Detection Of Heavy Metals Research Articles

Application of Convolutional Neural Networks for Creation of Photoluminescent Carbon Nanosensor for Heavy Metals Detection

Application of Convolutional Neural Networks for Creation of Photoluminescent Carbon Nanosensor for Heavy Metals Detection

A new eco-friendly fluorescent microcapsules for effective and selective detection of Hg(II)&Cu(II)

The detection of heavy metals in wastewater with eco-friendly materials and sustainable processes is extremely important for the environment and human health. In this study, sporopollenin, which is a natural polymer material, was derivatized with an innovative macrocyclic compound, and then fluorescence property was acquired. Bodipy and Pillar[5]arene were used to prepare fluorescent microcapsules (Sp-P[5]-bodipy) based on organic compounds. The compounds used in the preparation of fluorescent microcapsules were synthesized by conventional procedures and characterized by several methods such as NMR, FT-R, mass spectroscopy, elemental analysis, and melting point. The characterization of the obtained surfaces was carried out with TGA, FT-IR and SEM device in the determination of the surface morphology and the functional groups. The target fluorescent microcapsules, Sp-P[5]-bodipy, were performed using fluorescence spectroscopy to detect metal ions in aqueous solutions that the modified surfaces encapsulated Hg(II) and Cu(II) ions, respectively. Moreover, some parameters such as pH, temperature, response time, limit of detection (LOD) and binding stoichiometry were examined for practical chemo-sensor applications that Sp-P[5]-bodipy have a low LOD for both Cu(II) (6.16 µM) and Hg(II) ions (3.42 µM).

Elucidating the Role of Honey Bees as Biomonitors in Environmental Health Research.

Recently, the One Health concept, which recognizes the interconnectedness of environmental, animal, and human health, has gained popularity. To collect data on environmental pollutants potentially harmful to human health over time, researchers often turn to natural organisms known as biomonitors. Honey bees, in particular, prove to be exceptionally valuable biomonitors due to their capacity to accumulate pollutants from the air, soil, and water within a specific radius during their foraging trips. This systematic literature review summarizes the previous application of the bee species Apis mellifera in pollutant monitoring in articles published during the period of 2010-2020. Nineteen studies were included in this systematic literature review. Of these studies, the majority (n = 15) focused on the detection of heavy metals in honey bees and beehive products, while 4 studies focused on air pollution by polycyclic aromatic hydrocarbons or particulate matter. The matrix most often applied was the whole honey bee. The included studies demonstrated that honey bees and hive products deliver quantitative and qualitative information about specific pollutants. In this regard, the whole honey bee was found to be the most reliable biomonitor. We found that the included studies differed in design and the methods used. Standardized studies could foster a more consistent interpretation of the levels detected in beehive matrices from an environmental health perspective.

Multifunctional core@shell structured gold nanodendrites@gold nanoclusters: An efficient catalytic and sensor domain for environmental remediation applications

Over the recent decades, rapid industrialization, the excess use of chemical reagents, and their improper waste disposal to the environment caused severe damage to the ecosystem. To get rid of these serious issues, the propitious solution would be finding a multifunctional catalyst system that could detect and degrade/inactivate the poisonous pollutants released in the environment. In this regard, core@shell structured Au nanodendrites@Au nanoclusters (AuND@AuNC) were prepared by a facile one-step inverted process using methionine for pollutant degradation and heavy metal detection. There is no surfactant, polymer, or seed was employed in the preparation of AuND@AuNC. In the preparation of AuND@AuNC, the concentration of AuCl4- was optimized and it was observed that beyond 1.5 mM of Au concentration, formed gold sols aggregate immediately. Prepared AuND@AuNC were characterized well using high-resolution transmission electron microscopy (HRTEM), selected area electron diffraction technique (SAED), X-ray diffraction (XRD), UV-Vis absorption spectroscopy, and X-ray photoelectron spectroscopy (XPS). Interestingly, the prepared AuND@AuNC demonstrates excellent catalytic reduction/degradation of nitroaromatic compounds and organic dye molecules with the aid of sodium borohydride. The results of the kinetic studies confirm the superior catalytic activity of present AuND@AuNC over already published results. Further, AuND@AuNC prepared with 1.5 mM Au concentration exhibits excellent colorimetric sensing behaviour towards cadmium ion (Cd2+) in the presence of 500 µM of interfering ions with a limit of detection of 2.5 µM. The excellent catalytic and sensing behavior of AuND@AuNC material is attributed to its unique structural features and methionine functionalization.

