Displaying publications 1 - 20 of 133 in total

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  1. Sonochemical synthesis of gold nanoparticles by using high intensity focused ultrasound
    Yusof NS, Ashokkumar M
    Chemphyschem, 2015 Mar 16;16(4):775-81.
    PMID: 25598360 DOI: 10.1002/cphc.201402697
    The sonochemical synthesis of gold nanoparticles (GNPs) with different shapes and size distributions by using high-intensity focused ultrasound (HIFU) operating at 463 kHz is reported. GNP formation proceeds through the reduction of Au(3+) to Au(0) by radicals generated by acoustic cavitation. TEM images reveal that GNPs show irregular shapes at 30 W, are primarily icosahedral at 50 W and form a significant amount of nanorods at 70 W. The size of GNPs decreases with increasing acoustic power with a narrower size distribution. Sonochemiluminescence images help in the understanding of the effect of HIFU in controlling the size and shapes of GNPs. The number of radicals that form and the mechanical forces that are generated control the shape and size of the GNPs. UV/Vis spectra and TEM images are used to propose a possible mechanism for the observed effects. The results presented demonstrate, for the first time, that the HIFU system can be used to synthesise size- and shape-controlled metal nanoparticles.
    Matched MeSH terms: Gold/chemistry*
  2. Electrochemical biosensor based on Temporin-PTA peptide for detection of microorganisms
    da Silva-Junio AG, Frias IAM, Lima-Neto RG, Migliolo L, E Silva PS, Oliveira MDL, et al.
    J Pharm Biomed Anal, 2022 Jul 15;216:114788.
    PMID: 35525110 DOI: 10.1016/j.jpba.2022.114788
    Bacterial and fungal infections are challenging due to their low susceptibility and resistance to antimicrobial drugs. For this reason, antimicrobial peptides (AMP) emerge as excellent alternatives to overcome these problems. At the same time, their active insertion into the cell wall of microorganisms can be availed for biorecognition applications in biosensing platforms. Temporin-PTA (T-PTA) is an AMP found in the skin secretions of the Malaysian fire frog Hylarana picturata, which presents antibacterial activity against MRSA, Escherichia coli, and Bacillus subtilis. In this work, T-PTA was explored as an innovative sensing layer aiming for the electrochemical differentiation of Klebsiella pneumoniae, Acinetobacter baumannii, Bacillus subtilis, Enterococcus faecalis, Candida albicans, and C. tropicalis based on the structural differences of their membranes. The biosensor was analyzed through electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). In this approach, the different structural features of each microorganism resulted in different adherence degrees and, therefore, different electrochemical responses. The transducing layer was fabricated by the self-assembling of a 4-mercaptobenzoic acid (MBA) monolayer and gold-capped magnetic nanoparticles (Fe3O4@Au) implemented to improve the electrical signal of the biointeraction. We found that each interaction, expressed in variations of electron transfer resistance and anodic peak current, demonstrated a singular response from which the platform can discriminate all different microorganisms. We found expressive sensitivity towards Gram-negative species, especially K. pneumoniae. A detection limit of 101 CFU.mL-1 and a linear range of 101 to 105 CFU.mL-1 were obtained. The T-PTA biosensor platform is a promising and effective tool for microbial identification.
    Matched MeSH terms: Gold/chemistry
  3. Spiked nanorosette: A novel zinc oxide-gold textured nanostructure for impedance biosensing of target DNA signatures
    Haarindraprasad RP, Thurga Devi N, Thevendran R, Maheswaran S
    Biotechnol J, 2023 Aug;18(8):e2300092.
