Triangular Silver Nanoprisms Research Articles

Colorimetric detection of platinum (IV) ions based on triangular silver nanoprism particles in aqueous environmental sample

Colorimetric detection of platinum (IV) ions based on triangular silver nanoprism particles in aqueous environmental sample

Photoinduced Stitching of Self-Assembled Triangular Silver Nanoprisms at the Air-Water Interface.

This study investigates the influence of optical excitation on the self-assembly of triangular nanoprisms of silver into a continuous monolayer at the air-water interface. Langmuir monolayers of octadecylamine (ODA) have been used to electrostatically assemble citrate-capped silver triangular nanoprisms (AgTNPs) in the presence and absence of light. Under optical excitation, the nanoprisms were observed to assemble into a well-ordered monolayer through plasmon-mediated stitching, whereas the particles were merely in close contact during assembly in the dark. These findings suggest new avenues for tailoring particle properties through light-mediated assembly in two dimensions.

One-drop micro-array towards accelerated optical quantification of dopamine in human biofluids using triangular silver nanoparticles: Smartphone-assisted biomedical analysis by colorimetric sensing and Lab-on-paper technology

Trace-level detection of Dopamine (DA) in human body fluids is crucial for diagnosing neurological disorders, understanding mental health, and advancing drug discovery, but found challenging with rapid and low-cost detection technologies. Herein, an innovative paper-based photochemical method has been developed for the detection of DA using triangular silver nanoprism (AgNPrs), as an optical nanoprobe, in human blood plasma and urine samples. The redox reaction between DA and AgNPrs was evaluated through a color change at two pHs (5.35and 6.14), which can be analyzed by UV–Vis spectrophotometry and microfluidic paper-based colorimetric device (µPCD) with low limit of quantification of 0.01 µM. This study presents pioneering work with the potential to inspire the development of simple and effective on-site semi quantifying recognition devices for other neurotransmitters, requiring only a lightweight piece of paper and a single drop of the necessary reagent.

One-pot synthesis of near-infrared absorbing silver nanoprisms via a simple photochemical method using an ultraviolet-C light source

This study describes a simple one-pot photochemical method to synthesize triangular silver nanoprisms (T-AgNPs), for which a mixture of silver nitrate (AgNO3) and citrate was irradiated with an ultraviolet-C (UVC) lamp reactor. We successfully synthesized T-AgNPs with edge lengths ranging from 50 to 150 nm, showing a significant localized surface plasmon resonance (LSPR) band over a wavelength of 1200 nm. This photochemical reaction appears to be unrestricted by plasmon resonance conditions, allowing for the formation of colloidal T-AgNPs with an LSPR band in the near-IR region. In addition, this new method does not require any highly reactive reducing agents or initially prepared silver seed solution. The reduction of Ag+ ions by citrate is induced by UVC light, and the nascent Ag first undergoes nucleation to form spherical or quasi-spherical silver nanoparticles (S-AgNPs). Subsequently, continuous irradiation with UVC light facilitates the transformation of these S-AgNPs into T-AgNPs. The growth kinetics of the nanoparticles with different reaction conditions were examined using ultraviolet–visible–near-infrared spectroscopy and transmission electron microscopy. This new method offers a simple, efficient, and cost-effective means to synthesize T-AgNPs with near-IR LSPR, contributing to wider applications in the fields of optoelectronics, spectroscopics, photovoltaics, etc.

Triangular silver nanoprism-based chemosensor for recognition of hyaluronic acid in human biofluids: a new platform for monitoring osteoarthritis treatment using smartphone-assisted digital image analysis.

