Synthesis of surface nano-molecularly imprinted polymers for sensitive baicalin detection from biological samples

Assembly of black phosphorus quantum dots-doped MOF and silver nanoclusters as a versatile enzyme-catalyzed biosensor for solution, flexible substrate and latent fingerprint visual detection of baicalin

In this work, a versatile enzyme-catalyzed biosensor was developed by using the assembled nanohybrids of black phosphorus quantum dots (BPQDs)-doped metal-organic frameworks (MOF) and silver nanoclusters (AgNCs). The nanohybrids of AgNCs/BPQDs/MOF exhibit dual-emissive fluorescence (FL) centers at 630 nm (red) and 535 nm (blue) under excitation at 440 nm. Baicalin enhances the activity of catalase and catalytic decomposition of H₂O₂. With increase of baicalin contents in the mixture containing nanohybrids, catalase and H₂O₂, the catalase-caused decomposition of H₂O₂ was accelerated and the excessive H₂O₂ was consumed. Baicalin can restrain the oxidation capability of H₂O₂. The red-FL (response signal) of AgNCs adhering to MOF increases, while blue-FL (reference signal) of BPQDs doped into MOF has negligible changes. A new ratiometric FL biosensor was designed based on nanohybrids and enzyme-catalyzed reaction. This biosensor enables the detection of baicalin in the range of 0.01-500 μg mL^-1, with a limit of detection of 3 ng mL^-1. This biosensor has high sensitivity, selectivity and stability for baicalin detection in practical samples. Especially, it performed the solution, flexible substrate and latent fingerprint visual detection of baicalin through direct observation of FL color shades with naked eyes. This work explored a facile and efficient semi-quantitative method for versatile FL visual detection, which can promote the development of advanced chemo/bio-sensors and analysis methods.

Recent Progress of Imprinted Nanomaterials in Analytical Chemistry

Molecularly imprinted polymers (MIPs) are a type of tailor-made materials that have ability to selectively recognize the target compound/s. MIPs have gained significant research interest in solid-phase extraction, catalysis, and sensor applications due to their unique properties such as low cost, robustness, and high selectivity. In addition, MIPs can be prepared as composite nanomaterials using nanoparticles, multiwalled carbon nanotubes (MWCNTs), nanorods, quantum dots (QDs), graphene, and clays. This review paper aims to demonstrate and highlight the recent progress of the applications of imprinted nanocomposite materials in analytical chemistry.

Application of nanotechnology in biosensors for enhancing pathogen detection

Rapid detection and identification of pathogenic microorganisms is fundamental to minimizing the spread of infectious disease, and informing clinicians on patient treatment strategies. This need has led to the development of enhanced biosensors that utilize state of the art nanomaterials and nanotechnology, and represent the next generation of diagnostics. A primer on nanoscale biorecognition elements such as, nucleic acids, antibodies, and their synthetic analogs (molecular imprinted polymers), will be presented first. Next the application of various nanotechnologies for biosensor transduction will be discussed, along with the inherent nanoscale phenomenon that leads to their improved performance and capabilities in biosensor systems. A future outlook on characterization and quality assurance, nanotoxicity, and nanomaterial integration into lab-on-a-chip systems will provide the closing thoughts. This article is categorized under: Diagnostic Tools > Diagnostic Nanodevices Diagnostic Tools > Biosensing.

Novel surface imprinted magnetic mesoporous silica as artificial antibodies for efficient discovery and capture of candidate nNOS–PSD-95 uncouplers for stroke treatment

Magnetic mesoporous silica imprinted materials as artificial antibodies for the discovery and capture of candidate nNOS–PSD-95 uncouplers for stroke treatment.

