Colorimetric Nanosensor Research Articles

Sonochemical synthesis of graphene oxide-Ag2O nanozyme as an oxidize-like mimic for the highly sensitive detection of lithium in blood serum

Bipolar disorder is commonly treated with lithium carbonate. The concentration of lithium in the blood serum should be closely monitored in patients who require long-term lithium therapy. To date, no colorimetric method of detecting lithium ions has been reported using nanosensors. We have developed a novel chemosensor based on nanozyme (NZ) to address this clinical need. The GO-Ag2O NZs were synthesized by a sonochemical method and used as a colorimetric nanosensor to detect lithium ions in human blood serum (Li (I)). To characterize NZs, various techniques were employed, including XRD, FTIR, TEM, FESEM, EDX, Raman spectroscopy, BET, DLS, Zeta potential, and ICP-OES. According to TEM and FESEM images of GO-Ag2O, the nanoparticles (NPs) of Ag2O are uniformly distributed on the surface of 2D graphene oxide sheets. In addition, silver oxide nanoparticles exhibited a cubic morphology with an average size of 3.5 nm. We have examined the performance of the NZs in an aqueous medium and in human blood serum that contains Li (I). A colorimetric test revealed that NZs synthesized in the presence of ultrasound were more sensitive to Li (I). According to the linearity of the calibration curves’ ranges, Li (I) has a limit of detection (LOD) of 0.01 µg/mL. Furthermore, it displayed a linear range between 0 and 12 µg/mL. GO-Ag2O NZs showed noticeable color changes from green to orange after exposure to Li (I). An incubation time of two minutes was found to be the most effective for sensing. This innovative approach provides a reliable method for monitoring lithium levels and ensuring patient safety during long-term lithium therapy for bipolar disorder.

Triazole thiazole 4-Nitrobenzohydrazide Schiff base-stabilized silver nanoparticles for selective and efficient detection of neomycin

The widespread usage of antibiotics is leading to an increased negative impact on living organisms due to the consumption of polluted water containing drug residues. The emergence of drug-resistant bacteria has additionally manifested a growing need to identify commonly available medications in water sources. A rapid colorimetric nanosensor is developed in this study to selectively detect Neomycin, an antibiotic of class aminoglycosides. A straightforward reduction method was employed for the formation of Schiff base (4-nitrobenzohydrazide triazole thiazole) capped silver nanoparticles (4NHTS-AgNPs). Upon treatment with Neomycin, the colloidal solution of 4NHTS-AgNPs exhibited an immediate color change from yellow to red while no visible change was observed by addition of other competitive drugs. With an increase in drug concentration, the plasmonic characteristic peak of 4NHTS-AgNPs at 405 nm exhibited a progressive reduction. Furthermore, incubation with NeO resulted in a bathochromic shift and broadening to longer wavelength, specifically to 565 nm. The combined quenching and shift of the plasmonic peak were attributed to the aggregation of 4NHTS-AgNPs induced by the NeO through hydrogen bonding. The 4NHTS-AgNPs based sensor demonstrated a linear dynamic range of 0.02–100 μM, with a limit of detection and limit of quantification of 0.0061 μM and 0.020 μM, respectively. Even in the presence of interfering drugs and for real sample analysis, the selectivity of 4NHTS-AgNPs based sensor towards neomycin remained consistent.

Fagonia arabica extract-stabilized gold nanoparticles as a highly selective colorimetric nanoprobe for Cd2+ detection and as a potential photocatalytic and antibacterial agent