Hyaluronic acid (HA) possesses unique viscoelastic properties and low immunogenicity, making it suitable for various biomedical purposes such as viscosupplementation in osteoarthritis treatment, assistance in eye surgery, and wound regeneration. The need for its quantification in human biofluids is crucial in clinical studies. This research work presents a novel approach using paper-based and parafilm-based photochemical techniques, employing triangular silver nanoprisms (TA-AgNPrs) as optical nanoprobes for HA detection in human biofluids. The interaction between HA and TA-AgNPrs leads to a notable change in the absorption spectrum, facilitating rapid and reliable measurement with a detection limit of less than 0.5 μM to 30 mM. The developed colorimetric setups, along with the single-drop parafilm colorimetric substrate, enable fast and on-site HA analysis. This research marks the maiden use of TA-AgNPrs for direct, rapid and sensitive HA detection in real samples, without the need for sample pre-preparation. The use of a digital image analysis strategy enhances the simplicity, affordability, and portability of this sensor, presenting promising potential for monitoring HA levels. This new technique is poised to enable early diagnosis of diseases associated with abnormal HA levels in human biofluids, thanks to its high sensitivity and selectivity in detecting HA.

A dual-signal output plasmonic sensor based on glucose oxidase-triggered etching of triangular silver nanoprism for sensitive detection of fumonisins

A dual-signal output plasmonic sensor based on glucose oxidase (GOx)-triggered etching of triangular silver nanoprisms (TAgNPRs) was developed for detecting fumonisins (FBs). In the sensor, glucose oxidase (GOx)-FB1 conjugation was used as competitive antigens that compete with FBs to bind with anti-FBs monoclonal antibody (McAb) coated in microplate well. GOx catalyzed glucose to produce hydrogen peroxide (H2O2) which acted as an oxidant to etch TAgNPRs. As a result, the wavelength of localized surface plasmon resonance (LSPR) peak blue shifted along with a color change of the solution. The amount of FBs was correlated to the wavelength shift of LSPR peak and the color change of the solution from light blue to violet in a linear range of 0.1–500 ng/mL. The colorimetric and LSPR detection limits were 0.1 ng/mL and 0.06 ng/mL respectively. The sensitivity of the dual-signal output sensor is better than those of aggregation plasmonic sensor and magnetoimmunosensor.

One-step surfactant-free photoreduction synthesis of single-crystal silver triangular nanoprisms by surface modified chemically patterned ferroelectric crystals for SERS application

Anisotropic metal nanoparticles with plasmonic and photocatalytic action exhibit significant applications for SERS detection and green transformation. Current synthetic approaches using multiple chemicals cause substantial resource consumption and surface chemical residues that hinder analyte adsorption and thus prevent efficient action. Herein, we present a green production process using surface modified ferroelectric templates to grow triangular Ag nanoprisms for surface enhanced Raman spectroscopy (SERS). Surface modification of ferroelectric templates with positively charged ions suppresses the Ag nucleation on template surface and enables the reaction-controlled process to promote anisotropic photoreduction for the growth of Ag nanoprisms. Under optimal experimental conditions, numerous Ag nanoprisms with the (111) plane can be photoreduced with sharp tips and edges and greatly strengthen the excited electric field for Raman signal enhancement. The synthesized Ag nanoprism array presents superior SERS performance, including enhancement factor of 3.78 × 108, limit of detection as low as 4.95 × 10-9 M, and Raman signal enhancement by 8.63 times. The practical application of Ag nanoprisms is effectively demonstrated by the SERS detection of antibiotics. The reaction control by utilization of surface-modified ferroelectric templates provides a promising prospect for the green synthesis of anisotropic metal nanomaterials and the technical development of green applications.