Superior photocatalytic and electrochemical activity of the MoSe2 modified ZIF-67 for the reduction and detection of Cr (VI)

The removal and detection of heavy metals from wastewater have proven to be challenging due to the limitations of the materials and technologies. Therefore, in this work, we have synthesized novel Z-scheme-based MoSe2-modified ZIF-67 by a two-step method and tested it for environmental safety by electrochemical detection and photocatalytic reduction of carcinogenic heavy metal pollutant (hexavalent chromium (Cr (VI)). The nanosheets and polyhedrons-like morphology of MoSe2 and ZIF-67 were confirmed using Field emission scanning electron microscope (FESEM) and High-resolution transmission electron microscope (HRTEM), respectively. The nanocomposite exhibited superior activity for photocatalytic reduction (∼89% within 30 min) towards Cr (VI) along with the detection (LOD-0.01 µM) with high stability. The superior activity of the MZ67 nanocomposite is attributed to enhanced recombination time (4.65 ns) with respect to pristine ZIF-67 (1.21 ns) as observed from time-correlated single photon counting (TCSPC) studies. The scavenger test and electron paramagnetic resonance (EPR) studies confirmed the Z-scheme of the nanocomposite. The electrochemical sensing for Cr (VI) combined with the photocatalytic reduction, tends to provide a trustworthy tool for wastewater management.

Selective and Sensitive Detection of Hg2+ and Ag+ by a Fluorescent and Colorimetric Probe with Large Stokes Shift.

Development of fluorescent sensors with large Stokes shift for selective detection of heavy metals is of great importance. A novel fluorescent probe with extremely large Stokes shift (212nm) was synthesized for selective and simultaneous detection of Hg2+ and Ag+ ions. The deep yellow probe turned colorless or pale yellow after addition of Hg2+ or Ag+. The new probe could be utilized for absorption spectral detection of Hg2+ and Ag+ both in ethanol and aqueous solution. Addition of Hg2+ and Ag+ ions caused significant decrease in the fluorescence intensity of the new probe and the selective recognition of Hg2+ and Ag+ was not interfered by common competitive metal ions including Li+, Na+, K+, Cu2+, Fe2+, Zn2+, Co2+, Ni2+, Mn2+, Sr2+, Ca2+, Mg2+, Al3+, Cr3+ and Fe3+. The detection limit for Hg2+ and Ag+ was calculated to be 4.68μM and 4.29μM, respectively. Application of the new probe for quantitative determination of Hg2+ and Ag+ concentrations in real water samples was accomplished.

New fluorescent Schiff base modified nanocellulose-based chemosensors for the selective detection of Fe3+, Zn2+ and Cu2+ in semi-aqueous media and application in seawater sample

Stimulus-responsive fluorescent-modified biopolymers have received significant attention in the field of chemosensors. Herein, four new fluorescent dyes, namely, S1: (PDA-DANC), S2: (SAL-PDA-DANC), S3: (BrSAL-PDA-DANC) and S4: (ClSAL-PDA-DANC) have been successfully synthesized from 2,3-dialdehyde nanocellulose (DANC) for the detection of heavy metals. The microstructural and photophysical properties of nanocellulose (NC), microcrystalline cellulose (DANC) and the synthesized S1 to S4 dyes were investigated by FT-IR, SEM-EDX, XRD, TGA, DLS and photoluminescence. NC, obtained from conversion of MCC, shows an average size of 802.4 nm with 0.141 of polydispersity index (PdI), and a crystalline index (CI) of 82.40 % and crystallite size of 4.68 nm. The synthesized dyes present good fluorescent properties and have been therefore exploited for developing new probes for heavy metal ions detection. Remarkable “turn off” and/or “turn on” behaviors with Fe3+ and Cu2+ and with Zn2+ in DMF/water solution have been demonstrated, allowing the sensitive and selective determination of these heavy metal ions with a low limit of detection (LOD). Finally, the evaluation of the Fe3+ sensing in a real seawater sample was investigated.

