Concentration Detection Limit Research Articles

Enhanced ethanol sensors based on MOF-derived ZnO/Co3O4 bimetallic oxides with high selectivity and improved stability

ZnO/Co3O4 ethanol sensors based on metal-organic framework (MOF-74) were prepared by one-step hydrothermal method. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and gas-sensitive tests were performed. The gas sensing test results show that MOF-derived ZnO/Co3O4 (ZnO/Co3O4-MOF1:2) has higher sensitivity, better selectivity, and lower operating temperature than ZnO/Co3O4 without MOF template (ZnO/Co3O4–N1:2). The response value of ZnO/Co3O4-MOF1:2–50 ppm ethanol gas can reach 19.75, which is 13 times higher than that of ZnO/Co3O4–N1:2. Moreover, ZnO/Co3O4-MOF1:2 has excellent selectivity, outstanding reproducibility and good stability. The limit of detection concentration is up to 500 ppb. The improved ethanol sensing performance of MOF-74-derived ZnO/Co3O4 is mainly due to the porous structure of MOF-74 with a large number of internal pores, which provides more active sites for the surface adsorption and desorption of gas molecules. In addition, the amount of surface-defective and adsorbed oxygen involved in the sensing reaction is significantly increased, leading to a larger change in resistance during the redox reaction and a higher final response.

Fluorescence Enhancement of a Metal-Organic Framework for Ultra-Efficient Detection of Trace Benzene Vapor.

Indoor detection of volatile organic compounds (VOCs) concentration is necessary due to the serious toxicity hazards even at trace level. However, physisorbents usually exhibit weak interactions especially in the presence of trace concentrations of VOCs, thus exhibiting poor responsive signal. Herein, we report a new flexible metal-organic framework (MOF) that exhibits interesting pore-opening behavior after immersing in H2 O. The pore-opening phase shows significant (≈116 folds) and extremely fast (<1 minute) fluorescence enhancement after being exposed to saturated benzene vapor. The limit of detection concentration for benzene vapor can be calculated as 0.133 mg L-1 . Thus this material represents the first MOF to achieve visual detection of trace benzene vapor by the naked eyes. Theoretical calculations and single-crystal structure reveal that the special "bilateral π-π stacking" interactions between the host and guest, which facilitate electron transfer and greatly enhance the intensity of fluorescence.

Fluorescence Enhancement of a Metal‐Organic Framework for Ultra‐Efficient Detection of Trace Benzene Vapor

AbstractIndoor detection of volatile organic compounds (VOCs) concentration is necessary due to the serious toxicity hazards even at trace level. However, physisorbents usually exhibit weak interactions especially in the presence of trace concentrations of VOCs, thus exhibiting poor responsive signal. Herein, we report a new flexible metal–organic framework (MOF) that exhibits interesting pore‐opening behavior after immersing in H2O. The pore‐opening phase shows significant (≈116 folds) and extremely fast (&lt;1 minute) fluorescence enhancement after being exposed to saturated benzene vapor. The limit of detection concentration for benzene vapor can be calculated as 0.133 mg L−1. Thus this material represents the first MOF to achieve visual detection of trace benzene vapor by the naked eyes. Theoretical calculations and single‐crystal structure reveal that the special “bilateral π–π stacking” interactions between the host and guest, which facilitate electron transfer and greatly enhance the intensity of fluorescence.

A Compact UV-LED-Induced Fluorescence With Short Metal Capillary and Low Light Leakage: Application to Noninvasive Glucose Detection

Laser-induced fluorescence (LIF) is one of the most sensitive techniques for detection. As for the LIF with UV excitation, replacing UV laser with UV LED (i.e., UV LED-IF) has advantages of long life time and low cost. However, for LED-IF, the background signal (noise) would be much higher, due to the poor beam quality of LED. Here, an axial-excitation UV LED-IF with short metal capillary (MC) and black sealing (i.e., MC-LED-IF) was proposed for noninvasive detection of human saliva glucose (HSG). The SNR was improved 3.1-fold by employing the black sealing, due to the effective suppression of the background signal, which mainly results from light leakage. Moreover, the transmission loss of UV LED light in MC and saliva-filled MC was investigated, and an optimal MC length of only 4 cm was obtained. By using the MC-LED-IF, a detection limit of concentration (DLC) of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2.4 \mu \text{M}$ </tex-math></inline-formula> was realized for detecting HSG via conventional 3-(4-hydroxyphenyl)-propionic acid (HPPA) reagent with good selectivity and reliability. The MC-LED-IF features low cost and compact ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$11\times 4\times $ </tex-math></inline-formula> 4 cm), which is suitable for personal use.

