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@inproceedings{bib_A_la_2024, AUTHOR = {Zahra, Dr. Andleeb and Sinha, Swarnim and Modak, Alimpan and Siddiqui, Imran and Syed, Azeemuddin and Bhimalapuram, Prabhakar and Sau, Tapan Kumar and Kumar, Pawan and Abbas, Zia }, TITLE = {A label-free sensing of creatinine using radio frequency-driven lab-on-chip (loc) system}, BOOKTITLE = {Engineering Research Express}. YEAR = {2024}}

Skip to content IOP Science home Accessibility Help Search Journals Books Publishing Support Login Engineering Research Express Inclusive Publishing Trusted Science, find out more. Purpose-led Publishing, find out more. ACCEPTED MANUSCRIPT A label-free sensing of creatinine using radio frequency-driven lab-on-chip (loc) system Andleeb Zahra1, Swarnim Sinha2, Alimpan Modak3, Imran Siddiqui4, Azeemuddin Syed5, Prabhakar Bhimalapuram6, Tapan K. Sau7, Pawan Kumar8 and Zia Abbas9 Accepted Manuscript online 2 August 2024 • © 2024 IOP Publishing Ltd What is an Accepted Manuscript? DOI 10.1088/2631-8695/ad6ad5 DownloadAccepted Manuscript PDF Download PDF Article metrics 6 Total downloads Submit Submit to this Journal Permissions Get permission to re-use this article Share this article Article and author information Abstract This paper presents a promising avenue of Radio Frequency (RF) biosensors for sensitive and real-time monitoring of creatinine detection. Knowing creatinine levels in the human body is related to its possible association with renal, muscular, and thyroid dysfunction. The detection was performed using an Inter-Digitated Capacitor (IDC) made of copper (Cu) metal over an FR4 substrate. To demonstrate our methodology, we have chosen Phosphate Buffer (PB) as our solvent for making the creatinine solutions of different concentrations. Moreover, Assayed Chemistry Control (ACC), a reference control consisting of human serum-based solutions has been mixed with the different concentrations of creatinine in a ratio of 1:9 to spike the creatinine value in the ACC solution. The sensor has been designed using a High-Frequency Structure Simulator (HFSS) tool with an operating frequency of 2.53 GHz. Then the design is fabricated over the FR4 printed circuit board (PCB) and tested using a Vector Network Analyzer (VNA). However, the sensitive area of the IDC is introduced to grade 4 Whatman filter paper for the Sample Under Test (SUT) handling unit. The main advantage of using Whatman filter paper is that the uniform spreading of liquid reduces experimental error, and less volume is required for testing the sample. The principal idea implemented in the biosensor design is to track the shift in the operating frequency in the presence of different concentrations of creatinine mix in ACC solution with Phosphate Buffer (PB) solution as a reference.

@inproceedings{bib_Enha_2023, AUTHOR = {Mazumder, Annesha and Bhimalapuram, Prabhakar and Syed, Azeemuddin and Sau, Tapan Kumar }, TITLE = {Enhancement of Sensitivity of Radio Frequency Based Biomolecule Detection in the Presence of Gold Nanoparticles: A Feasibility Study}, BOOKTITLE = {International Conference on Numerical Electromagnetic and Multiphysics Modeling and Optimization}. YEAR = {2023}}

In this work, the role of gold nanoparticles in enhancing the sensitivity of Radio Frequency based biomolecule detection is assessed. A facile, efficient and rapid microstrip patch antenna based sensor, resonating at 61.747 GHz is utilized for the analysis. Gold nanoparticles are placed in the vicinity of biomolecules, and the extent of improvement is studied under various conditions. In particular, different morphological variations and arrangements of gold particles are investigated. The results indicate that, in general, the presence of gold nanoparticles contributes towards sensitivity improvement. However, the amount of enhancement strongly depends upon the morphological features and arrangements of gold particles and varies within 5-65% for the scenarios studied in this case.

@inproceedings{bib_Role_2023, AUTHOR = {Mazumder, Annesha and Bhimalapuram, Prabhakar and Syed, Azeemuddin and Sau, Tapan Kumar }, TITLE = {Role of presence of gold nanoparticles onenhancement of RF biosensing sensitivity}, BOOKTITLE = {Engineering Research Express}. YEAR = {2023}}

In this work, we explore the enhancement of sensitivity of sensing of biomolecules using Radio Frequency (RF) based sensing, by utilizing gold particles. In particular, we investigate the impact of various parameters of gold particles such as shape, size and arrangements on enhancing sensitivity. The work uses a Microstrip Patch Antenna designed to resonate at 96.84 GHz. The sensor is facile, rapid and efficient, and uses sample volume of 17.5 nL. The results indicate that the presence of gold particles helps in improving the performance of RF sensors in detecting biomolecules. However, the extent of improvement depends on the properties of gold particles and is in the range of 30-80% for the different cases studied in this work.