Analytical Approaches for the Detection of Heavy Metals and Agrochemicals in the Environment Samples and their Recent Technologies

At part per billion (ppb) concentrations, heavy metals and pesticides both pose a significant health risk. Over-ingestion of pesticides and heavy metals in the environment may cause various diseases and effects on human life. So, a systematic analysis for detecting and removing pesticides and heavy metals from the environment is required. This review provides a comprehensive study of the several analytical methodologies employed in the quantification of heavy metal ions and agrochemicals in environmental samples. Furthermore, the detrimental impacts of these substances on both human health and plant life are also discussed. Moreover, a concise overview of the latest developments in the design of nanomaterial-based sensors, specifically focusing on colorimetric and electroanalytical approaches. These sensors are utilized for the detection and analysis of heavy metals and pesticides. In addition, the information garnered from the study will improved the capability to detect and remove contaminants from environmental samples.

Development of lycopene-based whole-cell biosensors for the visual detection of trace explosives and heavy metals

Residual explosives in conflicting zones have caused irreversible damage to human safety and the environment. Whole-cell biosensors can to detect remnants of buried explosives, such as 2,4-dinitrotoluene (DNT), a stable and highly volatile compound in explosives. However, all the reported whole-cell biosensors utilize fluorescence or luminescence as the biological markers, making their detection difficult in real minefields. Here, we presented a lycopene-based whole-cell biosensor in Escherichia coli to output visible signals in response to DNT, which can help in the visual detection of buried explosives. To construct the whole-cell biosensor, the DNT-responsive promoter yqjF was used as the sensing element, and the lycopene synthetic gene cassette crtEBI was served as the reporting element. Then, the metabolic flux for lycopene production was enhanced to improve the output signal of the whole-cell biosensor, and a terminator was utilized to reduce the background interference. The optimized biosensor LSZ05 could perceive at least 1 mg/L DNT. The DNT-specificity and robust performance of the biosensor under different environmental factors were confirmed. Our results showed that converting the biosensor into a lyophilized powder was an effective storage method. The biosensor LSZ05 could effectively detect DNT in two kinds of soil samples. The lycopene-based whole-cell biosensor could also be used to visually detect heavy metals. Our findings laid the foundation for visually detecting buried explosives in minefields, which was a valuable supplement to the reported biosensors. The methods used for optimizing the lycopene-based whole-cell biosensor, including the improvement of the output signal and reduction of background interference, were quite effective.

Detection of heavy metals using atomic absorption and emission spectroscopy in drinking water of Faisalabad, Pakistan: microbial safety and quality status assessment

Synthetic dyes from textile industries are designated as hazardous waste since they release heavy metals and dangerous contaminants in water that harm the environment and human health. The current study was aimed at investigating the heavy metals (Cd, Cu, Pb, Ni, Zn, Cr, and Mn) in drinking water in seven regions of Faisalabad, Pakistan, through atomic absorption spectroscopy (AAS) and optical emission spectroscopy (OES). The physicochemical quality of 86.36% of the water samples met the WHO standards in the targeted regions, while 13.64% failed to meet the criteria. The water quality index (WQI) of selected water samples was calculated by integrating 11 physicochemical parameters, and the results indicated fair quality, whereas Madina, Jinnah, and Lyallpur Town showed poor water quality with contamination of Mn > Ni > Pb. The order of contamination for heavy metals in groundwater was Ni > Cu > Zn > Cr > Pb > Mn > Cd. The total plate count (TPC) and total coliform count (TCC) were found within the permissible range of WHO guidelines. Hence, consuming groundwater in the research regions may not present major health risks due to ingested metal toxicity; however, levels of Mn, Ni, and Pb might pose risks.

Sunlight-Mediated Synthesis of Metallic Silver Nanoparticles with Coffee (<i>Robusta/Arabica</i>) Pulp Aqueous Extract for Hg<sup>2+</sup> Ion Detection

On-site and portable detection of heavy metals, especially in water, is critical for public health safety. Mercury is a toxic heavy metal and poses environmental and health hazard concerns causing neurological and behavioral disorders. Metallic nanoparticles possess unique optical properties, which can be used for heavy metal sensing applications. In this study, a colorimetric method for detecting mercury using silver nanoparticles was developed. The reduction of Ag+ to AgNP was initiated using sunlight with coffee pulp aqueous extract as a reducing agent. The UV-Vis spectrum of the as-prepared AgNP solution shows a maximum absorption peak at 433 nm due to the metal’s localized surface plasmon resonance (LSPR). The SEM analysis of the dried sample shows an aggregate of AgNPs with spherical morphology with diameters less than 100 nm. The dynamic light scattering distribution curve shows a bimodal peak with a mean hydrodynamic radius of 12.73 nm and 145 nm, respectively. The large hydrodynamic radius of more than 100 nm may be attributed to the presence of AgNP aggregates in the solution. The synthesized AgNP was shown to selectively detect Hg2+ ions in solution colorimetrically. A linear calibration curve was obtained for the Hg2+ solution between 0.04 mM and 0.2 mM with R2 equal to 0.9934. This proposed method can potentially be used in the analysis of actual water samples.

