Oriented surface imprinted 96-well microplate-based fluorescent biosensor for glycoprotein detection by boronate affinity sandwich assay.

Glycoproteins perform vital functions in numerous biological processes and have important clinical implications. Many glycoproteins have been used as biomarkers and therapeutic targets for disease diagnosis. Due to low concentration of glycoprotein biomarkers and the presence of high-abundance interfering species in biological samples, a selective and sensitive detection method for glycoprotein is essential for real-world applications. In this study, we develop an oriented surface imprinted microplate-based fluorescent biosensor by boronate-affinity sandwich assay (BASA) for the specific, sensitive and high throughput determination of glycoproteins in complex samples. The structure of the BASA is based on sandwich formation between boronate affinity-oriented surface-imprinted microplates, target glycoproteins, and boronate affinity fluorescence probes. The imprinted microplates ensure the high specificity, high affinity and high throughput, while the fluorescence probes, consisting of boronic acid-modified CdTe QDs, provide high sensitivity. The proposed approach could exhibit a wide linear range of 1 ng/mL-105 ng/mL, with a low LOD of 0.528 ng/mL using horseradish peroxidase (HRP) as a model glycoprotein. As compared with traditional "turn off" fluorescent sensor, the developed "turn on" fluorescent sensor provided three orders of magnitude higher sensitivity at least. The fluorescent biosensor achieved average recoveries ranging from 96.8 % to 106.0 % in urine samples.

Multiplexed colorimetry collaborated with smartphone-based image analysis for simultaneous and fast visualization of dyes in both environmental and food samples.

In this work, a multiplexed colorimetric strategy was initiated for simultaneous and fast visualization of dyes using low-cost and easy-to-prepare indicator papers as sorbents. Response surface methodology (RSM) was employed to model statistically and optimize the process variables for dyes extraction and colorimetric assays. Multiplexed colorimetry was realized by virtue of synchronous color alignments from different dimensions of multiple dyes co-stained colorimetric cards under RSM-optimized conditions, and smartphone-based image analysis was subsequently performed from different modes to double-check the credibility of colorimetric assays. As concept-to-proof trials, simultaneous visualization of dyes in both beverages and simulated dye effluents was experimentally proved with results highly matched to HPLC or spiked amounts at RSM-predicted staining time as short as 50 s ∼3 min, giving LODs as low as 0.97 ± 0.22/0.18 ± 0.08 µg/mL (tartrazine/brilliant blue) for multiplexed colorimetry, which much lower than those obtained by single colorimetry. Since this is the first case to propose such a RSM-guided multiplexed colorimetric concept, it will provide a reference for engineering of other all-in-one devices which can realize synchronous visualization applications within limited experimental steps.

Clinical Microfluidic Chip Platform for the Isolation of Versatile Circulating Tumor Cells.

Circulating tumor cells (CTCs) are significant in cancer prognosis, diagnosis, and anti-cancer therapy. CTC enumeration is vital in determining patient disease since CTCs are rare and heterogeneous. CTCs are detached from the primary tumor, enter the blood circulation system, and potentially grow at distant sites, thus metastasizing the tumor. Since CTCs carry similar information to the primary tumor, CTC isolation and subsequent characterization can be critical in monitoring and diagnosing cancer. The enumeration, affinity modification, and clinical immunofluorescence staining of rare CTCs are powerful methods for CTC isolation because they provide the necessary elements with high sensitivity. Microfluidic chips offer a liquid biopsy method that is free of any pain for the patients. In this work, we present a list of protocols for clinical microfluidic chips, a versatile CTC isolating platform, that incorporate a set of functionalities and services required for CTC separation, analysis, and early diagnosis, thus facilitating biomolecular analysis and cancer treatment. The program includes rare tumor cell counting, clinical patient blood preprocessing, which includes red blood cell lysis, and the isolation and recognition of CTCs in situ on microfluidic chips. The program allows the precise enumeration of tumor cells or CTCs. Additionally, the program includes a tool that incorporates CTC isolation with versatile microfluidic chips and immunofluorescence identification in situ on the chips, followed by biomolecular analysis.

Combination of colorimetry, inner filter effect-induced fluorometry and smartphone­based digital image analysis: A versatile and reliable strategy for multi-mode visualization of food dyes.

