Long-term all-cause death prediction by coronary, aortic, and valvular calcification in patients with acute ST-segment elevation myocardial infarction.

BACKGROUND: To determine the prognostic value of cumulative calcification score of coronary artery calcification (CAC), thoracic aortic calcification (TAC) and aortic valve calcification (AVC) in acute ST segment elevation myocardial infarction (STEMI) patients. METHODS: This was a retrospective, single-center cohort study. A total of 332 STEMI patients who received primary percutaneous coronary intervention (PPCI) were enrolled in this study between January 2010 to October 2018. We assessed the calcification in the left anterior descending branch (LAD), left circumflex branch (LCX), right coronary artery (RCA), thoracic aorta, and aortic valve. Calcification of each part was counted as 1 point, and the cumulative calcification score was calculated as the sum of all points. The primary endpoint was all-cause mortality. Multivariate Cox proportional hazards models were used to determine association of cumulative calcification score with end points. The performance of the score was evaluated by receiver operating characteristic (ROC) curve analysis and absolute net reclassification improvement (NRI), compared with the Global Registry of Acute Coronary Events (GRACE) risk score. RESULTS: The overall population's calcification score was 2.0 ± 1.6. During a mean follow-up time of 69.8 ± 29.3 months, the all-cause mortality rate was 12.1%. Kaplan-Meier curve showed that the score was significantly associated with mortality (log-rank p < 0.001). The multivariable Cox proportional hazard analyses showed that a calcification score of 4-5 was independently associated with all-cause death in STEMI patients [hazard ratio (HR) = 2.32, 95% confidence interval (CI): 1.01-5.31, p = 0.046]. The area under the ROC curve (AUC) of the calcification score was 0.67 (95% CI: 0.61-0.72), and the AUC of the GRACE score was 0.80 (95% CI: 0.75-0.84). There was no statistical difference in the predictive value between both scores for 3-year mortality in STEMI patients after PPCI (p = 0.06). Based on the NRI analysis, the calcification score showed better risk classification compared with the GRACE score (absolute NRI = 6.63%, P = 0.027). CONCLUSION: The cumulative calcification score is independently associated with the long-term prognosis of STEMI patients after PPCI.

T790M mutation upconversion fluorescence biosensor via mild ATRP strategy and site-specific DNA cleavage of restriction endonuclease.

A unique combination of a specific nucleic acid restriction endonuclease (REase) and atom transfer radical polymerization (ATRP) signal amplification strategy was employed for the detection of T790M mutations prevalent in the adjuvant diagnosis of lung cancer. REase selectively recognizes and cleaves T790M mutation sites on double-stranded DNA formed by hybridization of a capture sequence and a target sequence. At the same time, the ATRP strategy resulted in the massive aggregation of upconverted nanoparticles (UCNPs), which significantly improved the sensitivity of the biosensor. In addition, the UCNPs have excellent optical properties and can eliminate the interference of autofluorescence in the samples, thus further improving the detection sensitivity. The proposed upconversion fluorescent biosensor is characterized by high specificity, high sensitivity, mild reaction conditions, fast response time, and a detection limit as low as 0.14 fM. The performance of the proposed biosensor is comparable to that of clinical PCR methods when applied to clinical samples. This work presents a new perspective for assisted diagnosis in the pre-intervention stage of tumor diagnostics in the early stage of precision oncology treatments.

Recent Advances in Synthesis of Non-Alternating Polyketone Generated by Copolymerization of Carbon Monoxide and Ethylene.

The copolymers of carbon monoxide (CO) and ethylene, namely aliphatic polyketones (PKs), have attracted considerable attention due to their unique property and degradation. Based on the arrangement of the ethylene and carbonyl groups in the polymer chain, PKs can be divided into perfect alternating and non-perfect alternating copolymers. Perfect alternating PKs have been previously reviewed, we herein focus on recent advances in the synthesis of PKs without a perfect alternating structure including non-perfect alternating PKs and PE with in-chain ketones. The chain structure of PKs, catalytic copolymerization mechanism, and non-alternating polymerization catalysts including phosphine-sulfonate Pd, diphosphazane monoxide (PNPO) Pd/Ni, and phosphinophenolate Ni catalysts are comprehensively summarized. This review aims to enlighten the design of ethylene/CO non-alternating polymerization catalysts for the development of new polyketone materials.

