Resonance Plasma Research Articles

Crystalline TiO2 shell microcapsules modified by Co3O4/GO nanocomposites for thermal energy storage and photocatalysis

Modified microcapsule is devised to achieve the integration of thermal energy storage and light energy conversion of solar energy. This composite structure integrates the nanomaterial composed of graphene oxide (GO) and Co3O4 nanoparticles, on the microencapsulated paraffin coated by crystalline TiO2 shell. Compared with TiO2@paraffin microcapsules, introducing a thermal conductivity improved element of Co3O4/GO substantially increased the thermal conductivity by 57.7% and retained specific heat capacity of 2.154 J·g−1·K−1 and latent heat above 140 J·g−1. Microcapsules exhibited full-spectrum sunlight absorption ability, and the photothermal conversion efficiency was increased by 88.9%. Microcapsules are connected to the oxygen-containing functional groups on the flat of Co3O4/GO via hydrogen bonds and shared electron pairs, constituting a highly efficient Z-scheme heterojunction. By synergistic catalysis of photothermal, synergetic effects of semiconductor, and plasma resonance, the degradation rate of MB increased by 70.75%. This sophisticated multilevel structure of microcapsule possessed outstanding thermal cycling stability, which retains high thermal conductivity and specific heat capacity for microcapsule, while the latent heat loss rate was only 1.26%. This research implies a new insight for the field of energy storage microcapsules modification and multifunctional utilization of solar energy.

Regulation of Ag/g-C3N4 Contact Type by the Shape Control

In a metal/semiconductor nanocomposite, the contact type (Ohmic or Schottky contact) is usually decided by the relative magnitude of the working function of the metal and the semiconductor. In this paper, the Ag/g-C3N4 contact type is regulated by controlling the shape of loaded Ag nanoparticles. Under light irradiation, the intensity of internal local electric field of Ag nanoparticle, generated from its surface plasma resonance absorption, will change with the shape of Ag nanoparticles, resulting in different contact types in Ag nanospheres/g-C3N4 nanocomposite and Ag nanoplates/g-C3N4 nanocomposite.

Exploring the promoting mechanisms of bovine serum albumin, lignosulfonate, and polyethylene glycol for lignocellulose saccharification from perspective of molecular interactions with cellulase

Bovine serum albumin (BSA), polyethylene glycol (PEG) and lignosulfonate (LS) have been extensively employed as synergistic agents in lignocellulose saccharification. Nevertheless, the promoting mechanisms have not been fully understood and there are a number of controversial opinions existed. All attention has been paid to the interactions between respective additive and substrate. However, rarely attention has been paid to the interactions between additives and enzymes (cellulase from Trichoderma reesei in this investigation). This interaction is actually more important since cellulase interacts with the additives before it contacts with substrate. Therein, Quartz crystal microbalance with dissipation monitoring (QCM-D), surface plasma resonance (SPR) and small angel X-ray scattering (SAXS) were incorporated to study the interaction between enzyme and additives. The results showed synergistic agents have different interaction modes with cellulase. BSA and LS can form complexes with cellulase and the formed complexes prevent them from nonproductive binding by residue lignin; what’s more, the cellulase-BSA complexes improve the hydrolytic capability of pristine enzyme whereas cellulase-LS complexes reduce. PEG prevents the unproductive binding of cellulase to the residual lignin by forming a thin layer that actually acts as a steric hindrance to the residual lignin. This investigation helps us to understand the sophisticated interactions among the components in the complicated enzymatic system, especially the interactions between enzymes and synergistic agents. It will be helpful in the design and utilization of synergistic additives in the lignocellulose biorefinery process as well.