@inproceedings{bib_Part_2022, AUTHOR = {RAY, PARIJAT and Lodha, Tushar and BISWAS, ARUNANGSHU and Sau, Tapan Kumar and Ramana, Ch. Venkata }, TITLE = {Particle specific physical and chemical effects on antibacterial activities: A comparative study involving gold nanostars, nanorods and nanospheres}, BOOKTITLE = {Colloids and Surfaces A: Physicochemical and Engineering Aspects}. YEAR = {2022}}

The present report compares the antibacterial properties of unique (sphere+rod)-shaped gold nanostar with its structural components, i.e., gold nanorods and nanosphere. Gold nanostars, nanorods, and nanospheres have been synthesized using literature reported protocols. Clinical isolates of gram-negative E. coli and gram-positive S. aureus bacteria have been used as model pathogens for the antibacterial studies. The antibacterial activities of the nanoparticles have been assessed using various techniques. To compare the antimicrobial activity of the nanoparticles, we have investigated the effects of varying gold concentrations of different nanoparticles on bacterial growth kinetics. The impacts of the leached/residual gold ions and the surface capping agent and charge of the particles on the antibacterial activity have also been assessed. Studies of the nanoparticle’s dose and exposure time show the highest antibacterial activity for nanostars and lowest for nanospheres for a given quantity of gold. Bradford’s Reagent Assay and confocal fluorescent microscopy studies confirm the trend of the particle-specific antibacterial activities. SEM/TEM and DNA extraction studies show that the bactericidal activities involve a combination of effects like the destruction of cell membrane, fragmentation of bacterial DNA, internalization of particles, etc. To assess the antibacterial impacts of the amount of leached/residual gold ions, their concentrations have been determined by inductively coupled plasma - optical emission (ICP-OES) and mass (ICP-MS) spectroscopic studies as well as the effects of the added gold ions have been studied. No discernible effects have been observed due to the variation in the leached/residual gold ions amount. The DCHF-DA fluorescence assay has been employed to determine the levels of reactive oxygen species (ROS) produced by different nanoparticle systems, which corresponds to the trend in antibacterial activities observed. The nature and magnitude of the surface charge have been determined by zeta potential measurements. Analyses of the impacts of various parameters/factors like gold ions, capping agents, surface charges, ROS levels, etc., show that the antibacterial activities of the gold nanoparticles of different morphology arise from both morphology-specific physical and chemical effects of the gold nanoparticles.

@inproceedings{bib_RF_s_2022, AUTHOR = {Mazumder, Annesha and Sau, Tapan Kumar and Syed, Azeemuddin and Bhimalapuram, Prabhakar }, TITLE = {RF sensor-based tracking of nanoparticle’s morphological and relative arrangement variations}, BOOKTITLE = {Microfluidics and Nanofluidics}. YEAR = {2022}}

This article explores the feasibility of utilizing an interdigitated capacitor (IDC) based RF sensor for studying nanoparticle properties. The parameters include their size, shape, thickness, and relative arrangement in aqueous media. The analysis is carried out using the CAD tool high frequency structure simulator (HFSS). We study the variation in properties of spherical, cubical, disc-shaped, and polyhedral gold nanoparticles. The change in the resonance frequency, resonance amplitude, and − 3 dB bandwidth is analyzed for each case. The findings show that the change in the IDC-based RF sensor’s resonance characteristics can be used to track the variations in morphology and arrangements of gold nanoparticles.

@inproceedings{bib_Mult_2022, AUTHOR = {Mazumder, Annesha and Syed, Azeemuddin and Sau, Tapan Kumar and Bhimalapuram, Prabhakar and BISWAS, ARUNANGSHU }, TITLE = {Multi-parameter RF based Characterization of NanoparticlesandBiomolecules}, BOOKTITLE = {IEEE Conference on Nanotechnology}. YEAR = {2022}}

In this work, we explore the use of Radio frequency (RF) based sensing in uniquely identifying nanoparticles and biosamples by utilizing multi-parameter characterization. Most conventional RF sensors suffer from an inability to perform proper identification due to the dependence of the methodology on a single parameter variation. This paper combats this drawback by proposing a technique that extracts multiple parameters from the frequency response of a narrow band, IDC based RF sensor for performing the analysis. Furthermore, to illustrate the method, the identification is performed for different samples, including Biotin, BSA-conjugated Biotin, Gold Nanorods and Silica-coated Goldnanospheres. The results indicate that multi-parameter characterization yields unique spectral signatures for all samples, and thus identification can efficiently be performed.

