scholarly journals Cicada Wing Inspired Template-Stripped SERS Active 3D Metallic Nanostructures for the Detection of Toxic Substances

Sensors ◽  
2021 ◽  
Vol 21 (5) ◽  
pp. 1699
Author(s):  
Srijit Nair ◽  
Juan Gomez-Cruz ◽  
Gabriel Ascanio ◽  
Aristides Docoslis ◽  
Ribal Georges Sabat ◽  
...  
Keyword(s):  
World Health ◽  
Excitation Wavelength ◽  
Sers Substrate ◽  
Toxic Substances ◽  
Label Free ◽  
Large Area ◽  
Uv Curable ◽  
Sensing Applications ◽  
Label Free Detection ◽  
Polarization Independent

This article introduces a bioinspired, cicada wing-like surface-enhanced Raman scattering (SERS) substrate based on template-stripped crossed surface relief grating (TS-CSRG). The substrate is polarization-independent, has tunable nanofeatures and can be fabricated in a cleanroom-free environment via holographic exposure followed by template-stripping using a UV-curable resin. The bioinspired nanostructures in the substrate are strategically designed to minimize the reflection of light for wavelengths shorter than their periodicity, promoting enhanced plasmonic regions for the Raman excitation wavelength at 632.8 nm over a large area. The grating pitch that enables an effective SERS signal is studied using Rhodamine 6G, with enhancement factors of the order of 1 × 104. Water contact angle measurements reveal that the TS-CSRGs are equally hydrophobic to cicada wings, providing them with potential self-cleaning and bactericidal properties. Finite-difference time-domain simulations are used to validate the nanofabrication parameters and to further confirm the polarization-independent electromagnetic field enhancement of the nanostructures. As a real-world application, label-free detection of melamine up to 1 ppm, the maximum concentration of the contaminant in food permitted by the World Health Organization, is demonstrated. The new bioinspired functional TS-CSRG SERS substrate holds great potential as a large-area, label-free SERS-active substrate for medical and biochemical sensing applications.

Photonic crystals: A platform for label-free and enhanced fluorescence biomolecular and cellular assays

2008 ◽  
Vol 1133 ◽  
Author(s):  
Brian T. Cunningham ◽  
Leo Chan ◽  
Patrick C. Mathias ◽  
Nikhil Ganesh ◽  
Sherine George ◽  
...  
Keyword(s):  
Photonic Crystal ◽  
Photonic Crystals ◽  
High Throughput Screening ◽  
High Sensitivity ◽  
Excitation Wavelength ◽  
Label Free ◽  
Crystal Surfaces ◽  
Enhanced Fluorescence ◽  
Preferred Direction ◽  
Label Free Detection

Abstract Photonic crystal surfaces represent a class of resonant optical structures that are capable of supporting high intensity electromagnetic standing waves with near-field and far-field properties that can be exploited for high sensitivity detection of biomolecules and cells. While modulation of the resonant wavelength of a photonic crystal by the dielectric permittivity of adsorbed biomaterials enables label-free detection, the resonance can also be tuned to coincide with the excitation wavelength of common fluorescent tags - including organic molecules and semiconductor quantum dots. Photonic crystals are also capable of efficiently channeling fluorescent emission into a preferred direction for enhanced extraction efficiency. Photonic crystals can be designed to support multiple resonant modes that can perform label free detection, enhanced fluorescence excitation, and enhanced fluorescence extraction simultaneously on the same device. Because photonic crystal surfaces may be inexpensively produced over large surface areas by nanoreplica molding processes, they can be incorporated into disposable labware for applications such as pharmaceutical high throughput screening. In this talk, the optical properties of surface photonic crystals will be reviewed and several applications will be described, including results from screening a 200,000-member chemical compound library for inhibitors of protein-DNA interactions, gene expression microarrays, and high sensitivity of protein biomarkers.

scholarly journals Application of Aluminum Hydroxide for Improvement of Label-Free SERS Detection of Some Cephalosporin Antibiotics in Urine

Biosensors ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 91 ◽  
Author(s):  
Natalia E. Markina ◽  
Alexey V. Markin
Keyword(s):  
Aluminum Hydroxide ◽  
Surface Enhanced Raman Spectroscopy ◽  
Negative Influence ◽  
Quantitative Detection ◽  
Therapeutic Drug ◽  
Excitation Wavelength ◽  
Sers Substrate ◽  
Label Free ◽  
Surface Enhanced Raman ◽  
Sers Detection

