Microchimica Acta

Lazanas, Alexandros Ch.; Prodromidis, Mamas I.

doi: 10.1007/s00604-020-04674-0pmid: 33389171

This review (with 178 references) focuses on inorganic layered materials (ILMs) and the use of their two-dimensional nanosheets in the development of novel electrochemical (bio)sensors, analytical devices, and gas-phase sensing applications. The text is organized in three main sections including the presentation of the most important families of ILMs, a comprehensive outline of various “bottom-up”, “top-down,” and hydro(solvo)thermal methods that have been used for the production of ILM nanosheets, and finally an evaluative survey on their utility for the determination of analytes with interest in different sectors of contemporary analysis. Critical discussion on the effect of the production method on their electronic properties, the suitability of each nanomaterial in different sensing technologies along with an assessment of the performance of the (bio)sensors and devices that have been proposed within the last 5 years, is enclosed. The perspectives of further improving the utility of 2D inorganic nanosheets in sensing applications, in real-world samples, are also discussed.Graphical abstract[graphic not available: see fulltext]

Li, Bin; Ge, Lilin; Lyu, Peng; Chen, Meijuan; Zhang, Xiongfei; Xie, Shuping; Wu, Qinan; Kwok, Hang Fai

doi: 10.1007/s00604-020-04687-9pmid: 33389237

A simple and feasible pH meter–based immunoassay is reported for detection of C-reactive protein (CRP) using glucose oxidase (GOD)–conjugated dendrimer loaded with platinum nanozyme. Initially, platinum nanozymes were loaded into the dendrimers through an in situ synthetic method. Then, GOD and monoclonal anti-CRP antibody with a high molar ratio were covalently conjugated onto carboxylated dendrimers via typical carbodiimide coupling. The immunoreaction was carried out with a competitive mode in a CRP-coated microplate. Along with formation of immunocomplex, the added glucose was oxidized into gluconic acid and hydrogen peroxide by GOD, and the latter was further decomposed by platinum nanozyme, thus accelerating chemical reaction in the positive direction. The produced gluconic acid changed the pH of detection solution, which was determined using a handheld pH meter. Under optimum conditions, the pH meter–based immunoassay gave a good signal toward target CRP from 0.01 to 100 ng mL−1. The limit of detection was 5.9 pg mL−1. An intermediate precision ≤ 11.2% was acquired with batch-to-batch identification. No nonspecific adsorption was observed during a series of procedures to detect target CRP, and the cross-reaction against other biomarkers was very low. Importantly, our system gave well-matched results for analysis of human serum samples relative to a referenced ELISA kit.Graphical abstract[graphic not available: see fulltext]

Wu, Pu; Du, Qiuzheng; Chen, Li; Yang, Manli; Sun, Yiyang; Zhi, Hao; Dramou, Pierre; He, Hua

doi: 10.1007/s00604-020-04664-2pmid: 33409815

A new metal-organic framework compound (MOF@MOF, NUZ-8) comprised of NH2-UiO-66 and ZIF-8 under the polyvinylpyrrolidone (PVP) as the structure modifier was synthesized through an internal extended growth method (IEGM). The resulting NUZ-8 emerged the unreported unique polyhedron shape and showed considerable specific surface area (1466.1862 m2/g), excellent adsorption capacity, and fluorescence. NUZ-8 was used as a probe for the rapid optical detection of natural antioxidant quercetin (QCT). Its outstanding selectivity and sensitivity to QCT are derived from the fact that NH2-UiO-66 acted as an optical tentacle to perceive QCT in virtue of its luminescence advantages, and ZIF-8 realized the selective enrichment of the QCT through its electron-rich framework structure. The experiments were carried out at an excitation wavelength of 335 nm and an emission wavelength range of 370–530 nm. Under conditions of the investigation, this probe realized the rapid detection of QCT and considerable adsorption capacity with wide linearity (0.3–80 μM), a low detection limit (0.14 μM), and acceptable recoveries (84.0–97.0%) in red wine samples, properties which were superior to many other detection platforms. The synthesis and the use of the above polyhedral composite provide guidance for the application of the IEGM in enhancing chemical sensing and instant determination of drugs.Graphical abstractFlow chart of this paper.[graphic not available: see fulltext]