    PMID: 37139895 DOI: 10.1002/biot.202300092
    The creation of nanostructure is profound for the generation of nanobiosensors in several medical diagnosis. Here, we employed an aqueous hydrothermal route using Zinc-oxide (ZnO) and Gold (Au), which under optimal conditions formed an ultra-crystalline rose-like nanostructure textured with nanowires on the surface, coined as "spiked nanorosette." The spiked nanorosette structures was further characterized to possess crystallites of ZnO and Au grains with average sizes of 27.60 and 32.33 nm, respectively. The intensity for both ZnO (002) and Au (111) planes of the nanocomposite was inferred to be controlled by fine-tuning the percentage of Au nanoparticles doped in the ZnO/Au matrix, as referred by X-ray diffraction analysis. The formation of ZnO/Au-hybrid nanorosettes were additionally verified by the distinct corresponding peaks from photoluminescence and X-ray photoelectron spectroscopy, supported by electrical validations. The biorecognition properties of the spiked nanorosettes were also examined using custom targeted and non-target DNA sequences. The DNA targeting capabilities of the nanostructures were analyzed by Fourier Transform Infrared and electrochemical impedance spectroscopy. The fabricated nanowire-embedded nanorosette exhibited a detection limit at the lower picomolar range of 1 × 10-12 M, with high selectivity, stability and reproducibility and good linearity, under optimal conditions. Impedance-based techniques are more sensitive to the detection of nucleic acid molecule whereas this novel spiked nanorosette demonstrate promising attributes as excellent nanostructures for nanobiosensor developments and their potential future application for nucleic-acids or disease diagnostics.
    Matched MeSH terms: Gold/chemistry
  4. A simulation study on the radiosensitization properties of gold nanorods
    Taheri A, Khandaker MU, Moradi F, Bradley DA
    Phys Med Biol, 2024 Feb 15;69(4).
    PMID: 38286017 DOI: 10.1088/1361-6560/ad2380
    Objective. Gold nanorods (GNRs) have emerged as versatile nanoparticles with unique properties, holding promise in various modalities of cancer treatment through drug delivery and photothermal therapy. In the rapidly evolving field of nanoparticle radiosensitization (NPRS) for cancer therapy, this study assessed the potential of gold nanorods as radiosensitizing agents by quantifying the key features of NPRS, such as secondary electron emission and dose enhancement, using Monte Carlo simulations.Approach. Employing the TOPAS track structure code, we conducted a comprehensive evaluation of the radiosensitization behavior of spherical gold nanoparticles and gold nanorods. We systematically explored the impact of nanorod geometry (in particular size and aspect ratio) and orientation on secondary electron emission and deposited energy ratio, providing validated results against previously published simulations.Main results. Our findings demonstrate that gold nanorods exhibit comparable secondary electron emission to their spherical counterparts. Notably, nanorods with smaller surface-area-to-volume ratios (SA:V) and alignment with the incident photon beam proved to be more efficient radiosensitizing agents, showing superiority in emitted electron fluence. However, in the microscale, the deposited energy ratio (DER) was not markedly influenced by the SA:V of the nanorod. Additionally, our findings revealed that the geometry of gold nanoparticles has a more significant impact on the emission of M-shell Auger electrons (with energies below 3.5 keV) than on higher-energy electrons.Significance. This research investigated the radiosensitization properties of gold nanorods, positioning them as promising alternatives to the more conventionally studied spherical gold nanoparticles in the context of cancer research. With increasing interest in multimodal cancer therapy, our findings have the potential to contribute valuable insights into the perspective of gold nanorods as effective multipurpose agents for synergistic photothermal therapy and radiotherapy. Future directions may involve exploring alternative metallic nanorods as well as further optimizing the geometry and coating materials, opening new possibilities for more effective cancer treatments.
    Matched MeSH terms: Gold/chemistry
  5. Fulltext Gold-Based Medicine: A Paradigm Shift in Anti-Cancer Therapy?
    Yeo CI, Ooi KK, Tiekink ERT
    Molecules, 2018 Jun 11;23(6).
