Sai SATHISH Ramamurthy

• Professor (Assistant) at Sri Sathya Sai Institute of Higher Learning

Abstract Chapter 3, "Nanoengineering at Functional Plasmonic Interfaces," provides a comprehensive overview of the fundamental principles and recent advancements in plasmonics, focusing on the synthesis, characterization, and applications of nano-engineered plasmonic materials. The chapter begins by introducing the basic concepts of plasmonics, inc...

Conventionally, techniques based on electrochemistry, optical feedback (including absorbance, fluorescence and scattering), electronic response (pH and conductivity) are being explored and revised in addition to the use of exorbitant methodologies such as GC–MS and Mass spectroscopy to analyze the quality of water from various water bodies includin...

Point-of-care (POC) diagnostic platforms are globally employed in modern smart technologies to detect events or changes in the analyte concentration and provide qualitative and quantitative information in biosensing. Surface plasmon-coupled emission (SPCE) technology has emerged as an effective POC diagnostic tool for developing robust biosensing f...

This series provides information on the nature of dyes, their harmful effects, and dye degrading techniques. The first volume of this series presents a fundamental concept of dye degradation. The information on target-oriented dye mitigation is intended to give readers a better understanding of the dye degradation process to sustain a healthy envir...

Different classes of biologically and environmentally relevant molecules and ions are quantitatively and qualitatively analyzed using the synergistic approach wherein the properties of both the plasmonic nanomaterials and the fluorescent moieties are explored. In this study, such hybrid systems, called plasmophores (or plasmon coupled fluorophores)...

Photoplasmonic platforms are being demonstrated as excellent means for bridging nanochemistry and biosensing approaches at advanced interfaces, thereby augmenting the sensitivity and quantification of the desired analytes. Although resonantly coupled electromagnetic waves at the surface plasmon-coupled emission (SPCE) interface are investigated wit...

Purpose Dengue is a mosquito vector-borne disease caused by the dengue virus, which affects 125 million people globally. The disease causes considerable morbidity. The disease, based on symptoms, is classified into three characteristic phases, which can further lead to complications in the second phase. Molecular signatures that are associated with...

We report the synthesis of electrospun PVA nanofibers doped with Titania nanoparticles (NPs) utilized in plasmon-coupled fluorescence studies to obtain augmented enhancements. Amongst the three NPs used for the study, the highest enhancements (~ 150-fold) was achieved utilizing TiCN-doped nanofibers. The high enhancements from nanofibers allowed us...

Metallic nanosystems with strong surface plasmon resonance have been a predominant choice for surface plasmon-coupled emission (SPCE), leading to a plethora of sensing and diagnostic applications. The Ohmic losses and strong isotropic scattering of the emissive photons in such systems still remain major challenges that limit the sensitivity, reliab...

There is an increasing interest in low-cost, facile and versatile thermoplastic bonding for microfluidic applications that can be easily transitioned from laboratory prototyping to industrial manufacturing. In addition, owing to the surge in the usage of thermoplastic microfluidics and its adverse effect on the environment, it is prudent to source...

Engineering photo-plasmonic platforms with heterometallic nanohybrids are of paramount significance for realizing augmented sensitivity in fluorescence-based analytical detection. Although myriad nanomaterials with versatile functionalities have been explored in this regard in the surface plasmon-coupled emission (SPCE) interface, light harvesting...

Conventionally, nanoassemblies are synthesized using widely adopted template-based approaches. External stimuli such as electric and magnetic fields and light-induced reactions have recently been investigated. The exploration using a temperature gradient in this spotlight is very nascent. In this context, soret colloids are nanoparticle (NP) assemb...

Contamination detection often requires lengthy culturing steps to detect low-level bioburden. To increase the rate of detection and decrease the limit of detection (LOD), a system featuring microfluidics and a multichannel fluorometer has been developed. The eight-channel fluorometer enables parallel testing of multiple samples with the LOD as low...

Increased demand for high sensitivity techniques has resulted in a sustained search for sensing platforms that could provide reliable and highly sensitive detection of bio analytes and chemical species. Surface plasmon-coupled directional emission (SPCDE) has been explored as an alternative to conventionally used fluorescence detection methodologie...