Area under curve and zero order spectrophotometric determination copper complexation with N,N'-cyclohexane-l,2-diylidene-bis(4-methaxybenzoythydrazide)

This paper describes the development of a spectrophotometric for the determination of copper by coupling with ligand (CHMBH). The a maximum absorption at (415nm) .Beer’s Lambert law is obeyed over the concentration ( 4-24 mg/L) limit of detection and limit of quantitation were found to be 0.00338 mg/L and 0.01025 mg/L for the area under curve and 0.1677 mg/L and 0.508 mg/L for zero order method, the high accuracy of both methods was 99.356 % for the area under curve method and 100.087 % for the zero order method respectively. Both methods have applied successfully to determination of copper with (CHMBH).Keywords: Cu(ll), (CHMBH), (AUC), zero order.

Sensing and simulation of self-inductance of a flat, circular coil in the presence of four water-based nanofluids

Inductive sensors (ISs) are extremely sensitive sensing platforms that offer high resolution and currently serve as a relatively popular sensing platform for the detection of metals, nonmetals, and semiconductors. However, in spite of wonderful usability, there is a startling lack of IS implementation as a chemical sensor. Similarly, nanofluids (NFs) have gained more traction in the past decade since the physical properties of base fluids become heightened with the addition of nanoparticles (NPs). Regardless of these advantages, both areas lack studies regarding the behavior of NFs under a magnetic field (B-field). We show how a novel technique using a high-resolution, non-invasive inductance-to-digital converter (LDC) sensor is used to detect different NFs of varying physical properties. The LDC proves highly capable of not only serving as an extremely accurate and precise chemical sensor but also allowing us to determine how exposing several NFs to an inductor's B-field affects particle behavior in solution with extremely low signal and concentration detection limits. The four NF systems contain diamond, rutile, magnetite, and gold NPs where the sensor demonstrated superior sensitivity to gold-enhanced NFs. This exciting finding followed expected theoretical trends based on Faraday's laws of magnetism, and the experimental results were validated with finite element simulations within less than 1.0% error.

Simple Sensor Application: Determination of Electrochemical Properties of Carvedilol in CPE Based on Zinc Oxide Nanoparticles and Development of the Method for its Determination in Pharmaceutical Samples

In the study, the electrochemical characteristics of carvedilol were determined by cyclic voltammetry and square wave voltammetry on carbon paste electrode with zinc oxide nanoparticles at pH 8.0 in Britton Robinson buffer. The adsorption characteristics of the molecule on the modified electrode and the electron number accompanying the electrode reaction were calculated. In addition, a new square wave anodic adsorptive stripping voltammetry process was suggested for the determination of carvedilol drug samples. The linear concentration range and detection limit of the process were found to be 0.07 µM–2.61 µM and 0.09 µM, respectively. Recovery studies of CAR in the pharmaceutical sample were performed to check the accuracy of the developed process. With the developed process, results with high reliability, reproduceability, accuracy and precision were obtained for the determination of CAR in pharmaceutical samples.

On-chip ultrasensitive and rapid hydrogen sensing based on plasmon-induced hot electron–molecule interaction

Hydrogen energy is a zero-carbon replacement for fossil fuels. However, hydrogen is highly flammable and explosive hence timely sensitive leak detection is crucial. Existing optical sensing techniques rely on complex instruments, while electrical sensing techniques usually operate at high temperatures and biasing condition. In this paper an on-chip plasmonic–catalytic hydrogen sensing concept with a concentration detection limit down to 1 ppm is presented that is based on a metal–insulator–semiconductor (MIS) nanojunction operating at room temperature and zero bias. The sensing signal of the device was enhanced by three orders of magnitude at a one-order of magnitude higher response speed compared to alternative non-plasmonic devices. The excellent performance is attributed to the hydrogen induced interfacial dipole charge layer and the associated plasmonic hot electron modulated photoelectric response. Excellent agreements were achieved between experiment and theoretical calculations based on a quantum tunneling model. Such an on-chip combination of plasmonic optics, photoelectric detection and photocatalysis offers promising strategies for next-generation optical gas sensors that require high sensitivity, low time delay, low cost, high portability and flexibility.

