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Vasudeva N, Jayasing A, Sindogi K, Yadav I, Row TNG, Jain SK, Pandey A. Embedding plasmonic nanoparticles in soft crystals: an approach exploiting CTAB-I structures. NANOSCALE ADVANCES 2024; 6:2602-2610. [PMID: 38752143 PMCID: PMC11093265 DOI: 10.1039/d4na00008k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/03/2024] [Accepted: 02/28/2024] [Indexed: 05/18/2024]
Abstract
Embedding nanoparticles with different functionalities into soft substrates is a convenient tool to realize technologically significant multifunctional materials. This study focuses on incorporating bimetallic plasmonic nanoparticles into soft crystals made of cetyltrimethylammonium bromide-iodide. We observed the emergence of a novel symmetry-lowered cetrimonium crystal polymorph that enables the realization of strong interparticle plasmonic coupling in these composite materials. The observed crystal polymorph exhibits a triclinic structure with significantly reduced unit cell volume compared to standard CTAB. Solid-state nuclear magnetic resonance studies revealed an enhanced cetrimonium chain rigidity and a commensurate decrease in the mobility of the methyl groups. This is attributed to iodide incorporation. To study the influence of these interactions on solution phase dynamical properties, we employed light scattering measurements using gold nanospheres as markers, where we observed aggregation of these particles. We then develop a two step synthetic scheme that successfully enables high levels (533 particles per μm2) of incorporation of bimetallic plasmonic particles into the emergent crystal polymorph.
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Affiliation(s)
- Navyashree Vasudeva
- Solid State and Structural Chemistry Unit, Indian Institute of Science, CV Raman Road Bengaluru 560012 India
| | - Annie Jayasing
- Solid State and Structural Chemistry Unit, Indian Institute of Science, CV Raman Road Bengaluru 560012 India
| | - Kishorkumar Sindogi
- Solid State and Structural Chemistry Unit, Indian Institute of Science, CV Raman Road Bengaluru 560012 India
| | - Isha Yadav
- Solid State and Structural Chemistry Unit, Indian Institute of Science, CV Raman Road Bengaluru 560012 India
| | - T N Guru Row
- Solid State and Structural Chemistry Unit, Indian Institute of Science, CV Raman Road Bengaluru 560012 India
| | - Sheetal K Jain
- Solid State and Structural Chemistry Unit, Indian Institute of Science, CV Raman Road Bengaluru 560012 India
| | - Anshu Pandey
- Solid State and Structural Chemistry Unit, Indian Institute of Science, CV Raman Road Bengaluru 560012 India
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2
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Wenck C, Leopoldt D, Habib M, Hegermann J, Stiesch M, Doll-Nikutta K, Heisterkamp A, Torres-Mapa ML. Colorimetric detection of oral bacteria using functionalized gold nanoparticles as a plasmonic biosensor array. NANOSCALE ADVANCES 2024; 6:1447-1459. [PMID: 38419865 PMCID: PMC10898432 DOI: 10.1039/d3na00477e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Accepted: 01/16/2024] [Indexed: 03/02/2024]
Abstract
Early detection of specific oral bacterial species would enable timely treatment and prevention of certain oral diseases. In this work, we investigated the sensitivity and specificity of functionalized gold nanoparticles for plasmonic sensing of oral bacteria. This approach is based on the aggregation of positively charged gold nanoparticles on the negatively charged bacteria surface and the corresponding localized surface plasmon resonance (LSPR) shift. Gold nanoparticles were synthesized in different sizes, shapes and functionalization. A biosensor array was developed consisting of spherical- and anisotropic-shaped (1-hexadecyl) trimethylammonium bromide (CTAB) and spherical mercaptoethylamine (MEA) gold nanoparticles. It was used to detect four oral bacterial species (Aggregatibacter actinomycetemcomitans, Actinomyces naeslundii, Porphyromonas gingivalis and Streptococcus oralis). The plasmonic response was measured and analysed using RGB and UV-vis absorbance values. Both methods successfully detected the individual bacterial species based on their unique responses to the biosensor array. We present an in-depth study relating the bacteria zeta potential and AuNP aggregation to plasmonic response. The sensitivity depends on multiple parameters, such as bacterial species and concentration as well as gold nanoparticle shape, concentration and functionalization.