Surface plasmon-coupled fluorescence (SPCF) technique has developed as a highly sensitive, specific, and versatile methodology for quantitative and qualitative bioassays. It relies on the ability of prism-coupling approach to channelize the emitted photons into sharply directional emission with attributes of propagating surface plasmons resulting i...

In the past decade, various interfacial materials have been explored for better sensor performance in nanoplasmonics. Despite gold being an ideal candidate for many plasmonic applications, its use in the field of surface plasmon-coupled emission (SPCE) platform is limited due to its inherent quenching phenomenon. Different methodologies have been r...

Plasmonic silver nanoparticles (AgNPs) of anisotropic geometries are being increasing explored in advanced functional nanointerfaces. Here, Ag nanocubes were synthesized using bioinspired and frugal approach with the use of proteins extracted from sesame oil seed cakes and UV-exposure methodology. The protein functions as both the reducing and capp...

Copper nanoparticles (CuNPs) with antimicrobial and cytotoxic properties were obtained using extracts from Hyptis suaveolens (L.) commonly called wild tulsi. Green synthesis using plant extracts is a preferred means to obtain nanoparticles because of the simplicity, efficiency, and clean process. Plant extracts contain phytochemicals that provide m...

Gold nanoparticles (AuNPs) possess tunable size- and shape-dependent properties that are ideal for catalytic properties for many applications. However, the challenge lies in the synthesis of highly stable and ultra-small NPs. We report an energy-efficient galvanostatic route to engineer gold-curcumin (Au-CM) nanocomposites constituting small-sized...

Conventionally nanoparticles (NPs) are synthesized using reducing and capping agents that are often hazardous for the environment and are not economically viable. Consequently, there is a growing requirement for bio-friendly methodologies for nanosynthesis via the green chemistry approach. The present study discusses the frugal and cost effective o...

Medical professionals have complained of extreme discomfort and fatigue from continuous wearing of N95 respirators (N95) overlaid with surgical masks (SM) and face shields (FS) during COVID-19 pandemic. However, there are no reports on the effect of face coverings on transdermal CO2 (TrCO2) levels (a measure of blood CO2) during moderate activity....

We report a facile electrosynthesis (constant current of 0.5 mA) of gold-curcumin (Au-CM) nanocomposite using a gold wire (anode) and glassy carbon electrode (cathode, GCE) in a solution of curcumin. A thin and stable film of the nanocomposite was deposited on the GCE in 30 minutes. Extensive morphological and structural characterizations were carr...

Improving life expectancy necessitates prevention and early diagnosis of any disease state based on active self-monitoring of symptoms and longitudinal biochemical profiling. Non-invasive and continuous measurement of molecular biomarkers that reflect metabolism and health must however be established to realize this plan. Human samples non-invasive...

Background Edinburgh Postnatal Depression Scale (EPDS) is a validated screening tool widely used to assess perinatal depression (PND). However, due to stigma associated with PND, respondents could answer sensitive questions differently depending on the mode of administration, especially in culturally and linguistically diverse country like India. T...

Nanocavities forms the basis for plasmon-enhanced luminescence-based sensing technologies. Although surface plasmon-coupled emission platform has progressed with interdisciplinary applications, detrimental Ohmic losses in them hamper luminescence enhancement. An analogous micro-photonic platform, photonic crystal-coupled emission platform overcomes...

A variety of materials such as low dimensional carbon substrates (1D, 2D, and 3D), nanoprisms, nanocubes, proteins, ceramics, and DNA to name a few, have been explored in surface plasmon-coupled emission (SPCE) platform. While these offer new physicochemical insights, investigations have been limited to silver as primary plasmonic material. Althoug...

Nanoparticle assemblies obtained using adiabatic cooling methodology is termed soret colloids (SCs). They are utilized in different sensing applications on account of their unique material properties. Here, silver (Ag) SCs were synthesized incorporating low-dimensional graphene oxide (GO) in the nanoassembly to engineer hybrid architectures. The pl...

BACKGROUND Edinburgh Postnatal Depression Scale (EPDS) is a validated screening tool widely used to assess perinatal depression (PND). However, due to stigma associated with PND, respondents could answer sensitive questions differently depending on the mode of administration, especially in culturally and linguistically diverse country like India. T...

In this manuscript, we demonstrate rapid decoration of titania nanotube (TiNT) with noble metals using electrochemical synthesis and its application as a hybrid metal-dielectric spacer and cavity material in surface plasmon-coupled emission (SPCE) platform. Using the metal-dielectric spacer architecture consisting of Pt decorated titania nanotubes,...