Zhang, Haipin; Song, Huijia; Tian, Xuemeng; Wang, Yue; Hao, Yi; Wang, Wenting; Gao, Ruixia; Yang, Wan; Ke, YuShen; Tang, Yuhai

doi: 10.1007/s00604-020-04693-xpmid: 33403455

A synergistic imprinting strategy of covalent and non-covalent interactions is proposed to prepare magnetic molecularly imprinted polymers (DI-MMIPs) for highly selective separation of procyanidin B2 (PC) from grape seed samples. Dopamine and 3-amino-phenylboronic acid as cooperative functional monomers endow the imprinted sites with synergistic tailoring. Benefiting from the synergistic effect, the DI-MMIPs exhibit enhanced imprinting performance with high adsorption capacity (27.71 mg g−1), fast kinetic equilibrium time (within 30 min), outstanding selectivity (IF = 5.8, SC > 3.2), and satisfactory regeneration ability. In addition, the DI-MMIPs possess good magnetism, uniform morphology with typical core-shell structure, and stable crystallization. Furthermore, the established DI-MMIPs coupled with HPLC-UV (~ 280 nm) method has a wide linearity range of 0.05–200 μg mL−1 with correlation coefficient of 0.9997, high recoveries (> 93.1%) with RSDs from 2.9 to 5.5%, and low LOD (0.0008 μg mL−1). Consequently, this work provides an effective and easily tailored way to fabricate magnetic imprinted nanomaterials with both rapid recognition rate and high selectivity and thus holds great promise to realize the extraction and detection of PC from real samples.Graphical abstract[graphic not available: see fulltext]

He, Baoshan; Wang, Senyao

doi: 10.1007/s00604-020-04688-8pmid: 33404928

An electrochemical aptasensor, including the polyethyleneimine-graphite-like carbon nitride/Au nanowire nanocomposite (PEI-C3N4/AuNWs) and exonuclease-assisted signal amplification strategy was constructed for the determination of chloramphenicol (CAP). Initially, a nanocomposite with substantial electrocatalytic property was synthesized by PEI-C3N4/AuNWs. This improves the conductivity and specific surface area of the PEI-C3N4/AuNW–modified gold electrode. Next, a DNA with a complementary sequence to a CAP aptamer (cDNA) was immobilized on the PEI-C3N4/AuNW–modified electrode, followed by the CAP aptamer hybridized with cDNA. The lower signal at this time is due to the negatively charged phosphate group of the oligonucleotide and [Fe (CN)6]3−/4− electrostatically repelling each other. The presence of the CAP would cause aptamer on the electrode surface to fall off and be digested by Recjf exonuclease, which resulted in target recycling, and a significant increase in DPV signal can be observed at a potential of 0.176 V (vs. Ag/AgCl). Under optimal conditions, there is a linear relationship between the peak current and the logarithm of CAP concentration in the range 100 fM–1 μM, and the detection limit of this aptasensor is 2.96 fM (S/N = 3). Furthermore, the resultant aptasensor has excellent specificity, reproducibility, and long-term stability, and has been applied to the detection of CAP in milk samples.Graphical abstractThe detection principle of the electrochemical aptasensor for CAP detection was based on PEI-C3N4/AuNWs and exonuclease-assistant signal amplification. It is based on the fact that PEI-C3N4/AuNWs nanocomposites on the surface of the electrode can effectively improve the performance of the aptasensor, and Recjf exonuclease initiates the target recycling process, causes signal amplification.[graphic not available: see fulltext]