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Affiliation(s)
- Christina Wenck
- Institute of Quantum Optics, Leibniz University Hannover Germany
- Lower Saxony Centre for Biomedical Engineering, Implant Research and Development (NIFE) Germany
| | - Dorthe Leopoldt
- Institute of Quantum Optics, Leibniz University Hannover Germany
- Lower Saxony Centre for Biomedical Engineering, Implant Research and Development (NIFE) Germany
| | - Mosaieb Habib
- Institute of Inorganic Chemistry, Leibniz University Hannover Germany
- Lower Saxony Centre for Biomedical Engineering, Implant Research and Development (NIFE) Germany
| | - Jan Hegermann
- Research Core Unit Electron Microscopy, Institute of Functional and Applied Anatomy, Hannover Medical School Germany
| | - Meike Stiesch
- Department of Prosthetic Dentistry and Biomedical Materials Science, Hannover Medical School Germany
- Lower Saxony Centre for Biomedical Engineering, Implant Research and Development (NIFE) Germany
| | - Katharina Doll-Nikutta
- Department of Prosthetic Dentistry and Biomedical Materials Science, Hannover Medical School Germany
- Lower Saxony Centre for Biomedical Engineering, Implant Research and Development (NIFE) Germany
| | - Alexander Heisterkamp
- Institute of Quantum Optics, Leibniz University Hannover Germany
- Lower Saxony Centre for Biomedical Engineering, Implant Research and Development (NIFE) Germany
| | - Maria Leilani Torres-Mapa
- Institute of Quantum Optics, Leibniz University Hannover Germany
- Lower Saxony Centre for Biomedical Engineering, Implant Research and Development (NIFE) Germany
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3
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Chang H, Lozier EH, Ma E, Geiger FM. Quantification of Stern Layer Water Molecules, Total Potentials, and Energy Densities at Fused Silica:Water Interfaces for Adsorbed Alkali Chlorides, CTAB, PFOA, and PFAS. J Phys Chem A 2023; 127:8404-8414. [PMID: 37775181 DOI: 10.1021/acs.jpca.3c04434] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/01/2023]
Abstract
We have employed amplitude- and phase-resolved second-harmonic generation spectroscopy to investigate ion-specific effects of monovalent cations at the fused silica:water interface maintained under acidic, neutral, and alkaline conditions. We find a negligible dependence of the total potential (as negative as -400 mV at pH 14), the second-order nonlinear susceptibility (as large as 1.5 × 10-21 m2 V-1 at pH 14), the number of Stern layer water molecules (1 × 1015 cm-2 at pH 5.8), and the energy associated with water alignment upon going from neutral to high pH (ca. -24 kJ mol-1 to -48 kJ mol-1 at pH 13 and 14, close to the cohesive energy of liquid water but smaller than that of ice) on chlorides of the alkali series (M+ = Li+, Na+, K+, Rb+, and Cs+). Attempts are presented to provide estimates for the molecular hyperpolarizability of the cations and anions in the Stern layer at high pH, which arrive at ca. 20-fold larger values for αtotal ions(2) = αM+(2) + αOH-(2) + αCl-(2) when compared to water's molecular hyperpolarizability estimate from theory and point to a sizable contribution of deprotonated silanol groups at high pH. In contrast to the alkali series, a pronounced dependence of the total potential and the second-order nonlinear susceptibility on monovalent cationic (cetrimonium bromide, CTAB) and anionic (perfluorooctanoic and perfluorooctanesulfonic acid, PFOA and PFOS) surfactants was quantifiable. Our findings are consistent with a low surface coverage of the alkali cations and a high surface coverage of the surfactants. Moreover, they underscore the important contribution of Stern layer water molecules to the total potential and second-order nonlinear susceptibility. Finally, they demonstrate the applicability of heterodyne-detected second-harmonic generation spectroscopy for identifying perfluorinated acids at mineral:water interfaces.