Topological insulator Bi2Se3 for highly sensitive, selective and anti-humidity gas sensors

Chemiresistive gas sensors generally surfer from low selectivity, inferior anti-humidity, low response signal or signal-to-noise ratio, severely limiting the precise detection of chemical agents. Herein, we exploit high-performance gas sensors based on topological insulator Bi2Se3 that is distinguished from conventional materials by robust metallic surface states protected by time-reversal symmetry. In the presence of Se vacancies, Bi2Se3 nanosheets exhibit excellent gas sensing capability toward NO2, with a high response of 93% for 50ppm and an ultralow theoretical limit of detection concentration about 0.06ppb at room temperature. Remarkably, Bi2Se3 demonstrates ultrahigh anti-humidity interference characteristics, as the response with standard deviation of only 3.63% can be achieved in relative humidity range of 0-80%. These findings are supported by first-principles calculations, with analyses on adsorption energy and charge transfer directly revealing the anti-humidity and selectivity. This work may pave the way for implementation of exotic quantum states for intelligent applications.

Signal-to-Noise Ratio Analysis for the Voltage-Mode Read-Out of Quartz Tuning Forks in QEPAS Applications

Quartz tuning forks (QTFs) are employed as sensitive elements for gas sensing applications implementing quartz-enhanced photoacoustic spectroscopy. Therefore, proper design of the QTF read-out electronics is required to optimize the signal-to-noise ratio (SNR), and in turn, the minimum detection limit of the gas concentration. In this work, we present a theoretical study of the SNR trend in a voltage-mode read-out of QTFs, mainly focusing on the effects of (i) the noise contributions of both the QTF-equivalent resistor and the input bias resistor RL of the preamplifier, (ii) the operating frequency, and (iii) the bandwidth (BW) of the lock-in amplifier low-pass filter. A MATLAB model for the main noise contributions was retrieved and then validated by means of SPICE simulations. When the bandwidth of the lock-in filter is sufficiently narrow (BW = 0.5 Hz), the SNR values do not strongly depend on both the operating frequency and RL values. On the other hand, when a wider low-pass filter bandwidth is employed (BW = 5 Hz), a sharp SNR peak close to the QTF parallel-resonant frequency is found for large values of RL (RL > 2 MΩ), whereas for small values of RL (RL < 2 MΩ), the SNR exhibits a peak around the QTF series-resonant frequency.

Graphene Quantum Dots Incorporated UiO-66-NH 2 Based Fluorescent Nanocomposite for Highly Sensitive Detection of Quercetin

Quercetin can help with a variety of health problems. Most methods for measuring quercetin in biological fluids are characterized by low sensitivity and selectivity. The employment of metal–organic frameworks in sensor applications with carbon-based materials ushers in a new era. In this study, blue fluorescent graphene quantum dots (GQDs) embedded in a UiO-66-NH₂ metal–organic framework-based nanoprobe (GQDs@UiO-66-NH₂) were constructed for quercetin sensing. Initially, maize husk was used to produce blue fluorescent GQDs, whereas zirconium tetrachloride and 2-aminoterephthalic acid were used to synthesize extremely luminous UiO-66-NH₂. The addition of quercetin to GQDs@UiO-66-NH₂ leads to fluorescence dampening due to the adsorption potential of UiO-66-NH₂. The complexation of zirconium ions with the 3-OH and 4-C＝O functionalities of quercetin resulted in fluorescence quenching. The sensor has a linear concentration range and limit of detection for quercetin of 50–500 and 2.82 ng/mL, respectively. The nanoprobe’s usefulness for quercetin detection was then validated by a selectivity investigation in the presence of interfering chemicals. Furthermore, the percentage relative standard deviations were 4.20% and 2.90%, respectively, indicating great stability and repeatability. Fluorescence “Turn-On–Off” nanoprobes provide a simple, quick, sensitive, and selective method for monitoring quercetin.

Using eDNA sampling for species-specific fish detection in tropical oceanic samples: limitations and recommendations for future use.

