Breathing-Driven Self-Powered Pyroelectric ZnO Integrated Face Mask for Bioprotection.

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 ZnO bond lengths and OZnO 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.

Laser-Shock-Driven In Situ Evolution of Atomic Defect and Piezoelectricity in Graphitic Carbon Nitride for the Ionization in Mass Spectrometry.

Nanostructures─coupled with mass spectrometry─have been intensively investigated to improve the detection sensitivity and reproducibility of small biomolecules in laser desorption/ionization mass spectrometry (LDI-MS). However, the impact of laser-induced shock wave on the ionization of the nanostructures has rarely been reported. Herein, we systematically elucidate the laser shock wave effect on the ionization in terms of the in situ development of atomic defects and piezoelectricity in two-dimensional graphitic carbon nitride nanosheets (g-C3N4 NS) by short laser pulses. The mass analysis results of immunosuppressive drugs verify the enhanced LDI-MS performance, structurally originating from anisotropic lattice distortions in g-C3N4 NS, i.e., in-plane extension (contraction) and out-of-plane contraction (extension) that modulate the charge carrier motion. Along with the experimental investigations, density functional theory calculations on Mulliken charges and dipole moments demonstrate the contribution of defect and piezoelectricity to the ionization. The results of this study provide a mechanistic understanding of the underlying ionization processes, which is crucial for revealing the full potential of laser shock waves in LDI-MS.

Simultaneous analysis of acylcarnitines using MALDI-TOF mass spectrometry based on a parylene matrix chip.

Short and medium chain acylcarnitines have been used for the diagnosis of various fatty acid oxidation and organic acid disorders. This report presents a multiplex and quantitative analysis of acylcarnitines using MALDI-TOF MS based on a parylene matrix chip. The parylene matrix chip was fabricated by the deposition of a nanoporous film of parylene on an organic matrix array, which reduced the number of mass peaks from the organic matrix in the low m/z range. Quantitative analysis was possible using the parylene matrix chip because of the formation of nano-sized sample crystals on the nanoporous parylene film. Seven acylcarnitines were quantitatively analyzed using the chip; the method detection range included the cut-off values for metabolic disorders. The seven acylcarnitines of different concentrations were simultaneously detected using the parylene matrix chip and the interference from the mixed carnitines was estimated. Real L-carnitine (C0) samples were analyzed using serial dilution, and the recoveries were calculated by comparisons with a standard curve.

Photothermal Structural Dynamics of Au Nanofurnace for In Situ Enhancement in Desorption and Ionization.

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 TiO2 nanowire photocatalyst for dual-ion production in laser desorption/ionization (LDI) mass spectrometry.

It has been challenging to detect small analytes in both positive and negative ion modes using organic matrices in conventional matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS). Herein, TiO2 nanowires are presented as a solid matrix to form dual ions of analytes regardless of their chemical properties and to demonstrate versatile applicability in LDI-MS.

Simultaneous Analysis of Multiple Cancer Biomarkers Using MALDI-TOF Mass Spectrometry Based on a Parylene-Matrix Chip.

Recently, the parylene-matrix chip was developed for quantitative analysis of small molecules less than 1 kDa. In this study, MALDI-TOF MS based on the parylene-matrix chip was performed to clinically diagnose intrahepatic cholangiocarcinoma (IHCC) and colorectal cancer (CRC). The parylene-matrix chip was applied for the detection of small cancer biomarkers, including N-methyl-2-pyridone-5-carboxamide (2PY), glutamine, lysophosphatidylcholine (LPC) 16:0, and LPC 18:0. The feasibility of MALDI-TOF MS based on the parylene-matrix chip was confirmed via analysis of spot-to-spot and shot-to-shot reproducibility. Serum metabolite markers of IHCC, N-methyl-2-pyridone-5-carboxamide (2PY), and glutamine were quantified using MALDI-TOF MS based on the parylene-matrix chip. For clinical diagnosis of CRC, two water-insoluble (barely soluble) biomarkers, lysophosphatidylcholine (LPC) 16:0 and LPC 18:0, were quantified. Finally, glutamine and LPC 16:0 were simultaneously detected at a range of concentrations in sera from colon cancer patients using the parylene-matrix chip. Thus, this method yielded high-throughput detection of cancer biomarkers for the mixture samples of water-soluble analytes (2PY and glutamine) and water-insoluble analytes (LPC 16:0 and LPC 18:0).