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Affiliation(s)
- HanByul Chang
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Emilie H Lozier
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Emily Ma
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Franz M Geiger
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
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Ahmed W, Suliman A, Khan GA, Qayyum H. Electrostatically enabled dye reduction using laser synthesized gold nanoparticles. J Mol Liq 2023. [DOI: 10.1016/j.molliq.2023.121712] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/29/2023]
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Kim J, Martin OJF. Trap-and-Track for Characterizing Surfactants at Interfaces. Molecules 2023; 28:molecules28062859. [PMID: 36985832 PMCID: PMC10058797 DOI: 10.3390/molecules28062859] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Revised: 03/18/2023] [Accepted: 03/18/2023] [Indexed: 03/30/2023] Open
Abstract
Understanding the behavior of surfactants at interfaces is crucial for many applications in materials science and chemistry. Optical tweezers combined with trajectory analysis can become a powerful tool for investigating surfactant characteristics. In this study, we perform trap-and-track analysis to compare the behavior of cetyltrimethylammonium bromide (CTAB) and cetyltrimethylammonium chloride (CTAC) at water-glass interfaces. We use optical tweezers to trap a gold nanoparticle and statistically analyze the particle's movement in response to various surfactant concentrations, evidencing the rearrangement of surfactants adsorbed on glass surfaces. Our results show that counterions have a significant effect on surfactant behavior at the interface. The greater binding affinity of bromide ions to CTA+ micelle surfaces reduces the repulsion among surfactant head groups and enhances the mobility of micelles adsorbed on the interface. Our study provides valuable insights into the behavior of surfactants at interfaces and highlights the potential of optical tweezers for surfactant research. The development of this trap-and-track approach can have important implications for various applications, including drug delivery and nanomaterials.
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Affiliation(s)
- Jeonghyeon Kim
- Nanophotonics and Metrology Laboratory, Swiss Federal Institute of Technology Lausanne (EPFL), 1015 Lausanne, Switzerland
| | - Olivier J F Martin
- Nanophotonics and Metrology Laboratory, Swiss Federal Institute of Technology Lausanne (EPFL), 1015 Lausanne, Switzerland
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Osonga FJ, Eshun GB, Sadik OA. Ligand effect on controlling the synthesis of branched gold nanomaterials against fusarium wilt diseases. RSC Adv 2022; 12:31855-31868. [PMID: 36380935 PMCID: PMC9639171 DOI: 10.1039/d2ra05478g] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2022] [Accepted: 10/18/2022] [Indexed: 07/22/2023] Open
Abstract
The widespread wilt disease caused by Fusarium solani spp is a pressing problem affecting crop production and intensive farming. Strategic biocontrol of Fusarium solani spp using phytochemical mediated nano-materials is eco-friendly compared to harsh synthetic fungicides. The present study demonstrates the comparative dose effects of QPABA-derived branched gold nanomaterial (AuNF) and quercetin-mediated spherical gold nanoparticles (s-AuNPs) against Fusarium solani spp. Quercetin-para aminobenzoic acid (QPABA) was synthesized using reductive amination by reacting para-aminobenzoic acid with quercetin in an eco-friendly solvent at 25 °C. The structure elucidation was confirmed using 1H and 13C-NMR. TLC analysis showed that QPABA (R f = 0.628) was more polar in water than quercetin (R f = 0.714). The as-synthesized QPABA serves as a reducing and capping agent for the synthesis of gold nanoflowers (AuNFs) and gold nanostars (AuNSs). The UV-vis, XRD, and TEM confirmed the SPR peak of gold (550 nm) and gold element with a particle size distribution of 20-80 nm for the nanostars respectively. AuNFs exhibited a significant (P < 0.05) inhibitory effect against F. solani in a dose-dependent manner using Agar well diffusion. Nevertheless, spherical-AuNPs were not effective against F. solani. The inhibitory effect was influenced by the size, dose treatment, and particle shape. The minimum inhibitory concentration (MIC) value of AuNFs was 125.7 ± 0.22 μg mL-1. Our results indicate that AuNFs show considerable antifungal activity against F. solani as compared to spherical AuNPs. This study shows a greener synthesis of gold anisotropic nanostructures using QPAB, which holds promise for the treatment of fungal pathogens impacting agricultural productivity.