    PMID: 29891764 DOI: 10.3390/molecules23061410
    A new era of metal-based drugs started in the 1960s, heralded by the discovery of potent platinum-based complexes, commencing with cisplatin [(H₃N)₂PtCl₂], which are effective anti-cancer chemotherapeutic drugs. While clinical applications of gold-based drugs largely relate to the treatment of rheumatoid arthritis, attention has turned to the investigation of the efficacy of gold(I) and gold(III) compounds for anti-cancer applications. This review article provides an account of the latest research conducted during the last decade or so on the development of gold compounds and their potential activities against several cancers as well as a summary of possible mechanisms of action/biological targets. The promising activities and increasing knowledge of gold-based drug metabolism ensures that continued efforts will be made to develop gold-based anti-cancer agents.
    Matched MeSH terms: Gold/chemistry*
  6. Recent Advancement in Disposable Electrode Modified with Nanomaterials for Electrochemical Heavy Metal Sensors
    Mohamad Nor N, Ramli NH, Poobalan H, Qi Tan K, Abdul Razak K
    Crit Rev Anal Chem, 2023;53(2):253-288.
    PMID: 34565248 DOI: 10.1080/10408347.2021.1950521
    Heavy metal pollution has gained global attention due to its high toxicity and non-biodegradability, even at a low level of exposure. Therefore, the development of a disposable electrode that is sensitive, simple, portable, rapid, and cost-effective as the sensor platform in electrochemical heavy metal detection is vital. Disposable electrodes have been modified with nanomaterials so that excellent electrochemical properties can be obtained. This review highlights the recent progress in the development of numerous types of disposable electrodes modified with nanomaterials for electrochemical heavy metal detection. The disposable electrodes made from carbon-based, glass-based, and paper-based electrodes are reviewed. In particular, the analytical performance, fabrication technique, and integration design of disposable electrodes modified with metal (such as gold, tin and bismuth), carbon (such as carbon nanotube and graphene), and metal oxide (such as iron oxide and zinc oxide) nanomaterials are summarized. In addition, the role of the nanomaterials in improving the electrochemical performance of the modified disposable electrodes is discussed. Finally, the current challenges and future prospect of the disposable electrode modified with nanomaterials are summarized.
    Matched MeSH terms: Gold/chemistry
  7. Fulltext ROS-generating alginate-coated gold nanorods as biocompatible nanosonosensitisers for effective sonodynamic therapy of cancer
    Loke YL, Beishenaliev A, Wang PW, Lin CY, Chang CY, Foo YY, et al.
    Ultrason Sonochem, 2023 Jun;96:106437.
    PMID: 37187119 DOI: 10.1016/j.ultsonch.2023.106437
    Sonodynamic therapy (SDT) emerges as a promising non-invasive alternative for eradicating malignant tumours. However, its therapeutic efficacy remains limited due to the lack of sonosensitisers with high potency and biosafety. Previously, gold nanorods (AuNRs) have been extensively studied for their applications in photodynamic or photothermal cancer therapy, but their sonosensitising properties are largely unexplored. Here, we reported the applicability of alginate-coated AuNRs (AuNRsALG) with improved biocompatibility profiles as promising nanosonosensitisers for SDT for the first time. AuNRsALG were found stable under ultrasound irradiation (1.0 W/cm2, 5 min) and maintained structural integrity for 3 cycles of irradiation. The exposure of the AuNRsALG to ultrasound irradiation (1.0 W/cm2, 5 min) was shown to enhance the cavitation effect significantly and generate a 3 to 8-fold higher amount of singlet oxygen (1O2) than other reported commercial titanium dioxide nanosonosensitisers. AuNRsALG exerted dose-dependent sonotoxicity on human MDA-MB-231 breast cancer cells in vitro, with ∼ 81% cancer cell killing efficacy at a sub-nanomolar level (IC50 was 0.68 nM) predominantly through apoptosis. The protein expression analysis showed significant DNA damage and downregulation of anti-apoptotic Bcl-2, suggesting AuNRsALG induced cell death through the mitochondrial pathway. The addition of mannitol, a reactive oxygen species (ROS) scavenger, inhibited cancer-killing effect of AuNRsALG-mediated SDT, further verifying that the sonotoxicity of AuNRsALG is driven by the production of ROS. Overall, these results highlight the potential application of AuNRsALG as an effective nanosonosensitising agent in clinical settings.
