Centre for Nanotechnology

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Mass Loading Effect of Resonant Structures in Surface Acoustic Wave Devices Suitable for Sensing Applications
(2010) Ramakrishnan, N.
Surface acoustic wave (SAW) devices are widely used in sensors, actuators, filters, and telecommunication systems. Surface acoustic waves are elastic waves launched on a piezoelectric substrate when an electrical signal is applied to metallic comb-like electrodes patterned on the surface of the substrate. SAW devices used in sensing applications extensively employ mass loading effect of a sensing film coated over the surface of the device. Changes in the properties of the sensing film due to the measurand cause variation in mass loading that alters the velocity of the surface wave and results in deviation in the electrical properties of the device, e.g. change in resonance frequency in a SAW resonator. Some other properties of sensing films that can affect SAW velocity are conductivity, permittivity, viscosity, and temperature; hence sensing films can be developed accordingly. In this thesis, mass loading effect of resonant structures (in place of sensing films) has been investigated. High aspect ratio pillars are proposed as the resonant structures to be fabricated on SAW resonators. Finite Element Method (FEM) simulation shows that when the resonance frequency of the pillars is close to the resonance frequency of the resonator, extraordinary changes in mass loading occur. The pillars and the SAW resonator form a system of coupled resonators, and the deviations in the system frequency are large when the resonance frequencies of the two coupled systems are close. The rapid variation in the mass loading characteristics at the resonance frequency can be used to develop highly sensitive sensors. It is observed that the sensitivity with resonant pillars is at least 10 times that obtained by thin film as the sensing medium. FEM simulation is carried out for wide range of pillar dimensions and it is observed that the thinner pillars offer greater sensitivity implying that nano size pillars will be the most desirable sensing medium. As an example, a hydrogen sensor using nano size pillars of palladium as sensing medium has been simulated and the results show high sensitivity for sensing hydrogen at concentrations below 1%. Experiments are carried out by fabricating SAW resonators with SU-8 micro-pillars of varying dimensions. Experimental results and the FEM simulation show typical characteristics of a system of coupled resonators, viz. increase in frequency in certain cases and the state of zero mass loading. The present work is not restricted to any specific sensor; rather introduces a technique for the development of a novel class of SAW sensors. In addition to the highly sensitive sensors, the technique has potential applications in filters and other SAW devices....
Spectroscopic Studies of Diameter Dependent Properties, Defects and Defect Engineering in Single-Walled and Multi-Walled Carbon Nanotubes
(2010) Singh, Dilip Kumar
Carbon nanotubes (CNTs) are unique one-dimensional nanostructures with remarkable electronic, optical, mechanical and thermal properties. Since its discovery in 1991, CNTs have caught widespread attention of researchers worldwide for studies of fundamental properties as well as device applications. Carbon nanotubes were first thought of as perfect seamless cylindrical graphene sheets- a defect-free structure. However, with time and as more studies have been undertaken, it has emerged that nanotubes are not necessarily that perfect i.e. it may contains various kinds of topological defects. The issue is further complicated by the fact that the quality of a nanotube sample depends very much on the growth method such as commonly used chemical vapor deposition (CVD). As-grown nanotubes containing various forms of carbon and other impurities can be purified by various methods. However, often defects are created on the tube walls during growth as well as in the process of purification. Several exotic properties of single walled carbon nanotubes (SWCNTs) predicted by theory have been verified experimentally to a reasonable extent. However, presence and role of defects in the nanotube properties are yet to be understood properly. Detrimental effects of defects in CNTs have been recognized from studies of nanoelectronic devices fabricated from CNTs that often have very short lifetime and high failure rates. Defective nanotubes are known to be highly electron emitting and lifetime of these devices are too short for commercial applications. Defect induced enhanced conductivity and defect-enhanced dispersion of carbon nanotube in DNA solutions have been reported recently for multiwalled carbon nanotubes (MWCNTs). Thus, defects are expected to play a significant role in determining various functionalities of carbon nanotube based devices. A controlled spectroscopy, positron annihilation lifetime spectroscopy etc. Use of the sophisticated techniques like ultrahigh vacuum scanning tunneling microscopy (UHV-STM), high resolution transmission microscopy (HRTEM) for monitoring structural defects in CNTs are often time consuming and can not be used for the bulk characterization. In the literature, UHV-STM and aberration corrected low voltage HRTEM have been used recently to obtain evidence of defects and defect dynamics in nanotubes. However, nondestructive techniques like Raman spectroscopy, PL spectroscopy and ESR spectroscopy are not explored in the literature to study the presence and influence of structural defects in the structural and optical properties of carbon nanotubes. introduction of defects and nondestructive evaluation of defects in nanotubes are of immense significance for their potential applications in various devices. Understanding the influence of specific type of defects in the nanotube structure on the electronic and optical properties is of particular interest. During the growth of carbon nanotubes, the number and nature of defects is decided by various factors like temperature of growth, carbon source feeding rate, carrier gas flow rate, nature of carbon source being used etc. The identification of various kinds of defects and their methods of characterization is not established for carbon nanotubes using traditional methods like Raman spectroscopy, electron spin resonance (ESR), photoluminescen...................