@inproceedings{bib_Pd_n_2022, AUTHOR = {BISWAS, ARUNANGSHU and PRADHAN, OISHIKA and ANAND, THATI and Mukherjee, Debdyuti and Sau, Tapan Kumar and Chowdhury, Shubhajit Roy }, TITLE = {Pd nanoparticle-mediated acetone sensing performance improvement of SnO2 substrate: A combined DFT and experimental study}, BOOKTITLE = {Current Applied Physics}. YEAR = {2022}}

The article presents a combined theoretical and experimental study attempting to show how Pd nanoparticles (NPs) loading onto SnO2 substrate improves the acetone gas sensing performance. Pristine nanostructured SnO2 and Pd nanoparticles (Pd NPs) loaded SnO2 substrates have been prepared, characterized, and their acetone sensing performances have been measured. Experimental measurements have shown that Pd NP loading onto SnO2 suppresses the interfering effects of ethanol, water vapors, etc., and enhances the acetone sensor response, reversibility, response/recovery speeds, and signal-to-noise ratio. Various parameters like the adsorption energy, HOMO–LUMO energy gap, charge distribution, polarizability change, electrophilicity index, global hardness, etc., of several model systems, have been computed by using DFT. The computed parameters have been correlated with the conductivity, local reactivity, sensor response and selectivity, response/recovery times, etc., of the systems to understand the molecular-level effects of the Pd NP loading onto the SnO2 on the gas sensing process.

@inproceedings{bib_Mult_2021, AUTHOR = {Mazumder, Annesha and Syed, Azeemuddin and Bhimalapuram, Prabhakar and Sau, Tapan Kumar }, TITLE = {Multi-parameter based Characterization of Biosamples using a Broadband Microstrip Patch based RF Sensor}, BOOKTITLE = {IEEE International Conference on Nano/Molecular Medicine and Engineering}. YEAR = {2021}}

In this study, we characterize biosamples using a microstrip patch based Radio Frequency (RF) sensor by integrating both resonant and non-resonant parameters. In particular, the resonance frequency, the resonance amplitude, −10 dB bandwidth, range of operation, and return loss at center frequency were employed to perform the analysis. The idea was to utilize multiple parameters to build a comprehensive understanding of different bio-samples. In order to demonstrate the working of the methodology, two sets of analytes were studied-(i) aqueous solutions of biomolecules and (ii) body fluids. For both sets of analytes, the method demonstrated significant efficiency in performing qualitative characterization.

@inproceedings{bib_Role_2020, AUTHOR = {Mazumder, Annesha and Syed, Azeemuddin and Sau, Tapan Kumar and Bhimalapuram, Prabhakar }, TITLE = {Role of Shape of Gold Nanoparticles in Sensing Biomolecules using Radio-Frequency based Sensors}, BOOKTITLE = {Sensors}. YEAR = {2020}}

In this paper, the role of the shape of gold nanoparticles in improving the efficiency of sensing of biomolecules using Radio Frequency (RF) has been studied. The analysis has been performed with the help of an Interdigitated Capacitor (IDC) based structure using the CAD tool, High Frequency Structure Simulator (HFSS). The frequency response and E-Field distribution of various shapes of gold nanoparticles have been analysed. The results indicate that the detection efficiency of RF sensing of biomolecules improves significantly in the presence of gold nanoparticles. The shape, as well as the position of biomolecules around the gold nanoparticles, affects the efficiency of detection. These results open up new avenues for developing highly efficient nanoparticle-Radiofrequency-based sensors.

@inproceedings{bib_Stud_2020, AUTHOR = {Mazumder, Annesha and Syed, Azeemuddin and Sau, Tapan Kumar and Bhimalapuram, Prabhakar }, TITLE = {Study of Gold Particles in HFSS with Varying Physical Parameters and Arrangements}, BOOKTITLE = {2020 IEEE 15th International Conference on Nano/Micro Engineered and Molecular System}. YEAR = {2020}}

Radio Frequency (RF) based sensors have shown great potential for the qualitative and quantitative analysis of different chemical and biological entities. In this work, the feasibility of performing RF based sensing by using gold particles has been explored with the help of the computational tool, HFSS (High Frequency Structure Simulator). The analysis is performed for an Interdigitated Capacitor based sensor. Various physical parameters of cylindrical gold particles such as radius and thickness have been varied, and the electrical parameters of the sensor systems have been studied. In particular, the reflection coefficients have been determined for various cases. In addition to the physical parameters, different configurations of the gold particles such as their linear and non-linear arrangements have been analyzed. The analyses offer promising results for the development of efficient sensing platforms.