Plasma enhanced light emission from the Si+-N+ co-implanted SOI in the violet-blue waveband

Silicon (Si) has been established for a long time as the footing stone of the whole microelectronics industry. This does not come into true in the photonics domain yet, where the limited degrees of freedom in material design and the indirect bandgap are the major constraints. Therefore, making Si as an efficient light-emitting material is an important approach for Si photonics, even for achieving the all-Si-based photoelectronic and microelectronic integration engineering. Here we reported a facile and effective method for enhancing the photoluminescence (PL) from the Si+/N+ ion co-implanted Si film by coating the polystyrene (PS)-sphere@metal complex core-shell structure upon the Si film on insulator (SOI) wafers. The PL enhanced phenomena have been demonstrated in the violet-blue waveband by the three kinds of single-layer PS sphere array capping with different metal films (namely Ag, Au, and Al), respectively. The experiments and theoretic calculation based on the finite difference time domain (FDTD) model indicate that the plasma resonance is responsible for the PL enhancement, and these core-shell structures take advantage of both metal plasma and photonic crystal in the PL enhancing process.

Flower spherical-like Bi7O9I3/AgI S-scheme heterojunction for phenol photodegradation: The synergetic effect of dual surface plasmon resonance and photothermal property

The flower spherical-like S-scheme Bi7O9I3/AgI heterostructure was successfully fabricated through hydrothermal as well as calcination reduction method. The Ag and Bi nanoparticles generated during calcination reduction process are tightly fixed on surface of Bi7O9I3 and AgI, severally, which was distinctly beneficial to the charge transfer. On account of the enhanced light absorption and surface plasma resonance of Ag and Bi, Bi-Bi7O9I3/Ag-AgI possessed conspicuous photothermal effect. The results show that Bi-Bi7O9I3/Ag-AgI possessesed the optimal photodegradation efficiency and TOC removal rate of phenol, which are 100% and 95.38% within 80 min and 120 min. The light-induced carriers could be efficaciously separated by establishing an S-scheme photocatalytic system. A possible photocatalytic degradation mechanism of the as-constructed samples was investigated by free radical capture experiment as well as EPR technique. In addition, the photocatalyst exhibited the high stability. This work will supply a new perspective with the synthesis of novel S-scheme heterostructure.

Synthesis, characterization, and applications with the manifestation of antifungal activity and seed germination properties of nickel doped zinc oxide nano platform by biochemical contrivance

In the recent era, nanotechnology, a rapidly emerging field, has been explored as the most studied field worldwide. The goal of this study is to use neem leaves extract as an effective ‘reducing agent’ and ‘stabilizing agent’ in the green synthesis of bio-medically important Zn1-XNiXO (X = 0.00, 0.04, 0.08, 0.12) nanoparticles. The molar concentrations of nickel nitrate and zinc nitrate are varied to produce nickel-doped ZnO nanoparticles. Color change is the first indicator of nanoparticle formation during this biosynthesis. The hexagonal wurtzite structure with good crystallinity is confirmed by X-ray diffraction. FTIR analysis reveals the fact that the Zn–O stretching vibration shifts with the introduction of impurities into the ZnO matrix. UV–Vis spectra show the typical surface plasma resonance around 370 nm and the hydrodynamic diameter is larger than the size calculated from the XRD value, according to DLS. The main finding of this study is that Ni0.12Zn0.88O has a strong antifungal activity against and a significant growth rate after treating wheat seeds with biologically synthesized Ni0.12Zn0.88O nanoparticles.

Insight into CeO2 decorated hierarchical tremella-like Ag/g-C3N4 boosting organic contaminants removal: Maximum redox capacity and local surface plasma resonance effects

