Perylene diimide-based sensors for multiple analyte sensing (Fe2+/H2S/ dopamine and Hg2+/Fe2+): cell imaging and INH, XOR, and encoder logic

In this report, we present our results on the recognition of multiple analytes using trisubstituted PDI-based chemosensors DNP and DNB in 50% HEPES buffered-CH₃CN solution. Upon the addition of Hg²⁺, DNB showed a decrease and increase in absorbance intensity at 560 and 590 nm, respectively, with a detection limit of 7.17 μM and bleaching of the violet color (de-butynoxy). Similarly, the addition of Fe²⁺ or H₂S to the solution of DNP or DNB resulted in ratiometric changes (A_688nm/A_560nm) with respective detection limits of 185 nM and 27.6 nM for Fe²⁺, respectively, and a color change from violet to green. However, the addition of >37 μM H₂S caused a decrease in absorbance at 688 nm with a concomitant blue shift to 634 nm. Upon the addition of dopamine, the DNP + Fe²⁺ assay showed ratiometric (A_560nm/A_688nm) changes within 10 s along with a color change from green to violet. Moreover, DNP has been successfully used for the exogenous detection of Fe²⁺ in A549 cells. Further, the multiple outputs observed with DNP in the presence of H₂S have been used to construct NOR, XOR, INH and 4-to-2 encoder logic gates and circuits.

Cu/CuO-Doped ZnO Nanocomposites via Solution Combustion Synthesis for Catalytic 4-Nitrophenol Reduction

The synthesis of optoelectrically enhanced nanomaterials should be continuously improved by employing time- and energy-saving techniques. The porous zinc oxide (ZnO) and copper-doped ZnO nanocomposites (NCs) were synthesized by the time- and energy-efficient solution combustion synthesis (SCS) approach. In this SCS approach, once the precursor-surfactant complex ignition point is reached, the reaction starts and ends within a short time without the need for any external energy. The TGA-DTA analysis confirmed that 500 °C was the point at which stable metal oxide was obtained. The doping and heterojunction strategy improved the optoelectric properties of the NCs more than the individual constituents, which then enhanced the materials' charge transfer and optical absorption capabilities. The porosity, nanoscale crystallite size (15-50 nm), and formation of Cu/CuO-ZnO NCs materials were confirmed from the XRD, SEM, and TEM/HRTEM analyses. The obtained d-spacing values of 0.275 and 0.234 nm confirm the formation of ZnO and CuO crystals, respectively. The decrease in photoluminescence intensity for the doped NCs corroborates a reduction in electron-hole recombination. On the Mott-Schottky analysis, the positive slope for ZnO confirms the n-type character, while the negative and positive slopes of the NCs confirm the p- and n-type characters, respectively. A diffusion-controlled type of charge transfer process on the electrode surface was confirmed from the cyclic voltammetric analysis. Thus, the overall analysis shows the applicability of the less expensive and more efficient SCS for several applications, such as catalysis and sensors. To confirm this, an organic catalytic reduction reaction of 4-nitrophenol to 4-aminophenol was tested. Within three and a half minutes, the catalytic reduction result showed the great potential of NCs over ZnO NPs. Thus, the energy- and time-saving SCS approach has a great future outlook as an industrial pollutant catalytic reduction application.

2D MXene-Based Biosensing: A Review

MXene emerged as decent 2D material and has been exploited for numerous applications in the last decade. The remunerations of the ideal metallic conductivity, optical absorbance, mechanical stability, higher heterogeneous electron transfer rate, and good redox capability have made MXene a potential candidate for biosensing applications. The hydrophilic nature, biocompatibility, antifouling, and anti-toxicity properties have opened avenues for MXene to perform in vitro and in vivo analysis. In this review, the concept, operating principle, detailed mechanism, and characteristic properties are comprehensively assessed and compiled along with breakthroughs in MXene fabrication and conjugation strategies for the development of unique electrochemical and optical biosensors. Further, the current challenges are summarized and suggested future aspects. This review article is believed to shed some light on the development of MXene for biosensing and will open new opportunities for the future advanced translational application of MXene bioassays.