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Affiliation(s)
- Francis J Osonga
- BioSensor Materials for Advanced Research and Technology (The BioSMART Center), Chemistry and Environmental Science Department, New Jersey Institute of Technology, University Heights 161 Warren Street Newark NJ 07102 USA
| | - Gaddi B Eshun
- BioSensor Materials for Advanced Research and Technology (The BioSMART Center), Chemistry and Environmental Science Department, New Jersey Institute of Technology, University Heights 161 Warren Street Newark NJ 07102 USA
| | - Omowunmi A Sadik
- BioSensor Materials for Advanced Research and Technology (The BioSMART Center), Chemistry and Environmental Science Department, New Jersey Institute of Technology, University Heights 161 Warren Street Newark NJ 07102 USA
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Nguyen TTT, Haam S, Park JS, Lee SW. Cysteine-Encapsulated Liposome for Investigating Biomolecular Interactions at Lipid Membranes. Int J Mol Sci 2022; 23:ijms231810566. [PMID: 36142476 PMCID: PMC9500635 DOI: 10.3390/ijms231810566] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2022] [Revised: 09/05/2022] [Accepted: 09/07/2022] [Indexed: 11/29/2022] Open
Abstract
The development of a strategy to investigate interfacial phenomena at lipid membranes is practically useful because most essential biomolecular interactions occur at cell membranes. In this study, a colorimetric method based on cysteine-encapsulated liposomes was examined using gold nanoparticles as a probe to provide a platform to report an enzymatic activity at lipid membranes. The cysteine-encapsulated liposomes were prepared with varying ratios of 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) and cholesterol through the hydration of lipid films and extrusions in the presence of cysteine. The size, composition, and stability of resulting liposomes were analyzed by scanning electron microscopy (SEM), dynamic light scattering (DLS), nuclear magnetic resonance (NMR) spectroscopy, and UV-vis spectrophotometry. The results showed that the increased cholesterol content improved the stability of liposomes, and the liposomes were formulated with 60 mol % cholesterol for the subsequent experiments. Triton X-100 was tested to disrupt the lipid membranes to release the encapsulated cysteine from the liposomes. Cysteine can induce the aggregation of gold nanoparticles accompanying a color change, and the colorimetric response of gold nanoparticles to the released cysteine was investigated in various media. Except in buffer solutions at around pH 5, the cysteine-encapsulated liposomes showed the color change of gold nanoparticles only after being incubated with Triton X-100. Finally, the cysteine-encapsulated liposomal platform was tested to report the enzymatic activity of phospholipase A2 that hydrolyzes phospholipids in the membrane. The hydrolysis of phospholipids triggered the release of cysteine from the liposomes, and the released cysteine was successfully detected by monitoring the distinct red-to-blue color change of gold nanoparticles. The presence of phospholipase A2 was also confirmed by the appearance of a peak around 690 nm in the UV-vis spectra, which is caused by the cysteine-induced aggregation of gold nanoparticles. The results demonstrated that the cysteine-encapsulated liposome has the potential to be used to investigate biological interactions occurring at lipid membranes.
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Affiliation(s)
- Trang Thi Thuy Nguyen
- Department of Chemical and Biological Engineering, Gachon University, Seongnam-si 13120, Korea
| | - Seungjoo Haam
- Department of Chemical and Biomolecular Engineering, Yonsei University, Seoul 03722, Korea
| | - Joon-Seo Park
- Department of Chemistry, Eastern University, St. Davids, PA 19087, USA
- Correspondence: (J.-S.P.); (S.-W.L.)
| | - Sang-Wha Lee
- Department of Chemical and Biological Engineering, Gachon University, Seongnam-si 13120, Korea
- Correspondence: (J.-S.P.); (S.-W.L.)