Many optimization strategies have been applied to the construction of materials with excellent organic contaminants removal activity, whereas the interaction mechanisms of these strategies have rarely been revealed. Here, based on the analysis and evaluation of CeO2-decorated hierarchical tremella-like Ag/g-C3N4 (Ce@15-AC) materials, the mechanism of oxidation activity enhancement is studied in depth. Finite–difference time–domain (FDTD) simulations and density functional theory (DFT) calculations reveal the mechanism of local surface plasma resonance (LSPR) effects and interfacial electric fields. The synergistic effect of the Z-scheme electrons transfer direction and Ce4+/Ce3+ redox couple conversion enable Ce@15-AC to achieve the maximum redox capacity. The hierarchical structure can generate scattering and reflection of sunlight and provide a variety of channels for light transmission. Moreover, experiments and characterizations prove that Ce@15-AC material has fantastic photoelectrochemical, physical and optical properties. The removal efficiency of tetracycline (TC) by Ce@15-AC reaches 91.7% within 40 min (20 mg/L, 100 mL), and TC is almost completely degraded after 60 min. The apparent reaction rate constant (k) of Ce@15-AC is approximately 0.05974 min−1, which is 10.71 times higher than 3DT-CN (0.00558 min−1). This work provides a meritorious instance in the advanced oxidation of organic contaminants application field.

Colorimetric assay for tetracyclines based on europium ion-induced aggregation of gold nanoparticles.

Oxytetracycline-capped gold nanoparticles (OTC-Au NPs) were prepared using sodium borohydride as the reductant and OTC as the capping agent, respectively. The prepared OTC-Au NPs with a size of 6nm have a maximum surface plasma resonance (SPR) absorption located at 514nm. The OTC on the surface of Au NPs still can coordinate with Eu3+ ions. Due to the property that OTC has multivalent binding sites with Eu3+ ions, Eu3+ ions can induce the aggregation of OTC-Au NPs. Based on the Eu3+ ions-aggregated OTC-Au NPs, a simple aptamer-free colorimetric sensing method for TCs was developed. Briefly, free TCs compete with OTC on the surface of Au NPs resulting in the change of OTC-Au NPs from an aggregation state to a dispersed state. The whole process takes only 5min, and as low as 20nM OTC, 14nM tetracycline (TC), and 20nM doxycycline (DC) could be sensitively detected, respectively. The proposed method was also featured as good repeatability and specificity, and was applied to the detection of OTC in lake water with satisfactory recovery.

Gold nanomaterials for oral cancer diagnosis and therapy: Advances, challenges, and prospects.

Early diagnosis and treatment of oral cancer are vital for patient survival. Since the oral cavity accommodates the second largest and most diverse microbiome community after the gut, the diagnostic and therapeutic approaches with low invasiveness and minimal damage to surrounding tissues are keys to preventing clinical intervention-related infections. Gold nanoparticles (AuNPs) are widely used in the research of cancer diagnosis and therapy due to their excellent properties such as surface-enhanced Raman spectroscopy, surface plasma resonance, controlled synthesis, the plasticity of surface morphology, biological safety, and stability. AuNPs had been used in oral cancer detection reagents, tumor-targeted therapy, photothermal therapy, photodynamic therapy, and other combination therapies for oral cancer. AuNPs-based noninvasive diagnosis and precise treatments further reduce the clinical intervention-related infections. This review is focused on the recent advances in research and application of AuNPs for early screening, diagnostic typing, drug delivery, photothermal therapy, radiotherapy sensitivity treatment, and combination therapy of oral cancer. Distinctive reports from the literature are summarized to highlight the latest advances in the development and application of AuNPs in oral cancer diagnosis and therapy. Finally, this review points out the challenges and prospects of possible applications of AuNPs in oral cancer diagnosis and therapy.

A self-powered photoelectrochemical aptasensor based on dual-photoelectrode photofuel cell for chloramphenicol detection

Inspired by the power generation mechanism of photofuel cell (PFC), a sensitive chloramphenicol (CAP) detection method was developed through the dual-photoelectrode photoelectrochemical (PEC) aptasensor. Assisted with the localized plasma resonance effect (LSPR) of AuNPs, the three-dimensional (3D) graphite carbon nitride (g-C3N4) was acted as the photoanode to output high and stable photocurrent. The photocathode used porous metal organic framework (MOF) and Cu2O to form an N doped core-shell structure, which improved the aptasensor performance by co-participating in the photoresponse with the photoanode. The oxidation-reduction reaction together with the bias voltage of two electrodes completed a PFC system, which realized spontaneously power supply capability. In addition to the sensitivity, the selectivity, stability and repeatability of the as-fabricated device were also guaranteed, which was suitable for practical application. The novel PFC-based dual-photoelectrode PEC sensing system can be regarded as a potential method for antibiotics detection.