Implications of Nanoparticle-Polymer Composites as Probes and Therapeutic Agents
(2010) Sanpui, Pallab
Abstract not available
Autonomous Motion Driven by Catalytic Nanoparticles
(2011) Dey, Krishna Kanti
Attainment of incisively directed autonomous motion of nano and microscale objects holds promise towards deterministic transportation of materials at smaller length scales. Controlled manipulation of dynamics of such objects not only opens possibilities for targeted delivery of useful biomolecules but also excavates smarter scopes for biosensing, fluidics and minimally invasive surgeries. The very first attempt towards controlled autonomous transport was to harness the self propelling ability of natural biomolecular motors, which naturally evolve and carry things within the cell with extraordinary efficiency. The approach had been to couple these proteins with inorganic structures and then to allow them to move along the cytoskeleton in a directed manner. Applications of these bio-integrated motors were, nevertheless, found to be limited not only for the need of defined environment for protein activation but also for their quick natural degradation. The challenge, therefore, lies in the fabrication of inorganic or organic micro/nano structures exhibiting two and three dimensional autonomous movements, preferably in a liquid, whose motion can be precisely steered inside the medium as desired. These structures must offer flexibility in terms of ease of synthesis and degree of scalability. Attainment of such self-propulsion would not only ensure correct understanding of small scale particle dynamics but also would find importance in targeted transport of materials at the submicronscale. Autonomous motion of micron scale objects was realized in our laboratory with polymer microstructures coated with metal nanoparticles - immersed in dilute hydrogen liquid with finite speed. Control over the motion of these objects was achieved by tuning the properties of the composite as well as that of the medium in which the particles moved. With an aim to attain controlled self-propulsion of an DallD inorganic catalytic object, we used palladium (Pd) nanoparticles incorporated cobalt ferrite (CoFe2O4) micro particles in dilute H2O2 solution. This essentially allowed observation of self propelled motion at smaller length scales, where the Brownian fluctuations were yet to dominate the dynamics. It also established the fabrication of stable magnetic microstructures capable of moving autonomously in a highly reactive medium like H2O2, for a considerably longer period of time. With Pd nanoparticles coated polymer microstructures, we finally demonstrated the first ever example of inorganic pH taxis in a liquid, where the particles were seen to migrate spontaneously from a region of low pH to a higher one. The observation not only established the fabrication of structures that mimic the bacterial behavior across a pH gradient but also marked the development of a novel, quick and efficient pH sensing method. All our observations were theoretically modeled using laws of classical physics. The calculations aided in quantifying the observations - providing estimates on the possible controls achievable over the dynamics of these objects, by manipulating different external and internal parameters. peroxide (H2O2) solution. The nanoparticles (of palladium, nickel and gold) deposited over the polymer surface were capable of decomposing H2O2 catalytically under specific conditions. This essentially generated bubbles of oxygen (O2) that remained tethered to the polymer surface after they were forme......
Metal Nanoparticles and nanocomposites as antibacterial and anticancer agents
(2012) Sharma, Shilpa
In the present era of nanotechnology advances are being made in the understanding of the physico-chemical and optoelectronic properties of materials at nanoscales in order to develop impressive functional nanomaterials with applications in divers areas of science and technology. ....
Fluorescent nanomaterials for biological applications
(2013) Jaiswal, Amit
Nanoparticles are always accompanied with the appearance of novel properties irrespective of the metallic or semiconductor origin. Evolution of the unique physical, chemical and electronic properties at the nanoscale forms the essence of the various applications of nanoscience and nanotechnology. ....