A perylenediimide modified SiO2@TiO2 yolk-shell light-responsive nanozyme: Improved peroxidase-like activity for H2O2 and sarcosine sensing

Although light-responsive nanozyme have been widely used in colorimetric sensing, some limitations such as poor catalytic activity, low detection efficiency, and unclear structure-activity relationships remain unresolved. Herein, we prepared an excellent light-responsive peroxidase (POD) mimic, perylenediimide (PDI-OH) modified SiO₂ @TiO₂ yolk-shell spheres (SiO₂ @TiO₂/PDI-OH), based on DFT-assisted design. The experiment and DFT calculation revealed that the enhanced POD-like activity was mainly attributed to a suitable built-in electric field among adjacent PDI-OH molecules on the surface of the SiO₂ @TiO₂ and the unique yolk-shell structure with more reaction sites of SiO₂ @TiO₂. Consequently, the highly selective and ultrasensitive detection of H₂O₂ is achieved with a detection limit (LOD) of 7.6 × 10^-8M. Further, the selective detection of sarcosine with LOD of 1.2 × 10^-7 M was also achieved by introducing sarcosine oxidase (SOx). This colorimetric assay is successfully applied to selectively detect H₂O₂ and sarcosine levels in real samples. Controlled response time, anti-interference, and the robustness of the developed colorimetric sensor are the key advantages. And the present work firstly clarifies the effect of PDIs substituents on the POD-like activity of light-responsive nanozymes and provided new guidelines to develop high-performance nanozymes for hazardous substances detection.

Copper oxide integrated perylene diimide self-assembled graphitic pencil for robust non-enzymatic dopamine detection

Exploring a robust, extremely sensitive, cost-effective and reliable assay platform for the precise analysis of dopamine (DA) has become a big challenge predominantly at the clinical level. To participate in this quest, herein, we fabricated a perylene diimide (PDI) self-assembled graphitic surface of the graphitic pencil electrode (GPE) anchored copper oxide (CuO). The self-assembled N-rich PDI led to the fast movement of ions by decreasing the bandgap and improved the electron transport kinetics with more exposed catalytic active sites, thus resulting in the robust electrochemical sensing of DA. The designed sensor exhibited good sensitivity (4 μM-1 cm-2), high structural stability, repeatability and excellent reproducibility with an RSD value of 2.9%. Moreover, the developed system showed a wide linear range (5 μM to 500 μM) and reliable selectivity even in the presence of co-existing interferants, such as ascorbic acid and uric acid. The fabricated nanohybrid was eventually employed to analyze DA in spiked physiological fluids and provided satisfactory recoveries. The designed PDI-CuO based interface also showed a very low detection limit of 6 nM (S/N = 3), consequently confirming its suitability for clinical and biological applications.

The excellent peroxidase-like activity of uniform CuCo2O4 microspheres with oxygen vacancy for fast sensing of hydrogen peroxide and ascorbic acid

The uniform CuCo₂O₄ microspheres with oxygen vacancy were firstly found to possess excellent peroxidase-like activity which is essential for constructing a rapid and facile colorimetric sensor to determine H₂O₂ and interrelated biomolecules.

Colorimetric detection of hypoxanthine in aquatic products based on the enzyme mimic of cobalt-doped carbon nitride

A colorimetric method for the rapid detection of Hx in aquatic products was established based on the peroxidase-like activity of cobalt-doped graphite phase carbon nitride (Co-doped-g-C3N4).