    Matched MeSH terms: Gold/chemistry
  8. Gold nanoparticles-based photothermal therapy for breast cancer
    Dheyab MA, Aziz AA, Khaniabadi PM, Jameel MS, Oladzadabbasabadi N, Rahman AA, et al.
    Photodiagnosis Photodyn Ther, 2023 Jun;42:103312.
    PMID: 36731732 DOI: 10.1016/j.pdpdt.2023.103312
    AuNPs-mediated photothermal therapy (PTT) is gaining popularity in both laboratory research and medical applications. It has proven clear advantages in breast cancer therapy over conventional thermal ablation because of its easily-tuned features of irradiation light with inside hyperthermia ability. Notwithstanding this significant progress, the therapeutic potential of AuNPs-mediated PTT in cancer treatments is still impeded by several challenges, including inherent non-specificity, low photothermal conversion effectiveness, and the limitation of excitation light tissue penetration. Given the rapid progress of AuNPs-mediated PTT, we present a comprehensive overview of significant breakthroughs in the recent advancements of AuNPs for PTT, focusing on breast cancer cells. With the improvement of chemical synthesis technology, AuNPs of various sizes and shapes with desired properties can be synthesized, allowing breast cancer targeting and treatment. In this study, we summarized the different sizes and features of four major types of AuNPs in this review: Au nanospheres, Au nanocages, Au nanoshells, and Au nanorods, and explored their benefits and drawbacks in PTT. We also discussed the diagnostic, bioconjugation, targeting, and cellular uptake of AuNPs, which could improve the performance of AuNP-based PTT. Besides that, potential challenges and future developments of AuNP-mediated PTT for clinical applications are discussed. AuNP-mediated PTT is expected to become a highly promising avenue in cancer treatment in the near future.
    Matched MeSH terms: Gold/chemistry
  9. Colloidal surface-enhanced Raman spectroscopic study of grouper epidermal mucus using acidified sodium sulphate as the aggregating agent
    Leong N, Yaacob MH, Md Zain AR, Tengku Abdul Aziz TH, Christianus A, Chong CM, et al.
    Spectrochim Acta A Mol Biomol Spectrosc, 2024 Apr 15;311:123974.
    PMID: 38377639 DOI: 10.1016/j.saa.2024.123974
    Fish epidermal mucus is an important reservoir of antipathogenic compounds which serves as the first line of the immune defence. Despite its significant role in the physiology and health of fish, detailed profiling of fish epidermal mucus has yet to be explored. Therefore, this study investigates a label-free colloidal surface-enhanced Raman spectroscopic (SERS) method for profiling grouper mucus. Gold nanoparticles were first synthesised using the standard citrate reduction and characterised using ultraviolet-visible spectroscopy, transmission electron microscopy and dynamic light scattering. The influence of acidified sodium sulphate (Na2SO4) at pH 3 as the aggregating agent on the enhancement of the SERS spectrum of different analyte samples including rhodamine 6G (R6G) dye, lysozyme solution and hybrid grouper (Epinephelus fuscoguttatus × Epinephelus lanceolatus) mucus was observed. Based on the results, an optimal Na2SO4 concentration of 1 M was recorded to achieve the highest enhancement of the SERS signal for R6G and grouper mucus, while the optimal concentration for lysozyme was 0.1 M. The results indicated a higher degree of aggregation induced by lysozyme than R6G and grouper mucus. A few overlapping peaks of the SERS spectra of lysozyme and grouper mucus made it possible to confirm the presence of lysozyme as potential biomarkers.
    Matched MeSH terms: Gold/chemistry
  10. Fulltext Gold nanoparticle trapping and delivery for therapeutic applications
    Aziz MS, Suwanpayak N, Jalil MA, Jomtarak R, Saktioto T, Ali J, et al.
    Int J Nanomedicine, 2012;7:11-7.