In the current study, polar leaves extract of the plant Fagonia arabica (FALE) from the Zygophyllaceae family was used to synthesize sunlight-assisted gold nanoparticles (FALE@AuNPs) with defined size and shape and of excellent colloidal stability. The effect of different physiochemical parameters (FALE dosage, Au3+ ions concentration, sunlight exposure time) on the formation of AuNPs was also studied. The synthesized FALE@AuNPs were characterized using UV–visible spectrophotometry, scanning electron microscopy-energy dispersive X-rays (SEM-EDX), Fourier-transform infrared spectroscopy (FTIR), powder XRD, zeta potential (ZP) and dynamic light scattering (DLS). The successful synthesis of FALE@AuNPs in solution was confirmed by the appearance of a localized surface plasmon resonance (LSPR) characteristic peak at 535 nm in UV–Vis spectra. The size estimated by UV–Vis (∼59 nm) was found in good agreement with that determined by SEM (∼60 nm) and DLS (∼61 nm). A zeta potential value of -28±1.5 mV confirms the colloidal stability of FALE@AuNPs. The FALE@AuNPs were utilized as a colorimetric nano-sensor for Cd2+ ion 15 nM limit of detection (LOD) and linear range detection of 0–600 nM. When utilized to identify Cd2+ ion in actual water samples, the nano-probe demonstrated high recovery rates of over 98 % and a low relative standard deviation (RSD) of about 4 %, demonstrating its dependability and efficiency in doing so. FALE@AuNPs were found to be antibacterial against gram-positive as well as gram-negative bacteria. An exceptionally high photocatalytic activity was shown by FALE@AuNPs with 80 % efficiency of degradation examined against methylene blue and methyl orange dye.

Analysis and Modification of a Colorimetric Nanosensor for Rapid Detection of Escherichia coli in Water

This research analyzed the mechanisms of work and modified a colorimetric nanosensor to make it more cost-effective for the detection of Escherichia coli (E. coli) in water. The base nanosensors modified herein rely on a competitive binding detection mechanism, where positively charged gold nanoparticles coated with polyethyleneimine (PEI-AuNPs) preferably bind to negatively charged E. coli in the presence of β-galactosidase (β-Gal) enzymes and chlorophenol red β-d-galactopyranosides (CPRG). The positive surface charge of the nanoparticle, rather than nanoparticle composition or type of chemical coating on its surface, was hypothesized herein as the governing factor for the nanosensor functionality. Thus, positively charged nanoparticles and polymers were tested as potential alternatives for gold nanoparticles for detecting E. coli. Positively charged silver and iron oxide nanoparticles coated with branched PEI detected E. coli as low as 105 and 107 colony-forming units per milliliter (CFU/mL), respectively. Furthermore, the branched PEI polymer itself (without nanomaterial) detected E. coli at 107 CFU/mL. These findings suggest that the positive charge, rather than the nanoparticle type was likely responsible for the detection of E. coli using the competitive binding approach. Therefore, other types of recyclable and cost-effective nanomaterials and polymers can be developed for E. coli detection using this rapid colorimetric sensing technique.

Highly sensitive biofunctionalized nanostructures for paper-based colorimetric sensing of hydrogen peroxide in raw milk

Hydrogen Peroxide (H2O2) is a highly hazardous, toxic, and carcinogenic chemical compound utilised in various industries-based applications. Despite strict restriction, they are deliberately added to food items such as milk as preservatives to increase its shelf life. Herein, we have formulated a green rapid colorimetric nanosensor for detection of H2O2 in milk using cotton leaves as both reducing and functionalizing agent for synthesis of silver nanoparticles (AgNPs). UV–Vis spectra exhibit a strong plasmonic peak at around 434 nm. X-Ray Diffraction (XRD) analysis was performed to determine the crystallinity of the nanoparticles. Field Emission Scanning Electron Microscope (FESEM) and Transmission Electron Microscope (TEM) characterizations revealed spherical morphology with size approximately ∼16 nm. This functionalized nanoparticle could colorimetrically sense presence of H2O2 in milk samples both in liquid media and on paper substrates with Limit of Detection (LOD) of 8.46 ppm even in presence of other interfering substances in milk. This inexpensive route will pave the way for in depth research.