This report is dedicated to development of surface-enhanced Raman spectroscopy (SERS) based analysis protocol for detection of antibiotics in urine. The key step of the protocol is the pretreatment of urine before the detection to minimize background signal. The pretreatment includes extraction of intrinsic urine components using aluminum hydroxide gel (AHG) and further pH adjusting of the purified sample. The protocol was tested by detection of a single antibiotic in artificially spiked samples of real urine. Five antibiotics of cephalosporin class (cefazolin, cefoperazone, cefotaxime, ceftriaxone, and cefuroxime) were used for testing. SERS measurements were performed using a portable Raman spectrometer with 638 nm excitation wavelength and silver nanoparticles as SERS substrate. The calibration curves of four antibiotics (cefuroxime is the exception) cover the concentrations required for detection in patient’s urine during therapy (25/100‒500 μg/mL). Random error of the analysis (RSD < 20%) and limits of quantification (20‒90 μg/mL) for these antibiotics demonstrate the applicability of the protocol for reliable quantitative detection during therapeutic drug monitoring. The detection of cefuroxime using the protocol is not sensitive enough, allowing only for qualitative detection. Additionally, time stability and batch-to-batch reproducibility of AHG were studied and negative influence of the pretreatment protocol and its limitations were estimated and discussed.

scholarly journals Rapid label-free SERS detection of foodborne pathogenic bacteria based on hafnium ditelluride-Au nanocomposites

2020 ◽  
Vol 13 (05) ◽  
pp. 2041004 ◽  
Author(s):  
Yang Li ◽  
Yanxian Guo ◽  
Binggang Ye ◽  
Zhengfei Zhuang ◽  
Peilin Lan ◽  
...  
Keyword(s):  
Pathogenic Bacteria ◽  
Limit Of Detection ◽  
Principal Component ◽  
High Sensitivity ◽  
Chemical Mechanism ◽  
Sers Substrate ◽  
Label Free ◽  
Label Free Detection ◽  
Surface Enhanced Raman ◽  
Foodborne Pathogenic Bacteria

Two-dimensional (2D) nanomaterials have captured an increasing attention in biophotonics owing to their excellent optical features. Herein, 2D hafnium ditelluride (HfTe[Formula: see text], a new member of transition metal tellurides, is exploited to support gold nanoparticles fabricating HfTe2-Au nanocomposites. The nanohybrids can serve as novel 2D surface-enhanced Raman scattering (SERS) substrate for the label-free detection of analyte with high sensitivity and reproducibility. Chemical mechanism originated from HfTe2 nanosheets and the electromagnetic enhancement induced by the hot spots on the nanohybrids may largely contribute to the superior SERS effect of HfTe2-Au nanocomposites. Finally, HfTe2-Au nanocomposites are utilized for the label-free SERS analysis of foodborne pathogenic bacteria, which realize the rapid and ultrasensitive Raman test of Escherichia coli, Listeria monocytogenes, Staphylococcus aureus and Salmonella with the limit of detection of 10 CFU/mL and the maximum Raman enhancement factor up to [Formula: see text]. Combined with principal component analysis, HfTe2-Au-based SERS analysis also completes the bacterial classification without extra treatment.

scholarly journals Dual-Cavity Triple-Metal Gate-Underlap Dielectric-Modulated Charge-Plasma-based TFET for the Biomolecules Recognition

2021 ◽  
Author(s):  
Abhijeet Sahu ◽  
Mamta Khosla ◽  
Neetu Sood ◽  
Girish Wadhwa
Keyword(s):  
Drain Current ◽  
Transfer Characteristic ◽  
Label Free ◽  
Metal Gate ◽  
Sensing Applications ◽  
High K ◽  
Label Free Detection ◽  
Silvaco Atlas ◽  
K 12 ◽  
Gate Underlap

In this era of technology, biosensors play an essential role in living life. Today’s research and investigation revolved around its higher responsiveness and speed of detection. Normal TFET has many disadvantages like fabrication complexity, random dopant fluctuation, and the lower ON-State current. We are introducing a device that is a Dual-Cavity Triple-Metal gate-underlap DM-CPTFET for label-free detection. This device has a dual cavity for sensing different types of biomolecules simultaneously. We used the tool i.e SILVACO ATLAS TCAD Simulator for the sensing applications. High K material and gate work function engineering help us to improve drain current and better sensitivity. We used this TCAD tool, for analyzing the different parameter variations like energy band variation, surface potential, transfer characteristic, and output characteristic using different biomolecules Gelatin(k=12), Keratin(K=8), Biotin(K=2.63), etc.