A theoretical study on hydrated sodium ion-phenylalanine clusters Na+(Phe)(H2O)n (n = 0-6; Phe = phenylalanine).

The cation-π interaction is of importance in many chemical and biological processes such as those involving protein geometries and functionals and ion channels. In this study, to understand the cation-π interaction between essential ions and protein in the water-aqueous environment, geometries, electronic structures, bonding properties, and dynamic stabilities of hydrated Na+-phenylalanine clusters Na+(Phe)(H2O)n (n = 0-6) were studied using density functional theory calculations and ab initio molecular dynamics simulations. After the addition of water molecules, Na+(Phe)(H2O)n structures change from a tridentate complex to quadridentate or pentadentate complexes while the cation-π interaction always exists. The fluctuation between quadridentate and pentadentate complexes results from the competition between cation-O bonding and hydrogen bonding. The charge analysis reveals that the positive charge is mainly located on the Na ion, whereas the further addition of water reduces the binding energy of water, electron affinity, and ionization potential. As the number of water molecules increases, the bonding interactions between the sodium ion and the remaining phenylalanine-water complex increase and correlate with the coordination number, in which the electrostatic interaction contributes more than the orbital interaction. The important orbital interaction terms come from the donation of the carboxyl and amino groups and water to the Na+ ion. Molecular dynamic simulations revealed that Na+(Phe)(H2O)6 is stable at 300 K.

Amphiphilic Polyethylene-b-poly(L-lysine) Block Copolymer: Synthesis, Self-Assembly, and Responsivity.

Polyethylene-b-polypeptide copolymers are biologically interesting, but studies of their synthesis and properties are very few. This paper reports synthesis and characterization of well-defined amphiphilic polyethylene-block-poly(L-lysine) (PE-b-PLL) block copolymers by combining nickel-catalyzed living ethylene polymerization with controlled ring-opening polymerization (ROP) of ε-benzyloxycarbonyl-L-lysine-N-carboxyanhydride (Z-Lys-NCA) and sequential post-functionalization. Amphiphilic PE-b-PLL block copolymers self-assembled into spherical micelles with a hydrophobic PE core in aqueous solution. The pH and ionic responsivities of PE-b-PLL polymeric micelles were investigated by means of fluorescence spectroscopy, dynamic light scattering, UV-circular dichroism, and transmission electron microscopy. The variation of pH values led to the conformational alteration of PLL from α-helix to coil, thereby changing the micelle dimensions.

p113 isoform encoded by CUX1 circular RNA drives tumor progression via facilitating ZRF1/BRD4 transactivation.

BACKGROUND: Metabolic reprogramming sustains tumorigenesis and aggressiveness of neuroblastoma (NB), the most common extracranial malignancy in childhood, while underlying mechanisms and therapeutic approaches still remain elusive. METHODS: Circular RNAs (circRNAs) were validated by Sanger sequencing. Co-immunoprecipitation, mass spectrometry, chromatin immunoprecipitation (ChIP) sequencing, and RNA sequencing assays were applied to explore protein interaction and target genes. Gene expression regulation was observed by ChIP, dual-luciferase reporter, real-time quantitative RT-PCR, and western blot assays. Gain- and loss-of-function studies were performed to observe the impacts of circRNA-encoded protein and its partners on the lipid metabolism, mitochondrial activity, growth, invasion, and metastasis of NB cells. RESULTS: A novel 113-amino acid protein (p113) of CUT-like homeobox 1 (CUX1) was identified in NB cells treated by serum deprivation. Further validating studies revealed that nuclear p113 was encoded by circRNA of CUX1, and promoted the lipid metabolic reprogramming, mitochondrial activity, proliferation, invasion, and metastasis of NB cells. Mechanistically, p113 interacted with Zuotin-related factor 1 (ZRF1) and bromodomain protein 4 (BRD4) to form a transcriptional regulatory complex, and mediated the transactivation of ZRF1/BRD4 in upregulating ALDH3A1, NDUFA1, and NDUFAF5 essential for conversion of fatty aldehydes into fatty acids, fatty acid ß-oxidation, and mitochondrial complex I activity. Administration of an inhibitory peptide blocking p113-ZRF1 interaction suppressed the tumorigenesis and aggressiveness of NB cells. In clinical NB cases, high expression of p113, ZRF1, or BRD4 was associated with poor survival of patients. CONCLUSIONS: These results indicate that p113 isoform encoded by CUX1 circular RNA drives tumor progression via facilitating ZRF1/BRD4 transactivation.