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8
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Saini B, Khamari L, Mukherjee TK. Kinetic and Mechanistic Insight into the Surfactant-Induced Aggregation of Gold Nanoparticles and Their Catalytic Efficacy: Importance of Surface Restructuring. J Phys Chem B 2022; 126:2130-2141. [PMID: 35254808 DOI: 10.1021/acs.jpcb.2c00702] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Understanding the fundamental interactions between plasmonic metal nanoparticles (MNPs) and small molecules is of utmost importance in various applications such as catalysis, sensing, drug delivery, optoelectronics, and surface-enhanced Raman spectroscopy. Herein, we have investigated the early stage of the aggregation pathway of citrate-stabilized Au NPs with surfactants and explored their catalytic efficacy. Our findings reveal that (17 ± 2)-nm-sized citrate-stabilized Au NPs undergo concentration and time-dependent aggregation with positively charged cetyltrimethylammonium bromide (CTAB). Kinetic analyses revealed the presence of two distinct kinds of aggregates, namely, smaller clusters and a larger branched network of Au nanochains. At longer times and in the presence of higher concentrations of CTAB, these branched networks of Au nanochains transform into dense compact globular aggregates. The catalytic efficacy of Au NPs, branched Au nanochains, and dense compact aggregates has been explored with respect to the reductive hydrogenation of 4-nitophenol in the presence of excess NaBH4. Our study revealed that the catalytic rate decreases in the order of Au NPs > branched Au nanochains > compact aggregates. Interestingly, pre-equilibrating different Au NP samples with excess NaBH4 prior to the onset of the reaction results in similar catalytic activity irrespective of the aggregation state of Au NPs. This observation has been explained by considering efficient surface restructuring via ligand exchange with H- ions and the subsequent disruption of CTAB-induced aggregates of Au NPs. Moreover, the aggregated Au NPs can be recycled over several consecutive cycles for the reductive hydrogenation of 4-NP upon ligand exchange with H- ions. Taken together, our present study highlights the early-stage aggregation kinetics of Au NPs with CTAB surfactants and demonstrates the importance of the surface restructuring of Au NPs on their catalytic efficacy.
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Affiliation(s)
- Bhawna Saini
- Department of Chemistry, Indian Institute of Technology (IIT) Indore, Simrol, Indore 453552, Madhya Pradesh, India
| | - Laxmikanta Khamari
- Department of Chemistry, Indian Institute of Science Education and Research (IISER) Bhopal, Bhauri, Bhopal 462066, Madhya Pradesh, India
| | - Tushar Kanti Mukherjee
- Department of Chemistry, Indian Institute of Technology (IIT) Indore, Simrol, Indore 453552, Madhya Pradesh, India
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9
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Tunable self-assembled Casimir microcavities and polaritons. Nature 2021; 597:214-219. [PMID: 34497392 DOI: 10.1038/s41586-021-03826-3] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Accepted: 07/15/2021] [Indexed: 11/08/2022]
Abstract
Spontaneous formation of ordered structures-self-assembly-is ubiquitous in nature and observed on different length scales, ranging from atomic and molecular systems to micrometre-scale objects and living matter1. Self-ordering in molecular and biological systems typically involves short-range hydrophobic and van der Waals interactions2,3. Here we introduce an approach to micrometre-scale self-assembly based on the joint action of attractive Casimir and repulsive electrostatic forces arising between charged metallic nanoflakes in an aqueous solution. This system forms a self-assembled optical Fabry-Pérot microcavity with a fundamental mode in the visible range (long-range separation distance about 100-200 nanometres) and a tunable equilibrium configuration. Furthermore, by placing an excitonic material in the microcavity region, we are able to realize hybrid light-matter states (polaritons4-6), whose properties, such as coupling strength and eigenstate composition, can be controlled in real time by the concentration of ligand molecules in the solution and light pressure. These Casimir microcavities could find future use as sensitive and tunable platforms for a variety of applications, including opto-mechanics7, nanomachinery8 and cavity-induced polaritonic chemistry9.