    PMID: 22275818 DOI: 10.2147/IJN.S27417
    A new optical trapping design to transport gold nanoparticles using a PANDA ring resonator system is proposed. Intense optical fields in the form of dark solitons controlled by Gaussian pulses are used to trap and transport nanoscopic volumes of matter to the desired destination via an optical waveguide. Theoretically, the gradient and scattering forces are responsible for this trapping phenomenon, where in practice such systems can be fabricated and a thin-film device formed on the specific artificial medical materials, for instance, an artificial bone. The dynamic behavior of the tweezers can be tuned by controlling the optical pulse input power and parameters of the ring resonator system. Different trap sizes can be generated to trap different gold nanoparticles sizes, which is useful for gold nanoparticle therapy. In this paper, we have shown the utility of gold nanoparticle trapping and delivery for therapy, which may be useful for cosmetic therapy and related applications.
    Matched MeSH terms: Gold/chemistry*
  11. Fulltext Electrical characterization of gold-DNA-gold structures in presence of an external magnetic field by means of I-V curve analysis
    Khatir NM, Banihashemian SM, Periasamy V, Ritikos R, Majid WHA, Rahman SA
    Sensors (Basel), 2012;12(3):3578-3586.
    PMID: 22737025 DOI: 10.3390/s120303578
    This work presents an experimental study of gold-DNA-gold structures in the presence and absence of external magnetic fields with strengths less than 1,200.00 mT. The DNA strands, extracted by standard method were used to fabricate a Metal-DNA-Metal (MDM) structure. Its electric behavior when subjected to a magnetic field was studied through its current-voltage (I-V) curve. Acquisition of the I-V curve demonstrated that DNA as a semiconductor exhibits diode behavior in the MDM structure. The current versus magnetic field strength followed a decreasing trend because of a diminished mobility in the presence of a low magnetic field. This made clear that an externally imposed magnetic field would boost resistance of the MDM structure up to 1,000.00 mT and for higher magnetic field strengths we can observe an increase in potential barrier in MDM junction. The magnetic sensitivity indicates the promise of using MDM structures as potential magnetic sensors.
    Matched MeSH terms: Gold/chemistry*
  12. Fulltext Thickness Dependent Nanostructural, Morphological, Optical and Impedometric Analyses of Zinc Oxide-Gold Hybrids: Nanoparticle to Thin Film
    Perumal V, Hashim U, Gopinath SC, Haarindraprasad R, Liu WW, Poopalan P, et al.
    PLoS One, 2015;10(12):e0144964.
    PMID: 26694656 DOI: 10.1371/journal.pone.0144964
    The creation of an appropriate thin film is important for the development of novel sensing surfaces, which will ultimately enhance the properties and output of high-performance sensors. In this study, we have fabricated and characterized zinc oxide (ZnO) thin films on silicon substrates, which were hybridized with gold nanoparticles (AuNPs) to obtain ZnO-Aux (x = 10, 20, 30, 40 and 50 nm) hybrid structures with different thicknesses. Nanoscale imaging by field emission scanning electron microscopy revealed increasing film uniformity and coverage with the Au deposition thickness. Transmission electron microscopy analysis indicated that the AuNPs exhibit an increasing average diameter (5-10 nm). The face center cubic Au were found to co-exist with wurtzite ZnO nanostructure. Atomic force microscopy observations revealed that as the Au content increased, the overall crystallite size increased, which was supported by X-ray diffraction measurements. The structural characterizations indicated that the Au on the ZnO crystal lattice exists without any impurities in a preferred orientation (002). When the ZnO thickness increased from 10 to 40 nm, transmittance and an optical bandgap value decreased. Interestingly, with 50 nm thickness, the band gap value was increased, which might be due to the Burstein-Moss effect. Photoluminescence studies revealed that the overall structural defect (green emission) improved significantly as the Au deposition increased. The impedance measurements shows a decreasing value of impedance arc with increasing Au thicknesses (0 to 40 nm). In contrast, the 50 nm AuNP impedance arc shows an increased value compared to lower sputtering thicknesses, which indicated the presence of larger sized AuNPs that form a continuous film, and its ohmic characteristics changed to rectifying characteristics. This improved hybrid thin film (ZnO/Au) is suitable for a wide range of sensing applications.