Over the past decade, environmental DNA (eDNA) has become a resourceful tool in conservation and biomonitoring. Environmental DNA has been applied in a variety of environments, but the application to studies of marine fish, particularly at tropical latitudes, are limited. Since many commercially important Caribbean fishes are overexploited, these species are optimal candidates to explore the use of this method as a biomonitoring tool. Specifically, for many of these species, the formation of fish spawning aggregations (FSAs) marks a critical life history event where fishes will gather in large numbers for reproduction. These FSAs are ephemeral in nature, lasting only a few days, but are predictable in time and space which makes them susceptible to overfishing. In this study, we test the feasibility of using an eDNA sampling approach (water and sediment collection) to detect the presence of known FSAs off the west coast of Puerto Rico, with cytochrome c oxidase subunit 1 (CO1) and 12S rRNA (12S) primers designed to target specific species. A total of 290 eDNA samples were collected and, of those, 206 eDNA samples were processed. All eDNA samples varied in DNA concentration, both between replicates and collection methods. A total of 12 primer sets were developed and tested using traditional PCR and qPCR. Despite validation of primer accuracy and sample collection during known peak spawning times, the use of traditional PCR and qPCR with both molecular markers failed to produce species-specific amplification. Thus, a trial test was conducted using the CO1 primers in which target fish DNA was 'spiked' at various concentrations into the respective eDNA samples to determine the target species DNA concentration limit of detection. Upon successful amplification of the trial, results indicated that eDNA samples were below the detection threshold of our methods, suggesting that the number of fish present at the spawning aggregations was inadequate for single-species detection methods. In addition, elements such as the unavoidable presence of non-target DNA, oceanic environmental conditions, shedding rates of target fish, among other biotic and abiotic factors could have affected DNA persistence and degradation rates at the sites. We provide recommendations for species-specific fish detection in lower latitudes, and suggestions for studies aiming to monitor or detect fish spawning aggregations using eDNA sampling.

A Developed Colorimetric Assay Using Unmodified Gold Nanoparticles for the Identification of Acinetobacter baumannii Isolates from Different Clinical Samples

Acinetobacter baumannii (A. baumannii ) is considered a critical healthcare problem for patients in intensive care units due to its high ability to be multidrug-resistant to most commercially available antibiotics. The aim of this study is to develop a colorimetric assay to quantitatively detect the target DNA of A. baumannii based on unmodified gold nanoparticles (AuNPs) from different clinical samples (burns, surgical wounds, sputum, blood and urine). A total of thirty-six A. baumannii clinical isolates were collected from five Iraqi hospitals in Erbil and Mosul provinces within the period from September 2020 to January 2021. Bacterial isolation and biochemical identification of isolates were carried out followed by DNA extraction from 36 isolates and six negative ATCC strains (Salmonalle typhi, Escherichia coli, Klebsiella pneumonia, Pseudomonas aeruginosa, Enterobacter aeruginosa, Staphylococcus aures) and only one positive control ATCC A. baumannii using Phenol/Chloroform method. AuNPs were synthesized using the citrate reduction method and examined by XDR, FTIR, UV-VIS, FE-SEM, and TEM. The optimized colorimetric assay was employed based on unmodified spherical AuNPs and PCR amplification of 16S rRNA intergenic spacer sequences (ITS) with species-specific DNA oligo-targeters. Detection and optimization of A. baumannii amplicons using unmodified AuNPs were performed based on species-specific DNA oligonucleotide. The AuNPs assay was able to colorimetrically detect and distinguish A. baumannii from other ATCC bacterial isolates. The turnaround time of this assay was about 3 hours, including sample preparation and amplification, to show (0.025-6 ngµl-1) as a detection limit of DNA concentration. The efficacy of colorimetric detection was proved to effectively diagnose A. baumannii isolates with high sensitivity, simplicity, and robustness to rapidly diagnose A. baumannii isolates from different clinical samples.