Simulation for measurement of lightning channel temperature using a dual-band high-precision lightning imaging spectrometer.

A dual-band high-precision lightning imaging spectrometer (DHLIS) is designed to capture the fine spectrum of transient lightning. DHLIS improves the theoretical spectral resolution limit to 10-3nm and broadens the spectral range to 30-40 nm by employing double echelle gratings in the arms of a spatial heterodyne spectrometer. Four strong and three fine spectral lines are selected to retrieve the temperature of the lightning channel using the Boltzmann plot method. The experimental results indicate that the inversion accuracy of the temperature obtained by inserting fine spectral lines is higher than that by implementation of four strong spectral lines.

Simulation and observation for volume emission rates emitted from O2(0-1) and O(1S) nightglow in northwest China.

Being susceptible to the change of atmospheric conditions, the volume emission rate (VER) is very suitable to be used as a light source by passive remote sensing for measuring atmospheric wind and temperature. Thus, the VERs emitted from O2(0-1) and O(S1) of the nightglow at 80-120 km are studied in this paper. Based on the Naval Research Laboratory Mass Spectrometer Incoherent Scatter (NRLMSISE-00) model data and the ground-based airglow imaging interferometer (GBAII) instrument observation for a local time and place, simulated VER profiles represented by four layers are obtained for the nightglow of O2(0-1) and O(S1). The O2(0-1) nightglow model peak values at 94 km on 6 December 2013 and 8 November 2011 are 8111 photons·cm-3·s-1 and 8406 photons·cm-3·s-1, respectively; however, the O(S1) VER peak at a higher altitude of about 96 km on 18 December 2011 is only 338 photons·cm-3·s-1. The upper atmospheric VER values have been derived to transfer into the ground-based detected column intensities by our GBAII prototype. The calculated column integrated emission rates (IERs) of O2(0-1) for 0° and 45° zenith angles are 1.48×107 and 1.91×107 photons·cm-2·s-1, respectively; the calculated column IERs of O(S1) are 5.53×105 and 7.03×105 photons·cm-2·s-1, respectively. Correspondingly, the detected column IERs obtained by GBAII are 2.43×107 for O2(0-1) and 6.57×105 photons·cm-2·s-1 for O(S1).

Long-Lived Room-Temperature Phosphorescence for Visual and Quantitative Detection of Oxygen.

An unconventional organic molecule (TBBU) showing obvious long-lived room temperature phosphorescence (RTP) is reported. X-ray single crystal analysis demonstrates that TBBU molecules are packed in a unique fashion with side-by-side arranged intermolecular aromatic rings, which is entirely different from the RTP molecules reported to date. Theoretical calculations verify that the extraordinary intermolecular interaction between neighboring molecules plays an important role in RTP of TBBU crystals. More importantly, the polymer film doped with TBBU inherits its distinctive RTP property, which is highly sensitive to oxygen. The color of the doped film changes and its RTP lifetime drops abruptly through a dynamic collisional quenching mechanism with increasing oxygen fraction, enabling visual and quantitative detection of oxygen. Through analyzing the grayscale of the phosphorescence images, a facile method is developed for rapid, visual, and quantitative detection of oxygen in the air.

Investigation on temperature-induce conformational change of immobilized ß2 adrenergic receptor.

The ß2 adrenergic receptor (ß2-AR) is a prototypical family A G protein-coupled receptor (GPCR) and an excellent model system for studying the mechanism of GPCR activation. Purified ß2-AR was immobilized on macroporous silica gel to obtain liquid chromatographic stationary phase. The resulting phase was packed into a stainless steel column (4.6 × 50 mm, 7 µm) and used for on-line chromatographic system. When column oven temperature increased from 20.0 °C to 40.0 °C, uncomplete separate chromatographic peaks of ephedrine and pseudoephedrine as receptor conformational probe were gradually merged into one peak, meanwhile retention time and resolution of the probes were reduced correspondingly, which suggested that temperature could regulate protein conformation. Temperature-induced conformational change of immobilized ß2-AR, especially changes at higher temperatures, indicated that constructed receptor chromatography could simulate fever disease state of human body and clarify receptor conformation change at pathological condition. At the same time this study could also provide new ideas for screening active components in pathological conditions.