@inproceedings{bib_Sol-_2019, AUTHOR = {ITTEBOINA, RAMAKRISHNA and Sau, Tapan Kumar }, TITLE = {Sol-gel synthesis and characterizations of morphology-controlled Co3O4 particles}, BOOKTITLE = {Materials Today: Proceedings}. YEAR = {2019}}

Cobalt oxide particles have emerged as one of the promising metal oxide systems for their unique properties and various applications. This article reports syntheses of nano to micrometer sized morphology-controlled cobalt oxide particles by using the sol-gel synthesis method. The method can produce cobalt oxide particles in gram quantity. We explored the effects of various factors such the metal precursor, capping agent, solvent, calcination temperature, etc. on the size and morphology of the synthesized particles. FTIR and XRD studies confirmed the formation of crystalline Co3O4 particles. Field-emission scanning electron microscopy (FE-SEM) show that particles with sizes ranging from 180 nm to 6 μm and morphologies mainly smoothed surfaced octahedra formed depending on the metal precursor, capping agent, solvent and calcination temperature. The effects of three calcination temperatures have been explored based on the thermal behavior of the particles as studied by the thermogravimetric and differential thermal analysis (TGA/DTA). The powdered particles offer ~50 to ~75 m2 /g Brunner-Emmett-Teller (BET) surface area. The sol-gel technique is rapid, straightforward, and cost-effective and requires low processing temperatures to produce the particles compared to solvothermal methods. The present study shows that a proper choice of reaction conditions in a sol-gel method could be used to produce morphology-controlled cobalt oxide particles of nanometer to micrometer sizes in high yield

@inproceedings{bib_Dete_2018, AUTHOR = {Mazumder, Annesha and BISWAS, ARUNANGSHU and Sau, Tapan Kumar and Syed, Azeemuddin and Bhimalapuram, Prabhakar }, TITLE = {Determination of Critical Micelle Concentration of Surfactant Using RF Sensing}, BOOKTITLE = {Sensors}. YEAR = {2018}}

This paper utilizes RF Sensing to develop a facile methodology for the determination of Critical Micelle Concentration (CMC) of surfactants. The study is undertaken with the help of an Interdigitated Capacitor based RF Sensor. Due to change in permittivity, the sensor yields distinct resonant frequencies when introduced to solutions of varying concentration of Sodium Dodecyl Sulphate as the electrolyte. As the surfactant approaches micellization, the resonant frequency shift drastically alters, and this sudden transition is used to determine the value of CMC. The proposed technique estimates the CMC of SDS to be 6.5 x10 -3 M The introduced method is effective and less cumbersome as compared to traditional techniques.

@inproceedings{bib_Desi_2017, AUTHOR = {MURLIDHAR, PORWAL PRATIK and Syed, Azeemuddin and Bhimalapuram, Prabhakar and Sau, Tapan Kumar }, TITLE = {Design of fractal geometry based RF sensor for detection of complex permittivity of unknown sample}, BOOKTITLE = {IEEE Asia Pacific Microwave Conference}. YEAR = {2017}}

In this paper, RF resonant sensor is designed for measurement of complex permittivity of unknown sample. It takes advantage of peano curve fractal geometry (i.e. higher capacitance in minimum area). It operates in the ISM (industrial, scientific and medical) frequency band of 4-5 GHz. An empirical model of sensor is developed for the accurate calculation of complex permittivity of an unknown sample in terms of shifts in the resonant frequencies and reflection coefficients (S11) under loaded condition. Due to homogeneous E-field at fractal capacitor, placement position of sample will not affect the sensitivity. Significant frequency shifts as high as 60 M Hz, 80 M Hz, 116 M Hz and 134 M Hz are observed for relative permittivity of 5.4, 6.5, 8.9 and 10.6 respectively.

