Determination of self-exchange rate of alkanethiolates in self-assembled monolayers on gold using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry

Kang, Hyunook; Kim, Yongbin; Choi, Inseong; Chang, Rakwoo; Yeo, Woon‐Seok

doi:10.1016/j.aca.2014.07.028

Cited by 18 publications

(24 citation statements)

References 59 publications

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“…After 20 min incubation in DMSO atmosphere at room temperature, the spotted gold surface was rinsed thoroughly by DMSO and by ethanol followed by incubation in ethanolic solution of 1 mM C10-COOH for 10 min - at this step, the rest of the gold area is functionalized [ 15 ]. Due to very slow exchange kinetics of alkyl thiols [ 28 , 29 ] we assume that this procedure does not lead to any essential modification of the formerly coated spots by C11-N + (CH 3 ) 3 Cl − alkyl thiol. Then, the prism was rinsed by ethanol, dried, and mounted in the SPM device.…”

Section: Methodsmentioning

confidence: 99%

Plasmonic detection and visualization of directed adsorption of charged single nanoparticles to patterned surfaces

2016

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It has recently been shown that surface plasmon microscopy (SPM) allows single nanoparticles (NPs) on sensor surfaces to be detected and analyzed. The authors have applied this technique to study the adsorption of single metallic and plastic NPs. Binding of gold NPs (40, 60 and 100 nm in size) and of 100 nm polystyrene NPs to gold surfaces modified by differently ω-functionalized alkyl thiols was studied first. Self-assembled monolayers (SAM) with varying terminal functions including amino, carboxy, oligo(ethylene glycol), methyl, or trimethylammonium groups were deposited on gold films to form surfaces possessing different charge and hydrophobicity. The affinity of NPs to these surfaces depends strongly on the type of coating. SAMs terminated with trimethylammonium groups and carboxy group display highly different affinity and therefore were preferred when creating patterned charged surfaces. Citrate-stabilized gold NPs and sulfate-terminated polystyrene NPs were used as negatively charged NPs, while branched polyethylenimine-coated silver NPs were used as positively charged NPs. It is shown that the charged patterned areas on the gold films are capable of selectively adsorbing oppositely charged NPs that can be detected and analyzed with an ~1 ng⋅mL−1 detection limit. Graphical abstractSelf-assembled monolayers of ω-functionalized alkyl thiols were deposited on a gold layer of a patterned sensor array. The charge-selective binding of single nanoparticles to such surfaces was registered by wide-field surface plasmon microscopy. Electronic supplementary materialThe online version of this article (doi:10.1007/s00604-016-1956-7) contains supplementary material, which is available to authorized users.

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Section: Methodsmentioning

confidence: 99%

Plasmonic detection and visualization of directed adsorption of charged single nanoparticles to patterned surfaces

2016

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“…AuNPs (40 nm diameter) were prepared by the method previously reported by Schwartzberg et al 16 Deuterated tri(ethylene glycol)-terminated alkanethiol (for the dAm-tag) was also prepared as previously reported. 17 Gold chips were prepared via the vacuum deposition of titanium (10 nm), followed by gold (50 nm) onto cover slips. 1-Ethyl-3-(3dimethylaminopropyl) carbodiimide hydrochloride (EDC), N-hydroxysuccinimide (NHS), dimethyl sulfoxide, and PSA were purchased from Sigma-Aldrich (St. Louis, MO, USA).…”

Section: Reagents and Chemicalsmentioning

confidence: 99%

Determining the Ratio of Two Types of Prostate Specific Antigens with Biochips and Gold Nanoparticles for Accurate Prostate Cancer Diagnosis

Yoo

Yeo

2016

ANAL. SCI.

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Prostate-specific antigen (PSA) is a well-known biomarker for prostate-cancer diagnosis. However, the serum PSA measurement alone is insufficient for accurate diagnoses because the correlation with cancer is weak within the gray zone-the biomarker level range wherein a clear-cut diagnosis is impossible. As such, accurate prostate cancer diagnosis has been supplemented by measurements of the ratio of two types of PSA: free PSA (fPSA) and complexed PSA (cPSA; α-1-antichymotrypsin-bound PSA). Herein, we describe a new method for measuring the ratio of these two types of PSA by using gold nanoparticles (AuNPs) and biochips. Both types of PSA in a sample are captured by the antibody immobilized on a biochip based on self-assembled monolayers on gold. fPSA and cPSA on the biochip are then distinguished by AuNPs that present antibodies against fPSA and cPSA, respectively. The presence of PSAs in a sample is detected with laser desorption/ionization time-of-flight mass spectrometry by observing reporter molecules, called amplification tags (Am-tags), on the AuNPs. One of the reporter molecules is an Am-tag without isotope labeling, and the other is a deuterium-labeled Am-tag (dAm-tag). These tags amplify mass signals so as to enhance the sensitivity of the method. A comparison of the mass intensities between the Am-tag and dAm-tag signals allows the determination of the ratio between fPSA and cPSA. We validated the selective measurement of fPSA and cPSA at different ratios in 50, 75, and 100 pM of total PSA (fPSA + cPSA) solutions corresponding to the gray zone in prostate-cancer diagnosis (4 - 10 ng/mL). Finally, the two types of PSA were spiked in fetal bovine serum at various ratios, and our strategy greatly afforded their accurate ratios as spiked based on a constructed calibration curve. These results clearly indicate that the strategy is applicable to human serum as a diagnostic and prognostic assay for prostate cancer.

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“…SAMs of alkanethiolates on gold have been widely used in various biological studies [20][21][22][23][24][25], and Mrksich's and co-workers found that they are well-suited for analysis in conjunction with MALDI-TOF MS and named this technique SAMDI MS [26][27][28][29][30][31][32][33][34][35]. SAMDI analysis yields information on molecular weights of constituents of monolayers, and thus provides not only structural information but also quantitative information with regard to the composition of the monolayers.…”

Section: Introductionmentioning

confidence: 98%

On-chip enzymatic assay for chloramphenicol acetyltransferase using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry

Choi

Kim

Ahn

et al. 2015

Colloids and Surfaces B: Biointerfaces

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Determination of self-exchange rate of alkanethiolates in self-assembled monolayers on gold using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry

Cited by 18 publications

References 59 publications

Plasmonic detection and visualization of directed adsorption of charged single nanoparticles to patterned surfaces

Plasmonic detection and visualization of directed adsorption of charged single nanoparticles to patterned surfaces

Determining the Ratio of Two Types of Prostate Specific Antigens with Biochips and Gold Nanoparticles for Accurate Prostate Cancer Diagnosis

On-chip enzymatic assay for chloramphenicol acetyltransferase using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry

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