Solvatochromism of a silver-epoxy nanocomposite dispersed in organic solvents

Solvent-dependent colorimetric properties of coupled plasmonic silver nanoparticles have significant interest in sensing devices for biological and environmental applications. In this work, the solvatochromism of silver-epoxy nanocomposites was studied in aprotic solvents having different dielectric constants like acetone, N, N-dimethylformamide, and dimethylsulphoxide. Triangular silver nanoprisms with sharp corners, truncated triangular silver nanoprisms and stacks of elongated silver nanoparticles with strong coupling plasmonic may be obtained by simple dispersion of the nanocomposites in presence of these solvents, respectively. The color and hues parameters of the assemblies were originated by a solvent-induced coalescence mechanism involving seeds of silver nanoparticles in fresh and aged epoxy nanocomposites. Overall, the results showed that the dielectric constant of the solvent has an important impact on the optical properties, size distribution, morphology, and stability of the silver nanoparticles dispersed in epoxy resin.

Polarization Sensitive Photodetectors Based on Two-Dimensional WSe2.

In this work we show the possibility of imparting polarization-sensitive properties to two-dimensional films of graphene-like semiconductors, using WSe2 as an example, by the application of ordered silver triangular nanoprisms. In addition, such nanoprisms made it possible to increase the optical sensitivity of optical detectors created on two-dimensional films by a factor of five due to surface plasmon resonance. The peculiarities of the surface plasmon resonance were shown by theoretical modeling, and the optimal conditions of its occurrence were determined. This article demonstrates an effective approach to creating spectrally selective, polarization-sensitive detectors based on two-dimensional graphene-like semiconductors.

One metal-ion-regulated AgTNPs etching sensor array for visual discrimination of multiple organic acids

The detection and discrimination of organic acids (OAs) is of great importance in the early diagnosis of specific diseases. In this study, we established an effective visual sensor array for the identification of OA. This is the first time, to our best knowledge, that metal ions were used to regulate the etching of silver triangular nanoprisms (AgTNPs) in an OA discrimination sensor array. The sensor array was based on the oxidation etching of AgTNPs by three metal ions (Mn2+, Pb2+, and Cr3+) and accelerated etching of AgTNPs by OA. The introduction of metal ions alone led to a slight wavelength shift of the AgTNPs colloid solution, signifying the incomplete etching of the AgTNPs. Nevertheless, when metal ions and OA were introduced simultaneously to the solution, a significant blueshift of the localized surface plasmon resonance peak was detected, and a color change of the AgTNPs was observed, which were the consequences of morphological transitions of the AgTNPs. The addition of different OA accelerated AgTNPs etching in varying degrees, generating diverse colorimetric response patterns (i.e., RGB variations) as "fingerprints" associated with each specific organic acid. Pattern recognition algorithms and neural network simulation were employed to further data analysis, indicating the outstanding discrimination capability of the provided array for eight OA at the 33 µM level. Moreover, excellent results of selective experiments as well as real samples tests demonstrate that our proposed method possesses great potential for practical applications.

Smart inexpensive quantitative urine glucose and contaminant bromide ion sensor based on metal nanoparticles with deep learning approach

This present study reports a facile cost-effective colorimetric method for the estimation of glucose and bromide using colloidal silver triangular nanoprisms (STN). The quantitative glucose sensing is based on distinct color changes through the glucose oxidase enzymatic oxidation of STN at room temperature. Whereas, nonenzymatic visible bromide detection could be possible by only STN. A developed reference color scale could directly be used to estimate the different glucose concentration by bare eyes. Whereas, a smartphone-based analyte estimation app developed with You Only Look Once, Version 3 (YOLOv3) deep-learning algorithm to detect and estimate the glucose/bromide ion concentrations more accurately. With the increasing analyte (glucose/bromide) concentration, the localized surface plasmon resonance (LSPR) peak of STN shows gradual blue-shift in wavelength and decreased in absorbance. The experimental study was performed to estimate the urine glucose levels and shows high accuracy results when compared with standard methods. This highly sensitive glucose/bromide detection efficiency starts with a very low concentration of 0.010 mg/mL (1.0 mg/dL) and 0.005 mg/mL (0.5 mg/dL) for glucose and bromide ions respectively. This proposed non-invasive painless highly selective glucose sensing technique could be a promising point-of-care diagnostics or an environmental bromide monitoring tool for developing countries or in case of emergency uses.