Paper-based colorimetric nanosensor for detecting halides in aqueous media

The selective detection of halides in aqueous samples is crucial for addressing environmental and physiological concerns. Consequently, the development of an affordable, portable, and user-friendly sensing platform for rapid halide detection holds substantial promise. In this study, we present a novel paper-based nanosensor as an appealing alternative for selectively detecting halides in water. This nanosensor leverages the optical properties of silver nanoparticles (ranging from 50 to 250 nm) embedded in epoxy resin and printed on filter paper. We elucidate the colorimetric behavior of this nanosensor in response to specific halides (chloride, bromide, and iodide) upon contact. Importantly, this sensor discerns, through a single measurement, the presence of these halides in aqueous media with remarkable selectivity. The nanosensor manifests distinct color changes in reaction to different halides, particularly at elevated concentrations (ranging from 2 to 400 mM), surpassing the saturation levels observed in other proposed sensors. These discernible color changes are due to the oxidation of silver nanoparticles, changing their morphology and aggregation density, and can be readily detected and analyzed directly from a captured image. Consequently, it demonstrates considerable potential for integration into automated qualitative monitoring devices based on chromaticity analysis.

Plasmon-based colorimetric assay using green synthesized gold nanoparticles for the detection of bisphenol A.

Herein, we report a green synthesized gold nanoparticle (AuNPs) based colorimetric detection of bisphenol A (BPA). The AuNPs were synthesized using khat leaf extract as a reducing agent by optimizing factors affecting the AuNPs synthesis, including gold precursor concentration (1mM), and reaction temperature (60°C). The AuNPs characterization was carried out using ultraviolet-visible spectrophotometry and transmission electron microscopy, and it was found spherical with an average particle size of 17.3 ± 3.7nm. A colorimetric nanosensor was developed by conjugation of bio-inspired AuNPs with BPA-specific aptamer for a quick and easy detection of BPA in plastic bottled water. The colorimetric assay relies on the strong affinity of BPA for aptamer, which causes detachment of the aptamer from the AuNPs surface in the presence of BPA inducing AuNPs aggregation. To achieve the colorimetric detection of BPA, the concentrations of NaCl and aptamer were optimized. The detection of BPA was monitored visually using a naked eye, as well as quantitatively using an ultraviolet-visible spectrophotometer. The method visual limit of detection (LOD) was determined to be 0.1ng/mL and reached 0.09ng/mL using ultraviolet-visible spectrophotometer. The method demonstrated very good linearity (R2 = 0.9986) in the range of 0.1-100ng/mL. The proposed method showed high sensitivity to BPA detection in plastic bottled water with 86.7-98.0%, recovery. Therefore, the proposed colorimetric nanosensor can be used for determination of BPA in plastic bottled waters with reliable performance at lower concentrations.

Polydiacetylene based colorimetric nano-sensor for on-spot detection of aflatoxin in food matrices and animal feed

Global food security is constantly being challenged by the prevalence of aflatoxin (AF), a carcinogenic mycotoxin found in various staple foods consumed across the globe. This challenge is further compounded by unavailability of convenient, on-field aflatoxin sensing devices. In this study, liposome sensors conjugated with polydiacetylene (PDA) have been developed for robust, low-cost, on-site quantification of aflatoxin from feed samples assisted by a convenient mobile phone-based application. Soyabean-sourced phosphatidylcholine (content ≥ 94.0%) demonstrated to be a stronger structural backbone for developed lipoid sensor and is comparatively cheaper and sustainable alternative to conventional backbones like synthetic 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) and dipalmitoylphosphatidylcholine (DPPC) for the preparation of based liposomes. Anti-aflatoxin antibodies conjugated with chemically activated liposomes provide a consistent chromatic response with aflatoxin. These sensors were used to detect the presence of aflatoxin in food and animal feed matrices. The detection time of the developed sensor was 5 min and can provide rugged and reliable detection of AFB1 up to the limit of 5.7 parts per billion (ppb).