Herein, a multi-mode visualization platform was initiated for in-situ detection of food dyes (FDs) by combining colorimetry, fluorometry and smartphone­based digital image analysis, in which water-dispersible quantum dots (QDs) were served as nanoprobes. Colorimetry was achieved by color comparison, while both fluorometry and fluorescence quantification were performed through inner filter effect (IFE)-induced fluorescence quenching, then color information (RGB & gray-scale values) of colorimetry and fluorometry was picked by a smartphone to reconstruct digitized alignments. Since IFE mechanism was concentration-dependent but did not rely on the interaction between fluorophore and quencher, the whole process of fluorescence response could be finished within 10 s, and both color gradients and fluorescence changes showed fine mappings to FDs concentrations in the range of 1.0 × 10-3∼0.035 mg/mL for brilliant blue, and 1.0 × 10-4∼0.1 mg/mL for Allura red and sunset yellow. As a proof-of-concept, the in-situ multi-mode visualization of these FDs in real beverages was experimentally proved to be highly feasible and reliable as compared with instrumental techniques like UV-vis/fluorescence spectrometry, along with HPLC. Finally, this strategy was extended to the multi-mode visualization of non-food dyes in three simulated wastewater samples with high credibility by contrast with the true additive amounts of model dyes.

Colorimetry Combined with Inner Filter Effect-Based Fluorometry: A Versatile and Robust Strategy for Multimode Visualization of Food Dyes.

Herein, a strategy combining colorimetry and inner filter effect (IFE)-based fluorometry was developed for multimode visualization of food dyes (FDs) using CdTe quantum-dots-doped fluorescent indicator papers as a sample-to-answer device. Colorimetry was straightforwardly achieved by FDs extraction through electrostatic interaction and hydrophobic effect while fluorometry was implemented by IFE-induced fluorescence quenching. RGB/gray-scale values of colorimetry and fluorometry were furtherly picked by a smartphone application and applied to reconstruct color information-based digital image analysis for both direct alignments and linear regression analysis. The apparent color and fluorescence of FDs-bound indicator papers, together with their digitized color information, showed a good mapping to FDs concentrations in the range of 0-0.5 mg/mL for Sunset Yellow, 0-0.2 mg/mL for Allura Red, and 0-0.08 mg/mL for Brilliant Blue. As a proof of concept, the dosages of these FDs in real beverages and simulated dye effluents were deduced and cross-validated by different visualization modes, and finally double-checked by instrumental techniques such as spectrometric methods, high-performance liquid chromatography (HPLC), and mass spectroscopy (MS). The above findings concluded that (i) IFE mechanism is generally applicable to build fluorometric systems and (ii) cross validation of different visualization modes can markedly improve detection accuracy, which may provide references for design and fabrication of novel "lab-on-paper" devices for visualization applications with high reliability.

Double spiral chip-embedded micro-trapezoid filters (SMT filters) for the sensitive isolation of CTCs of prostate cancer by spectral detection.

Circulating tumor cells (CTCs) are cancer cells that are released from the original tumor and circulate in the blood vessels, carrying greatly similar constituents as the original tumor. Therefore, CTCs have a significant value in cancer prognosis, early diagnosis, and anti-cancer therapy. However, their rarity and heterogeneity make the isolation of CTCs an arduous task. In the present research, we propose a double spiral chip-embedded micro-trapezoid filter (SMT filter) for the sensitive isolation of the CTCs of prostate cancer by spectral detection. SMT filters were elongated to effectively capture CTCs and this distinctive design was conducive to their isolation and enrichment. The SMT filters were verified with tumor cells and artificial patient blood with a capture efficiency as high as 94% at a flow rate of 1.5 mL h-1. As a further validation, the SMT filters were validated in isolating CTCs from 10 prostate cancers and other cancers in 4 mL blood samples. Also, the CTCs tested positive for each patient blood sample, ranging from 83-114 CTCs. Significantly, we advanced hyperspectral imaging to detect the characteristic spectrum of CTCs both captured in situ on SMT filters and enriched after isolation. The CTCs could be positively identified by hyperspectral imaging with complete integrity of the cell morphology and an improved characteristic spectrum. This represents a breakthrough in the conventional surface-enhanced Raman scattering (SERS) spectroscopy of nanoparticles. Also, the characteristic spectrum of the CTCs would be highly beneficial for distinguishing the cancer type and accurate for enumerating tumor cells with varied intensities. Furthermore, a novel integrated flower-shaped microfilter was presented with all these aforementioned merits. The success of both the SMT filters and characteristic spectral detection indicated their feasibility for further clinical analysis, the evaluation of cancer therapy, and for potential application.

