dhar, Cao et al. 2007). Silver and gold have the stable face-centered cubic (fcc) crystal structures but readily absorbs free neutrons due to its massive nucleus, which make them good absorbers for nucleus raidation. These unique features have enabled them to be applied to diverse applications such as those mentioned above, medical and dental applications, photography, electronics, nuclear reactors, catalysts, clothing and foods (http://en.wikipedia.org/wiki/Silver). The intrinsic features of noble metal also endow their nanoscale species with attractive physicochemical properties due to the size and shape effects, including unique optical properties (e.g. Localized Surface Plasmon Resonance: LSPR; Surface Enhanced Raman Scattering: SERS), catalytic/electric properties and bio-functions (Percival, Bowler et al. 2005; Jain, Huang et al. 2007; Schwartzberg and Zhang 2008; Zhou, Qian et al. 2008; VoDinh, Wang et al. 2009). Although ancient people used some features of Ag or Au nanocolloids (e.g. optical property) in fabrication of ceramic glazes for lustrous or iridescent effect in ancient Persia, they did not realize that these effects were due to nanoscale effects from size, shape and surface morphology dependent physicochemical properties of silver materials (Erhardt 2003; Brayner 2008). As materials science has progressed down to nanoscale, the unique properties of nanoscaled noble metal materials are only now being recognized and realized intentionally. These properties have shown vast applications in

In recent years, colorimetric biosensing has attracted much attention because of its low cost, simplicity, and practicality. Since color changes can be read out by the naked eye, colorimetric biosensing does not require expensive or sophisticated instrumentation and may be applied to field analysis and point-of-care diagnosis. For transformation of the detection events into color changes, a number of smart materials have been developed, including gold nanoparticles, magnetic nanoparticles, cerium oxide nanoparticles, carbon nanotubes, graphene oxide, and conjugated polymers. Here, we focus on recent developments in colorimetric biosensing using these smart materials. Along with introducing the mechanisms of color changes based on different smart materials, we concentrate on the design of biosensing assays and their potential applications in biomedical diagnosis and environmental monitoring.

Here we combine click chemistry and carbon nanotube peroxidase-like catalytic colour reaction together to develop a turn-on, highly sensitive and selective copper sensor.

Single-walled carbon nanotubes (SWNTs) have been considered to be leading candidates for nanodevice applications and novel drug delivery. Intriguingly, recent studies have shown that SWNTs have catalytic activity even in the absence of catalytic factors. Since hydrogen peroxide is an important oxidizing agent in biological systems, the catalytic reaction of SWNTs with H2O2 has received much attention. The SWNT catalytic mechanism is much debated, but it has been suggested that it is related to trace amounts of metal catalyst in SWNTs. H2O2 is a major reactive oxygen species in living organisms, and its overproduction is implicated in the development of numerous inflammatory diseases, such as atherosclerosis, chronic obstructive pulmonary disease, and hepatitis. Furthermore, as a product of many enzyme-catalyzed reactions, H2O2 can act as an indicator to monitor the quantity of biologically important molecules, such as glucose. Therefore, studying the catalytic reaction of SWNTs with H2O2 might offer a promising application for disease diagnosis and for the design of SWNT-based sensors. In this work, we report that SWNTs possess intrinsic peroxidase-like activity. That the catalytic activity does not depend on trace amounts of metal catalyst in the SWNTs is evidenced by energy-dispersive X-ray (EDX) analysis. In the presence of H2O2, SWNTs catalyze the reaction of the peroxidase substrate 3,3,5,5-tetramethylbenzidine (TMB) thereby producing a color change (Scheme 1). Our results indicate that the catalytic efficiency of SWNTs is strongly dependent on pH, temperature, and H2O2 concentration, similar to horseradish peroxidase (HRP). More importantly, we compared the catalytic efficiency of SWNTs containing different amounts of cobalt residues. The results clearly show that the observed “catalytic” effect of SWNTs can be attributed to their intrinsic properties rather than metal residues. Peroxidase activity has a great potential for practical application and has been used in the bioremediation of waste water or as diagnostic kits. As peroxidase mimics, SWNTs were used here for label-free colorimetric detection of disease-associated single-nucleotide polymorphism (SNP) with a direct detection limit of 1 nm based on the color reaction of TMB. It is well known that SNP detection is very important, and different kinds of detection methods have been reported; however, to our knowledge, this is the first demonstration of applying intrinsic SWNT peroxidase-like activity and color change for this purpose. This work will provide new insights into the utilization of SWNT peroxidase-like activity. To increase SWNT solubility in aqueous solution, we treated SWNTs with a mixture of concentrated sulfuric and nitric acids, as described previously. Figure S1 in the Supporting Information shows the mixed solution of H2O2 and TMB in the presence or absence of SWNTs. In the absence of SWNTs, the color of the solution does not change in 12 h; however, in the presence of SWNTs, the color changes from black to blue immediately. This result suggests that SWNTs can catalyze the reaction of TMB in the presence of [a] Y. Song, X. Wang, C. Zhao, K. Qu, Dr. J. Ren, Prof. X. Qu Laboratory of Chemical Biology Division of Biological Inorganic Chemistry State Key Laboratory of Rare Earth Resource Utilization Graduate School of the Chinese Academy of Sciences Changchun Institute of Applied Chemistry Chinese Academy of Sciences Changchun, Jilin 130022 (China) Fax: (+86)431-85262656 E-mail : xqu@ciac.jl.cn Supporting information for this article is available on the WWW under http://dx.doi.org/10.1002/chem.20090902643. Scheme 1. Schematic illustration of SWNTs catalyzing the reaction of peroxidase substrate TMB in the presence of H2O2 to give the blue product oxidized TMB (oxTMB).

An in siturapid cooling and passivating microfluidic process has been developed for the synthesis of nearly monodispersed cobalt samarium nanoparticles (NPs) with tunable crystal structures and surface properties. This process involves promoting the nucleation and growth of NPs at an elevated temperature and rapidly quenching the NP colloids in a solution containing a passivating reagent at a reduced temperature. We have shown that Cobalt samarium NPs having amorphous crystal structures and a thin passivating layer can be synthesized with uniform nonspherical shapes and size of about 4.8 nm. The amorphous CoSm NPs in our study have blocking temperature near 40 K and average coercivity of 225 Oe at 10 K. The NPs also exhibit high anisotropic magnetic properties with a wasp-waist hysteresis loop and a bias shift of coercivity due to the shape anisotropy and the exchange coupling between the core and the thin oxidized surface layer.

An overview of the current information and analyses on the microfluidic synthesis of different types of nanomaterial, including metallic and silica nanoparticles and quantum dots, is presented. Control of particle size, size distribution, and crystal structure of nanomaterials are examined in terms of the special features of microfluidic reactors.

We report here a folic acid conjugated graphene-hemin composite for selective, quantitative and fast colorimetric detection of cancer cells based on the peroxidase-like activity.

We report here a novel AMP biosensor based on the aptamer-induced disassembly of fluorescent and magnetic nano-silica sandwich complexes with a direct detection limit of 0.1 microM.