Characteristic Reflection Peak Research Articles

Characteristic Reflection Peak and Its Origin of Nanostructured Material Containing Small Metal Nanoparticles: Two Case Studies

Characteristic Reflection Peak and Its Origin of Nanostructured Material Containing Small Metal Nanoparticles: Two Case Studies

Multifunctional hydrogel microsphere with reflection in near-infrared region for in vivo pH monitoring and drug release in tumor microenvironment

• Near-infrared (NIR) reflective microspheres for continuous monitoring of pH. • pH monitoring and simultaneous drug release in tumor microenvironment. • Results of continuous pH monitoring correlated to the effectiveness of drug treatment. Tumor microenvironment (TME) is a pivotal factor in tumor progression. Here we report an injectable multifunctional hydrogel microsphere with responsive photonic structure for in vivo monitoring of TME pH. The pH determination is based on measurement of the characteristic reflection peak of the hydrogel microsphere in near-infrared (NIR) region that is sensitive to pH, and decreasing pH leads to a blue shift of the peak. With deep tissue penetration ability of the NIR light, the pH of normal and tumor tissues of mice are continuously monitored in vivo using the microspheres injected subcutaneously. The biocompatibility and the cytotoxicity of the material is investigated based on MTT assays to evaluate its potential for long-term continuous in vivo monitoring of TME pH. A drug for cancer treatment is also preloaded into the hydrogel microsphere for simultaneous drug release in TME and monitoring of the treatment effectiveness of drug by the TME pH tests.

Facile Synthesis of Au Nanoparticles Supported on TiO2 Inverse Opals with Biosensor

In this paper, a three-dimensional porous structure of TiO2 inverse opals loaded the large area gold nanoparticles (AuNPs) was used as an advanced material for detection of L-cysteine and Avidin molecule concentrations. We think that functionalized gold nanoparticles combined with TiO2 inverse opals of low cost can couple out a characteristic reflection peak. After biomolecules were successively linked to the gold particles supported on TiO2 inverse opals, it is found that the peak position linearly red shifted with a change of avidin concentration. The lower limit of detection concentration can be up to 2x10−7M. This maybe provide a kind of biosensor for detecting biomolecules in the future.

Characterization of Dynamic and Nanoscale Materials and Metamaterials with Continuously Referenced Interferometry

AbstractThe development of new optical materials and metamaterials has seen a natural progression toward both nanoscale geometries and dynamic performance. The development of these materials, such as optical metasurfaces which impart discrete, spatially dependent phase shifts on incident light, often benefits from the measurement of transmitted or reflected phase. Careful measurement of phase typically proves difficult to implement, due to high measurement sensitivity to practically unavoidable environmental sources of noise and drift. To date, no characterization technique has yet emerged as a frontrunner for these applications. This challenge is addressed using a custom‐designed three‐beam Mach–Zehnder interferometer capable of continuously referenced measurement of both phase and transmittance, resulting in a 10× reduction of noise and drift and phase measurement standard deviation over 10 min of 0.56° and over 16 h of 2.8°. High measurement stability provided by this method enables samples to be easily characterized under dynamic conditions. Temperature‐dependent measurements are demonstrated with phase‐change material vanadium dioxide (VO2), and with wavelength‐dependent measurements of a dielectric Huygens metasurface supporting a characteristic resonant reflection peak. A Fourier‐based signal filtering technique is applied, reducing measurement uncertainty to 0.13° and enabling discernment of monolayer thickness variations in 2D material MoS2.

In situ synthesis of multi-functional gelatin/resorcinol/silver nanoparticles composite films