An ultrasensitive Cd2+ detection biosensor based on DNAzyme and CRISPR/Cas12a coupled with hybridization chain reaction

The detection of cadmium is essential because it poses a significant threat to human health and the environment. Recent advancements in biosensors that detect nonnucleic-acid targets using CRISPR/Cas12a in combination with aptamers or DNAzymes show promising performance. Herein, we integrated DNAzyme, hybridization chain reaction (HCR) and CRISPR/Cas12a into a single biosensor for the first time and realized the ultrasensitive detection of Cd2+. A single phosphorothioate ribonucleobase (rA)-containing oligonucleotide (PS substrate) and a Cd2+-specific DNAzyme (Cdzyme) are used for Cd2+ recognition, releasing short single-stranded DNA. Then, the HCR is triggered by the cleavage products for signal transduction and amplification. Next, the trans-cleavage activity of Cas12a is activated due to the presence of crRNA complementary strands and PAM sites in the HCR products. As a result, FQ-reporters are cleaved, and the fluorescence values can be easily read using a fluorometer, allowing Cd2+ quantification by measuring the fluorescent signal. The Cd2+ detection biosensor is ultrasensitive with a detection limit of 1.25 pM. Moreover, the biosensor shows great stability under different pH and various anion conditions. The proposed sensor was utilized for environmental water sample detection, demonstrating the dependability of the detection system. Considering the high sensitivity and reliable performance of the assay, it could be further used in environmental monitoring. In addition, the design strategy reported in this study could extend the application of CRISPR/Cas12a in heavy metal detection.

Detection of heavy metals from Harpadon nehereus, Channa punctata and Pampus chinensis dried fishes and toxicity study of Channa punctata on embryonic zebrafish

ObjectivesGlobally, heavy metal pollution is one of the major serious environmental issues. The present investigations were carried out to determine the heavy metals concentrations from three dried fish along with the toxicity effects of Channa punctata dried fish on embryonic development of zebrafish. MethodsThe concentrations of heavy metals, Nickel (Ni), Chromium (Cr), Cadmium (Cd), Arsenic (As), and Lead (Pb) were detected from Harpadon nehereus, C. punctata and Pampus chinensis dried fish’s samples by Atomic Absorption Spectrophotometry (AAS) method. ResultsThe highest concentrations of As and Pb were 3.65 ± 0.08 and 3.29 ± 0.07 ppm, found in C. punctata followed by 3.11 ± 0.05 and 3.26 ± 0.07 ppm, in H. nehereus, respectively. Meanwhile, no significant levels of Ni, Cr and Cd were found in all the three tested dried fishes, compared with standard references. The treatments of 50 µg/ml and 100 µg/ml C. punctata dried fish solution on zebrafish embryos showed significant toxicity and abnormalities of unequal blastomeric curve, yolk sac edema, pericardial edema, spinal curvature and tail deformation at 24, 33, 48, 72 and 96 h post fertilization (hpf). ConclusionsThe present investigation revealed that the tested dried fishes contain heavy metals and C. punctata is highly toxic for zebrafish embryos.

Detection of heavy metals and VOCs in streambed sediment indicates anthropogenic impact on intermittent streams of the U.S. Virgin Islands

Global surges in industrialization and human development have resulted in environmental contamination. Streambed sediment contamination threatens ecological and human health due to groundwater leaching and downstream contaminant mobilization. This is especially true in the wider Caribbean region, where streambed sediment contamination is understudied. In the current study, we assessed human impact on intermittent streams by measuring heavy metals and volatile organic compounds (VOCs) in streambed sediment on St. Croix in the United States Virgin Islands (USVI), where intermittent streams receive limited conservation and research attention. In contrast to our hypothesis that streambed sediment pollutant concentrations would be higher in developed, compared to undeveloped areas, contaminant concentrations did not vary significantly according to land cover. Elevated lead, mercury, and zinc concentrations were correlated with commercial building density, suggesting an unnatural origin of these elements in streambed sediment. At some sites, levels of arsenic, cadmium, chromium, nickel, lead, thallium, or zinc exceeded regulatory limits. The most prevalent VOCs at both developed and undeveloped sites were benzene and toluene. Sub-groups of heavy metals identified by principal component analysis indicated potential pollution sources, including fuel combustion (chromium, nickel, arsenic, selenium), vehicle exhaust, oil refining, and gasoline leaks (2-butanone and xylenes), and plastics (acetone and styrene). Our results suggest USVI intermittent streams require further research attention and intervention strategies for pollution reduction.