Flexible porous aerogels decorated with Ag nanoparticles as an effective SERS substrate for label-free trace explosives detection

2020 ◽  
Vol 12 (33) ◽  
pp. 4123-4129
Author(s):  
Wei Liu ◽  
Zihao Song ◽  
Yifan Zhao ◽  
Yu Liu ◽  
Xuan He ◽  
...  
Keyword(s):  
Ag Nanoparticles ◽  
Porous Silica ◽  
Silica Aerogels ◽  
Explosives Detection ◽  
Sers Substrate ◽  
Label Free ◽  
Ag Nanoparticle ◽  
Label Free Detection ◽  
Trace Explosives

Ag nanoparticle decorated porous silica aerogels as a flexible SERS substrate for sensitive, stable and label-free detection of explosive NTO was reported. And this substrate has a certain application prospect in the field of explosives sensing.

Finite Element Method-based Design and Simulations of Micro-cantilever Platform for Chemical and Bio-sensing Applications

2016 ◽  
Vol 66 (5) ◽  
pp. 485 ◽  
Author(s):  
R. Agarwal ◽  
R. Mukhiya ◽  
R. Sharma ◽  
M.K. Sharma ◽  
A.K. Goel
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Label Free ◽  
Device Structure ◽  
Micro Electro Mechanical Systems ◽  
Sensing Applications ◽  
Toxic Agents ◽  
Label Free Detection ◽  
Micro Cantilever ◽  
Element Method

Micro-electro-mechanical systems (MEMS)-based cantilever platform have capability for the detection of chemical and biological agents. This paper reports about the finite element method (FEM) based design and simulations of MEMS-based piezoresistor cantilever platform to be used for detection of chemical and biological toxic agents. Bulk micromachining technique is adopted for the realisation of the device structure. MEMS piezoresistive biosensing platforms are having potential for a field-based label-free detection of various types of bio-molecules. Using the MEMMECH module of CoventorWare® simulations are performed on the designed model of the device and it is observed that principal stress is maximum along the length (among other dimensions of the micro-cantilever) and remains almost constant for 90 per cent of the length of the micro-cantilever. The dimensions of piezoresistor are optimised and the output voltage vs. stress analysis for various lengths of the piezoresistor is performed using the MEMPZR module of the CoventorWare®.

Phosphate-dependent DNA Immobilization on Hafnium Oxide for Bio-Sensing Applications

2009 ◽  
Vol 1191 ◽  
Author(s):  
Nicholas M Fahrenkopf ◽  
Serge Oktyabrsky ◽  
Eric Eisenbraun ◽  
Magnus Bergkvist ◽  
Hua Shi ◽  
...  
Keyword(s):  
Nucleic Acid ◽  
Hafnium Oxide ◽  
Dielectric Material ◽  
Field Effect Transistors ◽  
Leading Edge ◽  
High Sensitivity ◽  
Cmos Technology ◽  
Label Free ◽  
Sensing Applications ◽  
Label Free Detection

AbstractHafnium(IV) oxide (HfO2) has replaced silicon oxide as a gate dielectric material in leading edge CMOS technology, providing significant improvement in gate performance for field effect transistors (FETs). We are currently exploring this high-k dielectric for its use in nucleic acid-based FET biosensors. Due to its intrinsic negative charge, label-free detection of DNA can be achieved in the gate region of high-sensitivity FET devices. Previous work has shown that phosphates and phosphonates coordinate specifically onto metal oxide substrates including aluminum and titanium oxides. This property can therefore be exploited for direct immobilization of biomolecules such as nucleic acids. Our work demonstrates that 5’ phosphate-terminated single stranded DNA (ssDNA) can be directly immobilized onto HfO2 surfaces, without the need for additional chemical modification or crosslinking. Non-phosphorylated ssDNA does not form stable surface interactions with HfO2, indicating that immobilization is dependent upon the 5’ terminal phosphate. Further work has shown that surface immobilized ssDNA can be hybridized to complementary target DNA and that sequence-based hybridization specificity is preserved. These results suggest that the direct DNA-HfO2 immobilization strategy can enable nucleic acid-based biosensing assays on HfO2 terminated surfaces. This work will further enable high sensitivity electrical detection of biological targets utilizing transistor-based technologies.