Wide spectrum solar energy absorption based on germanium plated ZnO nanorod arrays: Energy band regulation, Finite element simulation, Super hydrophilicity, Photothermal conversion

• Simple process and low cost : ZnO nanorods were prepared by seed layer hydrothermal growth method. Germanium was deposited on the surface of the nanorods by magnetron sputtering. In addition, Ge can easily replace Zn in ZnO lattice structure to form ternary compound zinc orthogermanate (Zn 2 GeO 4 ). • Improved band gap and absorption bandwidth: Germanium reduces the band gap of the material to 1.25 eV, in which the ternary compound Zn 2 GeO 4 also plays an important role. This makes the absorbent based on germanium plated ZnO nanorods have high absorptivity in the wavelength range (300-800 nm). • High solar absorption rate: The LSPR effect on the surface of germanium deposited ZnO nanorods was analyzed by finite difference time domain (FDTD). FDTD results show that the visible light absorption effect of the material is greater than 91.8%. Meanwhile, the average spectral absorptivity of the absorbent based on germanium plated ZnO nanorods in the wavelength range (300-800 nm) is about 93.77%. • Highlight thermal conversion and self-cleaning: Properly increasing the thickness of germanium is helpful to improve its conversion efficiency, the surface temperature of the best sample increased from room temperature (80 ° f) to 57°C (135 ° f) in 10 minutes. ZnO nanorods with special nanorod clusters combine the germanium film with the germanium particles on the surface, this makes the ZnO nanorod film gradually improve to a hydrophilic surface. Here, we propose a simple germanium plated ZnO local surface plasmon resonance (LSPR) nanostructure to achieve broadband high absorption of solar radiation visible spectrum. This enhanced absorption is mainly due to strong plasmon resonance and the improvement of material band gap. Germanium reduces the band gap of the material to 1.25 eV, in which the ternary compound Zn 2 GeO 4 also plays an important role. The LSPR effect on germanium deposited ZnO nanorods surface is analyzed by finite difference time domain (FDTD) method. FDTD results showed that the visible light absorption effect was greater than 91.8%. Meanwhile, the average spectral absorptivity of the absorber based on germanium plated ZnO nanorods in the wavelength range (300-800 nm) is about 93.77%. ZnO nanorods with special nanorod clusters combine the germanium film with the germanium particles on the surface, this makes the ZnO nanorod film gradually improve to a hydrophilic surface, so that the material has better photothermal conversion performance and stronger self-cleaning ability of water droplets. More importantly, it provides new insights into the mechanism and concept of visible spectrum solar absorber. Therefore, these characteristics and findings show that this study has broad application prospects in the fields related to solar energy collection and utilization. Here, we propose a simple germanium plated ZnO local surface plasmon resonance (LSPR) nanostructure to achieve broadband high absorption of solar radiation visible spectrum. This enhanced absorption is mainly due to strong plasma resonance and the improvement of material band gap. Germanium reduces the band gap of the material to 1.25 eV, in which the ternary compound Zn 2 GeO 4 also plays an important role. The LSPR effect on germanium deposited ZnO nanorods surface is analyzed by finite difference time domain (FDTD) method. FDTD results showed that the visible light absorption effect was greater than 91.8%. Meanwhile, the average spectral absorptivity of the absorber based on germanium plated ZnO nanorods in the wavelength range (300-800 nm) is about 93.77%. ZnO nanorods with special nanorod clusters combine the germanium film with the germanium particles on the surface, this makes the ZnO nanorod film gradually improve to a hydrophilic surface, so that the material has better photothermal conversion performance and stronger self-cleaning ability of water droplets. More importantly, it provides new insights into the mechanism and concept of visible spectrum solar absorber. Therefore, these characteristics and findings show that this study has broad application prospects in the fields related to solar energy collection and utilization.