Identification of bioactive compounds in Shaoyao-Gancao decoction using ß2-adrenoceptor affinity chromatography.

Shaoyao-Gancao decoction, a Chinese herbal formula, is composed of Paeoniae Radix alba and Glycyrrhiza Radix et rhizoma. It has been widely used to treat muscle spasms and asthma. However, little is known about the bioactive components of Shaoyao-Gancao decoction. In the present study, the bioactive compounds in water-extract of Shaoyao-Gancao decoction were separated by the immobilized ß2 -adrenoceptor affinity column and identified using quadrupole time-of-flight mass spectrometry. The affinity constants of the separated compounds that bind to ß2 -adrenoceptor were determined by frontal analysis. Compound bioactivity was tested in a rat tracheal smooth muscle relaxation assay. We identified the bioactive compounds in the water extract of Shaoyao-Gancao decoction that bound to the ß2 -adrenoceptor as paeoniflorin and liquiritin. Paeoniflorin and liquiritin had only one binding site on the immobilized ß2 -adrenoceptor, and the affinity constants were (2.16 ± 0.10) × 104  M-1 and (2.95 ± 0.15) × 104  M-1 , respectively. Both compounds induced a concentration-dependent relaxation of tracheal smooth muscle following K+ -stimulated contraction, and the relaxation effects were abrogated by the ß2 -adrenoceptor antagonist, ICI 118551. Therefore, paeoniflorin and liquiritin are bioactive compounds in Shaoyao-Gancao decoction and the ß2 -adrenoceptor affinity chromatography is a useful tool for identifying potential ß2 -adrenoceptor ligands in natural products used in traditional Chinese medicine.

Identifying the antiasthmatic target of doxofylline using immobilized ß2 -adrenoceptor based high-performance affinity chromatography and site-directed molecular docking.

As a xanthine derivative, doxofylline is believed to be dominant for fighting against asthma in practice. Unlike other xanthines, the antiasthmatic effects of doxofylline lack any definite proof of target and mediating mechanism according to previous reports. In this work, the interaction between doxofylline and ß2 -AR was investigated by high performance affinity chromatography using frontal analysis and nonlinear model. The methodology involved the immobilization of ß2 -AR on the silica gel by a random linking method, the determination of the binding parameters by frontal analysis and nonlinear chromatography and the exploration of the binding mechanism by site-directed molecular docking. The association constant for doxofylline binding to immobilized ß2 -AR was determined to be 7.70 × 10(4) M(-1) by nonlinear chromatography and 5.91 × 10(4) M(-1) by frontal analysis. Ser(169) and Ser(173) were the binding sites for the receptor-drug interaction on which hydrogen bond was believed to be the main driven force during the interaction. These results indicated that the antiasthmatic effects of doxofylline may be behind the mediating mechanism of ß2 -AR. High performance affinity chromatography based on immobilized receptor has potential to become an alternative for drug target confirmation and drug-receptor interaction analysis. Copyright © 2016 John Wiley & Sons, Ltd.

α-Diamine Nickel Catalysts with Nonplanar Chelate Rings for Ethylene Polymerization.

A series of novel α-diamine nickel complexes, (ArNH-C(Me)-(Me)C-NHAr)NiBr2 , 1: Ar=2,6-diisopropylphenyl, 2: Ar=2,6-dimethylphenyl, 3: Ar=phenyl), have been synthesized and characterized. X-ray crystallographic analysis showed that the coordination geometry of the α-diamine nickel complexes is markedly different from conventional α-diimine nickel complexes, and that the chelate ring (N-C-C-N-Ni) of the α-diamine nickel complex is significantly distorted. The α-diamine nickel catalysts also display different steric effects on ethylene polymerization in comparison to the α-diimine nickel catalyst. Increasing the steric hindrance of the α-diamine ligand by substitution of the o-methyl groups with o-isopropyl groups leads to decreased polymerization activity and molecular weight; however, catalyst thermal stability is significantly enhanced. Living polymerizations of ethylene can be successfully achieved using 1/Et2 AlCl at 35 °C or 2/Et2 AlCl at 0 °C. The bulky α-diamine nickel catalyst 1 with isopropyl substituents can additionally be used to control the branching topology of the obtained polyethylene at the same level of branching density by tuning the reaction temperature and ethylene pressure.