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Li Y, Bian J, Lin T, Zhang Y, Liu X, Liu Y. Sensing of mercury and silver ions using branched Au nanoparticles prepared by hyperbranched polyethylenimine fabricated and capped AuNPs seeds. NANOTECHNOLOGY 2021; 32:375702. [PMID: 34044377 DOI: 10.1088/1361-6528/ac05eb] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/11/2021] [Accepted: 05/27/2021] [Indexed: 06/12/2023]
Abstract
Branched AuNPs usually have two or more local surface plasmon resonance (LSPR) absorption bands due to their structural anisotropy, and the LSPR performance is more sensitive to the changes of environmental refractive index than that of spherical AuNPs. The design and preparation of branched AuNPs as colorimetric probes is expected to improve the selectivity and sensitivity of detection of targets. In this paper, branched AuNPs were innovatively synthesized via hyperbranched polyethylenimine (HPEI) fabricated and capped AuNPs as seeds and cetyltrimethylammonium bromide (CTAB) as template agent. The branched AuNPs were characterized by TEM, DLS, zeta potentials and UV-vis spectra. Using the branched AuNPs as a colorimetric probe, the detection system for Hg2+and Ag+showed bright color changes from blue to orange and blue to green based on the morphological evolution of branched AuNPs. The branched AuNPs could selectively detect Hg2+and Ag+at concentrations as low as 77 and 140 nM, respectively. Moreover, this unusual colorimetric method has been successfully used in real water samples and has great potential as a simple, rapid, sensitive and selective method for the detection of Hg2+and Ag+.
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Affiliation(s)
- Yuxi Li
- School of Chemistry and Materials Science, Ludong University, Yantai 264001, People's Republic of China
| | - Jie Bian
- School of Chemistry and Materials Science, Ludong University, Yantai 264001, People's Republic of China
| | - Tao Lin
- School of Chemistry and Materials Science, Ludong University, Yantai 264001, People's Republic of China
| | - Yiyun Zhang
- School of Chemistry and Materials Science, Ludong University, Yantai 264001, People's Republic of China
| | - Xunyong Liu
- School of Chemistry and Materials Science, Ludong University, Yantai 264001, People's Republic of China
| | - Yi Liu
- School of Chemistry and Materials Science, Ludong University, Yantai 264001, People's Republic of China
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11
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Chen N, Pan B. Tributylhexadecylphosphonium Modification Strategy to Construct Gold Nanoprobes for the Detection of Aqueous Cr(III)-Organic Complexes. Anal Chem 2021; 93:1811-1817. [PMID: 33334097 DOI: 10.1021/acs.analchem.0c04688] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Most metal probes based on gold nanoparticles (AuNPs) are designed for free metal ions in synthetic waters, and very few are applicable in the detection of metal-organic complexes ubiquitous in real water samples. In this study, we proposed a novel colorimetric nanoprobe strategy for complexed Cr(III) species based on the analyte-induced aggregation of AuNPs, as coated by a cationic surfactant tributylhexadecylphosphonium bromide (THPB) instead of traditional carboxyl modifiers. Such a detection system could be realized via both naked eye and/or UV-vis spectroscopy with detection limits of 8.0 and 0.29 μM, respectively, much lower than its allowable maximum level in industrial effluent as regulated by China EPA (1.5 mg Cr/L, ∼30 μM). The proposed detection system also exhibits high selectivity against various interfering substances including free ions, small organic molecules, and other metal-citrate complexes. The unique hydrolysis and extremely slow decomplexation of Cr(III) are believed to favor the formation of the specific interaction between Cr(III)-citrate and THPB-AuNPs, as verified by X-ray photoelectron spectroscopy characterization, thus endowing the nanoprobe with specific discrimination of the complexed Cr(III) via the aggregation of THPB-AuNPs. Also, the THPB-AuNPs could be stored at room temperature for 30 days and maintain constant detection performance. Moreover, the quantitative detection of Cr(III)-organic complexes with the background of various real water samples agreed well with that based on inductively coupled plasma atomic emission spectrometry, making it an attractive alternative for on-site detection of authentic samples containing Cr(III)-organic species.