scholarly journals 3D-printed microfluidics integrated with optical nanostructured porous aptasensors for protein detection

2021 ◽  
Vol 188 (3) ◽  
Author(s):  
Sofia Arshavsky-Graham ◽  
Anton Enders ◽  
Shanny Ackerman ◽  
Janina Bahnemann ◽  
Ester Segal
Keyword(s):  
Limit Of Detection ◽  
Protein Detection ◽  
Target Protein ◽  
Superior Performance ◽  
Generic Model ◽  
Label Free ◽  
Uv Curable ◽  
Microfluidic Platform ◽  
Label Free Detection ◽  
3D Printed

AbstractMicrofluidic integration of biosensors enables improved biosensing performance and sophisticated lab-on-a-chip platform design for numerous applications. While soft lithography and polydimethylsiloxane (PDMS)-based microfluidics are still considered the gold standard, 3D-printing has emerged as a promising fabrication alternative for microfluidic systems. Herein, a 3D-printed polyacrylate-based microfluidic platform is integrated for the first time with a label-free porous silicon (PSi)–based optical aptasensor via a facile bonding method. The latter utilizes a UV-curable adhesive as an intermediate layer, while preserving the delicate nanostructure of the porous regions within the microchannels. As a proof-of-concept, a generic model aptasensor for label-free detection of his-tagged proteins is constructed, characterized, and compared to non-microfluidic and PDMS-based microfluidic setups. Detection of the target protein is carried out by real-time monitoring reflectivity changes of the PSi, induced by the target binding to the immobilized aptamers within the porous nanostructure. The microfluidic integrated aptasensor has been successfully used for detection of a model target protein, in the range 0.25 to 18 μM, with a good selectivity and an improved limit of detection, when compared to a non-microfluidic biosensing platform (0.04 μM vs. 2.7 μM, respectively). Furthermore, a superior performance of the 3D-printed microfluidic aptasensor is obtained, compared to a conventional PDMS-based microfluidic platform with similar dimensions. Graphical abstract

scholarly journals Distinguishing dopamine and calcium responses using XNA-nanotube sensors for improved neurochemical sensing

2021 ◽  
Author(s):  
Alice J. Gillen ◽  
Alessandra Antonucci ◽  
Melania Reggente ◽  
Daniel Morales ◽  
Ardemis A. Boghossian
Keyword(s):  
Neurological Diseases ◽  
Locked Nucleic Acid ◽  
Optical Biosensors ◽  
Label Free ◽  
Sensing Applications ◽  
Label Free Detection ◽  
Improved Stability ◽  
New Applications

AbstractTo date, the engineering of single-stranded DNA-SWCNT (DNA-SWCNT) optical biosensors have largely focused on creating sensors for new applications with little focus on optimising existing sensors for in vitro and in vivo conditions. Recent studies have shown that nanotube fluorescence can be severely impacted by changes in local cation concentrations. This is particularly problematic for neurotransmitter sensing applications as spatial and temporal fluctuations in the concentration of cations, such as Na+, K+, or Ca2+, play a central role in neuromodulation. This can lead to inaccuracies in the determination of neurotransmitter concentrations using DNA-SWCNT sensors, which limits their use for detecting and treating neurological diseases.Herein, we present new approaches using locked nucleic acid (LNA) to engineer SWCNT sensors with improved stability towards cation-induced fluorescence changes. By incorporating LNA bases into the (GT)15-DNA sequence, we create sensors that are not only more resistant towards undesirable fluorescence modulation in the presence of Ca2+ but that also retain their capabilities for the label-free detection of dopamine. The synthetic biology approach presented in this work therefore serves as a complementary means for enhancing nanotube optoelectronic behavior, unlocking previously unexplored possibilities for developing nano-bioengineered sensors with augmented capabilities.

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