Trimetallic PdCuAu Nanoparticles for Temperature Sensing and Fluorescence Detection of H 2 O 2 and Glucose

The design of palladium-based nanostructures has good prospects in various applications. This paper reports a simple one-step synthesis method of PdCuAu nanoparticles (PdCuAu NPs) prepared directly in aqueous solution. PdCuAu NPs have attracted much attention owing to their unique synergistic electronic effect, optical and catalytic performance. As temperature sensor, PdCuAu NPs are sensitive to the fluorescence intensity change in the temperature range of 4-95°C, which is due to its unique optical properties. The prepared PdCuAu NPs have excellent catalytic performance for peroxidase-like enzymes. It can catalyze TMB rapidly in the presence of hydrogen peroxide and oxidize it to visible blue product (oxTMB). Based on its unique peroxidase-like properties, this study used PdCuAu NPs colorimetric platform detection of hydrogen peroxide and glucose. The linear ranges of hydrogen peroxide and glucose were 0.1-300 μM and 0.5-500 μM, respectively, and the detection limits (LOD) were 5 and 25 nM, respectively. This simple and rapid method provides a good prospect for the detection of H2O2 and glucose in practical applications.

Magnetic Cu/Fe3O4@FeOOH with intrinsic HRP-like activity at nearly neutral pH for one-step biosensing

The convenience of colorimetric sensors is useful for practical applications. In this work, we constructed a novel colorimetric sensor with magnetic separation ability that can be operated in nearly neutral conditions and achieve one-step detection of metabolites. Magnetic Cu doped Fe₃O₄@FeOOH magnetic nanocomposite (Cu/Fe₃O₄@FeOOH) with an oxygen vacancy was prepared by a one-step self-assembly hydrothermal method, and fully characterized by different methods. The oxygen vacancy generated by the incorporation of Cu²⁺ cations into the Fe₃O₄@FeOOH structure was confirmed to be a vital reactive site for enhancing the catalytic activity, which opens up a new way of designing highly efficient enzyme mimics. Benefiting from its inherent horseradish-peroxidase-like activity, a simple and selective enzyme-based colorimetric sensor was developed for one-step detection of H₂O₂ and cholesterol, and 3,3',5,5'-tetramethylbenzidine was catalyzed by H₂O₂ to generate a colored product of oxidized 3,3',5,5'-tetramethylbenzidine for signaling. H₂O₂ and cholesterol can be linearly detected in the same range from 0.01 to 0.4 mmol L^-1 with detection limits of 0.0075 mmol L^-1 and 0.0082 mmol L^-1, respectively. The proposed colorimetric sensor has satisfactory reusability, accuracy, and practicability in human serum samples, indicating its potential application for the detection of different metabolites in the fields of life science and analytical science. Graphical abstract.

Peroxidase-like activity of palladium nanoparticles on hydrogen-bond supramolecular structures over a broader pH range and their application in glucose sensing

To circumvent the complicated natural peroxidases, palladium nanoparticles embedded in melamine cyanurate (MCA-Pd NPs) were synthesized. MCA-Pd NPs catalyzed the oxidation of ABTS2– by H2O2, and the solution turned green, which could be quantified via a typical absorption peak at 420 nm. MCA-Pd NPs had high peroxidase-like activity in a wider pH range than that of natural peroxidases. MCA-Pd NPs were used to develop a colorimetric sensor for H2O2 over the pH range of 7.0 to 11.0, which had same linear range, and their linear regression equations had similar slopes. Moreover, MCA-Pd NPs were applied to establish the biosensor for glucose by using glucose oxidase (GOx); it had a linear range of 5.0–120 μmol/L, with a linear regression equation of A = 0.04926 + 0.00536C (C: μmol/L, R = 0.9960) and a detection limit of 0.3 μmol/L (3σ/slope). When we applied it to detect glucose level in human blood, satisfactory results were obtained.