Polyethylene glycol (PEG) stabilized silver nanoparticles as colorimetric nano-sensor for diazinon detection in water

Polyethylene glycol (PEG) stabilized silver nanoparticles as colorimetric nano-sensor for diazinon detection in water

Bioinspired gold nanoparticles-based colorimetric nanosensor for detection of antimony in plastic bottled water

Bioinspired gold nanoparticles-based colorimetric nanosensor for detection of antimony in plastic bottled water

An achromatic colorimetric nanosensor for sensitive multiple pathogen detection by coupling plasmonic nanoparticles with magnetic separation

Rapid screening of multiple pathogens will greatly improve the efficiency of pandemic prevention and control. Colorimetric methods exhibit the advantages of convenience, portability, low cost, time efficiency, and free of sophisticated instruments, yet usually have difficulties in simultaneous detection and suffer from monotonous color changes with low visual resolution and sensitivity. Hence, coupled three kinds of plasmonic nanoparticles (NPs) with magnetic separation, we developed an achromatic colorimetric nanosensor with highly enhanced visual resolution for simultaneous detection of SARS-CoV-2, Staphylococcus aureus, and Salmonella typhimurium. The achromatic nanosensor was composed of SARS-CoV-2-targeting red gold NPs, S. aureus-targeting yellow silver NPs and S. typhimurium-targeting blue silver triangle NPs mixed as black color. In the detection, three corresponding magnetic probes were added into the above mixture. In the presence of a target pathogen, it would be recognized and combined with corresponding colored reporters and magnetic probes to form sandwich complexes, which were removed by magnetic separation, and the sensor changed from black to a chromatic color (the color of the reporters remained in supernatant). Consequently, different target pathogen induced different color. For example, SARS-CoV-2, S. aureus, and S. typhimurium respectively produced green, purple, and orange. While coexistence of S. aureus and S. typhimurium produced red, and coexistence of S. aureus and SARS-CoV-2 produced blue, etc. Therefore, by observing the color change or measuring the absorption spectra, multiple pathogen detection was achieved conveniently. Compared with most colorimetric sensors, this achromatic nanosensor involved rich color change, thus significantly enhancing visual resolution and inspection sensitivity. Therefore, this sensor opened a promising avenue for efficient monitoring and early warning of food safety and quality.

Orange Pomace Facilitated Synthesis of Cu2O/ZnO Nanocomposites for Visual and Optical Sensing of Silver Ions in Water for Environmental Remediation

AbstractThe presence of silver ions at toxic concentrations in wastewater has provoked many scientists to design novel methods to detect silver ions in water. Employing agro‐waste to design nanomaterials has incited the use of orange pomace to design fruitful and biocompatible nanomaterials for endorsing sustainable and green methods. Herein, we report a sensitive and selective colorimetric detection of silver ions employing biogenically synthesized Cu2O/ZnO nanocomposites (NCs). The Cu2O/ZnO NCs were fabricated using orange pomace (OP) holistically acting as a stabilizing and reducing agent. Sensing ability of Cu2O/ZnO NCs synthesized via greener route for the presence of different metal ions such as Na+, Ca2+, Cd2+, Sr2+, Ag+, Ni2+, Fe2+, Pb2+, Mg2+, and K+ has been examined at room temperature. A naked eye colour change form slight yellowish to black was noticed in case of silver ions, this is confirmed by the shifting of maximum wavelength from 453 nm to 362 nm. Thus, in this work Cu2O/ZnO NCs was demonstrated as an extremely specific and selective colorimetric nanosensor for silver ions in water and showed a good linearity over the range of 20 μM–2 mM and a limit of detection (LOD) of 13.1 μM. The green fabrication of nanosensor for silver ions further maintain the sustainability of environment and encourage the researchers for greener fabrication of colorimetric sensors.

A novel colorimetric biosensor for rapid detection of dengue virus upon acid-induced aggregation of colloidal gold.

The dengue virus, once transmitted to people through a mosquito bite, causes an infectious disease called dengue fever. Dengue fever can develop into two fatal syndromes, namely dengue shock syndrome and dengue hemorrhagic fever. The existing strategies for detecting dengue infection mainly employ serological immunoassays and a real time PCR technique. Along with the positive features of efficiency, accuracy, and reproducibility, these procedures are limited by being time-consuming, costly, requiring special equipment for analysis, and unable to be carried out at the point-of-care level. Herein, we developed a colorimetric nanosensor for detecting dengue virus in clinical samples that is rapid, accurate, sensitive, and less expensive. The sensing platform relies on the specific binding between the DNA-conjugated AuNPs and genomic RNA of dengue, which results in the DNA-RNA heteroduplex structure formation that turns the gold colloid's ruby red color to blue due to the nano-aggregation in an acidic environment, which can be detected by the naked eye or measuring the absorbance. The DNA probe was designed to bind to a genomic RNA conserved region recognized in all four dengue serotypes. Dengue virus serotype 1 was utilized as a framework for virus detection; the designed nanosensor exhibited great specificity and selectivity, with the detection limit of ∼1 pg μL-1 (∼1.66 × 106 RNA copies per reaction) and time of analysis of about 1 h including the RNA extraction step. The proposed colorimetric nanosensor offers an alternative tool for specific and highly sensitive detection of dengue that eliminates the requirement for thermal cycling and primer sets in PCR-based assays.