@inproceedings{bib_Desi_2017, AUTHOR = {MURLIDHAR, PORWAL PRATIK and Syed, Azeemuddin and Bhimalapuram, Prabhakar and Sau, Tapan Kumar }, TITLE = {Design of RF sensor for simultaneous detection of complex permeability and permittivity of unknown sample}, BOOKTITLE = {Progress in Electromagnetics Research C}. YEAR = {2017}}

DESIGN OF RF SENSOR FOR SIMULTANEOUS DETECTION OF COMPLEX PERMEABILITY AND PERMITTIVITY OF UNKNOWN SAMPLE

@inproceedings{bib_Dete_2017, AUTHOR = {MURLIDHAR, PORWAL PRATIK and Syed, Azeemuddin and Bhimalapuram, Prabhakar and Sau, Tapan Kumar }, TITLE = {Detection of ferritin concentration from blood sample using RF spiral inductor based cavity}, BOOKTITLE = {IEEE Asia Pacific Microwave Conference}. YEAR = {2017}}

In this paper, a novel microwave planar resonant sensor (using two spiral inductors) is designed and developed for detection of ferritin from the blood sample using non destructive technique. Due to concentration change of ferritin in blood, shift in resonant frequency arise. The frequency range of 15 GHz-16 GHz is used as it is effective for label-free analysis of ferritin. The sensor is designed using the full wave electromagnetic solver, HFSS 13.0, and an empirical model is developed for the accurate calculation of ferritin concentration in terms of shifts in the resonant frequency. Due to homogeneous H-field in spacing between two inductors, placement position of ferritin will not affect the sensitivity. Significant frequency shifts as high as 105 MHz, 192 MHz, 310 MHz and 655 MHz are observed for concentrations as low as 20 ng/ml, 50 ng/ml, 100 ng/ml and 320 ng/ml of ferritin respectively. Simulation results suggest …

@inproceedings{bib_Obse_2016, AUTHOR = {BHARDWAJ, SHWETA and ITTEBOINA, RAMAKRISHNA and Sau, Tapan Kumar }, TITLE = {Observing Ultra‐Small Gold Cluster to Plasmonic Nanoparticle Evolution in a One‐Pot Aqueous Synthesis}, BOOKTITLE = {ChemistrySelect}. YEAR = {2016}}

Studies of metal nanoclusters can provide valuable information on how various properties evolve in the nanoscale materials. Previously often mixed-sized products have been separated in order to study their size-related properties. We present here a one-pot aqueous synthesis protocol that allows direct observations of the evolutions of size-dependent optical and electrochemical properties of the gold nanoclusters while the clusters grow from a few-atom, ultra-small size to the plasmonic nanoparticle stage. Our selection of a mixed ligand system comprising of methionine and CTAB for the aqueous synthesis of gold nanoclusters by the chemical reduction of gold ions led to the slow growth of the nanoclusters making direct observations of the cluster growth and concomitant evolution of properties possible. UV-visible spectrophotometric and dynamic light scattering studies demonstrated the size-dependent transition from the molecule-like, non-plasmonic to plasmonic properties in the evolving nanoclusters. Differential pulse voltammetry studies demonstrated how the electrochemical properties changed from the molecule-like redox behavior to a quantized double-layer charging type with the growth of the nanocluster with time. Thermogravimetric analysis, MALDI-TOF mass spectrometry, etc. were employed to further characterize the nanocluster systems. This report will inspire further studies in understanding the evolution of the size-dependent

@inproceedings{bib_Dete_2016, AUTHOR = {MURLIDHAR, PORWAL PRATIK and Syed, Azeemuddin and Bhimalapuram, Prabhakar and Sau, Tapan Kumar }, TITLE = {Detection of biotin-streptavidin interaction using RF interdigitated capacitive cavity}, BOOKTITLE = {IEEE MTT-S International Microwave and RF Conference}. YEAR = {2016}}

In this paper, biotin streptavidin interaction has been sensed at microwave frequencies with the help of designed sensor. It takes advantage of two pole filter topology where interdigitated capacitor (IDC) is used as a coupling zone between resonators for higher sensitivity. Due to permittivity change of biotin streptavidin combination, shift in resonant frequency arise whereas due to conductivity, magnitude of reflection coefficient changes. The frequency range of 10 GHz - 25 GHz (γ-dispersion region) is used as it is effective for label free analysis of biotin streptavidin. Due to homogeneous E-field between the fingers of IDC, placement position of biotin-streptavidin will not affect the sensitivity. Significant frequency shifts as high as 19 MHz, 45 MHz and 70 MHz are observed for concentrations as low as 10 ng/ml, 20 ng/ml and 30 ng/ml of biotin-streptavidin respectively. Simulation results suggest that proposed biosensor …

@inproceedings{bib_Theo_2015, AUTHOR = {BHARDWAJ, SHWETA and RAI, SANDHYA and Sau, Tapan Kumar and Singh, Harjinder }, TITLE = {Theoretical studies of Raman scattering properties of methylphosphine and methylamine adsorbed on gold clusters}, BOOKTITLE = {Vibrational Spectroscopy}. YEAR = {2015}}