CuO Nanozymes as Multifunctional Signal Labels for Efficiently Quenching the Photocurrent of ZnO/Au/AgSbS2 Hybrids and Initiating a Strong Fluorescent Signal in a Dual-Mode Microfluidic Sensing Platform.

A novel dual-mode microfluidic sensing platform based on CuO nanozymes as a photoelectrochemical (PEC)-fluorescent (FL) multifunctional signal label was developed for ultrasensitive neuron specific enolase (NSE) detection. Herein, ZnO/Au/AgSbS2 hybrids, possessing excellent PEC properties, were first exploited as a sensing matrix to provide a stable photocurrent. The controlled synthesis of photoactive ZnO nanoflowers (NFs) was successfully conducted using a microfluidic reactor in the scale of seconds. Furthermore, the photocurrent of ZnO NFs decorated by Au and AgSbS2 nanoparticles significantly improved, owing to the local surface plasma resonance effect of Au and matching band structure between ZnO and AgSbS2. A strategy of catalytic oxidation ascorbic acid (AA) by CuO nanozymes was proposed to quench the PEC signals and initiate FL signals. CuO nanoparticles growing on conductive carbon spheres (CuO@CSs) as secondary antibodies' labels could efficiently catalyze the oxidation of AA to achieve a PEC "signal-off" state. Then, the produced dehydroascorbic acid reacting with o-phenylenediamine opportunely generated a strong FL signal. Importantly, wide linear ranges of 0.0001-150 ng/mL for the PEC technique and 0.001-150 ng/mL for the FL method with a low detection limit of 0.028 and 0.25 pg/mL, respectively, could guarantee the sensitive detection of NSE.

DNA-mediated Au@Ag@silica nanopopcorn fluorescent probe for in vivo near-infrared imaging of probiotic Lactobacillus Plantarum

Foodborne probiotics substantially impact human health. Thus, there is an urgent need for real-time and in situ detection of targeted probiotics. In this paper, a novel nanopopcorn fluorescent probe based on DNA-mediated Au@Ag@silica was designed and shown to display plasma resonance characteristics that generated more hot spots. This led to >18-fold greater fluorescence of indocyanine green dye with strong emission in the near-infrared (NIR-I and NIR-II) regions. Moreover, the new fluorescent probe exhibited high stability and low biotoxicity, having a strong linear relationship (R2 = 0.9615) with Lactobacillus Plantarum concentration over the range of 105−109 cfu/mL; it enabled in vivo tracing of exogenous probiotics. Compared with the traditional inductively coupled mass spectrometry (ICP-MS), the results are consistent (Correlation coefficient = 0.994), but the analysis time is much reduced by 89.6%. It is remarkable that the probe enabled real-time and in situ monitoring of target probiotic behavior in a simple, robust, and effective manner.

Green Synthesis of Silver Nanoparticles Using Hypericum perforatum L. Aqueous Extract with the Evaluation of Its Antibacterial Activity against Clinical and Food Pathogens.

The rapid development of nanotechnology and its applications in medicine has provided the perfect solution against a wide range of different microbes, especially antibiotic-resistant ones. In this study, a one-step approach was used in preparing silver nanoparticles (AgNPs) by mixing silver nitrate with hot Hypericum perforatum (St. John’s wort) aqueous extract under high stirring to prevent agglomeration. The formation of silver nanoparticles was monitored by continuous measurement of the surface plasma resonance spectra (UV-VIS). The effect of St. John’s wort aqueous extract on the formation of silver nanoparticles was evaluated and fully characterized by using different physicochemical techniques. The obtained silver nanoparticles were spherical, monodisperse, face-centered cubic (fcc) crystal structures, and the size ranges between 20 to 40 nm. They were covered with a capping layer of organic compounds considered as a nano dimension protective layer that prevents agglomeration and sedimentation. AgNPs revealed antibacterial activity against both tested Gram-positive and Gram-negative bacterial strains causing the formation of 13–32 mm inhibition zones with MIC 6.25–12.5 µg/mL; Escherichia coli strains were resistant to tested AgNPs. The specific growth rate of S. aureus was significantly reduced due to tested AgNPs at concentrations ≥½ MIC. AgNPs did not affect wound migration in fibroblast cell lines compared to control. Our results highlighted the potential use of AgNPs capped with plant extracts in the pharmaceutical and food industries to control bacterial pathogens’ growth; however, further studies are required to confirm their wound healing capability and their health impact must be critically evaluated.