A novel polymeric nanocomposite based on TiO2 NPs containing β-cyclodextrin membrane for ultratrace naked-eye detection of Pb and Cd ions

A unique, selective, and sensitive colorimetric nanosensor for the naked-eye detection and adsorption of Pb(II) and Cd(II) in aqueous media has been synthesized based on the organic–inorganic hybrid. Acrylamide (AM) and 2-acrylamido-2-methylpropanesulfonic acid (AMPS) as hydrophilic monomers, functionalized β-cyclodextrin (f-β-CD) as host-guest complex formation agent, and vinyl-dithizone (f-DTZ) as an efficient ligand were used. The β-CD with a hydrophobic interior and hydrophilic exterior can form a host-guest inclusion complex with a ligand that enhances nanosensors’ dispersion in aqueous media. The immediate color change of the sensor has been observed from gray to pink and blue for Pb(II) and Cd(II) with a wide linear range of [(1 ppb- 40 ppb)] and [(1 ppb- 60 ppb)], respectively. This study also considered the adsorption qualities of these heavy metals under various factors, including pH, time length, and initial ion concentration. The maximum adsorption capacity of Cd(II) via polymeric nanocomposite was 166 mg·g−1 at optimum condition. The experimental info has been investigated using the Langmuir and Freundlich isotherms and the pseudo-first-order and pseudo-second-order kinetic models.

Designing a colorimetric nanosensor based on dithizone and cholesteric liquid crystals loaded in electrospun cellulose acetate nanofibers: Monitoring the quality of pistachio as a case study

AbstractWe describe colorimetric electrospun nanosensors designed to work at temperatures of 35–36°C. The mode of operations is based on a combination of the ability of dithizone to exhibit appropriate color and cholesteric liquid crystals presenting a wide range of melting points at various mixing ratios. To this end, different levels of dithizone (IUPAC name 1‐anilino‐3‐phenyliminothiourea), different ratios of cholesteric liquid crystals to cellulose acetate and cholesteryl oleyl carbonate to cholesteryl nanoate were defined as independent variables and the total color difference was considered as the response in the response surface methodology approach. The results showed that the range of color palette changes of the designed samples was diverse and could be applied to different products. As a case study, the applicability of the sensor was evaluated on the 4‐month shelf life of pistachio nuts at 35°C whilst the spoilage criteria were reconciled with the color changes in the designed sensor.

A sensitive dual mode turn-on fluorescence and colorimetric nanosensor for ultrasensitive detection of trace amount of gluten proteins in bread products based on crystalline nano cellulose and gold nanoparticles

In this work, Gold nanoparticles (AuNPs) encapsulated in the surface of crystalline nano cellulose grafted poly citric acid (CNC-g-PCA) and CNC-g-PCA/Au nanocomposite were synthesized successfully that exhibited stable and intense fluorescence property in aqueous buffer. A dual-mode nanosensor is reported with both colorimetric and fluorimetric readout based on citrate-protected AuNPs for discriminative detection of gluten proteins. The proposed sensing system consists of AuNPs and fluorescent CNCs, where CNCs function as a fluorimetric reporter and AuNPs serve a dual function as a colorimetric reporter and fluorescence quencher. The mechanism of the reported dual-mode nanosensor is based on two distance-dependent phenomena, the color change of AuNPs and FRET. The presence of gluten proteins can reverse the process by enlarging the inter-particle distance between AuNPs and CNCs and recovering the fluorescence emission of CNC. The linear range was 0.05 to 0.40 μgmL−1 for UV–vis spectroscopy and 0.017 to 0.298 μgmL−1 for fluorescence spectroscopy, The limit of detection was 4.43 ± 0.019 ngmL−1 for UV–vis spectroscopy and 3.13 ± 0.033 ngmL−1 for fluorescence spectroscopy (n = 6). The fabricated nanosensor was applied to the gluten analysis in gluten-free bread successfully.