Unusual Capacity Increases with Cycling for Ladder-Type Microporous Polymers

Microporous polymers using triptycene vertices and various ladder-type benzimidazole linkers are synthesized and tested as lithium-ion battery anodes. An unusual increase in performance is observed upon cycling, affording high capacities of 783 and 737 mAh g^-1 for a perylene derivative and the pyromellitic derivative after 1000 cycles. The high performance of these materials after cycling is attributed to favorable electrode morphology and high crystallinity for perylene derivative, and the presence of charge carriers for pyromellitic derivative. By studying the effect of various linkers on the electrochemical performance, structure-property relationships are proposed that can be used to guide the development of high-performance materials for lithium-ion batteries.

Porphyrin functionalized Co(OH)2/GO nanocomposites as an excellent peroxidase mimic for colorimetric biosensing

A colorimetric sensor based on the enhanced peroxidase-like activity of Por/Co(OH)₂/GO for the sensitive detection of H₂O₂ and GSH.

Nanomaterials with enzyme-like characteristics (nanozymes): next-generation artificial enzymes (II)

An updated comprehensive review to help researchers understand nanozymes better and in turn to advance the field.

Synthesis, structure and photophysical properties of dibenzofuran-fused boron dipyrromethenes

Regioselective functionalization of core per-substituted boron dipyrromethenes (BODIPYs) has been achieved efficiently based on tetrabromoBODIPY, which affords a series of dibenzofuran-fused chromophores, via a regioselective nucleophilic substitution reaction followed by direct palladium-catalyzed two-fold intramolecular ring fusion. These rigid dibenzofuran-fused BODIPYs showed impressive photophysical properties such as clearly red-shifted absorption and emission bands, enhanced absorption coefficients upon and intense fluorescence (close to unity).

Preparation of porphyrin modified CO9S8 nanocomposites and application for colorimetric biosensing of H2O2

Hydrogen peroxide detection has been widely applied in the fields of biology, medicine, and chemistry. Colorimetric detection of hydrogen peroxide has proven to be a fast and convenient method. In this work, 5,10,15,20-tetrakis(4-chlorophenyl) porphyrin modified Co[Formula: see text]S[Formula: see text] nanocomposites (H[Formula: see text]TClPP-Co[Formula: see text]S[Formula: see text] were prepared via a facile one-step hydrothermal method. H[Formula: see text]TClPP-Co[Formula: see text]S[Formula: see text] nanocomposites were demonstrated to possess an enhanced mimetic peroxidase activity toward the substrate, 3,3[Formula: see text],5,5[Formula: see text]-tetramethylbenzidine (TMB), which can be oxidized to oxTMB (oxidized TMB) in a buffer solution of hydrogen peroxide with a color change from colorless to blue. The catalytic activity of H[Formula: see text]TClPP-Co[Formula: see text]S[Formula: see text] was further analyzed by steady-state kinetics, and H[Formula: see text]TClPP-Co[Formula: see text]S[Formula: see text] had high affinity towards both TMB and H[Formula: see text]O[Formula: see text]. Furthermore, fluorescence and ESR data revealed that the catalytic mechanism of the peroxidase activity of H[Formula: see text]TClPP-Co[Formula: see text]S[Formula: see text] is due to hydroxyl radicals generated from decomposition of H[Formula: see text]O[Formula: see text]. Based on the catalytic activity of H[Formula: see text]TClPP-Co[Formula: see text]S[Formula: see text], a sensitive colorimetric sensor of H[Formula: see text]O[Formula: see text] with a detection limit of 6.803 [Formula: see text]M as well as a range of 7–100 [Formula: see text]M was designed.

Crystal structure of [(1,2-bis(dicyclohexylphosphino)-1,2-dicarba-closo-dodecaborane-κ2 P,P′]dibromidonickel(II)), C26H54B10NiBr2P2

C26H54B10NiBr2P2, monoclinic, C2/c (no. 15), a = 13.064(7) Å, b = 15.655(8) Å, c = 16.652(9) Å, β = 95.830(7)°, V = 3388(3) Å3, Z = 4, R gt(F) = 0.0603, wR ref(F 2) = 0.1364, T = 298(2) K.