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Affiliation(s)
- Ningyi Chen
- State Key Laboratory of Pollution Control and Resource Reuse, School of Environment, Nanjing University, Nanjing 210023, China
| | - Bingcai Pan
- State Key Laboratory of Pollution Control and Resource Reuse, School of Environment, Nanjing University, Nanjing 210023, China.,Research Center for Environmental Nanotechnology (ReCENT), Nanjing University, Nanjing 210023, China
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12
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Li R, Cheng C, Wang Z, Gu X, Zhang C, Wang C, Liang X, Hu D. Conformational Stability of Poly (N-Isopropylacrylamide) Anchored on the Surface of Gold Nanoparticles. MATERIALS (BASEL, SWITZERLAND) 2021; 14:443. [PMID: 33477518 PMCID: PMC7831095 DOI: 10.3390/ma14020443] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/13/2020] [Revised: 01/13/2021] [Accepted: 01/14/2021] [Indexed: 12/14/2022]
Abstract
To verify the temperature sensitive failure of poly (N-isopropylacrylamide) (PNIPAM) anchored on the surface of gold nanoparticles (AuNPs), the UV-Vis spectra with temperature variations of the following aqueous solutions respectively containing AuNPs-PNIPAM, Au-PNIPAM/PNIPAM, PNIPAM, in different media (including salt, ethanol, HCl and cetyltrimethylammoniumbromide (CTAB)), were systematically determined. The results indicated that the UV-Vis spectrum of AuNPs-PNIPAM suspension hardly changed even above the Lower Critical Solution Temperature (LCST) of PNIPAM, but that of Au-PNIPAM/PNIPAM sharply increased only in absorbance intensity. A possible mechanism of the failed temperature sensitivity of PNIPAM anchored on the surface of AuNPs was proposed. Being different from free PNIPAM molecules, a strong interaction exists among PNIPAM molecules anchored on the surface of AuNPs, restraining the change in conformation of PNIPAM. The temperature sensitivity of Au-PNIPAM/PNIPAM originates from the free PNIPAM molecules rather than the anchored PNIPAM one. The changing electrostatic interaction could effectively regulate the aggregation behavior of AuNPs-PNIPAM and enhance its sensitivity to temperature.
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Affiliation(s)
- Runmei Li
- Engineering Research Center of Historical and Cultural Heritage Protection, Ministry of Education, School of Materials Science and Engineering, Shaanxi Normal University, Xi’an 710062, China; (R.L.); (C.C.); (Z.W.); (C.Z.); (C.W.)
| | - Cong Cheng
- Engineering Research Center of Historical and Cultural Heritage Protection, Ministry of Education, School of Materials Science and Engineering, Shaanxi Normal University, Xi’an 710062, China; (R.L.); (C.C.); (Z.W.); (C.Z.); (C.W.)
| | - Zhuorui Wang
- Engineering Research Center of Historical and Cultural Heritage Protection, Ministry of Education, School of Materials Science and Engineering, Shaanxi Normal University, Xi’an 710062, China; (R.L.); (C.C.); (Z.W.); (C.Z.); (C.W.)
| | - Xuefan Gu
- College of Chemistry and Chemical Engineering, Xi’an Shiyou University, Xi’an 710065, China;
| | - Caixia Zhang
- Engineering Research Center of Historical and Cultural Heritage Protection, Ministry of Education, School of Materials Science and Engineering, Shaanxi Normal University, Xi’an 710062, China; (R.L.); (C.C.); (Z.W.); (C.Z.); (C.W.)
| | - Chen Wang
- Engineering Research Center of Historical and Cultural Heritage Protection, Ministry of Education, School of Materials Science and Engineering, Shaanxi Normal University, Xi’an 710062, China; (R.L.); (C.C.); (Z.W.); (C.Z.); (C.W.)
| | - Xinyue Liang
- Institute of Industrial Hygiene of Ordnance Industry, Xi’an 710065, China;
| | - Daodao Hu
- Engineering Research Center of Historical and Cultural Heritage Protection, Ministry of Education, School of Materials Science and Engineering, Shaanxi Normal University, Xi’an 710062, China; (R.L.); (C.C.); (Z.W.); (C.Z.); (C.W.)
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