Abstract Silver nanoparticles (AgNP) were synthesized in situ by reducing AgNO3 using resorcinol and gelatin to prepare functional gelatin/resorcinol/AgNP nanocomposite films (Gel/Res/AgNP). The nanocomposite film exhibited a characteristic light absorption peak of AgNP at 420 nm and improved UV-light barrier property. X-ray diffraction (XRD) results also showed a characteristic reflection peak of crystalline AgNP around 2θ = 38° corresponding to the (111) diffraction plane of AgNP. The water vapor permeability (WVP), water contact angle (WCA), surface morphology and thermal stability of the composite films were not affected, but the tensile strength (TS) of the composite film decreased and the elongation at break (E) increased by the formation of AgNP. The Gel/Res/AgNP nanocomposite film showed a strong antioxidant property with high DPPH and ABTS free radical scavenging activity. Also, the Gel/Res/AgNP nanocomposite films exhibited strong antimicrobial activity against foodborne pathogenic bacteria, Escherichia coli and Listeria monocytogenes. The developed Gel/Res/AgNP composite films with potent antimicrobial and antioxidant activities have a high potential to be used in food packaging to increase the shelf life of packaged food.

Establishment of a Multivariate Analysis Based on Photonic Crystal Hydrogel Bead Arrays and Its Application for Detecting Platelet-specific Antibodies

ABSTRACTPhotonic crystals are nanomaterials with unique structural coloration, and they have been used in multiple analyses, gene function analyses, and nanoarray biosensors. Here, we used agarose hydrogel microcarriers with characteristic reflection peak codes to improve the biocompatibility of the material and the efficiency of detection, which may be helpful for further clinical applications. The paper has two parts: condition optimization and product application. Goat antihuman immune globulin G, human immune globulin G, and fluorescein isothiocyanate-labeled goat antihuman immune globulin G are commonly used materials in double-antibody sandwich techniques, which are used for optimization in the application of advanced composite materials. Goat antihuman immune globulin G was immobilized on the surfaces of photonic crystal hydrogel beads through chemical bonding. When the target immune globulin G was captured, the fluorescence-labeled antibody could combine with photonic crystal hydrogel beads. The reaction conditions were optimized using the gray-scale value of fluorescent intensities. Photonic crystal hydrogel beads with different reflection spectra were coated with purified platelet glycoprotein IIb/IIIa and glycoprotein Ib/IX. A total of 64 clinical samples including sera from patients with immune thrombocytopenia (n = 32) and healthy human sera (n = 32) were tested using photonic crystal hydrogel beads and monoclonal antibody immobilization of platelet antigen (MAIPA). Photonic crystal hydrogel bead array reaction conditions were established for multiple analysis, showing similar sensitivity and specificity with MAIPA in testing different platelet antibodies and shortening the analysis time. The features of these composite materials make them suitable for potential applications in clinical screening assays.

Aptamer-based hydrogel barcodes for the capture and detection of multiple types of pathogenic bacteria

Rapid and sensitive diagnosing hematological infections based on the separation and detection of pathogenic bacteria in the patient's blood is a significant challenge. To address this, we herein present a new barcodes technology that can simultaneously capture and detect multiple types of pathogenic bacteria from a complex sample. The barcodes are poly (ethylene glycol) (PEG) hydrogel inverse opal particles with characteristic reflection peak codes that remain stable during bacteria capture on their surfaces. As the spherical surface of the particles has ordered porous nanostructure, the barcodes can provide not only more surface area for probe immobilization and reaction, but also a nanopatterned platform for highly efficient bioreactions. In addition, the PEG hydrogel scaffold could decrease the non-specificity adsorption by its anti-adhesive effect, and the decorated aptamer probes in the scaffolds could increase the sensitivity, reliability, and specificity of the bacteria capture and detection. Moreover, the tagged magnetic nanoparticles in the PEG scaffold could impart the barcodes with controllable movement under magnetic fields, which can be used to significantly increase the reaction speed and simplify the processing of the bioassays. Based on the describe barcodes, it was demonstrated that the bacteria could be captured and identified even at low bacterial concentrations (100 CFU mL−1) within 2.5h, which is effectively shortened in comparison with the “gold standard” in clinic. These features make the barcodes ideal for capturing and detecting multiple bacteria from clinical samples for hematological infection diagnostics.

Assessment of Binding Affinity between Drugs and Human Serum Albumin Using Nanoporous Anodic Alumina Photonic Crystals.