    Matched MeSH terms: Gold/chemistry*
  13. Fulltext Synthesis and ultraviolet visible spectroscopy studies of chitosan capped gold nanoparticles and their reactions with analytes
    Mohd Sultan N, Johan MR
    ScientificWorldJournal, 2014;2014:184604.
    PMID: 25215315 DOI: 10.1155/2014/184604
    Gold nanoparticles (AuNPs) had been synthesized with various molarities and weights of reducing agent, monosodium glutamate (MSG), and stabilizer chitosan, respectively. The significance of chitosan as stabilizer was distinguished through transmission electron microscopy (TEM) images and UV-Vis absorption spectra in which the interparticles distance increases whilst retaining the surface plasmon resonance (SPR) characteristics peak. The most stable AuNPs occurred for composition with the lowest (1 g) weight of chitosan. AuNPs capped with chitosan size stayed small after 1 month aging compared to bare AuNPs. The ability of chitosan capped AuNPs to uptake analyte was studied by employing amorphous carbon nanotubes (α-CNT), copper oxide (Cu2O), and zinc sulphate (ZnSO4) as the target material. The absorption spectra showed dramatic intensity increased and red shifted once the analyte was added to the chitosan capped AuNPs.
    Matched MeSH terms: Gold/chemistry*
  14. Fulltext Electronic Characterization of Au/DNA/ITO Metal-Semiconductor-Metal Diode and Its Application as a Radiation Sensor
    Al-Ta'ii HM, Periasamy V, Amin YM
    PLoS One, 2016;11(1):e0145423.
    PMID: 26799703 DOI: 10.1371/journal.pone.0145423
    Deoxyribonucleic acid or DNA molecules expressed as double-stranded (DSS) negatively charged polymer plays a significant role in electronic states of metal/silicon semiconductor structures. Electrical parameters of an Au/DNA/ITO device prepared using self-assembly method was studied by using current-voltage (I-V) characteristic measurements under alpha bombardment at room temperature. The results were analyzed using conventional thermionic emission model, Cheung and Cheung's method and Norde's technique to estimate the barrier height, ideality factor, series resistance and Richardson constant of the Au/DNA/ITO structure. Besides demonstrating a strongly rectifying (diode) characteristic, it was also observed that orderly fluctuations occur in various electrical parameters of the Schottky structure. Increasing alpha radiation effectively influences the series resistance, while the barrier height, ideality factor and interface state density parameters respond linearly. Barrier height determined from I-V measurements were calculated at 0.7284 eV for non-radiated, increasing to about 0.7883 eV in 0.036 Gy showing an increase for all doses. We also demonstrate the hypersensitivity phenomena effect by studying the relationship between the series resistance for the three methods, the ideality factor and low-dose radiation. Based on the results, sensitive alpha particle detectors can be realized using Au/DNA/ITO Schottky junction sensor.
    Matched MeSH terms: Gold/chemistry*
  15. An integrated paper-based sample-to-answer biosensor for nucleic acid testing at the point of care
    Choi JR, Hu J, Tang R, Gong Y, Feng S, Ren H, et al.
    Lab Chip, 2016 Feb 7;16(3):611-21.