Fabrication of apigenin nanoparticles using antisolvent crystallization technology: A comparison of supercritical antisolvent, ultrasonic-assisted liquid antisolvent, and high-pressure homogenization technologies.

Flavonoids have many positive pharmacological properties, such as antioxidant, antitumor, and anti-inflammatory activities. However, factors such as low water solubility and low dissolution rate limit their use. To overcome their poor solubility, carrier-free apigenin (API) microparticles and nanoparticles were prepared using three types of antisolvent precipitation technologies: supercritical antisolvent (SCF) technology, ultrasonic-assisted liquid antisolvent (UAL) technology, and high-pressure homogenization (HPH) technology. All three technologies can produce uniform tiny particles. However, the API particles obtained using these different techniques show subtle differences in terms of physical and chemical properties and biological activity. The preparation, characterization, and potential use of API microparticles and nanoparticles to improve in vitro release were studied. The resulting API particles were investigated and compared using Fourier-transform infrared spectroscopy, differential scanning calorimetry, X-ray powder diffraction, and scanning electron microscopy. We determined the optimum conditions for SCF, UAL, and HPH technologies to produce API microparticles and nanoparticles. The antioxidant and antitumor properties of the API particles were also investigated. The results demonstrated that the reduced particle size of the APIs prepared via SCF, UAL, and HPH technologies contributed to the enhanced dissolution rate, which in turn enhanced API bioactivity.

Filter paper-based colorimetric analysis: An instrument-free strategy for semiquantitative naked-eye detection of food colorants.

A filter paper-based colorimetric strategy for instrument-independent visual detection of artificial food colorants (FCs) was developed in this study. Indicator papers were prepared via the one-step polycondensation of silane coupling agents onto glass microfiber filter papers, and colorimetric cards with a fine one-to-one correspondence between their colors and FCs concentrations were straightforward obtained by the extraction of FCs with indicator papers by virtue of electrostatic interaction and hydrophobic effect. Filter papers post-modified via such a simple way were proved to be of improved binding class selectivity and colorimetric sensitivity, allowing for in-situ colorimetric assay of FCs in an unprecedently wide range of applicable pH (1.0-12.0) with high reliability and fine versatility. Finally, the semiquantitative naked-eye determination of FCs (Allura red, brilliant blue and sunset yellow) in real-world drink samples was experimentally confirmed to be feasible by comparison with the findings of UV-vis absorption spectra, HPLC and mass spectra.

Semiquantitative naked-eye detection of synthetic food colorants using highly-branched pipette tip as an all-in-one device.

The existing strategies for the determination of synthetic food colorants (FCs) in manufactured foods are highly relied on specialized instruments and skilled personnel which are limited by the high technical threshold and instrumentation cost. Herein, highly branched pipette tips (PTs) were fabricated as a robust all-in-one device for high-performance extraction and visual detection of FCs via handy aspiration and dispensing procedures of pipette controller. The density of extraction groups and inner specific surface area of PTs greatly increased after facile physical coating and subsequent layer-by-layer branching reactions, and the maximum increment in binding capacity of PTs was exceeded 300 times at 8-10 iterations of branching layers, enabling the PTs to be colored just by short-time extraction of FCs and to achieve the instrument-independent visual detection of FCs by virtue of their outstanding PT-SPE performance. As a proof-of-concept, the in-situ PT-based solid phase extraction (PT-SPE) with high recoveries (from 91.73 ± 4.76% to 99.90 ± 4.14%) and semiquantitative naked-eye detection of FCs (Allura red and brilliant blue) in real beverages were experimentally demonstrated to be highly feasible by comparison with classical techniques like spectrophotometry, HPLC, and mass spectrometry.

Dendritic Mesoporous Silica Nanospheres: Toward the Ultimate Minimum Particle Size for Ultraefficient Liquid Chromatographic Separation.