A review on the effects of heavy metals on the development of blow flies (Diptera: Calliphoridae)

AbstractHeavy metals such as lead, cadmium, zinc, copper, mercury, and others, are naturally occurring non degradable elements which can accumulate in the environment and in living organisms and can have a significant impact on their physiological functions. Studies have shown that heavy metals can also influence the development and morphology of insects. Insects are the most abundant organisms on earth and play a major role in different ecosystems. They help in the dispersion of organic matter and are an important part of different ecological processes. Forensic entomology focuses on the use of arthropods in legal investigations. Shortly after death, a corpse is quickly colonized by several insect families; blow flies (Diptera: Calliphoridae) are among the first colonizers and are therefore often used for the estimation of the time of colonization (TOC) or minimum post‐mortem interval (mPMI). Since larvae feed on the corpse, any xenobiotic present in the remains, including heavy metals, can be ingested, and accumulated by them; these substances can influence their development and, in turn, can alter the estimation of the mPMI. We analyzed the literature on studies pertaining to the detection of heavy metals in blow flies and on their variations in developmental rate, mass, length, fecundity, morphology, immune system, and mortality rate.This article is categorized under: Forensic Biology > Forensic Entomology Forensic Anthropology > Time Since Death Estimation Forensic Biology > Interpretation of Biological Evidence

Nanoscale Ag2O decorated UiO-66 metal organic framework for simultaneous electrochemical sensing of heavy metals, Cd2+ and Hg2+

Herein, we come up with a new electrochemical sensing strategy for detecting heavy metal ions present in aqueous media using metal organic framework (MOF) electrode decorated with Ag2O nanoparticles (NPs). Post-synthesis modification route was followed to load the Ag2O NPs into zirconium-based MOF UiO-66 host. In the composite, the NPs were believed to act as the electric current enhancer while UiO-66 provided adsorption sites for heavy metal ions. The ITO electrodes were modified with as prepared composite for the electrochemical detection of Hg2+ and Cd2+ independently as well as simultaneously. The detection of heavy metals was performed by the modified electrodes through differential pulse stripping voltammetry (DPSV) which offered excellent selectivity and with sensitivity values up to 551 μA·μM−1·cm−2 for Cd2+ and 341.2 μA·μM−1·cm−2 for Hg2+. The limit of detection (LOD) for the respective cases, were estimated to be 0.008 μM and 0.003 μM. Technical viability of this approach can be further extended to real sample analysis in soil, river basin, waste land and even ground water for simultaneous detection of heavy metal ions as and when desired.

Microfluidic Device Integrated With PDMS Microchannel and Unmodified ITO Glass Electrodes for Highly Sensitive, Specific, and Point-of-Care Detection of Copper and Mercury.

This work delves upon developing a two-layer plasma-bonded microfluidic device with a microchannel layer and electrodes for electroanalytical detection of heavy metal ions. The three-electrode system was realized on an ITO-glass slide by suitably etching the ITO layer with the help of CO2 laser. The microchannel layer was fabricated using a PDMS soft-lithography method wherein the mold created by maskless lithography. The optimized dimensions opted to develop a microfluidic device with length of 20 mm, width of 0.5 mm and gap of 1 mm. The device, with bare unmodified ITO electrodes, was tested to detect Cu and Hg by a portable potentiostat connected with a smartphone. The analytes were introduced in the microfluidic device with a peristaltic pump at an optimal flow rate of [Formula: see text]/min. The device exhibited sensitive electro-catalytic sensing of both the metals by achieving an oxidation peak at -0.4 V and 0.1 V for Cu and Hg respectively. Furthermore, square wave voltammetry (SWV) approach was used to analyze the scan rate effect and concentration effect. The device also used to simultaneously detect both the analytes. During simultaneous sensing of Hg and Cu, the linear range was observed between [Formula: see text] to [Formula: see text], the limit of detection (LOD) was found to be [Formula: see text] and [Formula: see text] for Cu and Hg respectively. Further, no interference with other co-existing metal ions was found manifesting the specificity of the device to Cu and Hg. Finally, the device was successfully tested with real samples like tap water, lake water, and serum with remarkable recovery percentages. Such portable devices pave way for detecting various heavy metal ions in a point-of-care environment. The developed device can also be used for detection of other heavy metals like cadmium, lead, zinc etc., by modifying the working electrode with the various nanocomposites.