Recent reports have demonstrated that nanoclusters of silver and gold can act as substrates for Raman signal enhancements. This article presents a density functional theory (DFT)-based study to explore how the variations in the nature of the cluster-binding heteroatom in the ligand molecule and the relative orientation of the alkyl group attached to the heteroatom affect the Raman signal enhancement in the ligand molecules. Our calculations involved nitrogen and phosphorus heteroatoms in two simple model molecules, methylphosphine and methylamine, as ligands and four small gold clusters, Aun (n = 6–9). In order to understand the interactions in the cluster-molecule systems, we have calculated various geometrical parameters such as Au–X (X = P, N) distances, ffC–X–Au angles and different bond lengths of free and cluster-bound molecules as well as various interaction energies. We have performed natural bond order (NBO) analysis and have calculated second order stabilization energies for the molecules bound to the gold clusters from the NBO analysis. In addition, we have performed detailed calculations pertaining to the change in polarisability, quantity of molecule to cluster charge transfer as well as molecular orientations relative to the clusters and have studied how these factors influence the Raman scattering cross-sections and vibrational frequency shifts. The quantity of charge transfer and the orientation effect have been found to be important contributors in the chemical Raman enhancement mechanism of the ligand molecules.

@inproceedings{bib_BREA_2015, AUTHOR = {Thati, Anand and BISWAS, ARUNANGSHU and Chowdhury, Shubhajit Roy and Sau, Tapan Kumar }, TITLE = {BREATH ACETONE-BASED NON-INVASIVE DETECTION OF BLOOD GLUCOSE LEVELS}, BOOKTITLE = {INTERNATIONAL JOURNAL ON SMART SENSING AND INTELLIGENT SYSTEMS}. YEAR = {2015}}

There has been a constant demand for the development of non-invasive, sensitive glucose sensor system that offers fast and real-time electronic readout of blood glucose levels. In this article, we propose a new system for detecting blood glucose levels by estimating the concentration of acetone in the exhaled breath. A TGS822 tin oxide (SnO2) sensor has been used to detect the concentration of acetone in the exhaled air. Acetone in exhaled breath showed a correlation with the blood glucose levels. Effects of pressure, temperature and humidity have been considered. Artificial Neural Network (ANN) has been used to extract features from the output waveform of the sensors. The system has been trained and tested with patient data in the blood glucose ranges from 80 mg/dl to 180 mg/dl. Using the proposed system, the blood glucose concentration has been estimated within an error limit of±7.5 mg/dl.

@inproceedings{bib_Comp_2013, AUTHOR = {Sau, Tapan Kumar and , Andrey L. Rogach }, TITLE = {Complex-shaped metal nanoparticles: bottom-up syntheses and applications}, BOOKTITLE = {Platinum Metals Review}. YEAR = {2013}}

The past few years have witnessed the development of non-spherical metal nanoparticles with complex morphologies, which offer tremendous potential in materials science, chemistry, physics and medicine. Covering all important aspects and techniques of preparation and characterization of metal nanoparticles with controlled morphology and architecture, this book provides a sound overview-from the basics right up to recent developments. Renowned research scientists from all over the world present the existing knowledge in the field, covering theory and modeling, synthesis and properties of these nanomaterials. By emphasizing the underlying concepts and principles in detail, this book enables researchers to fully recognize the future research scope and the application potential of the complex-shaped metal nanoparticles, inspiring further research in this field.

@inproceedings{bib_Surf_2012, AUTHOR = {Murphy, Catherine J. and Sau, Tapan Kumar and Orendorff, Christopher J. and Gole, Anand M. }, TITLE = {Surface enhanced Raman spectroscopy using shaped gold nanoparticles}, BOOKTITLE = {United States Patent}. YEAR = {2012}}

In one aspect, the invention relates to methods for enhancing a Raman signal comprising the steps of providing a sample comprising a metal surface, an analyte adhered to the surface, and a metallic nanoparticle coupled to the surface, wherein the nanoparticle has a plasmon resonance band; exposing the sample to incident energy of an excitation wavelength; and detecting the Raman signal of the analyte. In a further aspect, the invention relates to a compositiion comprising a metal surface, a functionalized self-assembled monolayer adhered to the surface, wherin the self-assembled monolayer comprises an analyte, and a cetyltrimethylammonium halide-capped metallic nanoparticle coupled to the surface. In a further aspect, the invention relates to a cetyltrimethylammonium bromide-capped gold nanoparticle and a method for preparing same. This abstract is intended as a scanning tool for purposes of …