Enzyme-free colorimetric nanosensor for the rapid detection of lactic acid in food quality analysis

Lactic acid is an essential organic chemical in food, clinical, chemical, and bioprocessing industries. We are reporting for the first time, a rapid and facile enzyme-free colorimetric sensor for the detection of lactic acid (LA) in food samples using nitrophenol ( p -NP) added copper nanoparticles (CuNPs). The responses of p -NP (5 mmol/L) to lactic acid in the presence of CuNPs were reported by analysing the UV-VIS absorption spectra in an aqueous solution. CuNPs were synthesized by the chemical reduction method and were identified to be in the Cubic phase using XRD analysis. The sample characterization studies were performed using the SEM, UV for obtaining good optical and selective lactic acid-sensing properties. The sensing mechanism is due to the aggregation responses of CuNPs conjugated p -NP in the presence of lactic acid as seen in the UV-VIS absorption spectra shift studied in an aqueous solution. The absorption spectrum of p -NP exhibited one intense band at 402 nm in the presence of CuNPs. Although the addition of lactic acid may cause π –π* transitions led to a hypsochromic shift (blue shift) with a subtle decrease in the wavelength from 402 to 315 nm, the solution underwent from being colored (greenish-yellow) to colorless. The stoichiometric ratio of a binding event is explained using Job's plot. The naked eye colorimetric response of the sensor-enabled detection limit of lactic acid to 0.33 mM. The sensor studies were compared with standard LC-MS/MS revealing a good recovery (95%) in food samples. This method is facile and alternate to the current high-cost techniques and enzymatic sensors. Schematic illustration of colorimetric sensor- CuNPs assisted catalytic reduction of p -nitrophenol (colored) to p -aminophenol (colorless) with the exposure of lactic acid. • Nonenzymatic colorimetric nanosensor for lactic acid detection. • The visual detection of trace amounts of lactic acid as low as 0.33 mM. • Sensor is based on the catalytic activity of copper nanoparticles. • Application of developed sensor for real time food sample analysis.

Colorimetric Nanosensor for the Determination of Glyphosate Herbicide in Aqueous Solutions

Detection of pesticides depends on complex, time-consuming, and costly techniques performed only in some regions of Brazil. Thus, this study aimed to develop a sensitive, portable, easy-to-handle, and fast nanosensor to determine the presence of glyphosate in aqueous solutions. The Co(OH)2 nanostructure was synthesized, and the kinetic study of the interaction with pesticide glyphosate-based was performed. The Co(OH)2 nanostructures had a fast and effective interaction, confirmed by UV-Visible spectroscopy. Through experimental planning, the process for obtaining nanostructures has been optimized, and the nanostructures obtained were in a size range of 434.2 nm with a hexagonal nanoplate structure. The lower limit of color-based glyphosate detection was 0.178 g.L-1. It was possible to identify the herbicide in the water of the tomato and sugar cane rinse by the change of the watercolor into pink. Although the samples showed low absorbance, the color change was noticeable to the naked eye. Therefore, to synthesize a structure that allows identifying glyphosate in a colorimetric way.

Poly (ethylene glycol)-400 crowned silver nanoparticles: a rapid, efficient, selective, colorimetric nano-sensor for fluoride sensing in an aqueous medium

Poly (ethylene glycol)-400 crowned silver nanoparticles: a rapid, efficient, selective, colorimetric nano-sensor for fluoride sensing in an aqueous medium

Paper-based plasmonic nanosensor monitors environmental lead pollution in real field

Development of a low-cost portable colorimetric nanosensor for real field pollution monitoring.