Study on magnetic mirror array image intensifier to work at room temperature.

In order to improve the detection capability of the current low-light-level (LLL) imaging systems at room temperature, a new device, a magnetic mirror array image intensifier (MMAII), is proposed in this paper. A magnetic mirror array device (MMAD) is coupled into an image intensifier which sits between the photocathode and the microchannel plate (MCP). The trace photoelectrons, one after another, are first sufficiently accumulated by the MMAD over a long time at room temperature, and then they are released and enter the MCP for further gain. These two steps are used to improve the detection capability at the LLL imaging system at room temperature. After the two-dimensional magnetic field distribution of the magnetic mirror array (MMA) is calculated, the MMA is designed and optimized with a rubidium Nd-Fe-B permanent magnet. Three groups of ideal parameters for the Nd-Fe-B permanent magnet MMAD, with a magnetic mirror ratio of 1.69, for all of them have been obtained. According to the research results on the noise of the escape cone of the MMAII, the angle between the incident direction and the axis is greater than 57°, so the trace electrons must be constrained by the magnetic mirror. We made 54 MMAs from Nd-Fe-B permanent magnets and packaged them in a container. Then the system was evacuated to 10-3 Pa at room temperature. It was found by experiment that the trace electrons could be actually constrained by the MMAD. The MMAII can be applied to images for static LLL objects.

Design of thermally stable amine-imine nickel catalyst precursors for living polymerization of ethylene: effect of ligand substituents on catalytic behavior and polymer properties.

Nickel complexes bearing amine-imine ligands with various backbone substituents were synthesized and employed as ethylene polymerization catalysts on activation with Et2 AlCl. The substituent on the backbone carbon atom of the amine moiety is decisive for the living nature of ethylene polymerization. A bulky amine-imine nickel precursor with a tert-butyl group on the carbon atom of the amine group can polymerize ethylene in a living fashion at an elevated temperature of 65 °C, which is the highest temperature of living polymerization of ethylene with late transition-metal catalysts. The wide applicable temperature range for living polymerization and sensitivity of the branch structure of the polyethylene to temperature enable precise synthesis of di- and triblock polyethylenes featuring different branched segments by sequential tuning of the polymerization temperature.

Amphiphilic nanocapsules entangled with organometallic coordination polymers for controlled cargo release.

A class of new amphiphilic nanocapsules entangled with organometallic coordination polymers has been developed for the first time. Poly(2-(N,N-dimethyl amino)ethyl methacrylate)-b-polystyrene capped with ß-cyclodextrin (ß-CD) (CD-PDMAEMA-b-PS) is first synthesized using sequent RAFT polymerization of styrene and 2-(N,N-dimethyl amino)ethyl methacrylate with xanthate modified ß-CD as chain transfer agent. The end group of ß-CD is allowed to include 4,4'-bipyridine through host-guest inclusion to yield PDMAEMA-b-PS terminated with an inclusion complex of ß-CD and bipyridine (bpy-PDMAEMA-b-PS), which is then used as surfactant to prepare emulsion droplets in toluene/water mixture. Upon addition of Ni(II), bipyridine coordinates with Ni(II) to form coordination polymers in the periphery of emulsion droplets, affording amphiphilic capsules entangled with organometallic coordination polymers, as confirmed by GPC, (1)H NMR, SEM, TEM, DLS, and so on. The organometallic coordination polymer capsules are capable of encapsulating organic cargoes. Interestingly, encapsulated cargoes can be extracted from the capsules without damaging the capsules. Such capsules are potential candidates for encapsulating and controlled release of organic cargoes.

Glass transition of poly(methyl methacrylate) nanospheres in aqueous dispersion.

Surfactant-free nanospheres and latex nanospheres of poly(methyl methacrylate) (PMMA) with diameter ranging from 20 to 220 nm are prepared by atom transfer radical polymerization (ATRP) in microemulsions and subsequent dialysis against deionized water. The glass transitions of these PMMA nanospheres are characterized using nano differential scanning calorimetry (nano-DSC) in aqueous dispersions. The glass transition temperature (Tg) of the surfactant-free PMMA nanospheres and nonionic PMMA latex nanospheres with diameters below 150 nm is less than that of the PMMA bulk, and Tg decreases with the decrease of the diameter. In contrast, Tg of the anionic PMMA latex nanospheres is size-independent and is near to that of the PMMA bulk. The influence of the environment surrounding the PMMA nanospheres on glass transitions as well as comparisons to our prior studies with polystyrene (PS) nanospheres in aqueous dispersions are discussed.