In this study, we report an innovative approach aiming to assess the binding affinity between drug molecules and human serum albumin by combining nanoporous anodic alumina rugate filters (NAA-RFs) modified with human serum albumin (HSA) and reflectometric interference spectroscopy (RIfS). NAA-RFs are photonic crystal structures produced by sinusoidal pulse anodization of aluminum that present two characteristic optical parameters, the characteristic reflection peak (λPeak), and the effective optical thickness of the film (OTeff), which can be readily used as sensing parameters. A design of experiments strategy and an ANOVA analysis are used to establish the effect of the anodization parameters (i.e., anodization period and anodization offset) on the sensitivity of HSA-modified NAA-RFs toward indomethacin, a model drug. To this end, two sensing parameters are used, that is, shifts in the characteristic reflection peak (ΔλPeak) and changes in the effective optical thickness of the film (ΔOTeff). Subsequently, optimized NAA-RFs are used as sensing platforms to determine the binding affinity between a set of drugs (i.e., indomethacin, coumarin, sulfadymethoxine, warfarin, and salicylic acid) and HSA molecules. Our results verify that the combination of HSA-modified NAA-RFs with RIfS can be used as a portable, low-cost, and simple system for establishing the binding affinity between drugs and plasma proteins, which is a critical factor to develop efficient medicines for treating a broad range of diseases and medical conditions.

Carbon Inverse Opal Rods for Nonenzymatic Cholesterol Detection.

Carbon inverse opal rods made from silica photonic crystal rods are used for nonenzymatic cholesterol sensing. The characteristic reflection peak originating from the physical periodic structure works as sensing signals for quantitatively estimating cholesterol concentrations. Carbon inverse opal rods work both in cholesterol standard solutions and human serum. They are suitable for practical use in clinical diagnose.

Rapid and sensitive suspension array for multiplex detection of organophosphorus pesticides and carbamate pesticides based on silica–hydrogel hybrid microbeads

A technique for multiplex detection of organophosphorus pesticides and carbamate pesticides has been developed using a suspension array based on silica–hydrogel hybrid microbeads (SHHMs). The main advantage of SHHMs, which consist of both silica and hydrogel materials, is that they not only could be distinguished by their characteristic reflection peak originating from the stop-band of the photonic crystal but also have low non-specific adsorption of proteins. Using fluorescent immunoassay, the LODs for fenitrothion, chlorpyrifos-methyl, fenthion, carbaryl and metolcarb were measured to be 0.02ng/mL, 0.012ng/mL, 0.04ng/mL, 0.05ng/mL and 0.1ng/mL, respectively, all of which are much lower than the maximum residue limits, as reported in the European Union pesticides database. All the determination coefficients for these five pesticides were greater than 0.99, demonstrating excellent correlations. The suspension array was specific and had no significant cross-reactivity with other chemicals. The results for the detection of pesticide residues collected from agricultural samples using this method agree well with those from liquid chromatography–tandem mass spectrometry. Our results showed that this simple method is suitable for simultaneous detection of these five pesticides residues in fruits and vegetables.

Photonic Crystal Encoded Microcarriers for Biomaterial Evaluation

Photonic crystal encoded biomaterials microcarriers made from silica-hybrid photonic crystal beads are reported. The characteristic reflection peak originating from the physical periodic structure is used as the code of the microcarriers. They are stable during cell adhesion and culture on their surface. Based on this method, Different biomaterials are incorporated into different PCBs and used as encoded microcarriers for the multiplex evaluation of the interaction of cells and materials in a single culture experiment. These encoded microcarriers are ideal for multiplex bioevaluation of biomaterials or drug applications.

Simultaneous Detection of Fenitrothion and Chlorpyrifos-Methyl with a Photonic Suspension Array

A technique was developed for simultaneous detection of fenitrothion (FNT) and chlorpyrifos-methyl (CLT) using a photonic suspension array based on silica colloidal crystal beads (SCCBs). The SCCBs were encoded with the characteristic reflection peak originating from the stop-band of colloidal crystal. This approach avoids the bleaching, fading or potential interference seen when encoding by fluorescence. SCCBs with a nanopatterned surface had increased biomolecule binding capacity and improved stability. Under optimal conditions, the proposed suspension array allowed simultaneous detection of the selected pesticides in the ranges of 0.25 to 1024 ng/mL and 0.40 to 735.37 ng/mL, with the limits of detection (LODs) of 0.25 and 0.40 ng/mL, respectively. The suspension array was specific and had no significant cross-reactivity with other chemicals. The mean recoveries in tests in which samples were spiked with target standards were 82.35% to 109.90% with a standard deviation within 9.93% for CLT and 81.64% to 108.10% with a standard deviation within 8.82% for FNT. The proposed method shows a potentially powerful capability for fast quantitative analysis of pesticide residues.