Novel biosensor platform for glucose monitoring via smartphone based on battery-less NFC potentiostat

Near-field communication (NFC) was used to control a portable glucose biosensor for diabetes diagnosis. The system comprised a smartphone and an NFC potentiostat connected to a screen-printed carbon electrode (SPCE) modified with Prussian blue-graphene ink and functionalized with gold nanoparticles-embedded poly (3,4ethylene dioxythiophene):polysulfonic acid coated with glucose oxidase (GOx-AuNPs-PEDOT:PSS/PB-G). GOx catalyzed the glucose redox reaction while the conductivity and sensitivity of the AuNPs-PEDOT:PSS composite enhanced electron transfer to the PB‐G, which was used as a mediator. The fabrication process was characterized by scanning electron microscopy (SEM) with energy dispersibe x-ray analysis (EDX). The platform was electrochemically characterized by electrical impedance spectroscopy (EIS) and cyclic voltammetry (CV). The NFC biosensing device was then applied to quantify glucose in human blood serum by amperometry. The linear concentration range and detection limit for glucose were 0.5–500 μM and 0.15 μM, respectively. The accuracy of the device was good and results were in agreement with the results obtained from the standard hospital method. This NFC glucose sensing device can be a simple, sensitive, selective and portable platform for medical diagnosis.

Fabrication of an electrochemical aptasensor for the determination of sarcosine based on synthesized CuCo2O4 nanosheets.

Sarcosine (SRN) detection in body fluids is related to the diagnosis of prostate cancer. However, the development of SRN biosensors has been limited due to the low concentration of SRN in body fluids. Here, a new electrochemical strategy for selective and accurate determination of SRN in urine samples is reported. CuCo2O4 nanosheets (CuCo2O4 NSs) have been synthesized and used as a new platform in the design of efficient electrochemical aptasensors for prostate cancer diagnosis. As far as we know, CuCo2O4 NSs have not been used so far in electrochemical aptasensor design. The presence of CuCo2O4 NSs on the electrode surface as a platform improves the conductivity and surface area. Therefore, it can be very effective in improving the diagnostic performance of the electrochemical aptasensor. The linear concentration range and limit of detection (LOD) for this strategy were calculated to be 1 pM- 8 μM and 350 fM, respectively.

Detection of rabies virus via exciton energy transfer between CdTe quantum dots and Au nanoparticles.

Rabies is a fatal encephalitis caused by the rabies virus. The diagnosis of the disease depends in large part on the exposure history of the victim and clinical manifestations of the disease. Rapid rabies diagnosis is an important step in its prevention and control. Therefore, for accurate and timely diagnosis and prevention of rabies, we developed nanomaterials for a novel photoelectrochemical biosensing approach (PBA) for the rapid and reliable diagnosis of rabies virus. This approach uses high-efficiency exciton energy transfer between cadmium telluride quantum dots and Au nanoparticles and is low cost, and easy to miniaturize. By constructing PBA, rabies virus can be detected quickly and with a high degree of sensitivity and specificity; the minimum detection concentration limit for rabies virus is approximately 2.16 ffu/mL of rabies virus particles, or 2.53 × 101 fg/mL of rabies virus RNA. PBA could also detect rabies virus in the brain and lung tissue from rabid dogs and mice with better sensitivity than RT-PCR.

Rapid identification of Ralstonia pickettii using PCR-nucleic acid test strips

To develop a method for rapid detection of Ralstonia pickettii in water for pharmaceutical purpose using PCR-nucleic acid test strips. The genomic DNA of Ralstonia pickettii was extracted by boiling method. A pair of specific primers targeting the 16S rDNA with FITC and biotin labeling of the 5' ends was designed and cloned into competent E. coli DH5α cells. The nucleic acid test strips were assembled, and the workload of streptavidin labeled with colloidal gold and antibody concentration in the reaction system was optimized. After verification of the reaction mechanism and assessment of the test sensitivity, specificity and stability, the test strip was used for detecting 7 known strains of Ralstonia pickettii detected in pharmaceutical water, and an evolutionary tree was constructed to analyze the source of contamination. The genomic DNA extracted by boiling method had a purity between 1.8 and 2.0, and the PCR products showed a 100% similarity of with Ralstonia pickettii 16S rDNA registered in GenBank. Using the colloidal gold amplification principle, in every 100 μL colloidal gold solution, 3.5 μL streptavidin was added; the detection line on nitrocellulose membrane was 2.0 mg·mL-1 anti FITC antibody, and the quality control line was 1.2 mg · mL-1 biotinylated BSA, and they generate a red band after binding with positive amplification product. Specificity test of the assembled test strip yielded consistent result with agarose gel electrophoresis without cross reaction with Acinetobacter, Aeromonas, Pseudomonas, or Leclercia adecarboxylata. Sensitivity test of the strip showed a lower detection limit for DNA concentration of 10-5 ng/μL, with a sensitivity 1000 times that of agarose gel electrophoresis. The test strip still had good performance after storage for 3, 6, 9 and 12 months. We successfully developed a PCR-nucleic acid test strip for convenient and cost-effective detection of Ralstonia pickettii with good specificity and sensitivity and low cost to facilitate daily monitoring of pharmaceutical water contaminations.