The Multi-Template Molecularly Imprinted Polymer Based on SBA-15 for Selective Separation and Determination of Panax notoginseng Saponins Simultaneously in Biological Samples

The feasible, reliable and selective multi-template molecularly imprinted polymers (MT-MIPs) based on SBA-15 (SBA-15@MT-MIPs) for the selective separation and determination of the trace level of ginsenoside Rb₁ (Rb₁), ginsenoside Rg₁ (Rg₁) and notoginsenoside R₁ (R₁) simultaneously from biological samples were developed. The polymers were constructed by SBA-15 as support, Rb₁, Rg₁, R₁ as multi-template, acrylamide (AM) as functional monomer and ethylene glycol dimethacrylate (EGDMA) as cross-linker. The new synthetic SBA-15@MT-MIPs were satisfactorily applied to solid-phase extraction (SPE) coupled with high performance liquid chromatography (HPLC) for the separation and determination of trace Rb₁, Rg₁ and R₁ in plasma samples. Under the optimized conditions, the limits of detection (LODs) and quantitation (LOQs) of the proposed method for Rb₁, Rg₁ and R₁ were in the range of 0.63⁻0.75 ng·mL-1 and 2.1⁻2.5 ng·mL-1, respectively. The recoveries of R₁, Rb₁ and Rg₁ were obtained between 93.4% and 104.3% with relative standard deviations (RSDs) in the range of 3.3⁻4.2%. All results show that the obtained SBA-15@MT-MIPs could be a promising prospect for the practical application in the selective separation and enrichment of trace Panax notoginseng saponins (PNS) in the biological samples.

Multifunctional gold nanoparticle layers for controllable capture and release of proteins

Protein modified functional surfaces have been applied extensively in the field of biomaterials and medicine. Regulation of the amount and activity of proteins on the material surface is always a challenge and a key research issue. A multifunctional micro/nano-composite based surface system for efficient controllable capture and release of proteins is proposed and studied in the present paper. This novel system contains (1) gold nanoparticles (AuNPs) co-modified with an enzyme and poly(methacrylic acid) (PMAA), e.g., AuNP-pyrophosphatase (PPase)-PMAA, as nanostructured protein carriers; (2) gold nanoparticle layers (GNPLs) modified with poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA), i.e., GNPL-PDMAEMA, as a micro/nano-structured support platform for surface bioactivity regulation. The capture-release of proteins and the regulation of surface bioactivity in this composite surface system were investigated under different conditions. The results showed that the proposed system is capable of protein capture and release with simple adjustment of the pH value from neutral pH to basic pH. When the pH of the system is stabilized at 7.0, the GNPL-PDMAEMA surface could adsorb plenty of AuNP-PPase-PMAA conjugates and maximum surface bioactivity occurred, but when the pH of the system is adjusted to 10.0, the GNPL-PDMAEMA surface could liberate almost all the AuNP-PPase-PMAA conjugates and thus surface bioactivity disappeared. Meanwhile, by cyclical variations between pH 7.0 and pH 10.0, this surface protein capture/release system could realize recycling and reuse of one certain protein multiple times, a series of proteins acting sequentially in accordance with pre-designed procedures, and a functional combination of multiple proteins. This recyclable multifunctional surface with the capability of protein capture/release has great potential in many applications, such as biomonitoring and biomolecule immobilization.

Preparation and selective adsorption of organic pollutants by an inorganic molecular imprinted polymer

A novel inorganic molecular imprinted polymer (MIP) was synthesized by adding Al(3+) to the Fe/SiO2 gel with Acid Orange II (AO II) as the template. The MIP was characterized by scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy and nitrogen adsorption-desorption measurement. Compared with the non-imprinted polymer (NIP), the MIP enhanced the adsorption capacity of the target pollutants AO II. The selective adsorption capacity study indicated that the MIP adsorbed more AO II than the interferent Bisphenol A (BPA), which also has the structure of a benzene ring, thus proving the selective adsorption capacity of the MIP for template molecules AO II. In addition, the adsorption of AO II over MIP belonged to the Langmuir type and pseudo-second adsorption kinetics, and Dubinin-Radushkevich model indicates that the adsorption process of AO II over MIP and NIP are both given priority to chemical adsorption. The MIP reusability in performance was demonstrated in at least six repeated cycles.