Colorimetric-photothermal-magnetic three-in-one lateral flow immunoassay for two formats of biogenic amines sensitive and reliable quantification.

Rapid, simple, sensitive and reliable approaches for biogenic amines quantification in various food samples are essential to food safety. Lateral flow immunoassay (LFIA) has been wildly utilized in point-of-care testing (POCT) owing to its advantage of flexibility and feasibility. Here, we reported a FeO@Au nanoparticles (NPs) (FeO@AuNPs) based multimodal readout LFIA for rapid putrescine (Put) and histamine (His) quantification with a LOD down to 10 and 10 ng/mL in naked eye mode, 2.

Enhancing the Sensitivity of Surface Plasmon Resonance Measurements Utilizing Polymer Film/Au Assemblies.

Surface plasmon resonance (SPR) is used to infer information about a sample that is in contact with an Au-coated glass slide coupled to the SPR prism. Shifts in the angle of the "SPR minimum reflection" can be related to changes in the refractive index (and/or thickness) of the sample that is in contact with the Au film, which can then be used to determine the concentration of an analyte in that sample. Here, we show that by depositing a layer of poly(-isopropylacrylamide--acrylic acid) [p(NIPAm--AAc)] microgel on the SPR's Au film, with a subsequent layer of Au deposited on top of the microgels, the sensitivity of SPR to changes in solution properties can be enhanced.

Stimuli-responsive microgels for controlled deposition of gold nanoparticles on surfaces.

A variety of gold nanoparticle (AuNP) core/poly(-isopropylacrylamide) (pNIPAm) shell microgels (Au@pNIPAm) were generated using seed-mediated polymerization. The shell thickness and AuNP core diameter were easily tunable at the time of synthesis. The resultant Au@pNIPAm microgels were characterized photon-correlation spectroscopy, transmission electron microscopy and ultraviolet-visible spectroscopy.

Graphene Quantum Dots for Optical Bioimaging.

Graphene quantum dots (GQDs) have shown great potential in bioimaging applications due to their excellent biocompatibility, low cytotoxicity, feasibility for surface functionalization, physiological stability, and tunable fluorescence properties. This Review first introduces the intriguing optical properties of GQDs that are suitable for biological imaging, and is followed by the GQDs' synthetic strategies. The emergent and latest development methods for tuning GQDs' optical properties are further described in detail.

Enzyme-assisted polymer film degradation-enabled biomolecule sensing with poly (N-isopropylacrylamide)-based optical devices.

A biosensor for mouse Immunoglobulin G (IgG) was generated from responsive polymer-based interference filters (etalons). To accomplish this, an excess amount of alkaline phosphatase-modified goat anti-mouse IgG (AP-GAM, F(ab') fragment specific to mouse IgG) was added to mouse IgG, and allowed to react for some time. After a given reaction time, the bound AP-GAM could be isolated from the unbound, excess AP-GAM by addition of goat anti-mouse IgG (Fc fragment specific)-modified magnetic microspheres (GAM-M) that bind the mouse IgG bound to AP-GAM.

Controlled release kinetics from a surface modified microgel-based reservoir device.

A device constructed by sandwiching a thin film of poly(N-isopropylacrylamide)-co-acrylic acid (pNIPAm-co-AAc) microgels between two thin layers of Au (all on a glass support) was used as a novel platform for controlled release of small molecules (drugs). In this submission, the model drug tris (4-(dimenthylamino)phenyl)methylium chloride (Crystal Violet, CV) was loaded into the microgel layer of the device by electrostatic interaction of its positive charge with the negative charges on the deprotonated AAc groups on the microgels at pH > 6.5.

Polymer brush-based optical device with multiple responsivities.

Poly (N-isopropylacrylamide)-co-(acrylic acid) (pNIPAm-co-AAc) polymer brushes were grown from Au-coated glass substrates via surface initiated atom transfer radical polymerization (SI-ATRP). Subsequently, another thin Au layer was deposited on top of the brush to yield a sandwich structure, with the brush confined between the two Au layers. This structure was shown to exhibit excellent optical properties and shows a response to multiple external stimuli, such as pH, temperature and humidity.