Introduction The emergence of the COVID-19 pandemic has led to widespread implementation of policies mandating mask wearing, especially in indoor public spaces. The WHO has similarly recommended wearing face masks on a daily basis, which has led to mask wearing in situations not previously considered. Along with this, there has been an increase in...

We report a novel nanocomposite composed of halloysite nanotubes (HNT) and gold nanoparticles (AuNPs) as an excellent sensing platform. Electrodeposition of AuNPs was carried out by cyclic voltammetry for 120 seconds on HNT/GCE in acidic medium to form Au/HNT/GCE. The nanocomposite was characterized by UV-visible spectroscopy and Scanning Electron...

1D photonic crystal engineering approach for femtomolar detection of Al3+ ions in nanocavity hot spots. 1D photonic crystal-coupled emission: An alternative sensing platform that can outperform conventional surface plasmon-coupled emission due to its lossless property. Femtomolar sensing of hazardous aluminum ions in drinking water was achieved bas...

Airborne spread of coronavirus disease 2019 (COVID‐19) by infectious aerosol is all but certain. However, easily implemented approaches to assess the actual environmental threat are currently unavailable. We present a simple approach with the potential to rapidly provide information about the prevalence of severe acute respiratory syndrome coronavi...

High refractive index, dielectric TiCN nanocubes presenting sharp nano-edges and nano-corners interfaced with plasmonic Ag nanofilms were evaluated with and without graphene oxide nanolayer in surface plasmon-coupled emission (SPCE) substrates. The sharply directional and polarized SPCE displayed >800-fold enhancements on account of integrated hots...

Plasmon-coupled luminescence emission technology has evolved into a resourceful biophotonic methodology for obtaining enhanced sensitivity and selectivity of sensor platform. Reliable and efficient devices have been demonstrated on account of sharply directional and highly p-polarized emission characteristics of SPCE, with excellent background supp...

The quest for auxiliary plasmonic materials with lossless properties began in the past decade. In the current study, a unique plasmonic response is demonstrated from a stratified high refractive index (HRI)-graphene oxide (GO) and low refractive index (LRI)-polymethyl methacrylate (PMMA) multistack. Graphene oxide plasmon-coupled emission (GraPE) r...

Metal-dielectric hybrid nanostructures have recently drawn interest because of their direct coupling between metal surface plasmon resonance and dielectric electric dipoles leading to hybridized modes resulting in low losses and high field enhancements. Surface plasmon-coupled emission is a similar phenomenon that exploits the surface plasmon polar...

The ability of nanoscale materials to trap electromagnetic field beyond the diffraction limit is seldom studied using multifunctional nanohybrids. To this end, we demonstrate a thermo-migratively assembled Soret nanoassembly that enable unique metal-metal, metal-graphene and metal-dielectric resonances. In contrast to the well-explored standalone p...

Enhancement of fluorescence emission from single-photon quantum emitters on plasmonic nanomaterials using surface plasmon-coupled emission (SPCE) platforms has seen significant advancements. In parallel, there has also been an exponential rise in applications involving two-dimensional (2D) transition-metal dichalcogenides (TMDs) that exhibit unique...

Puttaparthi is a birthplace of Bhagawan Sri Sathya Sai Baba and is a small town situated in the district of Anantapur, in Andhra Pradesh. Chitravathi River is the main water-body in Puttaparthi. The river remained dry for many years. Only in the recent years, rainfall events fed water to the river. Last year in 2019 a check-dam was also constructed...

Airborne spread of COVID-19 by infectious aerosol is all but certain. However, easily implemented approaches to assess the actual environmental threat are currently unavailable. We present a simple approach with the potential to rapidly provide information about the prevalence of SARS-CoV-2 in the atmosphere at any location. We used a portable dehu...

Background Longitudinal perinatal depression (PND) data is sparsely available in the Indian population. We have employed Edinburgh Postnatal Depression Scale (EPDS) to assess the prevalence and identify characteristics associated with PND in the south Indian population. PND was assessed longitudinally using EPDS scores with traditional cut-off appr...

Although luminescence spectroscopy has been a promising sensing technology with widespread applications in point-of-care diagnostics and chem-bio detection, it fundamentally suffers from low signal collection efficiency, considerable background noise, poor photostability, and intrinsic omnidirectional emission properties. In this regard, surface pl...

