Ultrastable and Biofunctionalizable Gold Nanoparticles

Gupta, Akash; Moyano, Daniel F.; Parnsubsakul, Attasith; Papadopoulos, Alexander; Wang, Lisheng; Landis, Ryan F.; Das, Rahul; Rotello, Vincent M.

doi:10.1021/acsami.6b02548

Cited by 135 publications

(113 citation statements)

References 53 publications

(98 reference statements)

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“…Scheme 1 shows the mechanism of how monodispersed (due to electrostatic repulsion), negatively charged AuNPs were synthesized by citrate reduction method. In the presence of an electrolyte such as NaCl, the charge repulsion between particles reduced which resulted in the aggregation of AuNPs 27,28 . Aggregation of AuNPs causes a shift in the absorbance peak to 630 nm and change in colour from wine red to blue.…”

Section: Resultsmentioning

confidence: 99%

Fabrication of microfluidic device for Aflatoxin M1 detection in milk samples with specific aptamers

Kasoju

Shahdeo

Khan

et al. 2020

Sci Rep

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This study describes the colorimetric detection of aflatoxin M1 (Afl M1) in milk samples using a microfluidic paper-based analytical device (µPAD). Fabrication of µPADs was done using a simple and quick approach. Each μPAD contained a detection zone and a sample zone interconnected by microchannels. The colorimetric assay was developed using unmodified AuNPs as a probe and 21-mer aptamer as a recognition molecule. The free aptamers were adsorbed onto the surface of AuNPs in absence of Afl M1, even at high salt concentrations. The salt induced aggregation of specific aptamers occurred in presence of Afl M1. Under optimum conditions, the analytical linear range was found to be 1 µM to 1 pM with limit of detection 3 pM and 10 nM in standard buffer and spiked milk samples respectively. The proposed aptamer based colorimetric assay was repeatable, quick, selective, and can be used for on-site detection of other toxins in milk and meat samples. Mycotoxins are secondary metabolites produced by filamentous fungi belonging to the genera Aspergillus and Penicillium 1. Mycotoxins are also found in animal derived foods such as milk due to intake of contaminated feed 2,3. Considering agricultural and economical aspects and possible implications on public health, the most relevant mycotoxins are aflatoxins, ochratoxins, fuminosins, T-2 toxin, and zearalenone (ZEA) 4. Aflatoxins pose a huge economic burden as they cause around 25% or more loss of the world's food crops every year 5. Afl M1 (4-hydroxy aflatoxin B1) and M2 (4-dihydroxy aflatoxin B1) have well proven carcinogenic and mutagenic potentiality and pose severe health consequences on milk consumers, including the risk of cancer and stunted growth in children below the age of 5 years 6. When B1 is ingested by a cow, it is secreted as hydroxylated metabolite aflatoxin M1 (Afl M1) in the urine and milk of the cow 7. Consumption of food containing aflatoxin concentrations of one milligram/kilogram or higher has been suspected to cause aflatoxicosis 8 , the prognosis of which consists of acute liver failure, jaundice, lethargy, and nausea, eventually leading to death within 1 to 2 weeks, based on past reports 9. Thus there is a need to develop rapid low cost technology based highly specific methods for detection of aflatoxins to improve surveillance and control in rural areas. A plethora of analytical techniques are available for aflatoxin M1 detection, ranging from chromatography and HPLC-MS used for regulatory control in official laboratories to rapid test kits for grain silos and farmers, especially for surveys when outbreaks occur 10,11. Conventional techniques for the detection of aflatoxins include gas chromatography (GC), fluorescence or UV based detection, thin layer chromatography (TLC) and enzyme linked immunosorbent assay (ELISA) 6-12. These techniques are routinely used and yield reliable results, however they are expensive, time consuming, require large scale instrumentation and large amounts of hazardous chemical reagents. Advancement in the development of bios...