Computational analysis of drug free silver triangular nanoprism theranostic probe plasmonic behavior for in-situ tumor imaging and photothermal therapy

IntroductionThe advanced features of plasmonic nanomaterials enable initial high accuracy detection with different therapeutic intervention. Computational simulations could estimate the plasmonic heat generation with a high accuracy and could be reliably compared to experimental results. This proposed combined theoretical-experimental strategy may help researchers to better understand other nanoparticles in terms of plasmonic efficiency and usability for future nano-theranostic research. ObjectivesTo develop innovative computationally-driven approach to quantify any plasmonic nanoparticles photothermal efficiency and effects before their use as therapeutic agents. MethodsThis report introduces drug free plasmonic silver triangular nanoprisms coated with polyvinyl alcohol biopolymer (PVA-SNT), for in vivo photoacoustic imaging (PAI) guided photothermal treatment (PTT) of triple-negative breast cancer mouse models. The synthesized PVA-SNT nanoparticles were characterized and a computational electrodynamic analysis was performed to evaluate and predict the optical and plasmonic photothermal properties. The in vitro biocompatibility and in vivo tumor abalation study was performed with MDA-MB-231 human breast cancer cell line and in nude mice model. ResultsThe drug free 140 μg∙mL−1 PVA-SNT nanoparticles with 1.0 W∙cm−2 laser irradiation for 7 min proved to be an effective and optimized theranostic approach in terms of PAI guided triple negative breast cancer treatment. The PVA-SNT nanoparticles exhibits excellent biosafety, photostability, and strong efficiency as PAI contrast agent to visualize tumors. Histological analysis and fluorescence-assisted cell shorter assay results post-treatment apoptotic cells, more importantly, it shows substantial damage to in vivo tumor tissues, killing almost all affected cells, with no recurrence. ConclusionThis is a first complete study on computational simulations to estimate the plasmonic heat generation followed by drug free plasmonic PAI guided PTT for cancer treatment. This computationally-driven theranostic approach demonstrates an innovative thought regarding the nanoparticles shape, size, concentration, and composition which could be useful for the prediction of photothermal heat generation in precise nanomedicine applications.

A novel “off-on-off” fluorescent sensor based on inner filter effect for ultrasensitive detection of protamine/trypsin and subcellular colocalization

Protease is an important physiological enzyme that can catalyze the hydrolysis of peptide bonds at specific sites and trypsin is a proteolytic enzyme present in the pancreas, the fluctuation of whom reflect dysfunction of body. Thus, it is necessary to develop sensitivity detections for protamine and trypsin. Herein, an "off-on-off" fluorescent sensor based on the inner filter effect was established for individually quantification of protamine and trypsin by using silicon quantum dots (SiQDs) and triangular silver nanoprisms (TSNPRs) based on the inner filter effect (IFE). The maximum absorption peak position of TSNPRs is 550 nm, which completely overlaps the emission peak (536 nm) of SiQDs and considerably improves sensitivity of the sensor. The proposed IFE-based sensor proved a good linearity from 0–30 ng/mL for protamine determination with detection limit of 5 ng/mL. For trypsin detection, the constructed sensor displayed a liner detection range from 0 to 40 ng/mL with a detection limit of 8 ng/mL. Besides, the SiQDs have equipped with the excellent capability for subcellular colocalization, providing a promising potential for practical applications.