Nanocomposites for Theranostic Applications
(2014) Sahoo, Amaresh Kumar
Nanomaterials have immense potential to improve healthcare by designing simple, low cost biosensors, generation of the novel therapeutics and delivery of the therapeutics with enhanced efficacy by suitable cargo. My PhD thesis works are focused on synthesi zing and engineering nanomaterials, having dual characteristics of diagnostic and therapy i.e. theranostics, in order to address important issues of healthcare. The thesis is divided into seven chapters. Chapter 1 - Introduction and Review of Literature - describes the scholastic insights of the reports available in the literature related to the present work and involving synthesis and characterization of the different nanomaterials suitable for biomedical applications. Also, the context of the present thesis vis-à-vis current technological challenge in nanobiotechnology is elaborated. In Chapter 2, synthesis of a novel fluorescent Au NP- composite has been reported, based on reaction of reaction of paracetamol (p-hyrdoxy acetanilide) - a well-known anti-pyretic and analgesic molecule, generally considered as safe for human consumption- and HAuCl4. The Au NP-PD composite employed in detection of both Gram positive and Gram negative bacteria. Next aim was to develop a novel antibacterial agent effective against common bacterial strains. The Ag NPs has been found to be highly bactericidal against both Gram positive and Gram negative bacteria. Hence, the synthesis of Ag NP-PD composite by reaction of the AgNO3 and paracetamol was reported in Chapter 3. Interestingly, enhancement in the reactive oxygen species (ROS) generation was observed in presence of the composite. It is proposed that the ROS generation led to oxidation of the dimer to N-acetyl p-benzoquinone imine (NAPQI). The generated NAPQI acted as a DNA gyrase inhibitor causing bacterial cell death following linearization of DNA. The above findings opened up the hope that the paracetamol dimer along with suitable ROS generator would be a potential cancer therapeutic agent. Thus, in Chapter 4, the cytotoxic effect of PD along with the ‘few atoms’ silver nanoparticles of size less than 2 nm, commonly called as silver nanoclusters (NCs), is reported. To perform targeted delivery folic acid was conjugated with the chitosan and carried out the cytotoxicity study for different types of cancer cells. Next, one step simple aqueous synthesis of the Au NCs by using the biopolymer chitosan as template is reported in Chapter 5. The chitosan Au NC composite was converted into polymeric nanoparticles and used for the suitable bioimaging agents. In order to convert these fluorescent NPs as theranostic NPs, suicide gene (CD-UPRT) was loaded and delivered in cervical cancer cells (HeLa) for induction of cell death. In Chapter 6, a simple way of synthesis of highly fluorescent Au NCs was devised by exploiting the polymerase chain reaction (PCR) condition and amplified DNA as template was reported. As the Au NC was found to be non-cytotoxic, therefore, the method offers exceptional promises for synthesizing highly fluorescent Au NCs and concurrently estimating DNA amplification, which can be applied for designing devices. Chapter 7 summarizes overall thesis works and describes future prospects. In brief, the present thesis is aimed at synthesizing nanomaterials, which are useful for the biomedical applications. Some of the methods developed during the pursuit of the thesis have important future implications in bacterial estimation and annihilation, fluorescence based imaging and killing of cancer cells and quantitative estimation of gene expression.
Fabrication and Characterization of Highly Environmental Sustainable Organic Field-Effect Transistors with Tri-Layer Gate Dielectrics
(2015) Subbarao, Nimmakayala V V
Abstract not available
Engineering devices with functional nanomaterials
(2016) Kumar, Sailapu Sunil
It is a commendable journey of human race to the 'age of super computers' from calculators, which were once regarded as 'big thing'. One cannot debate over 'integration of novel materials and techniques’ being a significant factor in achieving such a giant technological leap. In the contemporary age, sublime developments in science and technology are contributing to the staggering growth of innovations. There are great endeavours for generating novel materials and methods to construct devices of potential use. Prudent interest is judiciously invested towards 'small' dimension materials to achieve ‘the next big thing' in the world of devices. This may well be said as materials at the nanoscale dimensions are promising due to their versatile at the same time unique physical and chemical properties. The essence of nanotechnology is to utilize the fundamental knowledge associated with the intriguing properties prevailing at these dimensions. Hence, through effective design strategies properties at these 'small' dimensions prove to be vital in development and transformation of next generation devices and systems. The current dissertation has been directed towards engineering devices through effective integration of nanomaterials and thereby, use of their physico-chemical attributes. In particular, salient features like catalytic, magnetic, plasmonic and luminescence nature of nanoscale materials developed through bottom-up approach of chemical synthetic routes were availed to accomplish devices with on-board intelligence and clinical importance. A device with the ability to generate electrical energy from autonomous motion of microbots was engineered. Intelligent systems capable of decision making in the liquid media were developed. For disease diagnostics, a bench top device was constructed to perform polymerase chain reaction and array based gene and protein analyses. Another device for photodynamic therapy and optical based detection was achieved. These nanotechnology oriented devices indicate greater prospects and encourage further investigations to achieve other major technological leaps.