Low-cost and simple fabrication of hierarchical Al nanopit arrays for deep ultraviolet refractive index sensing

Herein, we proposed a simple non-lithographic way to fabricate hierarchical Al nanopit arrays performed as deep ultraviolet (DUV, 200–300 nm) refractive index sensing. Only by adjusting the Al deposition thickness on the Al nanopit array, the hierarchical Al nanopit arrays with tunable plasmonic properties in the DUV region were obtained. The prepared hierarchical Al nanopit arrays are of very good time stability and its RI sensitivity and concentration detection limit of adenine ethanol solution reach 311 nm/RIU and respectively, as the Al deposition thickness is 60 nm. Furthermore, the electric field distribution simulation results show that high RI sensing characteristic are mainly attributed to the local surface plasmon resonance. This investigation provides a facile way to develop low cost, high efficient and easily fabricated Al-based RI sensor in the DUV region.

Sensitive determination of ethosuximide in human fluids by electromembrane extraction coupled with high performance liquid chromatography ultraviolet spectroscopy

AbstractEthosuximide (ETX) is a common antiepileptic drug in the first line of absence epilepsy. In this study, for the first time, an economical and efficient electro‐membrane (EME) method for determination of ETX in a complex biological matrix using HPLC‐UV has been developed. Factors affecting conventional EME were evaluated. 1‐Octanol was immobilized in a polypropylene membrane and a voltage of 35 V was applied between two platinum electrodes for 15 min. The pH of acceptor and donor phases for ionization of ETX was adjusted to 13 and 11, respectively. Under optimal microextraction conditions, the enrichment factor was 21.02 and the linear range of ETX was 0.25 to 8.00 μg/mL with an acceptable R2 ≥ 0.9986. Inter‐day and intra‐day precision and accuracy of the suggested method were calculated with RSD &lt; 9.5% and relative error &lt;7.0%, respectively. The mean relative recovery of ETX in the human saliva and plasma samples was 81.68% and 74.47, respectively; while limit of detection and quantification concentrations were 0.08 and 0.25 μg/mL, respectively. Furthermore, to evaluate the application of the method, plasma and saliva samples of volunteers administering a single dose of ETX were analyzed successfully by EME‐HPLC‐UV method.

Surface Modification of Liquid Metal with p-Aniline Derivatives toward Bioapplications: Biosensing as an Example.

It is a long-lasting research topic to avoid the formation of oxidation layers on gallium-based liquid metals. This study has developed a simple general method for modification of the eutectic gallium-indium (EGaIn) surface with p-aniline derivatives to introduce a monolayer of organic molecules with versatile functional groups. The binding affinity of carboxylic acid groups, amine groups, or thiol groups with EGaIn is in the order SH > NH2 > COOH. For the first time, it is evidenced that both NH2 and SH groups can coexist on the EGaIn nanoparticle surface with the binding affinities of 30 and 70%, respectively. The formation of these organic molecules on the EGaIn surface antioxidizes and thus stabilizes the EGaIn nanoparticles, while increasing the conductivity of EGaIn significantly. The resulting EGaIn nanoparticles have very good distribution in both ethanol and aqueous solutions and rich surface chemistry, making them suitable for the following attachment of biomolecules such as aptamers, antibodies, or enzymes for biomedical applications. As an example, the EGaIn surface is successfully modified with p-aminobenzoic acid followed by the attachment of an insulin aptamer, which can be used for the electrochemical detection of insulin with the lowest detectable concentration limit of 1 pM. This study reveals the modification of EGaIn nanoparticles with p-aniline derivatives with versatile functional groups to antioxidize EGaIn in a biological environment, opening a door for gallium-based liquid metals toward biomedical applications.