MALDI-TOF Mass Spectrometry Based on Parylene-Matrix Chip for the Analysis of Lysophosphatidylcholine in Sepsis Patient Sera.

In this work, medical diagnosis of sepsis was conducted via quantitative analysis of lysophosphatidylcholine 16:0 (LPC 16:0) by using matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectrometry based on a parylene-matrix chip. In the first step, specific mass peaks for the diagnosis of sepsis were searched by comparing MALDI-TOF mass spectra of sepsis patient sera with healthy controls and pneumonia patient sera. Two mass peaks at m/z = 496.3 and 518.3 were chosen as those that are specifically different for sepsis sera to compare with healthy controls and pneumonia patient sera. These mass peaks were identified to be protonated and sodium adducts of LPC 16:0 by using tandem mass spectra (MS2 and MS3) of purely synthesized LPC 16:0 and extracted LPC 16:0 from a healthy control and a sepsis patient. In the next step, a standard curve for LPC 16:0 for the quantitative analysis of LPC 16:0 with MALDI-TOF MS based on the parylene-matrix chip was prepared, and the statistical correlation to the LC-MS analysis results was demonstrated by using the Bland-Altman test and Passing-Bablok regression. Finally, MALDI-TOF MS based on the parylene-matrix chip was used for the quantification of LPC 16:0 with sera from patients with severe sepsis and septic shock (n = 143), pneumonia patients (n = 12), and healthy sera (n = 31). The sensitivity and the selectivity of medical diagnosis of sepsis was estimated to be 97.9% and 95.5% by using MALDI-TOF MS based on the parylene-matrix chip, respectively.

Nanostructured TiO2 Materials for Analysis of Gout-Related Crystals Using Laser Desorption/Ionization Time-of-Flight (LDI-ToF) Mass Spectrometry.

Crystals of monosodium urate monohydrate (MSU) and calcium pyrophosphate dihydrate (CPPD) are known to induce arthropathic diseases called gout and pseudogout, respectively. These crystals are deposited in various joints or tissues, causing severe pain. Correct identification of crystals is crucial for the appropriate treatment of gout and pseudogout, which exhibit very similar symptoms. Herein, a novel approach of laser desorption/ionization time-of-flight (LDI-ToF) mass spectrometry (MS) was introduced to analyze MSU and CPPD crystals with three different types of nanostructured TiO2 materials including TiO2 nanoparticles (P25), TiO2 nanowires synthesized from wet-corrosion method, and the mixture of P25 and TiO2 nanowires (P25/TiO2 nanowires) as inorganic solid matrices. Furthermore, the feasibility of LDI-ToF MS based on these TiO2 nanostructures for the analysis of the two arthropathy-related crystals was tested using spiked samples in synovial fluid at known crystal concentrations. The mass analysis results of MSU and CPPD crystals demonstrated that (1) the electrostatic interaction between analytes and solid matrices was key for the analyte ionization and (2) LDI-ToF MS with nanostructured TiO2 materials has the potential to be a practical approach for the diagnosis of gout and pseudogout.

Synergistic Effect of the Heterostructure of Au Nanoislands on TiO2 Nanowires for Efficient Ionization in Laser Desorption/Ionization Mass Spectrometry.