Ground-based airglow imaging interferometer. Part 2: forward model and inverse method.

The ground-based airglow imaging interferometer (GBAII) observes the nighttime airglow of the O2(0-1) 867.7 nm line, peaked at 94 km altitude, to measure the upper atmospheric wind and temperature field. Its forward model, a code package in interactive data language (IDL), is developed to simulate the expected imaging interference fringes. It includes eight modules to simulate the light source, the atmospheric radiation transmission, the wide-angle Michelson interferometer, the interference filter, the optical system decay function, the responsivity, the imaging CCD, and the noises. The inverse method is also developed for obtaining the rest phase calibration, temperature, and wind. By means of both theoretical tools, we carry out a comparison of theoretical results with a field observation case. The apparent quantities J(1-p) from the forward model has the deviation of 1.5%-2.5% compared with that from the observation image. The temperature falls mainly in the range of 167-196 K with the precision of 2 K. The zonal and meridional winds are mainly in the region of 5.1 to 46.5 m/s and 12.5 to 48.3 m/s respectively, with errors of 13.2 to 21.5 m/s. The consistent trends between the observation results and standard models (MSISE90 and HWM93) suggest that the forward model and inverse method are suitable for GBAII.

Sunlight-Activated Hour-Long Afterglow from Transparent and Flexible Polymers.

Afterglow materials featuring long emission durations ranging from milliseconds to hours have garnered increasing interest owing to their potential applications in sensing, bioimaging, and anti-counterfeiting. Unfortunately, polymeric materials rarely exhibit afterglow properties under ambient conditions because of the rapid nonradiative decay rate of triplet excitons. In this study, hour-long afterglow (HLA) polymer films are fabricated using a facile molecular doping strategy. Flexible and transparent polymer films emitted a bright afterglow lasting over 11 h at room temperature in air, which is one of the best performances among the organic afterglow materials reported to date. Intriguingly, HLA polymer films can be activated by sunlight, and their cyan afterglow in air can be readily observed by the naked eye. Moreover, the HLA color of the polymer films could be tuned from cyan to red through the Förster resonance energy transfer mechanism. Their application in flexible displays and information storage has also been demonstrated. With remarkable advantages, including an hour-long and bright afterglow, tunable afterglow colors, superior flexibility and transparency, and ease of fabrication, the HLA polymer paves the way for the practical application of afterglow materials in the engineering sector.

Highly sensitive photoelectrochemical biosensing detection of early cardiac injury enabled by novel self-assembled Bi2O3/MgIn2S4 photoelectrode coupled with ZnSnO3 quencher.

The development of photoelectrochemical (PEC) biosensors plays a critical role in enabling timely intervention and personalized treatment for cardiac injury. Herein, a novel approach is presented for the fabrication of highly sensitive PEC biosensor employing Bi2O3/MgIn2S4 heterojunction for the ultrasensitive detection of heart fatty acid binding protein (H-FABP). The Bi2O3/MgIn2S4 heterojunction, synthesized through in-situ growth of MgIn2S4 on Bi2O3 nanoplates, offers superior attributes including a larger specific surface area and more homogeneous distribution, leading to enhanced sensing sensitivity. The well-matched valence and conduction bands of Bi2O3 and MgIn2S4 effectively suppress the recombination of photogenerated carriers and facilitate electron transfer, resulting in a significantly improved photocurrent signal response. And the presence of the secondary antibody marker (ZnSnO3) introduces steric hindrance that hinders electron transfer between ascorbic acid and the photoelectrode, leading to a reduction in photocurrent signal. Additionally, the competition between the ZnSnO3 marker and the Bi2O3/MgIn2S4 heterojunction material for the excitation light source further diminishes the photocurrent signal response. After rigorous repeatability and selectivity tests, the PEC biosensor exhibited excellent performance, and the linear detection range of the biosensor was determined to be 0.05 pg/mL to 100 ng/mL with a remarkable detection limit of 0.029 pg/mL (S/N = 3).