Use of smaller particle size of packing materials in liquid chromatography leads to faster separation and higher efficiency. This basic law has driven the evolution of packing materials for several generations. However, the use of nanoscale packing materials has been severely hampered by extremely high back pressure. Here, we report a new possibility of solving this issue via introducing novel nanomaterials with highly favorable structures. n-Octyl-modified monodispersed dendritic mesoporous silica nanospheres (DMSNs) with an unprecedentedly small diameter (ca. 170 nm) and appropriate pore size (5.6 nm) were controllably synthesized and demonstrated to be a practically applicable packing material offering ultrahigh efficiency. The center-radial centrosymmetric mesopore channels significantly improved the permeability of packed capillaries, enabling column packing and capillary electrochromatographic separation on regular instruments. Due to the unique morphology, very tiny particle size, and highly uniform packing, the packed column exhibited ultrahigh efficiency up to 3 500 000 plates/m. Powerful separation capability was demonstrated with glycan profiling of cancerous and normal cells, which revealed that cancerous cells exhibited characteristic N-glycans. Because DMSNs with tunable particle size and mesopores can be controllably prepared, DMSNs hold great potential to be a new record toward the ultimate generation of packing materials for ultraefficient liquid chromatographic separation.

Selective extraction of myoglobin from human serum with antibody-biomimetic magnetic nanoparticles.

Myoglobin (Mb) is an ideal biochemical marker for the diagnosis of certain diseases caused by damage to heart muscle or skeletal muscle. Nevertheless, serum myoglobin levels are usually very low while the interference components in real sample are extremely abundent. Hence, it is of great clinical significance to establish an effective method for Mb targeting. To obtain desired selectivity, targeting biomolecules like antibody and aptamer are essential to 'the state of the art'. However, such biomolecules suffer from many disadvantages, such as hard to prepare, susceptible to protease degradation, and high cost. Thus, novel alternatives that can overcome these issues are highly desirable. Herein, we pioneered a template-anchored controllable surface imprinting strategy for selective extraction of Mb from human serum via combining with facile magnetic separation of magnetic nanoparticles (MNPs). Mb-imprinted MNPs, as antibody-biomimetic materials, were prepared using amino group-modified MNPs as substrates and water-soluble self-polymerizable dopamine as imprinting monomer. The optimized imprinting time was 70 min, giving an optimal performance with high practical imprinting efficiency (up to 41%), high imprinting factor (4.2), high binding affinity (Kd=(2.05 ± 0.09) × 10-5 M), as well as excellent recognition selectivity. Moreover, compared to bare MNPs, Mb-imprinted MNPs possessed markedly better pH tolerance. Finally, the selective extraction of Mb from human serum sample by Mb-imprinted MNPs was experimentally confirmed and the recoveries of Mb in spiked serum ranged from (91.12 ± 6.81)% to (107.99 ± 7.76)%, indicating that the Mb-imprinted MNPs could be competent for the selective analysis of Mb in real bio-samples like human serum with high precision and reliability.

Immunomagnetic separation of circulating tumor cells with microfluidic chips and their clinical applications.

Circulating tumor cells (CTCs) are tumor cells detached from the original lesion and getting into the blood and lymphatic circulation systems. They potentially establish new tumors in remote areas, namely, metastasis. Isolation of CTCs and following biological molecular analysis facilitate investigating cancer and coming out treatment. Since CTCs carry important information on the primary tumor, they are vital in exploring the mechanism of cancer, metastasis, and diagnosis. However, CTCs are very difficult to separate due to their extreme heterogeneity and rarity in blood. Recently, advanced technologies, such as nanosurfaces, quantum dots, and Raman spectroscopy, have been integrated with microfluidic chips. These achievements enable the next generation isolation technologies and subsequent biological analysis of CTCs. In this review, we summarize CTCs' separation with microfluidic chips based on the principle of immunomagnetic isolation of CTCs. Fundamental insights, clinical applications, and potential future directions are discussed.

Reshaping of pipette tip: A facile and practical strategy for sorbent packing-free solid phase extraction.

Pipette tip-based solid phase extraction (PT-SPE) has been proved to be an effective and user-friendly separation technique due to its miniaturized procedure and practical convenience. However, the vast majority of existing PT-SPE devices consist of a filter-sorbents-filter sandwich structure, which may suffer the unforeseen risk of sorbents leakage caused by the looseness of filters. More importantly, many high-capacity nanosorbents with particle size smaller than pore size of filters are unavailable. Thus, sorbent packing-free and sample low-consumption PT-SPE could be a more robust strategy for separation and detection, but such a possibility has not been explored yet. Herein we report a tubing reshaping strategy for facile fabrication of sorbent packing-free PT-SPE devices. Three types of reshaped PTs, namely stretched tube-like, self-crimping and filter in-built PTs, were fabricated via simple heating and stretching operations. The reshaped PTs exhibited flexible surface chemical post-modification. The SPE process was directly performed in reshaped PTs with an obviously enhanced extraction efficiency compared to once-shaping PTs while no need of packing sorbents. Extraction of nucleosides from human urine by boronic acid-functionalized reshaped PTs was demonstrated. Our findings technically renovate the structural composition of PT-SPE devices. As PTs are inexpensive and high-plasticity, the sorbent packing-free SPE scheme presented herein could find more promising applications and provides a new perspective for design and fabrication of novel sorbent packing-free SPE devices.