Yang, Lili; Wang, Jiasheng; Lü, Haitao; Hui, Ni

doi: 10.1007/s00604-020-04673-1pmid: 33404773

A dual-sensing platform is proposed based on multi-walled carbon nanotubes/Prussian blue–functionalized polypyrrole nanowire array (PPY/MWCNTs/PB). Highly aligned PPY nanowire arrays were electrochemically prepared on the surface of glassy carbon electrodes, which were doped with MWCNTs/PB nanocomposites. The nanomaterial combines the characteristics of the PPY nanowires (high conductivity and large specific surface area) and MWCNTs/PB (excellent catalytic performance and intrinsic redox activity). Owing to the nanowire microstructure and outstanding electrical properties, the PPY/MWCNTs/PB nanowire arrays show excellent electrocatalysis of the reduction of hydrogen peroxide and facilitate the construction of a high-performance biosensing platform for microRNA (miRNA). A linear relationship between analytical signal and concentration of hydrogen peroxide and miRNA was obtained in the range 5 to 503 µM (1.4–5.1 mM) and 0.1 pM to 1 nM, and detection limits of 1.7 μM and 33.4 fM, respectively. This new supersensitive sensing platform has broad application prospects of biomolecule and other analyte determination in drug, biomedical, plant protection, and environmental analysis.Graphical abstractPrussian blue/multi-walled carbon nanotubes functionalized polypyrrole nanowire arrays (PPY/MWCNTs/PB) were prepared by a facile one-step electrochemical method. PPY/MWCNTs/PB nanowire arrays show excellent electrocatalysis of the reduction of H2O2 and facilitate the construction of a high-performance biosensing platform for microRNA.[graphic not available: see fulltext]

Hao, Yumin; Wang, Huiping; Wang, Zihan; Dong, Wenjuan; Hu, Qin; Shuang, Shaomin; Dong, Chuan; Gong, Xiaojuan

doi: 10.1007/s00604-020-04618-8pmid: 33399925

Nitrogen, sulfur, phosphorus, and chlorine co-doped carbon nanodots (NSPCl-CNDs) were fabricated by acid-base neutralization and exothermic carbonization of glucose. The obtained NSPCl-CNDs possess excellent fluorescence properties and good biocompatibility. Curcumin (Cur) can dramatically quench the fluorescence of NSPCl-CNDs based on a synergistic effect of electrostatic interaction, inner filter effect, and static quenching, so a “turn-off” fluorescent probe for Cur detection was constructed with linear ranges of 0.24–13.16 μM and 13.62–57.79 μM. The LOD and LOQ of this fluorescent probe for Cur are 8.71 nM and 29.03 nM, respectively. More importantly, the fluorescence of the NSPCl-CNDs-Cur system can be recovered by europium ion (Eu3+), so a “turn-on” fluorescent probe for Eu3+ determination was established. The linear range, LOD, and LOQ for the detection of Eu3+ were 2.36–32.91 μΜ, 73.29 nM, and 244.30 nM, respectively. The proposed fluorescence methods were successfully utilized for Cur and Eu3+ determination in real samples with recoveries in the range 95.64–104.13% and 97.06–98.70%, respectively. Furthermore, the qualitative analysis of Cur can be realized by reagent strips with satisfying results. Finally, the as-constructed “off-on” fluorescent probe was successfully used to sequentially analyze Cur and Eu3+ at the cellular level. This method is simple and easy to implement, manifesting that NSPCl-CNDs have potential application value in fluorescent probing, food and drug testing, environmental monitoring, and cellular labeling.Graphical abstract[graphic not available: see fulltext]

Li, Xiaoqing; Luo, Junjun; Jiang, Xingxing; Yang, Minghui; Rasooly, Avraham

doi: 10.1007/s00604-020-04667-zpmid: 33404771

A ratiometric fluorescence assay was designed for determination of dipicolinic acid (DPA), a spore-specific compound which is used as a biomarker for Bacillus anthracis spores for food and medical product safety analysis. The dual-channel fluorescence probe integrates two fluorescent materials, Eu3+ ion and gold nanocluster (Au NC). The Au NC is used as a reference channel to measure background noise and the Eu3+ ion as the DPA-specific response signal channel. The probe was prepared through simply combing bovine serum albumin (BSA)-scaffolded Eu3+ ion and Au NCs. When excited at 530 nm, in the presence of DPA, the fluorescence signals of Eu3+ ion at 595, 617, and 695 nm increased significantly while the 650 nm signal of Au NC reference remained relatively constant. This fluorescence probe has good photo-stability and also displays good selectivity and high sensitivity for DPA with a low detection limit of 0.8 μM. The linear range of the ratiometric probe for DPA is 1–50 μM. For determination of DPA released during the germination of Bacillus subtilis spores, the detection results were in agreement with measurements by conventional calorimetry assay. The method may have potential for measuring the level of contamination and germination by spores.Graphical AbstractDual-channel fluorescence biosensor was designed to detect dipicolinic acid, a spore-specific compound which is used as a biomarker for Bacillus anthracis spores for food and medical product safety analysis[graphic not available: see fulltext]