In this study, we report an eco-friendly green synthesis of silver nanoparticles decorated on reduced graphene oxide (Ag-rGO) nanocomposite by using the aqueous fruit extract of Phyllanthus acidus in basic medium. The Ag-rGO nanocomposite was characterized using UV–visible spectroscopy, infrared spectroscopy, scanning electron microscopy, energy di...

Surface plasmon-coupled emission (SPCE) has emerged as a potential nanophotonic technology to understand several physicochemical interactions of nanostructured materials and biomolecules. Although a variety of templates: low-dimensional carbon, intermetallics and nano-biocomposites have been explored with silver nanoparticles, these investigations...

Surface plasmon-coupled emission (SPCE) has emerged as an interdisciplinary, versatile sensing platform due to its highly directional, solid-state and polarized emission. Here, we report the distinct properties rendered by Ag-Soret Colloids (Ag-SCs) such as nanovoids and nanocavities to observe 104-fold enhancement in emission intensity of omnidire...

Coupling of photons with molecular emitters in different nanocavities have resulted in transformative plasmonic applications. The rapidly expanding field of surface plasmon-coupled emission (SPCE) has synergistically employed subwavelength optical properties of localized surface plasmon resonance (LSPR) supported by nanoparticles (NPs) and propagat...

Intrinsically lossy nature of plasmonic based detection platforms necessitates the use of alternative nanophotonic platforms such as one-dimensional photonic crystals (1DPhCs) to exploit properties pertaining to photonic stop-band (PSB), Bloch surface waves (BSWs), microcavity and band-edge modes. We present a highly desirable confinement of intern...

In the past decade, the exploration for frugal nanomaterials that manipulate electromagnetic field for development of next generation plasmonic technologies has been on the rise. Fractal nanoparticles with augmented electromagnetic field enhancements have their utility in broadband optics and electrochemical applications. Here we present a simple,...

Surface plasmon-coupled emission (SPCE) has emerged as a potential sensing platform owing to its >50% fluorescence signal collection efficiency. Further advancements towards boosting the coupling efficiency, can be achieved by relevant spacer and cavity engineering. Several composites of metal nanoparticles (NPs) have been used along with different...

In the present study, we report the synthesis and characterization of platinum nanoparticles decorated graphene (GPtNPs) nanocomposite toward the electrochemical determination of ascorbic acid (AA), dopamine (DA), and paracetamol (PCT). GPtNPs demonstrated synergistic catalytic activity with enhanced currents in all of the measurements when compare...

Fungi have a prominent status in fermentation for the production of different bio-products. Endophytic fungi isolated from medicinal plants are particularly formidable in their adaptability to solid state fermentation as an extension of its natural habitat and are also a potent source of broad-spectrum cellulolytic enzymes. We report for the first...

We demonstrate the achievement of 100-fold fluorescence enhancement and attomolar doxycycline (DC) detection with the use of Ag-lignin nanocomposite in spacer architecture in surface plasmon-coupled emission (SPCE) platform. Fluorescence quenching on π-π stacking of Rhodamine 6G (Rh6G) on lignin has been overcome due to the presence of silver nanop...

Surface plasmon-coupled emission (SPCE) has led to significant advancements in analytical techniques on account of its unique characteristics that include highly polarized photon-sorting ability. In this study, we report the use of a low-cost activated carbon as a plasmonic spacer in the SPCE substrate for achieving 30-fold enhancement in fluoresce...

The present study highlights the first time use of hybrid synergy electrocatalysis to design a cost effective, non-enzymatic ethanol sensor. The nanohybrid has been synthesized by decorating platinum palladium bimetallic nanoparticles (Pt‒PdNPs) on graphene nanosheets (G/Pt‒PdNPs). Field emission scanning electron microscopy, energy dispersive X-ra...

Renewable biomass-derived fuels are essential to meet the blend mandates and the sustainability goals. In our first-to-date study we investigated, individual and synergistic consortia of fungal cultures comprising Pycnoporous sanguineus (PS) in combination with Aspergillus oryzae (AO) and Trichoderma harzianum (TH) for production of cellulolytic en...