Preparation of molecularly imprinted polymers specific to glycoproteins, glycans and monosaccharides via boronate affinity controllable-oriented surface imprinting.

Molecularly imprinted polymers (MIPs) are materials that are designed to be receptors for a template molecule (e.g., a protein). They are made by polymerizing the polymerizable reagents in the presence of the template; when the template is removed, the material can be used for many applications that would traditionally use antibodies. Thus, MIPs are biomimetic of antibodies and in this capacity have found wide applications, such as sensing, separation and diagnosis. However, many imprinting approaches are uncontrollable, and facile imprinting approaches widely applicable to a large variety of templates remain limited. We developed an approach called boronate affinity controllable-oriented surface imprinting, which allows for easy and efficient preparation of MIPs specific to glycoproteins, glycans and monosaccharides. This approach relies on immobilization of a template (glycoprotein, glycan or monosaccharide) on a boronic-acid-functionalized substrate through boronate affinity interaction, followed by self-polymerization of biocompatible monomer(s) to form an imprinting layer on the substrate with appropriate thickness. Imprinting in this approach is performed in a controllable manner, permitting the thickness of the imprinting layer to be fine-tuned according to the molecular size of the template by adjusting the imprinting time. This not only simplifies the imprinting procedure but also makes the approach widely applicable to a large range of sugar-containing biomolecules. MIPs prepared by this approach exhibit excellent binding properties and can be applied to complex real samples. The MIPs prepared by this protocol have been used in affinity separation, disease diagnosis and bioimaging. The entire protocol, including preparation, property characterization and performance evaluation, takes ∼3-8 d, depending on the type of substrate and template used.

Pattern Recognition of Cells via Multiplexed Imaging with Monosaccharide-Imprinted Quantum Dots.

Recognition of cancer cells is essential for many important areas such as targeted cancer therapy. Multimonosaccharide-based recognition could be a useful strategy to improve the recognition specificity, but such a possibility has not been explored yet. Herein we report pattern recognition of cells via multiplexed imaging with monosaccharide-imprinted quantum dots (QDs). Imprinted with sialic acid, fucose, and mannose as the template, respectively, the QDs exhibited good specificity toward the template monosaccharides. Multiplexed imaging of cells simultaneously stained with these monosaccharide-imprinted QDs revealed the relative expression levels of the monosaccharides on the cells. Pattern recognition constructed using the intensities of multiplexed imaging unveiled the similarities and differences of different cell lines, allowing for the recognition of not only cancer cells from normal cells but also cancer cells of different cell lines. Thus, this study paved a solid ground for the design and preparation of novel cancer-cell targeting reagents and nanoprobes.

Probing Low-Copy-Number Proteins in a Single Living Cell.

Single-cell analysis techniques are essential for understanding the microheterogeneity and functions of cells. Low-copy-number proteins play important roles in cell functioning, but their measurement in single cells remains challenging. Herein, we report an approach, called plasmonic immunosandwich assay (PISA), for probing low-copy-number proteins in single cells. This approach combined in vivo immunoaffinity extraction and plasmon-enhanced Raman scattering (PERS). Target proteins were specifically extracted from the cells by microprobes modified with monoclonal antibody or molecularly-imprinted polymer (MIP), followed by labeling with Raman-active nanotags. The PERS detection, with Raman intensity enhanced by 9 orders of magnitude, provided ultrasensitive detection at the single-molecule level. Using this approach, we found that alkaline phosphatase and survivin were expressed in distinct levels in cancer and normal cells, and that extended culture passage resulted in reduced expression of survivin. We further developed acupuncture needle-based PISA for probing low-copy-number proteins in living bodies.

Boronate Affinity Fluorescent Nanoparticles for Förster Resonance Energy Transfer Inhibition Assay of cis-Diol Biomolecules.