Ultrasensitive detection of disinfection byproduct trichloroacetamide in drinking water with Ag nanoprism@MoS2 heterostructure-based electrochemical sensor

The chlorination disinfection of drinking water generates disinfection byproducts (DBPs), which are toxic, carcinogenic, mutagenic, and teratogenic. Recently, trichloroacetamide (TCAM) has been proved to be highly genotoxic and cytotoxic. In this study, a sensitive and selective electrochemical sensor for TCAM detection is reported that is based on the triangular silver nanoprism (AgNPR) and MoS2 nanosheet (AgNPR@MoS2) heterostructure. The AgNPR can catalyze the dechlorination reaction of TCAM; and the abundant S sites on the edge of MoS2 nanosheet can absorb H+, thereby accelerating the dechlorination hydrogenation reaction. The AgNPR@MoS2 heterostructure exhibits a high charge transfer rate, high electrocatalytic activity, and good stability in TCAM detection. The sensor shows two linear sensing ranges of 0.5−10 μM and 10−80 μM, a detection limit of 0.17 μM, and high specificity to coexist DBPs. This study is one of the first reports of electrochemical detection of TCAM, and has successfully demonstrated the significant potential of electrochemical sensor for the real-time analysis and monitoring of trace TCAM in drinking water.

Microfluidic nanopaper based analytical device for colorimetric and naked eye determination of cholesterol using the color change of triangular silver nanoprisms

A microfluidic nanopaper-based analytical device (μNPAD) has been prepared for the determination of cholesterol by using triangular silver nanoprisms (T-AgNPrs).

Ag/PVP/PAN nanocomposites with triangular nanoprisms of silver synthesized by UV-induced polymerization: Morphology manipulation and optical properties tuning

Solid nanocomposite films of “silver/polyvinylpyrrolidone/polyacrylonitrile” were synthesized for the first time by means of UV-induced polymerization. Structural characterization carried out by transmission electron microscopy revealed the presence of triangular silver nanoprisms with an edge length of ~40 nm and a thickness of ~15 nm in addition to spherical nanoparticles. The nanoparticles shape evolution process during synthesis and storage has been monitored in detail by UV-VIS-NIR spectroscopy and plasma resonance bands depending on the shape of the silver nanoparticles have been identified. Unlike spherical nanoparticles, which absorb light at 420–450 nm, the triangular nanoprisms demonstrate a clear absorption in the red range of the spectrum. The optical spectra of the composite films with incorporated silver nanoprisms manifest an intense in-plane dipole plasmon resonance band at 585–650 nm, as well as a weak out-of-plane quadrupole resonance band at 340 nm.

Plasmonic Effects on the Growth of Ag Nanocrystals in Solution.

The light-stimulated transformation of ensembles of spherical nanoparticles into anisotropic metal nanostructures mediated by localized surface plasmon resonance (LSPR) excitation is an elegant way of synthesizing triangular silver nanoprisms with extraordinary control over size and shape. Generally, the transformation occurs in oxidizing environments along a pathway that involves the oxidative etching of small preexisting Ag seeds, followed by plasmon-mediated reduction of the resulting Ag ions and Ag0 incorporation into the anisotropic nanocrystals. Here, we investigate pathways toward Ag nanoprisms from initially homogeneous AgNO3 solutions held under reducing conditions. Observations using in situ electron microscopy show that reducing environments and high Ag precursor concentrations in the presence of sodium citrate favor two alternative transformation routes of initial spherical nuclei into anisotropic nanoprisms: (i) the aggregation of spherical nanoparticles and plasmon-mediated conversion of small clusters into triangular prisms; (ii) shape fluctuations of individual small nanoparticles. Simulated field distributions confirm that the coupling of the LSPR excitation between closely spaced nanoparticles causes significant field enhancements near the local plasmonic hot spots, which facilitates accelerated Ag incorporation and thus supports the transformation into nanoprisms.