@inproceedings{bib_Plas_2012, AUTHOR = {Shao, Lei and Susha, Andrei S. and Cheung, Lap Shan and Sau, Tapan Kumar and Rogach, Andrey L. and Wang, Jianfang }, TITLE = {Plasmonic properties of single multispiked gold nanostars: correlating modeling with experiments}, BOOKTITLE = {Langmuir}. YEAR = {2012}}

Gold nanostars, possessing multiple sharp spikes, have emerged as promising plasmonic particles in the field of ultrasensitive sensing. We have developed a water-based method for high-yield synthesis of size-tunable anisotropic gold nanoparticles with a varying number of spiky surface protrusions, and performed systematic experimental and theoretical analyses of the optical properties of the single gold nanostars by characterizing them simultaneously with scanning electron microscopy and dark-field scattering spectroscopy. The morphologies and corresponding scattering spectra of the individual gold nanostars have been compared with electromagnetic simulations of the plasmonic resonances utilizing the finite-difference time-domain (FDTD) method. The study provides a correlation between the experimental and calculated scattering spectra and charge distributions of the different plasmon modes in the …

@inproceedings{bib_Meth_2012, AUTHOR = {Goia, Dan V and Lopez, Marco and Sau, Tapan Kumar and Jitianu, Mihaela-Ortansa }, TITLE = {Method for manufacture of noble metal alloy catalysts and catalysts prepared therewith}, BOOKTITLE = {United States Patent}. YEAR = {2012}}

The invention provides a method for manufacturing supported noble metal based alloy catalysts with a high degree of alloying and a small crystallite size. The method involves using polyol solvents as reaction medium and comprises a two-step reduction process in the presence of a support material. In the first step, the first metal (transition metal; eg Co, Cr, Ru) is activated by increasing the reaction temperature to 80 to 160 C. In the second step, the second metal (noble metal; eg Pt, Pd, Au) is added and the slurry is heated to the boiling point of the polyol solvent in a range of 160 to 300 C. The catalysts manufactured according to the method are used as electrocatalysts for polymer electrolyte membrane fuel cells (PEMFC), direct-methanol fuel cells (DMFC) or as gas phase catalysts for CO oxidation or exhaust gas purification.

@inproceedings{bib_Sele_2011, AUTHOR = {Hrelescu, Calin and Sau, Tapan Kumar and Rogach, Andrey L and Jäckel, Frank and Laurent, Guillaume and Charra, Fabrice }, TITLE = {Selective excitation of individual plasmonic hotspots at the tips of single gold nanostars}, BOOKTITLE = {Nano letters}. YEAR = {2011}}

Plasmonic hotspots in single gold nanostars are located at the tips and can be excited selectively by laser light as evidenced by photoelectron emission microscopy. Selectivity is achieved through wavelength and polarization of the excitation light. Comparing photoelectron emission intensity and dark-field scattering spectra of the same individual nanostars reveals differences in terms of observable plasmon resonance wavelengths and field enhancements. Differences are explained with the underlying near- and far-field processes of the two techniques.

@inproceedings{bib_Surf_2011, AUTHOR = {Murphy, Catherine J and Sau, Tapan Kumar and Orendorff, Christopher J and Gole, Anand M }, TITLE = {Surface enhanced raman spectroscopy using shaped gold nanoparticles Inventors}, BOOKTITLE = {United States Patent}. YEAR = {2011}}

Surface enhanced Raman scattering (SERS) spectra of 4-mercaptobenzoic acid (4-MBA) self-assembled monolayers (SAMs) on gold substrates is presented for SAMs onto which gold nanoparticles of various shapes have been electrostatically immobilized. SERS spectra of 4-MBA SAMs are enhanced in the presence of immobilized gold nanocrystals by a factor of 10 7-10 9 relative to 4-MBA in solution. Large enhancement factors are a likely result of plasmon coupling between the nanoparticles (localized surface plasmon) and the smooth gold substrate (surface plasmon polariton), creating large localized electromagnetic fields at their interface, where 4-MBA molecules reside in this sandwich architecture. Moreover, enhancement factors depend on nanoparticle shape, and vary by a factor of 10 2.