Crystal structure of tris(μ2-2-(pyridin-2-yl)ethan-1-olato-κ3 N,O:O)-trithiocyanato-κN-dicobalt(III), C24H24Co2N6O3S3

C24H24Co2N6O3S3, triclinic, P1̅ (no. 2), a = 10.5658(9) Å, b = 11.1693(11) Å, c = 11.7054(14) Å, α = 79.200(1)°, β = 84.714(1)°, γ = 89.519(2)°, V = 1351.1(2) Å3, Z = 2, R gt(F) = 0.0482, wR ref(F 2) = 0.1213, T = 298 K.

Novel fluorescent probes for the fluoride anion based on hydroxy-substituted perylene tetra-(alkoxycarbonyl) derivatives

The fluoride anion (F⁻) sensing abilities of 1-hydroxyl-3,4,9,10-tetra (n-butoxyloxycarbonyl) perylene (probe 1) and 1-hydroxyl-mono-five-membered S-heterocyclic annulated tetra (n-butoxyloxycarbonyl) perylene (probe 2) were studied through visual detection experiments, UV-Vis, fluorescence, and ¹H NMR titrations. The probes were sensitive and selective for distinguishing F⁻ from other anions (Cl⁻, Br⁻, I⁻, SO₄⁻, PF₆⁻, H₂PO₄⁻, BF₄⁻, ClO₄⁻, OH⁻, CH₃COO⁻, and HPO₄²⁻) through a change of UV-Vis and fluorescence spectra. The absorption and fluorescence emission properties of the probes arise from the intermolecular proton transfer (IPT) process between a hydrogen atom on the phenolic O position of probe and the F⁻ anion. The sensing mechanism was supported by theoretical investigation. Moreover, probe-based test strips can conveniently detect F⁻ without any additional equipment, and they can be used as fluorescent probes for monitoring F⁻ in living cells.

The fluoride anion (F⁻) sensing abilities of two fluorescent probes based on hydroxy-substituted perylene tetra-(alkoxycarbonyl) derivatives were studied through visual detection experiment, UV-Vis, fluorescence, and ¹H NMR titrations.

A gold nanoparticle based colorimetric and fluorescent dual-channel probe for acetylcholinesterase detection and inhibitor screening

Based on the competitive host–guest interaction between p-sulfonatocalix[6]arene (p-SC₆A) capped AuNPs and Rhodamine B (RhB)/acetylthiocholine, a fluorescent and colorimetric dual channel probe was developed for rapid detection of AChE with high sensitivity and selectivity. The detection limit was estimated to be 0.16 mU mL⁻¹. Crucially, due to the specific host–guest interaction, the high selectivity of the bioassay permitted the discrimination of AChE from other cations and proteins including biothiols and enzymes. Furthermore, the present method was also successfully applied to determinate AChE levels and screen AChE inhibitors in real cerebrospinal fluid (CSF) samples, which suggested that our proposed method has great potential to be applied in monitoring the disease progression and drug treatment effects of Alzheimer's disease (AD).

A novel colorimetric and fluorescent dual-channel probe was developed for acetylcholinesterase detection and inhibitor screening with high sensitivity and selectivity.

Synthesis of well-dispersed Fe3O4 nanoparticles loaded on montmorillonite and sensitive colorimetric detection of H2O2 based on its peroxidase-like activity

In this study, a simple strategy for the preparation of Fe₃O₄ nanoparticles (NPs) loaded on montmorillonite as a support is reported.

N,N′-Di-carboxymethyl perylene diimide functionalized magnetic nanocomposites with enhanced peroxidase-like activity for colorimetric sensing of H2O2 and glucose

Perylene diimides functionalized Fe₃O₄ nanoparticles are demonstrated to possess a higher intrinsic peroxidase-like activity than that of pure Fe₃O₄ nanoparticles.