A combination nanostructured matrix with metal Au nanoislands and semiconductor TiO2 nanowires is presented to enhance both desorption and ionization efficiency in laser desorption/ionization (LDI) mass spectrometry. The heterostructure of Au nanoislands on TiO2 nanowires was fabricated via (1) TiO2 nanowire synthesis through a modified wet-corrosion method and (2) Au nanoisland formation through thermal annealing of a sputtered Au layer on the TiO2 nanowires. Herein, the synergistic effect of this heterostructure for highly efficient ion production was experimentally elucidated in terms of the formation of high temperature on the surface of Au and the creation of a Schottky barrier at the Au-TiO2 interface. Finally, four types of immunosuppressors were analyzed to demonstrate the improved ionization performance of the heterostructure for LDI mass spectrometry.

Gold-nanoparticle-coated magnetic beads for concentration and ionization of analytes for laser desorption/ionization mass spectrometry.

RATIONALE: Magnetic particles coated with gold nanoparticles (Au NPs) (Au-MAGs) were developed and used (1) for sample concentration and (2) as a solid matrix for laser adsorption/desorption mass spectrometry (LDI-MS). METHODS: The Au-MAGs were prepared by (1) coating polystyrene on iron oxide NPs (PS-MNPs), (2) coating poly-l-lysine on the PS-MNPs (PLL-coated PS-MNPs), and (3) coating negatively charged Au NPs on the PLL-coated PS-MNPs (Au-MAGs). RESULTS: The Au-MAGs were used to concentrate the target analyte by means of electrostatic interactions between the positively charged GHP9 and the negatively charged Au-MAGs as well as selective interactions (such as gold-sulfur interactions) between glutathione (GSH) and Au-MAGs. Then, the concentrated analyte could be ionized for LDI-MS. CONCLUSIONS: The Au-MAGs were demonstrated (1) to concentrate the target analyte in a sample solution, tested by electrostatic interactions and selective interactions between gold and sulfur and (2) to ionize the concentrated analyte for LDI-MS.

TiO2 Nanowires from Wet-Corrosion Synthesis for Peptide Sequencing Using Laser Desorption/Ionization Time-of-Flight Mass Spectrometry.

In this work, TiO2 nanowires synthesized from a wet-corrosion process were presented for peptide sequencing by photocatalytic reaction with UV radiation. For the photocatalytic decomposition of peptides, the peptide sample was dropped on a target plate containing synthesized TiO2 nanowire zones and UV-irradiated. Subsequently, the target plate was analyzed by laser desorption/ionization time-of-flight (LDI-TOF) mass spectrometry using the synthesized TiO2 nanowires as a solid matrix. The feasibility of peptide sequencing based on the photocatalytic reaction with the synthesized TiO2 nanowires was demonstrated using six types of peptides GHP9 (G1-H-P-Q-G2-K1-K2-K3-K4, 1006.59 Da), BPA-1(K1-S1-L-E-N-S2-Y-G1-G2-G3-K2-K3-K4, 1394.74 Da), PreS1(F1-G-A-N1-S-N2-N3-P1-D1-W-D2-F2-N4-P2-N5, 1707.68 Da), HPQ peptide-1 (G-Y-H-P-Q-R-K, 884.45 Da), HPQ peptide-2 (K-R-H-P-Q-Y-G, 884.45 Da), and HPQ peptide-3 (R-Y-H-P-Q-G-K, 884.45 Da). The identification of three different peptides with the same molecular weight was also demonstrated by using the synthesized TiO2 nanowires for their photocatalytic decomposition as well as for LDI-TOF mass spectrometry as a solid-matrix.

A highly sensitive carbapenemase assay using laser desorption/ionization mass spectrometry based on a parylene-matrix chip.