Plasmon-enhanced fluorescence of gold nanoparticle/graphene quantum dots for detection of Cr3+ ions

Graphene quantum dots (GQDs), fascinating semiconductors with stable photoluminescence (PL), have important potential applications in the fields of biology, medicine, and new semiconductor devices. However, it is still challenging to overcome the weak PL intensity. Here, we report a strategy for selective resonance enhancement of GQD fluorescence using gold nanoparticles (AuNPs) as plasmas. Interestingly, the addition of low concentration AuNP makes AuNP/GQDs exhibit significant fluorescence enhancement of 2.67 times in the visible range. The addition of high concentration AuNP leads to the formation of an excitation peak at 421 nm and selectively enhances certain radiation modes. We concluded that the main reason for the selective enhancement of PL intensity in high concentration AuNP is the transfer of generous hot electrons at high energy states from AuNP to GQD and relaxation to the ground state. The electron resonance of low concentration AuNP transfers to GQD and relaxes to lower energy levels, exhibiting an overall enhancement of PL intensity. We apply it for detection of the heavy metal ion Cr3+, and verify that it has a correlation coefficient of 97.36%. We believe AuNP/GQDs can be considered excellent candidates for heavy metal detection and high fluorescence bio-imaging.

Biosensors Technological Advancement and Their Biomedical, Agricultural, Environmental and Food Industrial Applications: A Review

The biosensors are devices that receive the biological message and convert it into a sensible electrical signal. The biosensing involves a combination of biological entities like DNA, RNA, and proteins/enzymes to the electrochemical transducers. Biosensors comprise a biorecognition element (enzyme, antigen, antibody or nucleic) that mediates selective biocatalysis or specific binding of analyte and transducers that able to measure the signal. There are several types of biosensors being employed today, such as optical, surface plasmon resonance, enzymes, DNA, Phage, and microbial biosensors. Now days biosensor technologies have been employed in biomedicine, food safety standards, defense and environmental monitoring. Detection of the lower or higher limits of glucose in the body, microbial invasion in the body and food, heavy metal detection in soil, water and airborne microbes, pesticides in water and soil and various harmful chemicals produced by body, can be easily and timely monitored with high precision using the different types of biosensors. Biosensors can overcome all the limitation of the traditional methods of chemical and microbiological analyses by offering rapid, non-destructive and affordable methods for quality control. Thus, this review paper highlights biosensor and its components, types of biosensors and its application in different disciplines.

Gold Nanoparticle-Based Colorimetric Sensors: Properties and Application in Detection of Heavy Metals and Biological Molecules.

During the last decade, advances have been made in nanotechnology using nanomaterials, leading to improvements in their performance. Gold nanoparticles (AuNPs) have been widely used in the field of sensor analysis and are also combined with certain materials to obtain the desired characteristics. AuNPs are commonly used as colorimetric sensors in detection methods. In developing an ideal sensor, there are certain characteristics that must be met such as selectivity, sensitivity, accuracy, precision, and linearity, among others. Various methods for the synthesis of AuNPs and conjugation with other components have been carried out in order to obtain good characteristics for their application. AuNPs can be applied in the detection of both heavy metals and biological molecules. This review aimed at observing the role of AuNPs in its application. The synthesis of AuNPs for sensors will also be revealed, along with their characteristics suitable for this role. In the application method, the size and shape of the particles must be considered. AuNPs used in heavy metal detection have a particle size of around 15-50 nm; in the detection of biological molecules, the particle size of AuNPs used is 6-35 nm whereas in pharmaceutical compounds for cancer treatment and the detection of other drugs, the particle size used is 12-30 nm. The particle sizes did not correlate with the type of molecules regardless of whether it was a heavy metal, biological molecule, or pharmaceutical compound but depended on the properties of the molecule itself. In general, the best morphology for application in the detection process is a spherical shape to obtain good sensitivity and selectivity based on previous studies. Functionalization of AuNPs with conjugates/receptors can be carried out to increase the stability, sensitivity, selectivity, solubility, and plays a role in detecting biological compounds through conjugating AuNPs with biological molecules.