Glioma markers detection and assessment based on a photonic suspension array

A new multiplex glioma marker immunoassay was developed based on a photonic suspension array. The micro-carriers of this array were silica colloidal crystal beads (SCCBs). As the code of the micro-carriers is the characteristic reflection peak originating from the stop-band of the colloid photonic crystal, they could effectively avoid photo-bleaching, the potential interference of encoding fluorescence with analyte-detection fluorescence and chemical instability. Meanwhile, the fluorescence background of the SCCBs is very low, because no dyes or materials with related fluorescence are included. The proposed suspension array was used for simultaneous multiplex detection of three glioma markers in one test tube by forming a sandwich immunocomplex on the SCCBs. The results showed that the three markers, Bcl-2 protein, cyclinD1 and p21, could be assayed in the ranges of 10–180 ng ml−1, 0.1–13.5 ng ml−1, 0.053–0.9 ng ml−1, with limits of detection of 1 ng, 0.1 ng, 0.053 ng at 3σ, respectively. The proposed array has also shown storage stability and accuracy for sample detection. This technique provides a new strategy for low cost, automated, and simultaneous multiplex immunoassay.

Multiplex tumor marker detection with new chemiluminescent immunoassay based on silica colloidal crystal beads

A new multiplex chemiluminescent immunoassay (CLIA) based on silica colloidal crystal beads (SCCBs) was developed for tumor marker detection. As the code is the characteristic reflection peak originating from the stop-band of colloid crystal, they avoid photobleaching, the potential interference of encoding fluorescence with analyte-detection fluorescence and chemical instability. Meanwhile our SCCBs suspension array improved the luminescence analysis efficiency by using chemiluminescent detection of enzyme labels. By forming a sandwich immunocomplex on SCCBs, the proposed suspension array was used for simultaneous multiplex detection of tumor markers in one test tube. The results showed that the linear range was 0.5-100ng ml(-1) and 1.0-120ng ml(-1) for carcinoembryonic antigen (CEA) and alpha-fetoprotein (AFP) with a detection limit of 0.12ng ml(-1) and 0.16ng ml(-1) at 3sigma. The proposed array showed the storage stability and the accuracy for sample detection were acceptable, and the results were in acceptable agreement with the reference electrochemiluminescence method. This technique provided an automated, simple, sensitive and low-cost approach for multianalyte immunoassay.

Multiplex detection of tumor markers with photonic suspension array

A novel photonic suspension array was developed for multiplex immunoassay. The carries of this array were silica colloidal crystal beads (SCCBs). The codes of these carriers are the characteristic reflection peak originated from their structural periodicity, and therefore they do not suffer from fading, bleaching, quenching, and chemical instability. In addition, because no dyes or materials related with fluorescence are included, the fluorescence background of SCCBs is very low. With a sandwich format, the proposed suspension array was used for simultaneous multiplex detection of tumor markers in one test tube. The results showed that the four tumor markers, α-fetoprotein (AFP), carcinoembryonic antigen (CEA), carcinoma antigen 125 (CA 125) and carcinoma antigen 19-9 (CA 19-9) could be assayed in the ranges of 1.0–500 ng mL −1, 1.0–500 ng mL −1, 1.0–500 U mL −1 and 3.0–500 U mL −1 with limits of detection of 0.68 ng mL −1, 0.95 ng mL −1, 0.99 U mL −1 and 2.30 U mL −1 at 3 σ, respectively. The proposed array showed acceptable accuracy, detection reproducibility, storage stability and the results obtained were in acceptable agreement with those from parallel single-analyte test of practical clinical sera. This technique provides a new strategy for low cost, automated, and simultaneous multiplex immunoassay.