A quantitative carbapenemase assay was developed using laser desorption/ionization mass spectrometry (LDI-MS) based on a parylene-matrix chip. As a first step, the reproducibility (spot-to-spot, shot-to-shot, and day-to-day) of LDI-MS based on a parylene-matrix chip and the quantification ranges for four carbapenem antibiotics (doripenem, ertapenem, imipenem, and meropenem) were determined. A carbapenem-susceptibility test was performed using the four carbapenems and 51 bacterial strains that displayed (1) carbapenem resistance with carbapenemase, (2) carbapenem resistance without carbapenemase, or (3) carbapenem susceptibility. The susceptibility test results showed that LDI-MS based on a parylene-matrix chip was more sensitive and selective for detecting the carbapenemase reaction than conventional MALDI-TOF MS based on a 2,5-dihydroxybenzoic acid matrix.

Newborn screening by matrix-assisted laser desorption/ionization mass spectrometry based on parylene-matrix chip.

Newborn screening for diagnosis of phenylketonuria, homocystinuria, and maple syrup urine disease have been conducted by analyzing the concentration of target amino acids using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-ToF MS) based on parylene-matrix chip. Parylene-matrix chip was applied to MALDI-ToF MS analysis reducing the matrix peaks significantly at low mass-to-charge ratio range (m/z < 500). Reproducibility of inter-spot and intra-spot analyses of amino acids was less than 10%. Methanol extraction was adopted for simple and rapid sample preparation of serum before mass spectrometric analysis showing 13.3 to 45% of extraction efficiency. Calibration curves for diagnosis of neonatal metabolic disorders were obtained by analyzing methanol-extracted serum spiked with target amino acids using MALDI-ToF MS. They showed good linearity (R2 > 0.98) and the LODs were ranging from 9.0 to 22.9 µg/mL. Effect of proteins in serum was estimated by comparing MALDI-ToF mass spectra of amino acids-spiked serum before and after the methanol extraction. Interference of other amino acids on analysis of target analyte was determined to be insignificant. From these results, MALDI-ToF MS based on parylene-matrix chip could be applicable to medical diagnosis of neonatal metabolic disorders.

Hypersensitive antibiotic susceptibility test based on a ß-lactamase assay with a parylene-matrix chip.

Many kinds of susceptibility test for ß-lactam antibiotics have been used to determine the antibiotic resistance of bacterial strains. Here, a sensitive antibiotic susceptibility test was presented by using a specialized reaction tool for laser desorption/ionization time-of-flight mass spectrometry (LDI-TOF MS) based on parylene-matrix chip. The ß-lactamase assay was carried out in a specialized reaction tool by (1) concentrating the bacterial strain and (2) incubating the bacteria with penicillin-G. The parylene-matrix chip was produced by deposition of a partially porous parylene-N thin film on a dried organic matrix array, and the products of ß-lactamase reaction in the low range of mass-to-charge ratio (m/z<500) could be effectively analyzed by using a parylene-matrix chip. The sensing parameters were compared with conventional chromogenic antibiotic susceptibility test for ß-lactam antibiotics. Finally, LDI-TOF MS with a specialized reaction tool and parylene-matrix chip could achieve a limit of detection as low as 600 cells/spot for penicillin-G.

Analysis of benzylpenicillin in milk using MALDI-TOF mass spectrometry with top-down synthesized TiO2 nanowires as the solid matrix.

In this work, the wet-corrosion process for the synthesis of titanium oxide (TiO2) nanowires in the anatase phase was optimized as the solid matrix in MALDI-TOF mass spectrometry, and the solid matrix of the TiO2 nanowires was applied to the detection of antibiotics in a daily milk sample. The influence of the alkali concentration and the heat treatment temperature on the crystal structure of the TiO2 nanowires was investigated. The ionization activity of the TiO2 nanowires was estimated for each synthetic condition using amino acids as model analytes with low molecular weights. For the detection of antibiotics in milk, benzylpenicillin was spiked in daily milk samples, and MALDI-TOF mass spectrometry with the TiO2 nanowires was demonstrated to detect the benzylpenicillin at the cut-off concentration of the EU directive.

Highly sensitive bacterial susceptibility test against penicillin using parylene-matrix chip.