Surface plasma resonance biosensing of phosphorylated proteins via pH-adjusted specific binding of phosphate residues with UiO-66

The abnormal protein phosphorylation is closely related to a series of diseases including cancers, neurodegeneration, and other immune/inflammatory disorders. However, a simple, accurate, and pragmatic methodology for the direct detection of phosphorylation levels of target proteins is largely unavailable. Herein, a surface plasma resonance (SPR) biosensor was developed to detect phosphorylated protein based on significant SPR enhancement using UiO-66 and its high affinity for phosphate residues. Furthermore, the pH of the incubation buffer and the NaOH concentration in the washing solution to eliminate nonspecific adsorption of nanoparticles on the chip surface were optimized to adjust the surface charges of UiO-66. This improved the specificity and sensitivity of the proposed method. The designed biosensor could distinguish 1% phosphorylated peptides from non-phosphorylated peptides background. Moreover, the method could directly analyze the phosphorylation level of target protein in complex samples such as cell or tissue extracts without requiring a purification step in a single workflow. This simple and robust biosensor is a sensitive, accurate, and pragmatic toolbox to detect phosphorylated proteins without destroying the protein structure and can significantly facilitate phosphoproteomics and clinical diagnosis research.

Ultralow loss visible light metamaterials assembled by metaclusters

Abstract Optical metamaterials give birth to the control and regulation of light. However, because of strong energy dissipation and fabrication difficulty in meta-atoms, low-loss isotropic three dimensional negative index metamaterials (NIMs) in the visible spectrum has long been regarded as an extremely challenging. Here, we report an ultralow loss isotropic metamaterials for visible light and its inverse Doppler effect. The ball-thorn-shaped metaclusters with symmetrical structure consisting of the dielectric and its surface dispersed super-thin silver layer was proposed, the surface plasma resonance is formed by discrete silver layer with a thickness of two or three atomic layers. We invented a unique technique for preparing ultralow loss isotropic clusters and three-dimensional large block samples. The negative refractive index and the inverse Doppler effect of green and red light is measured by the prism method for the first time. The discrete super-thin silver layer produced by the photoreduction method greatly reduces the generation of loss and break through noble metal high energy losses of traditional optical frequency metamaterial, the metaclusters unfold bottleneck of the nano-assemble visible light metamaterials, opening a door for disorder assembling ultralow loss isotropic three-dimensional large block NIMs devices of arbitrary shape.

ELECTROMAGNETIC METHODS OF SEARCHING AND DEFINITION OF HYDROCARBON DEPOSITS

The article studies the characteristics of an anisotropic medium over hydrocarbons with the complex use of electromagnetic geo-exploration methods. The simulation of the components of dielectric permittivity tensors in the mode of amplitude-modulated, frequency-modulated, amplitude-frequency-modulated and radio pulse signals is carried out. The frequencies of the electron plasma and electron cyclotron resonances for the specified regimes are established. A study was made of the influence of modes of probing signals on the characteristics of an anisotropic medium above deposits and the components of the dielectric tensor. The effect of particle concentration variation on the real components of the components of the dielectric permittivity of an anisotropic medium above the UVZ is analyzed. Recommendations are given for improving the methods of electrical exploration and their application for prospecting geophysics.