Electrochemical sensors based on noble metal graphene nanocomposites in particular, are gaining popularity as they have the combined advantage of both high electrical conductivity of graphene and unique properties of the noble metals. In this study we present the synthesis and application of Palladium (Pd NPs) and Platinum-Palladium bimetallic nano...

We report the use of silver decorated plant proteins as spacer material for augmented surface plasmon-coupled emission (120-fold enhancement) and plasmon-enhanced Raman scattering. We extracted several proteins from different plant sources [Triticum aestivum (TA), Aegle marmelos (AM), Ricinus communis (RC), Jatropha curcas (JC) and Simarouba glauca...

In this work, we demonstrate for the first time ultrasensitive detection of Hg²⁺ ions with femtomolar sensitivity in water samples with the use of surface plasmon-coupled emission (SPCE) platform. The use of portable network diagnostic tools for water security and integrated water shed management is a topic of recent research interest. In this cont...

We report the application of single layered graphene oxide (SLGO) and silver decorated SLGO (Ag-SLGO) as plasmonic spacer material for obtaining enhanced fluorescence from a Rhodamine 6G (Rh6G) radiating dipole in a surface plasmon-coupled emission platform. To this end, we have decorated SLGO with biphasic silver nanoparticles using an in situ dep...

Biofuels are a sustainable and cost-effective alternative to existing transportation fuels. Currently a combination of chemical and enzymatic degradation of lignocellulosic biomass to fermentable sugars has been pursued despite economic challenges. In this study, we have critically investigated individual and synergistic combination of Asperigillus...

Hydrogen as an alternative green fuel for depleting fossil fuels has been considered for a long time now. In this regard pristine metal nanoparticles and metal decorated nanomaterials have been attracting huge attention as electrocatalysts on modified electrodes for hydrogen evolution reaction (HER). Among various electrodes carbon paste electrode...

The Back Cover picture depicts a cellphone-based tunable surface plasmon-coupled emission platform with silver loaded carbon nanotubes in spacer and cavity architectures for 100-fold fluorescence enhancements and attomolar dopamine detection. More information can be found in the Communication by S. S. Ramamurthy and co-workers on page 2791 in Issue...

We demonstrate for the first time, the tuning of qubit emission based on cavity engineering on plasmonic silver thin films. This tunable transition from weak to strong coupling regime in plasmon-coupled fluorescence platform was achieved with the use of palladium nanocomposites. In addition to our recently established correlation between Purcell fa...

In this study the applicability of Zirconium ion impregnated coconut fiber carbon (ZICFC) as an adsorbent for fluoride removal from water was investigated. The dependence of fluoride adsorption on the physicochemical properties includes pH, agitation time, adsorbent dosage, temperature, and the initial concentration of the adsorbate. Maximum defluo...

We report cellphone-based detection of dopamine with attomolar sensitivity in clinical samples with the use of surface plasmon-coupled emission (SPCE) platform. To this end, silver-coated carbon nanotubes were used as spacer and cavity materials on SPCE substrates to obtain in excess of 100 fold fluorescence enhancements. The presence of silver on...

Pristine palladium nanoparticles were decorated on graphene nanosheets for the development of a low cost, non-enzymatic ethanol sensor. The nanocomposite was characterized by ultraviolet-visible absorbance spectroscopy, infrared spectroscopy, and field emission scanning electron microscopy equipped with energy dispersive X-ray spectroscopy. Cyclic...

We demonstrate for the first time, the use of Fe-based nanoparticles on N-doped graphene as spacer and cavity materials and study their plasmonic effect on the spontaneous emission of a radiating dipole. Fe-C-MF was produced by pyrolizing FeOOH and Melamine formaldehyde precursor on graphene while Fe-C-PH was produced by pyrolizing Fe-phenanthrolin...

We demonstrate the successful application of DNA thin films as dynamic bio-spacers in a surface plasmon-coupled emission platform. Site-directed DNA modification using silver and carbon nanomaterials resulted in an amplified Purcell factor (PF) and >130-fold fluorescence enhancements. We present unique architectures of DNA as a plasmonic spacer in...

We demonstrate an important approach to correlate Purcell factor (PF) and surface plasmon-coupled emission (SPCE) enhancements with the use of finite difference time-domain (FDTD) simulations and time correlated single-photon counting (TCSPC) studies of a radiating dipole in cermet nanocavities. We observed >50-fold fluorescence enhancement with hi...