This work presented a highly sensitive bacterial antibiotic susceptibility test through ß-lactamase assay using Parylene-matrix chip. ß-lactamases (EC 3.5.2.6) are an important family of enzymes that confer resistance to ß-lactam antibiotics by catalyzing the hydrolysis of these antibiotics. Here we present a highly sensitive assay to quantitate ß-lactamase-mediated hydrolysis of penicillin into penicilloic acid. Typically, MALDI-TOF mass spectrometry has been used to quantitate low molecular weight analytes and to discriminate them from noise peaks of matrix fragments that occur at low m/z ratios (m/z<500). The ß-lactamase assay for the Escherichia coli antibiotic susceptibility test was carried out using Parylene-matrix chip and MALDI-TOF mass spectrometry. The Parylene-matrix chip was successfully used to quantitate penicillin (m/z: [PEN+H](+)=335.1 and [PEN+Na](+)=357.8) and penicilloic acid (m/z: [PA+H](+)=353.1) in a ß-lactamase assay with minimal interference of low molecular weight noise peaks. The ß-lactamase assay was carried out with an antibiotic-resistant E. coli strain and an antibiotic-susceptible E. coli strain, revealing that the minimum number of E. coli cells required to screen for antibiotic resistance was 1000 cells for the MALDI-TOF mass spectrometry/Parylene-matrix chip assay.

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry of small volatile molecules using a parylene-matrix chip.

RATIONALE: In matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry (MS), volatile small molecules have been nearly impossible to analyze because (1) such molecules evaporate under drying and vacuum conditions and (2) the organic matrix creates matrix peaks in the low mass-to-charge (m/z) range (m/z <500). In this work, the analysis of volatile small molecules using MALDI-TOFMS was realized using (1) a parylene-matrix chip to eliminate the matrix peaks of the organic matrix and (2) graphene for the effective adsorption of the small volatile molecules. METHODS: The parylene-matrix chip was produced by deposition of a partially porous parylene-N thin film on a dried organic matrix array. The sample solution of volatile small molecules was mixed with the graphene and then placed on the parylene-matrix chip for MALDI-TOFMS. Analogs of chemical agents called dimethyl methyl phosphonate (DMMP) and 2-chloroethylethylsulfide (CEES) were used as model compounds for the small volatile molecules, and the sensing parameters were estimated, such as the limit of detection (LOD) and the detection range. RESULTS: MALDI-TOFMS based on the parylene-matrix chip and graphene as the adsorbent could achieve a LOD of approximately 1 ppb in the detection range of 1 ppm-1 ppb for the highly volatile DMMP and CEES. CONCLUSIONS: The parylene-matrix chip with graphene can be applied for the detection of volatile small molecule analytes in the m/z ratio range of small molecules (m/z <500) using graphene as an effective adsorbent.

Nylon nanoweb with TiO2 nanoparticles as a solid matrix for matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.

RATIONALE: The solid matrices used for matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) enable the analysis of small molecules by preventing fragmentations of organic matrix molecules in the low mass-to-charge ratio (m/z) range. In this work, a nylon nanoweb with TiO(2) particles was developed as a solid matrix for MALDI-TOFMS to improve the low intensities of mass peaks, narrow detection ranges and low signal-to-noise levels. METHODS: The nylon nanoweb with TiO(2) particles was prepared by simultaneously electrospinning a nylon nanoweb and electrospraying TiO(2) nanoparticles measuring 25 nm in diameter to form TiO(2) spheres 300 nm in diameter. RESULTS: MS of multiple analytes was demonstrated in the low molecular weight range using eight amino acids. Additionally, leucine-enkephalin (555.6 g/mol) and cyclic citrullinated peptide (1668 g/mol) were used as model analytes to test the feasibility of a nylon nanoweb containing TiO(2) particles as a solid matrix for MALDI-TOFMS. CONCLUSIONS: The nylon nanoweb with TiO(2) particles can be applied for the detection of volatile small molecule analytes in the m/z ratio range of small molecules.