The physicochemical properties of nanostructured substrates significantly impact laser desorption/ionization mass spectrometry (LDI‐MS) performance. Fundamental understanding of the substrate ...properties can provide insights into the design and development of an efficient LDI matrix. Herein, a hybrid matrix of nanoporous Au‐modified TiO2 nanowires (npAu‐TNW) is developed to achieve enhanced LDI‐MS performance. Its origin is investigated based on hybrid matrix properties including photo–thermal conversion and electronic band structure. Notably, further improvement is obtained in the npAu‐TNW than in the pristine TNW and non‐porous Au nanoisland‐modified TNW (Au‐TNW) hybrid, which is attributed to the laser‐induced surface restructuring/melting phenomenon. Noticeable surface restructuring/melting occurs in the npAu by laser exposure through efficient photo–thermal conversion of the highly porous npAu. At this instant of npAu structural changes, internal energy transfer from the npAu to the adsorbed analyte is promoted, which facilitates desorption. Moreover, strain is developed in situ in the TNW adjacent to the restructuring npAu, which distorts the TNW lattice. The strain development reduces recombination rates of charge carriers by introducing shallow trap levels in the bandgap, which enhances the ionization process. Ultimately, the high LDI‐MS performance based on the npAu‐TNW hybrid matrix is demonstrated by analyzing neurotransmitter.
A hybrid matrix of nanoporous Au‐modified TiO2 nanowires (npAu‐TNW) is developed to achieve enhanced laser desorption/ionization performance. Its origin is investigated based on hybrid properties including photo–thermal conversion and electronic band structure. Surface restructuring/melting occurs noticeably in the npAu by laser exposure, which facilitates desorption through internal energy transfer and enhances ionization by introducing trap sites in the bandgap.
Rapid spread of infectious diseases is a global threat and has an adverse impact on human health, livelihood, and economic stability, as manifested in the ongoing coronavirus disease 2019 (COVID‐19) ...pandemic. Even though people wear a face mask as protective equipment, direct disinfection of the pathogens is barely feasible, which thereby urges the development of biocidal agents. Meanwhile, repetitive respiration generates temperature variation wherein the heat is regrettably wasted. Herein, a biocidal ZnO nanorod‐modified paper (ZNR‐paper) composite that is 1) integrated on a face mask, 2) harvests waste breathing‐driven thermal energy, 3) facilitates the pyrocatalytic production of reactive oxygen species (ROS), and ultimately 4) exhibits antibacterial and antiviral performance is proposed. Furthermore, in situ generated compressive/tensile strain of the composite by being attached to a curved mask is investigated for high pyroelectricity. The anisotropic ZNR distortion in the bent composite is verified with changes in ZnO bond lengths and OZnO bond angles in a ZnO4 tetrahedron, resulting in an increased polarization state and possibly contributing to the following pyroelectricity. The enhanced pyroelectric behavior is demonstrated by efficient ROS production and notable bioprotection. This study exploring the pre‐strain effect on the pyroelectricity of ZNR‐paper might provide new insights into the piezo‐/pyroelectric material‐based applications.
A ZnO nanorod‐modified paper (ZNR‐paper) integrated on a face mask has the potential in antibacterial and antiviral effects whose biocidal functionality is readily achieved by human breathing. Breathing‐driven temperature variations in the ZNR generate a pyroelectric voltage, which induces a pyrocatalytic process producing reactive oxygen species (ROS) and thereby results in notable bioprotection.
Fundamental properties of nanostructured substrates govern the performance of laser desorption/ionization mass spectrometry (LDI‐MS); however, limited studies have elucidated the ...desorption/ionization mechanism based on the physicochemical properties of substrates. Herein, the enhancement in desorption/ionization is investigated using a hybrid matrix of Au nanoisland‐functionalized ZnO nanotubes (AuNI‐ZNTs). The underlying origin is explored in terms of the photo‐electronic and ‐thermal properties of the matrix. This is the first study to report the effect of laser‐induced surface restructuring/melting phenomenon on the LDI‐MS performance. AuNI plays a central role as a photothermal nanofurnace, which facilitates the internal energy transfer from the AuNI to the adsorbed analytes by reconstruction in the structurally dynamic AuNI and therefore favors the desorption process. Moreover, piezoelectricity is driven in situ in the AuNI‐ZNT hybrid, which modulates the overall band structure and thereby promotes the ionization process. Ultimately, high LDI‐MS performance is demonstrated by analyzing small metabolites of fatty acids and monosaccharides, which are challenged to be detected in conventional LDI‐MS. This study emphasizing the understanding of matrix properties can provide insights into the design and development of a novel nanomaterial as an efficient LDI matrix. Furthermore, the developed hybrid matrix can overcome the major hurdles existing in conventional LDI‐MS.