A novel strategy to construct a direct Z-Scheme Bi@Bi2O2CO3/g-C3N4 heterojunction catalyst via PDA electronic bridge

A novel strategy was employed to construct Z-Scheme Bi@Bi2O2CO3/PDA/g-C3N4 (BPCN) heterojunction through polydopamine (PDA) modification of g-C3N4 followed by deposition of Bi2O2CO3 component to efficiently remove tetracycline (TC) from water, in which PDA served as the electron transfer bridge and reductant for Bi reduction. The surface plasma resonance (SPR) effect of Bi nanoparticles and conjugated π structure shared between PDA and g-C3N4 can delocalize π-π* electrons thus promote the transport of carriers synergistically. The 10% BPCN catalysts showed much higher photocatalytic activities than single Bi2O2CO3, g-C3N4, and dual PDA/g-C3N4. The phase structure, morphology features, optical absorption and photoelectrochemical properties of BPCN were investigated in depth. Furthermore, the possible TC degradation pathway has been established based on liquid chromatography-mass spectrometry (LC-MS) analysis, and the acute toxicity LD50 of rat, bioconcentration factor, developmental toxicity and mutagenicity of TC and its degraded intermediates were evaluated based on quantitative structure activity relationship (QSAR).

Nanobody-based label-free photoelectrochemical immunoassay for highly sensitive detection of SARS-CoV-2 spike protein

Until now, COVID-19 caused by SARS-CoV-2 is engulfing the worldwide and still ranging to date, continuing to threaten the public health. The main challenge facing COVID-19 epidemic is short of fast-response and high-efficiency methods to determine SARS-CoV-2 viral pathogens. Herein, a nanobody-based label-free photoelectrochemical (PEC) immunosensor has been fabricated for rapidly detecting SARS-CoV-2 spike protein. As a small-size and high-stability antibody, nanobody was directly and well immobilized with Au nanoparticles and TiO2 spheres by the interaction. Au deposited TiO2 nanomaterial possessed 8.5 times photoelectric performance in comparison with TiO2 in the presence of electron donor owing to surface plasma resonance effect of Au. Based on the steric hindrance effect, this immunoassay platform realized the linear detection from 0.015 to 15000 pg mL−1, and a limit of detection was low as 5 fg mL−1. The label-free PEC immunoassay design provides a new idea for convenient, rapid, and efficient test of SARS-CoV-2 spike protein and broadens further application of nanobody as an identification agent to specific biomarkers.

Antibodies to Cartilage Oligomeric Matrix Protein Are Pathogenic in Mice and May Be Clinically Relevant in Rheumatoid Arthritis

ObjectiveCartilage oligomeric matrix protein (COMP) is an autoantigen in rheumatoid arthritis (RA) and experimental models of arthritis. This study was undertaken to investigate the structure, function, and relevance of anti‐COMP antibodies.MethodsWe investigated the pathogenicity of monoclonal anti‐COMP antibodies in mice using passive transfer experiments, and we explored the interaction of anti‐COMP antibodies with cartilage using immunohistochemical staining. The interaction of the monoclonal antibody 15A11 in complex with its specific COMP epitope P6 was determined by x‐ray crystallography. An enzyme‐linked immunosorbent assay and a surface plasma resonance technique were used to study the modulation of calcium ion binding to 15A11. The clinical relevance and value of serum IgG specific to the COMP P6 epitope and its citrullinated variants were evaluated in a large Swedish cohort of RA patients.ResultsThe murine monoclonal anti‐COMP antibody 15A11 induced arthritis in naive mice. The crystal structure of the 15A11–P6 complex explained how the antibody could bind to COMP, which can be modulated by calcium ions. Moreover, serum IgG specific to the COMP P6 peptide and its citrullinated variants was detectable at significantly higher levels in RA patients compared to healthy controls and correlated with a higher disease activity score.ConclusionOur findings provide the structural basis for binding a pathogenic anti‐COMP antibody to cartilage. The recognized epitope can be citrullinated, and levels of antibodies to this epitope are elevated in RA patients and correlate with higher disease activity, implicating a pathogenic role of anti‐COMP antibodies in a subset of RA patients.