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Section: Resultsmentioning

confidence: 99%

Fabrication of microfluidic device for Aflatoxin M1 detection in milk samples with specific aptamers

Kasoju

Shahdeo

Khan

et al. 2020

Sci Rep

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show abstract

“…9 However, retention of enzymatic activity on a nanoparticle surface after lyophilization has yet to be explored. We chose to investigate the conjugation of horseradish peroxidase (HRP), an enzyme that has previously been attached to AuNPs and utilized for ELISA, increasing target sensitivities by multiple orders of magnitude compared to free HRP.…”

Section: Resultsmentioning

confidence: 99%

“…While PEG-thiols are clearly preferable for their increased tolerance to these conditions, they are not infallible; nonionic PEG-thiols have been shown to leave AuNPs subject to aggregation following freezing and lyophilization, both of which have been established as common, and sometimes necessary, storage techniques. 9 …”

mentioning

confidence: 99%

DNA Linkers and Diluents for Ultrastable Gold Nanoparticle Bioconjugates in Multiplexed Assay Development

2017

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A novel bioconjugation strategy leading to ultrastable gold nanoparticles (AuNPs), utilizing DNA linkers and diluents in place of traditional self-assembled monolayers, is reported. The protective capacity of DNA confers straightforward biomolecular attachment and multistep derivatization capabilities to these nanoparticles and, more significantly, substantially enhances their stability in demanding and complex sensing environments. The DNA/AuNPs were assembled through pH-assisted thiol-gold bonding of single stranded DNA and salt aging, with preconjugated biotin moieties facing outward from the gold surface. These nanoparticles remain a stable colloidal suspension under a wide range of buffers and ionic strengths and can endure multiple rounds of lyophilization while retaining high biological activity. Furthermore, the high stability of the DNA/AuNPs allows for multiple reactions and conjugations to be performed within the colloidal suspensions (i.e., Protein A and antibody binding) for tailored and specific recognition to take place. We have demonstrated the applications of the DNA/AuNPs for colorimetric assays and ELISA feasibility; additionally, SPR imaging analysis of a supported membrane microarray shows excellent results with DNA/AuNPs as the enhancing agent. Together, the properties imparted by this interface render the material suitable for clinical and point-of-care applications where stability, throughput, and extended shelf lives are needed.

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“…The high variability of the composition of antibodies impedes the development of a universal technique for obtaining such conjugates. Fairly often, the conjugates are unstable and quickly lose activity during storage [19,20], which is primarily a result of the process of particle aggregation [21].…”

Section: Introductionmentioning

confidence: 99%

A Mechanism of Gold Nanoparticle Aggregation by Immunoglobulin G Preparation

et al. 2020

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Conjugates of gold nanoparticles (GNPs) and antibodies are widely used in various fields of biochemistry and microbiology. However, the procedure for obtaining such conjugates remains precarious, and the properties of conjugates differ significantly for different antibody clones. One of the most common problems is the aggregation of GNPs in the course of their conjugation with antibodies. This article considers an example of the conjugation of monoclonal antibodies with non-stable aggregating product. The composition of the antibody preparation was studied using electrophoresis, asymmetrical flow field-flow fractionation, and ultracentrifugation. It was shown that the component that causes the aggregation of the GNPs is the light chains of immunoglobulins that appear due to the spontaneous decay of the antibodies. After separation of the fraction with a molecular weight of less than 30 kDa, stable conjugates of antibodies with GNPs were obtained. The high functional activity of the obtained conjugates was confirmed by immunochromatography.

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Ultrastable and Biofunctionalizable Gold Nanoparticles

Cited by 135 publications

References 53 publications

Fabrication of microfluidic device for Aflatoxin M1 detection in milk samples with specific aptamers

Fabrication of microfluidic device for Aflatoxin M1 detection in milk samples with specific aptamers

DNA Linkers and Diluents for Ultrastable Gold Nanoparticle Bioconjugates in Multiplexed Assay Development

A Mechanism of Gold Nanoparticle Aggregation by Immunoglobulin G Preparation

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