@inproceedings{bib_Meth_2011, AUTHOR = {Goia, Dan V. and Lopez, Marco and Sau, Tapan Kumar and Jitianu, Mihaela-Ortansa }, TITLE = {Method for manufacture of noble metal alloy catalysts and catalysts prepared therewith}, BOOKTITLE = {United States Patent}. YEAR = {2011}}

The present invention provides a method for manufacture of supported noble metal based alloy catalysts with a high degree of alloying and a small crystallite size. The method is based on the use of polyol solvents as reaction medium and comprises of a two-step reduction process in the presence of a support material. In the first step, the first metal (M1= transition metal; eg Co, Cr, Ru) is activated by increasing the reaction temperature to 80 to 160 C. In the second step, the second metal (M2= noble metal; eg Pt, Pd, Au and mixtures thereof) is added and the slurry is heated to the boiling point of the polyol solvent in a range of 160 to 300 C. Due to this two-step method, an uniform reduction occurs, resulting in noble metal based catalysts with a high degree of alloying and a small crystallite size of less than 3 nm. Due to the high degree of alloying, the lattice constants are lowered. The catalysts manufactured …

@inproceedings{bib_Meth_2010, AUTHOR = {Goia, Dan V. and Lopez, Marco and Sau, Tapan Kumar and Jitianu, Mihaela-Ortansa }, TITLE = {Method for manufacture of noble metal alloy catalysts and catalysts prepared therewith}, BOOKTITLE = {United States Patent}. YEAR = {2010}}

The present invention provides a method for manufacture of supported noble metal based alloy catalysts with a high degree of alloying and a small crystallite size. The method is based on the use of polyol solvents as reaction medium and comprises of a two-step reduction process in the presence of a support material. In the first step, the first metal (M1= transition metal; eg Co, Cr, Ru) is activated by increasing the reaction temperature to 80 to 160 C. In the second step, the second metal (M2= noble metal; eg Pt, Pd, Au and mixtures thereof) is added and the slurry is heated to the boiling point of the polyol solvent in a range of 160 to 300 C. Due to this two-step method, an uniform reduction occurs, resulting in noble metal based catalysts with a high degree of alloying and a small crystallite size of less than 3 nm. Due to the high degree of alloying, the lattice constants are lowered. The catalysts manufactured …

@inproceedings{bib_Labe_2010, AUTHOR = {Dondapati, Srujan K. and Sau, Tapan Kumar and Hrelescu, Calin and Klar, Thomas A and Stefani, Fernando D. and Feldmann, Jochen }, TITLE = {Label-free biosensing based on single gold nanostars as plasmonic transducers}, BOOKTITLE = {Acs Nano}. YEAR = {2010}}

Gold nanostars provide high sensitivity for single nanoparticle label-free biosensing. The nanostars present multiple plasmon resonances of which the lower energy ones, corresponding to the nanostar tips and core−tip interactions, are the most sensitive to environmental changes. Streptavidin molecules are detected upon binding to individual, biotin-modified gold nanostars by spectral shifts in the plasmon resonances. Concentrations as low as 0.1 nM produce a shift of the tip related plasmon resonances of about 2.3 nm (5.3 meV).

@inproceedings{bib_Cont_2009, AUTHOR = {Sau, Tapan Kumar and Urban, Alexander S and Dondapati, Srujan K and Fedoruk, Michael and Horton, Margaret R and Rogach, Andrey L and Stefani, Fernando D and Rädler, Joachim O. and Feldmann, ochen }, TITLE = {Controlling loading and optical properties of gold nanoparticles on liposome membranes Authors}, BOOKTITLE = {Colloids and Surfaces A: Physicochemical and Engineering Aspects}. YEAR = {2009}}

Gold nanoparticle-loaded liposomes can serve as important biophysical and biochemical tools. A rapid, green, one-step synthetic method has been used for direct and controlled loading of gold nanoparticles onto liposomes. The effects of various synthetic parameters on nanoparticle loading as well as on optical properties of the liposome-anchored nanoparticles are discussed. Gold nanoparticle-loaded individual liposomes have been characterized by dark-field microscopy and optical spectroscopy.

@inproceedings{bib_Sing_2009, AUTHOR = {Hrelescu, Calin and Sau, Tapan Kumar and Rogach, Andrey and Jaeckel, Frank and Feldmann, Jochen }, TITLE = {Single Gold Nanostars Enhance Raman Scattering}, BOOKTITLE = {Applied physics letters}. YEAR = {2009}}

We report on surface-enhanced Raman scattering (SERS) from single star-shaped gold nanoparticles coated with self-assembled monolayers of 4-mercaptobenzoic acid. SERS is observed without the formation of gold nanoparticle aggregates or resonant excitation of the analyte. Total Raman scattering enhancement factors for single nanostars are comparable to those of nanoparticle assemblies exhibiting coupled plasmon resonances. This renders gold nanostars promising for Raman imaging applications in complex environments such as cells or membranes.