A hybrid nanostructure of Au nanoisland‐functionalized ZnO nanotube (AuNI‐ZNT) is presented to show enhanced laser desorption/ionization mass spectrometry performance and its underlying origin of the enhancement is elucidated in terms of the hybrid properties. After laser exposure, morphological changes occur in the AuNI structure, which acts as a nanofurnace and further promotes the ionization process by the laser‐induced piezotronic effect.
For label-free and direct detection of C-reactive protein (CRP), an impedimetric sensor based on an indium tin oxide (ITO) electrode array functionalized with reduced graphene oxide-nanoparticle ...(rGO-NP) hybrid was fabricated and evaluated. Analytical measurements were performed to examine the properties of rGO-NP-modified ITO microelectrodes and to determine the influence upon sensory performance of using nanostructures modified for antibody immobilization and for recognition of CRP binding events. Impedimetric measurements in the presence of the redox couple Fe(CN)63−/4− showed significant changes in charge transfer resistance upon binding of CRP. The impedance measurements were highly target specific, linear with logarithmic CRP concentrations in PBS and human serum across a 1ngmL−1 and 1000ngmL−1 range and associated with a detection limits of 0.06 and 0.08ngmL−1 respectively.
Display omitted
•Reduced graphene oxide-nanoparticle (rGO-NP) layer enhances C-reactive protein (CRP) detection sensitivity.•Growth of rGO-NP on indium tin oxide (ITO) was achieved through cyclic voltammetry in 0 to −1.6V vs. Ag/AgCl.•The rGO-NP/ITO disk electrode had smallest diffusion layer thickness (61μm) and charge transfer resistance (22.99kΩ).•Dissociation constant Kd of CRP in human serum samples was found to be 39.67ngmL−1.•Proposed CRP sensor has a wide measurement range (1 to 10,000ngmL−1) with a detection limit of 0.08ngmL−1.
Paper-based microfluidic analytical devices (μPADs) have recently attracted attention as a point-of-care test kit because of their low cost and nonrequirement for external forces. To directly detect ...biomarkers in whole blood, however, they need to be assembled with a filter such as a plasma separation membrane (PSM) because the color of the blood cells interferes with the colorimetric assay. However, this assembly process is rather complicated and cumbersome, and the fluid does not uniformly move to the detection zone when the adhesion between the paper and PSM is not perfect. In this study, we report a simple three-dimensional (3D) printing method for fabricating PSM-integrated 3D-μPADs made of plastics without the need for additional assembly. In detail, PSM was coated with parylene C to prevent its dissolution from organic solvent during 3D printing. Then, the coated PSM was superimposed on the paper. Detection zones and a reservoir were printed on the paper and PSM via liquid photopolymerization, using a digital light processing printer. The limit of detection of the PSM-integrated 3D-μPADs for glucose in whole blood was 0.3 mM, and these devices demonstrated clinically relevant performance on diabetes patient blood samples. Our 3D-μPADs can also simultaneously detect multiple metabolic disease markers including glucose, cholesterol, and triglycerides in whole blood. Our results suggest that our printing method is useful for fabricating 3D-μPADs integrated with PSM for the direct detection of biomarkers in whole blood.
We have developed a carbon nanotube (CNT) film-based biosensor with a metal semiconductor field effect transistor structure (MESFET). A gold top gate was deposited on the middle of the CNT channel ...and probe antibodies were immobilized on the gold top gate with an antibody-binding protein, protein G or Escherichia coli outer membrane (OM) with autodisplayed Z-domains of protein A. These CNT-MESFET biosensors exhibited a higher sensitivity than the CNT-FET biosensor with probe antibodies immobilized using a chemical linker, since the orientation of immobilized antibodies was controlled by the antibody-binding proteins. In addition, nonspecific binding was effectively inhibited by E. coli OM. Using the CNT-MESFET biosensors with E. coli OM containing Z domain, we detected amyloid-β (Aβ) in human serum, one of the biomarkers for early diagnosis of Alzheimer's disease. Aβ at the level of 1pg/mL in human serum could be measured in real-time and without labeling, which was lower than a limit of detection for plasma Aβ using an enzyme-linked immune sorbent assay. These results suggested that our CNT-MESFET biosensors might be applicable for an early diagnosis of Alzheimer's disease.