    PMID: 26759062 DOI: 10.1039/c5lc01388g
    With advances in point-of-care testing (POCT), lateral flow assays (LFAs) have been explored for nucleic acid detection. However, biological samples generally contain complex compositions and low amounts of target nucleic acids, and currently require laborious off-chip nucleic acid extraction and amplification processes (e.g., tube-based extraction and polymerase chain reaction (PCR)) prior to detection. To the best of our knowledge, even though the integration of DNA extraction and amplification into a paper-based biosensor has been reported, a combination of LFA with the aforementioned steps for simple colorimetric readout has not yet been demonstrated. Here, we demonstrate for the first time an integrated paper-based biosensor incorporating nucleic acid extraction, amplification and visual detection or quantification using a smartphone. A handheld battery-powered heating device was specially developed for nucleic acid amplification in POC settings, which is coupled with this simple assay for rapid target detection. The biosensor can successfully detect Escherichia coli (as a model analyte) in spiked drinking water, milk, blood, and spinach with a detection limit of as low as 10-1000 CFU mL(-1), and Streptococcus pneumonia in clinical blood samples, highlighting its potential use in medical diagnostics, food safety analysis and environmental monitoring. As compared to the lengthy conventional assay, which requires more than 5 hours for the entire sample-to-answer process, it takes about 1 hour for our integrated biosensor. The integrated biosensor holds great potential for detection of various target analytes for wide applications in the near future.
    Matched MeSH terms: Gold/chemistry
  16. Fulltext 'Spotted Nanoflowers': Gold-seeded Zinc Oxide Nanohybrid for Selective Bio-capture
    Perumal V, Hashim U, Gopinath SC, Haarindraprasad R, Foo KL, Balakrishnan SR, et al.
    Sci Rep, 2015 Jul 16;5:12231.
    PMID: 26178973 DOI: 10.1038/srep12231
    Hybrid gold nanostructures seeded into nanotextured zinc oxide (ZnO) nanoflowers (NFs) were created for novel biosensing applications. The selected 'spotted NFs' had a 30-nm-thick gold nanoparticle (AuNP) layer, chosen from a range of AuNP thicknesses, sputtered onto the surface. The generated nanohybrids, characterized by morphological, physical and structural analyses, were uniformly AuNP-seeded onto the ZnO NFs with an average length of 2-3 μm. Selective capture of molecular probes onto the seeded AuNPs was evidence for the specific interaction with DNA from pathogenic Leptospirosis-causing strains via hybridization and mis-match analyses. The attained detection limit was 100 fM as determined via impedance spectroscopy. High levels of stability, reproducibility and regeneration of the sensor were obtained. Selective DNA immobilization and hybridization were confirmed by nitrogen and phosphorus peaks in an X-ray photoelectron spectroscopy analysis. The created nanostructure hybrids illuminate the mechanism of generating multiple-target, high-performance detection on a single NF platform, which opens a new avenue for array-based medical diagnostics.
    Matched MeSH terms: Gold/chemistry*
  17. Polymer Conjugated Gold Nanoparticles in Biomedical Applications
    Anniebell S, Gopinath SCB
    Curr Med Chem, 2018;25(12):1433-1445.
    PMID: 28093984 DOI: 10.2174/0929867324666170116123633
    BACKGROUND: Research interest on the properties of polymer conjugated gold nanoparticle (GNP) in biomedicine is rapidly rising because of the extensive evidences for their unique properties. In the field of biomedicine, GNPs have been widely used because of their inertness and low levels of cytotoxicity. Therefore, when exposed to cells, they are less prone to exert damaging effects. GNPs are capable of being functionalized as desired and are ideal as they do not encourage undesired side reactions that might counter react with the intention of the functionalization. Biofouling is an occurrence that takes place at cellular and biological molecular level, binds non-specifically on the detection surface and forms a wrong output. This undesired incidence can be avoided by conjugating the surface of biomolecules with polymers. Densely packed repeating chains of polymers such as polyethylene glycol are capable of decreasing non-specific reactions. Applications of polymer conjugated GNPs in the field of biomedicine are as biosensors, delivery and therapeutic agents.

    CONCLUSION: Therefore, the properties and applications of polymer conjugated GNPs are studied widely as overviewed here.

    Matched MeSH terms: Gold/chemistry*
  18. Aptamer-17β-estradiol-antibody sandwich ELISA for determination of gynecological endocrine function
    Huang Y, Zhang L, Li Z, Gopinath SCB, Chen Y, Xiao Y
    Biotechnol Appl Biochem, 2021 Aug;68(4):881-888.