Förster resonance energy transfer (FRET) has been essential for many applications, in which an appropriate donor-acceptor pair is the key. Traditional dye-to-dye combinations remain the working horses but are rather nonspecifically susceptive to environmental factors (such as ionic strength, pH, oxygen, etc.). Besides, to obtain desired selectivity, functionalization of the donor or acceptor is essential but usually tedious. Herein, we present fluorescent poly(m-aminophenylboronic acid) nanoparticles (poly(mAPBA) NPs) synthesized via a simple procedure and demonstrate a FRET scheme with suppressed environmental effects for the selective sensing of cis-diol biomolecules. The NPs exhibited stable fluorescence properties, resistance to environmental factors, and a Förster distance comparable size, making them ideal donor for FRET applications. By using poly(mAPBA) NPs and adenosine 5'-monophosphate modified graphene oxide (AMP-GO) as a donor and an acceptor, respectively, an environmental effects-suppressed boronate affinity-mediated FRET system was established. The fluorescence of poly(mAPBA) NPs was quenched by AMP-GO while it was restored when a competing cis-diol compounds was present. The FRET system exhibited excellent selectivity and improved sensitivity toward cis-diol compounds. Quantitative inhibition assay of glucose in human serum was demonstrated. As many cis-diol compounds such as sugars and glycoproteins are biologically and clinically significant, the FRET scheme presented herein could find more promising applications.

Targeting and Imaging of Cancer Cells via Monosaccharide-Imprinted Fluorescent Nanoparticles.

The recognition of cancer cells is a key for cancer diagnosis and therapy, but the specificity highly relies on the use of biorecognition molecules particularly antibodies. Because biorecognition molecules suffer from some apparent disadvantages, such as hard to prepare and poor storage stability, novel alternatives that can overcome these disadvantages are highly important. Here we present monosaccharide-imprinted fluorescent nanoparticles (NPs) for targeting and imaging of cancer cells. The molecularly imprinted polymer (MIP) probe was fluorescein isothiocyanate (FITC) doped silica NPs with a shell imprinted with sialic acid, fucose or mannose as the template. The monosaccharide-imprinted NPs exhibited high specificity toward the target monosaccharides. As the template monosaccharides used are over-expressed on cancer cells, these monosaccharide-imprinted NPs allowed for specific targeting cancer cells over normal cells. Fluorescence imaging of human hepatoma carcinoma cells (HepG-2) over normal hepatic cells (L-02) and mammary cancer cells (MCF-7) over normal mammary epithelial cells (MCF-10A) by these NPs was demonstrated. As the imprinting approach employed herein is generally applicable and highly efficient, monosaccharide-imprinted NPs can be promising probes for targeting cancer cells.

Molecularly Imprinted Polymer-Based Plasmonic Immunosandwich Assay for Fast and Ultrasensitive Determination of Trace Glycoproteins in Complex Samples.

Glycoproteins play significant roles in many biological processes. Assays of glycoproteins have significant biological importance and clinical values, for which immunoassay has been the workhorse tool. However, immunoassay suffers from some disadvantages, such as poor availability of high-specificity antibodies and limited stability of biological reagents. Herein, we present an antibody-free and enzyme-free approach, called molecularly imprinted polymer (MIP)-based plasmonic immunosandwich assay (PISA), for fast and ultrasensitive detection of trace glycoproteins in complex samples. A gold-based boronate affinity MIP array was used to specifically extract the target glycoprotein from complex samples. After washing away unwanted species, the captured glycoprotein was labeled with boronate affinity silver-based Raman nanotags. Thus, sandwich-like complexes were formed on the array. Upon being shined with a laser beam, the gold-based array generated a surface plasmon wave, which significantly enhanced the surface-enhanced Raman scattering (SERS) signal of the silver-based Raman nanotags. The MIP ensured the specificity of the assay, while the plasmonic detection provided ultrahigh sensitivity. Erythropoietin (EPO), a glycoprotein hormone that controls erythropoiesis or red blood cell production, was employed as a test glycoprotein in this study. Specific detection of EPO in solution down to 2.9 × 10-14 M was achieved. Using a novel strategy to accommodate the method of standard addition to a logarithmic dose-response relationship, EPO in human urine was quantitatively determined by this approach. The analysis time required only 30 min in total. This approach holds promising application prospects in many areas, such as biochemical research, clinical diagnosis, and antidoping analysis.

Surface-enhanced Raman scattering imaging of cancer cells and tissues via sialic acid-imprinted nanotags.

Molecularly imprinted nanoparticles were prepared as surface-enhanced Raman scattering tags for the selective imaging of cancer cells and tissues against normal cells and tissues relying on the use of sialic acid-templated imprinting to recognize cancer cells, which are over-expressed with sialic acid at the surface.