Lv, Yuanxia; Qin, Xiaohuan; Hu, Kun; Huang, Yong; Zhao, Shulin

doi: 10.1007/s00604-020-04675-zpmid: 33389155

A novel matrix-assisted laser desorption/ionization time-of-flight mass spectrometric method (MALDI-TOF MS) for determination of highly sensitive small molecular compounds was developed based on molybdenum disulfide nanosheets hybridized with ultrathin graphitic carbon nitride (MoS2/g-C3N4) as the matrix. With this approach, the synergistic effects of MoS2 and g-C3N4 enhance the UV absorption of MoS2/g-C3N4, increase both desorption and ionization efficiency in LDI MS, and induce higher signal-to-noise ratio of analytes when compared with the bare MoS2 and g-C3N4 matrix in the determination of amino acids, antibiotics, neutral oligosaccharides, uric acid, and polyethylene glycols (PEGs). The detection limits of these small molecular compounds are in the ranges 0.1 to 10 μg mL−1, 1*10−3 to 1.0 μg mL−1, 1.0 to 10 μg mL−1, and 2*10−4 μg mL−1, respectively, and the polydispersity index of these PEGs is less than 1.02. Moreover, high salt tolera`nce and homogeneous deposition on the spot results in good reproducibility. The relative standard deviations (RSDs) of shot-to-shot and spot-to-spot (n = 15) of these compounds are less than 10.1% and 12.5%, respectively. With MoS2/g-C3N4, the uric acid in complicated biological samples can be directly determined in combination with LDI-TOF MS.Graphical abstractWe synthesized MoS2/g-C3N4 nanohybrid as an efficient matrix for MALDI-TOF MS analysis of small molecules as well as quantitative detection of uric acid in human urine.[graphic not available: see fulltext]

Zhu, Junlun; Luo, Guan; Xi, Xiaoxue; Wang, Yijia; Selvaraj, Jonathan Nimal; Wen, Wei; Zhang, Xiuhua; Wang, Shengfu

doi: 10.1007/s00604-020-04690-0pmid: 33389187

A Cu2+-modified carboxylated hollow carbon nanospheres (Cu2+-HCNSs-COOH) was designed with enhanced peroxidase-like activity for the detection of hydrogen peroxide (H2O2) and degradation of methylene blue (MB). Hollow polymer nanospheres were fabricated from aniline, pyrrole, Triton-100, and ammonium persulfate via confined interfacial copolymerization reaction, which can be pyrolyzed to create HCNSs with the hollow gap diameter of about 20 nm under high temperature. Combining the synergistic effect of coordination and electrostatic interaction, Cu2+-HCNSs-COOH was constructed by anchoring Cu2+ on the surface of HCNSs-COOH. Furthermore, Cu2+-HCNSs-COOH has higher affinity for 3,3′,5,5′-tetramethylbenzidine and H2O2 of 0.20 mM and 0.88 mM, respectively. Based on the rapid response of Cu2+-HCNSs-COOH to H2O2, we constructed a colorimetric sensing platform by detecting the absorbance of the 3,3′,5,5′-tetramethylbenzidine-H2O2 system at 652 nm for quantifying H2O2, which holds good linear relationship between 1 and 150 μM and has a detection limit of 0.61 μM. We also investigated the degradation of MB in the presence of Cu2+-HCNSs-COOH and H2O2, which can degrade 80.7% pollutants within 30 min. This research developed an unusual nanozyme for bioassays and water pollution treatment, which broadened the way for the rapid development of clinical diagnostics and water pollution treatment.Graphical abstract[graphic not available: see fulltext]