    PMID: 33245588 DOI: 10.1002/bab.2008
    17β-Estradiol-E2 (17β-E2) is a steroid hormone that plays a major role in the reproductive endocrine system and is involved in various processes, such as pregnancy, fertility, and menopause. In this study, the performance of an enzyme-linked immunosorbent assay (ELISA) for 17β-E2 quantification was enhanced by using a gold nanoparticle (GNP)-conjugated aptamer. An anti-17β-E2-aptamer-GNP antibody was immobilized on an amine-modified ELISA surface. Then, 17β-E2 was allowed to interact with and be sandwiched by antibodies. Aptamer-GNP conjugation was confirmed by colorimetric assays via the naked eye and UV-visible light spectroscopy. The detection limit based on a signal-to-noise ratio (S/N) of 3 was estimated to be 1.5 nM (400 pg/mL), and the linear range was 1.5-50 nM. Control experiments (without 17β-E2/with a complementary aptamer sequence/with a nonimmune antibody) confirmed the specific detection of 17β-E2. Moreover, 17β-E2 spiking of human serum did not interrupt the interaction between 17β-E2 and its antibody and aptamer. Thus, the developed ELISA can be used as an alternate assay for quantification of 17β-E2 and assessment of endocrine-related gynecological problems.
    Matched MeSH terms: Gold/chemistry*
  19. Recent uses of carbon nanotubes & gold nanoparticles in electrochemistry with application in biosensing: A review
    Alim S, Vejayan J, Yusoff MM, Kafi AKM
    Biosens Bioelectron, 2018 Dec 15;121:125-136.
    PMID: 30205246 DOI: 10.1016/j.bios.2018.08.051
    The innovation of nanoparticles assumes a critical part of encouraging and giving open doors and conceivable outcomes to the headway of new era devices utilized as a part of biosensing. The focused on the quick and legitimate detecting of specific biomolecules using functionalized gold nanoparticles (Au NPs), and carbon nanotubes (CNTs) has turned into a noteworthy research enthusiasm for the most recent decade. Sensors created with gold nanoparticles or carbon nanotubes or in some cases by utilizing both are relied upon to change the very establishments of detecting and distinguishing various analytes. In this review, we will examine the current utilization of functionalized AuNPs and CNTs with other synthetic mixes for the creation of biosensor prompting to the location of particular analytes with low discovery cutoff and quick reaction.
    Matched MeSH terms: Gold/chemistry*
  20. Tailoring of peroxidase mimetics bifunctional nanocomposite: Dual mode electro-spectroscopic screening of cholesterol and hydrogen peroxide in real food samples and live cells
    Arul P, Nandhini C, Huang ST, Gowthaman NSK, Huang CH
    Food Chem, 2023 Jul 15;414:135747.
    PMID: 36841102 DOI: 10.1016/j.foodchem.2023.135747
    A simple and rapid screening of biomarkers in clinical and food matrices is urgently needed to diagnose cardiovascular diseases. The cholesterol (Chol) and hydrogen peroxide (H2O2) are critical bio-indicators, which require more inventive detection techniques to be applied to real food, and bio-samples. In this study, a robust dual sensor was developed for Chol and H2O2 using hybrid catalyst. Bovine serum albumin (BSA)-capped nanocatalyst was potentially catalyzed 3,3',5,5'-tetramethylbenzidine (TMB), and H2O2. The enzymatic nanoelectrocatalyst delivered a wide range of signaling concentrations from 250 nM to 3.0 mM and 100 nM to 10 mM, limit of detection (LOD) of 53.2 nM and 18.4 nM for Chol and H2O2. The cholesterol oxidase-BSA-AuNPs-metal-free organic framework (ChOx-BSA-AuNPs-MFOF) based electrode surface effectively operated in live-cells and real-food samples. The enzymatic sensor exhibits adequate recovery of real-food samples (96.96-99.44%). Finally, the proposed system is a suitable choice for the potential applications of Chol and H2O2 in clinical and food chemistry.
    Matched MeSH terms: Gold/chemistry
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