Azimuthal vector beam exciting silver triangular nanoprisms for increasing the performance of surface-enhanced Raman spectroscopy

Surface-enhanced Raman spectroscopy (SERS) with high-sensitivity performance is a very necessary detection technology. Here, we present a method for increasing the performance of SERS based on silver triangular nanoprism arrays (ATNAs) vertically excited via a focused azimuthal vector beam (AVB). The ATNA substrates with different structural parameters are prepared based on the traditional self-assembled and modified film lift-off technique. Based on a theoretical model established adopting the structural parameters of the ATNA substrates, theoretical simulation results show that AVB excitation can achieve greater electric-field enhancement than linearly polarized beam (LPB) excitation. Experimental result indicates that SERS sensitivity obtained via AVB excitation is 10−13 M (1 M = 1 mol/L) using rhodamine 6G (R6G) as the target analyte, which is 2 orders of magnitude lower than that of LPB excitation (10−11 M). Meanwhile, the uniformity and reproducibility of the ATNA substrates are examined using Raman mapping and batch-to-batch measurement, respectively, and the Raman enhancement factor is calculated to be ∼3.3×107. This method of vector light field excitation may be used to improve the SERS performance of the substrates in fields of ultra-sensitive Raman detection.

Colorimetric probe for Ni2+ based on shape transformation of triangular silver nanoprisms upon H2O2 etching

In this article, a highly sensitive and selective colorimetric method for the detection of Ni2+ ions is presented on the basis of hydrogen peroxide etching of triangular silver nanoprisms (AgNPrs). Triangular AgNPrs were synthesized by a modified seed-mediated growth method, and upon addition of Ni2+ ions these triangular AgNPrs showed a significant colorimetric change from blue to reddish brown, and eventually yellow to as a function of the Ni2+ ion concentration. Ni2+ ion do not act as a selective etchant to triangular AgNPrs, but instead serve as a catalyst for the generation of H2O2 in a citrate-capped triangular AgNPr colloidal solution. The oxidative etching with H2O2 formed in the colloidal solution sculptured the sharp corners/edges of the triangular AgNPrs to produce circular Ag nanodisk. Selectivity tests for Ni2+ ions by the triangular AgNPr probe were performed in the presence of other various cations and anions at the optimized conditions (pH 8, 15 °C, and 30 min of reaction time). The probe showed a high linearity between absorption ratio (A475/A750) and concentration in the range of 0 to 30 μM of Ni2+, with a limit of detection of 21.6 nM in aqueous solution. The color and UV–vis absorption spectrum of the triangular AgNPr probe indicated that it is quite stable for two weeks in ambient temperature and pH ranges of 4.0˜10.0. This triangular AgNPr probe was successfully employed for the detection of Ni2+ ions in spiked tap and pond water samples.

Robust Synthesis of Size-Dispersal Triangular Silver Nanoprisms via Chemical Reduction Route and Their Cytotoxicity.

Triangular silver nanocrystals, well-known as nanoprisms (Ag-NPrs), were successfully developed via a robust and straightforward direct chemical reduction synthetic approach, producing desirable tiny and well-controlled Ag-NPrs. This procedure was accomplished by fabricating a mixture of di-sodium succinate hexa-hydrate (DSSH) and tri-sodium citrate di-hydrate (TSCD) as capping agents at optimal synthetic conditions and under an open-air condition, which proved to be an enormous challenge. Additionally, the Ag-NPrs were fully characterized by UV-vis spectra, X-ray diffraction (XRD), scanning electron microscope (SEM), and dynamic light scattering (DLS). Likewise, the formation stages from spherical silver nanoparticles (Ag-NPs) to triangular Ag-NPrs were also captured simultaneously via transmission electron microscope (TEM) and high-resolution transmission electron microscope (HR-TEM) images. More interestingly, an active thin silica-shell was efficiently applied on the Ag-NPrs outer-layer to increase their functionality. Furthermore, to confirm their biocompatibility, we also carried out cell viability assays for the Ag-NPs, Ag-NPrs, and Ag-NPrs@SiO2 with different concentrations at 62.5, 125, and 250 µg/mL after 12, 24, and 48 h of exposure time, respectively, on a regular African green monkey kidney cell line. The cell viability test results exemplified that the three silver nanostructures were toxic-free and suitable for further potential biological applications in the near future.