•A carbon nanotube metal semiconductor field effect transistor (CNT-MESFET)-based biosensoris described to detect amyloid-beta in human serum, a biomarker of Alzheimer's disease.•The CNT-MESFET biosensor exhibited a higher sensitivity than the carbon nanotube field effect transistor (CNT-ET)-based biosensor.•Nonspecific binding was effectively blocked for the CNT-MESFET biosensor with E. coli outer membrane with utodisplayed z-domains of protein A.•Amyloid-beta at the level of 1pg/mL in human serum could be detected and a calibration curve could be obtained.
Sepsis remains a critical problem with high mortality worldwide, but there is still a lack of reliable biomarkers. We aimed to evaluate the serum lysophosphatidylcholine (LPC) 16:0 as a biomarker of ...sepsis using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). Patients admitted to intensive care unit at Severance Hospital from March 2017 through June 2018 were prospectively enrolled. The inclusion criteria were the fulfillment of at least two criteria of systemic inflammatory response syndrome (SIRS) or the presence of sepsis. Of the 127 patients, 14 had non-infectious SIRS, 41 had sepsis, and 72 had septic shock. The mean serum LPC 16:0 concentration (µmol/L) in non-infectious SIRS was significantly higher than in patients with sepsis and septic shock (101.1 vs. 48.92, p < 0.05; 101.1 vs. 25.88, p < 0.001, respectively). The area under the curve (AUC) predicting 28-day mortality using ΔLPC16:0 (D1-D0) levels was 0.7, which was comparable with the APACHE II score (AUC 0.692) and SOFA score (AUC 0.67). Mechanical ventilation, CRRT, lactate, Δ LPC16:0 (D1-D0) less than the cut-off value were significantly associated with 28-day mortality in multivariable analysis. Our results suggest that LPC16:0 could be a useful biomarker for sepsis diagnosis and mortality prediction in ICU patients.
Harvesting photosynthetic electrons （PEs） from plant or algal cells can be a highly efficient and environmentally friendly way of generating renewable energy. Recent work on nanoelectrode insertion ...into algal cells has demonstrated the possibility to directly extract PEs from living algal cells with high efficiencies. However, the instability of the inserted cells limits the practicality of this technology. Here, the impact of nanoelectrode insertion on intracellular extraction of PEs is characterized with the goal of stabilizing algal cells after nanoelectrode insertion. Using nanoelectrodes 〈 500 nm in diameter, algal cells remained stable for over one week after insertion and continued to provide PEs through direct extraction by the inserted nanoelectrodes. After nanoelectrode insertion, a photosynthetic current density of 6 mA.cm-2, which is several fold higher than the current densities attained using approaches based on isolated thylakoid membranes or photosystem I complexes, was observed in the dark and during illumination at various light intensities.
Variants in SLC26A4 (pendrin) are the most common reasons for genetic hearing loss and vestibular dysfunction in East Asians. In patients with Pendred syndrome and DFNB4 (autosomal recessive type of ...genetic hearing loss 4), caused by variants in SLC26A4, the hearing function is residual at birth and deteriorates over several years, with no curative treatment for these disorders. In the present study, we revealed that a novel small molecule restores the expression and function of mutant pendrin. High-throughput screening of 54,000 small molecules was performed. We observed that pendrin corrector (PC2–1) increased the surface expression and anion exchange activity of p.H723R pendrin (H723R-PDS), the most prevalent genetic variant that causes Pendred syndrome and DFNB4. Furthermore, in endogenous H723R-PDS-expressing human nasal epithelial cells, PC2–1 significantly increased the surface expression of pendrin. PC2–1 exhibited high membrane permeability in vitro and high micromolar concentrations in the cochlear perilymph in vivo. In addition, neither inhibition of Kv11.1 activity in the human ether-a-go-go-related gene assay nor cell toxicity in the cell proliferation assay was observed at a high PC2–1 concentration (30 μM). These preclinical data support the hypothesis of the druggability of mutant pendrin using the novel corrector molecule PC2–1. In conclusion, PC2–1 may be a new therapeutic molecule for ameliorating hearing loss and treating vestibular disorders in patients with Pendred syndrome or DFNB4.
PDF