Fabrication and Characterization of CVD Graphene Based Hybrid Nanostructures for Photoconductive and Photocatalytic Applications
(2016) Kumar, Biroju Ravi
Achieving large area wafer scale single layer graphene onto dielectric substrates without having any structural defects and layer non uniformity is still challenging. There is a lack of in-depth understanding on the role of defects in the interactions between graphene and foreign atoms and molecules. Investigating the various in-plane and edge defects including functional groups on the graphene using resonance Raman spectroscopy and HRTEM will provide the rich physics behind its electronic and optoelectronic applications. Physical and chemical functionalization of graphene preserving its sp2 crystallinity can reveal the change in the electronic structure due to covalent and noncovalent foreign material interaction with graphene. It is anticipated that a proper understanding on the interaction of noble metal with defective graphene would pave the way for controlled functionalization of graphene for cutting edge applications. Functionalized graphene and its exploitation in integrated optoelectronics is least explored in the literature. Further, origin of solid state PL from CDG is not understood well with the help of controlled environments. Fabrication and characterization of graphene based semiconducting hybrid NSs for enhanced photodetection applications is imperative to develop various optoelectronic devices. Visible light photocatalysis of graphene and functionalized graphene incorporating TM plasmonic hybrids are little explored. Graphene based TM plasmonic hybrid NSs for SERS and mechanism of SERS are still challenging. Unlimited possibility of exploiting graphene based hybrid NSs for photoconductive, photocatalytic and SERS applications still remains. This thesis focuses on the controlled growth of large area defect free graphene using CVD technique and synthesis of CDG functional materials. Extensive investigations on number of graphene layers, uniformity, functionalization and defects were probed using microRaman spectroscopy and HRTEM. Next, the fabrication of grapheneplasmonic hybrids with TM NPs such as Au, Ag, Cu and organic molecules as well as the graphene ZnO hybrid NSs and their SERS, photocatalytic and photoconductive applications were investigated.
Design and development of high performance polymer light emitting diode for solid state lighting
(2017) Das, Dipjyoti
The thesis entitled “Design and Development of High Performance Polymer Light Emitting Diode for Solid State Lighting” deals with fabrication of Polymer Light Emitting Diode (PLED), especially which emits white light, using different approaches such as physical doping, electroplex formation and phosphor sensitized system. The effect of processing conditions on the device performance has also been investigated. The electron transport property of polyfluorene was enhanced by incorporating strong electron acceptor moiety 1, 8-naphthalimide into polyfluorene main chain and efficient blue and white PLEDs were fabricated using this newly synthesized copolymer as emissive layer. A detailed study on the effect of electron injection barrier and the electron transport property of the widely used poly(9-vinylcarbazole) (PVK) on the device parameters such as current density, brightness and electroluminescent spectra, especially the electroplex formation of PVK based PLED is also carried out. White light was successfully obtained utilizing the concept of electroplex formation in such devices by device optimization. The effect of the device processing condition such as annealing temperature and the effect of mixed host were studied and by optimizing the annealing temperature and doping ration of the mixed host, highly efficient green PLEDs were fabricated. Furthermore, by utilizing FIrpic as the blue emitter and the bridge of energy transfer and Rubrene and DCJTB as orange/red dopant, white PLEDs utilizing the concept of phosphor sensitized system was realized.
Influence of electrode buffer layers in plasmonic bulk heterojunction solar cells
(2017) Singh, Ashish
The demand of cost efficient organic bulk heterojunction (BHJ) solar cells and different device architecture modulation methods are of prime importance for improving the power conversion efficiency (PCE) values. This thesis mainly focuses to modify the cathode and anode buffer layers to improve the PCE of very commonly studied organic BHJ system, namely, regioregular poly(3-hexylthiophene-2,5-diyl) (rrP3HT):[6,6]-Phenyl C61/71 butyric acid methyl ester (PC61/71BM). For modulating cathode contact, different types of hole and electron rich small molecules were introduced in the device structure, whereas, to modulate the anode contact various types of easily synthesized plasmon induced metal (Gold and Silver) nanoparticles were doped in the hole injecting PEDOT:PSS layer. The thesis mainly introduced a very simple, unique and robust methodology consisting of the combined effect of dual cathode buffer layers and different shaped plasmon induced metal nanoparticles for improving the PCE value as well as the morphological information of very commonly studied rrP3HT:PCBM system which can be further used in the next generation of solar cell technology.
Design and synthesis of novel conjugated organic semiconducting materials for organic light emitting diodes
(2017) Gopikrishna, P
Highly efficient materials (monomers & polymers) are developed as emissive layer for organic light emitting diode by utilizing the donor-acceptor monomers and AIE active compounds. The 1,8-naphthalimide is inserted as acceptor into the donor polyfluorene and polycarbazole main chain. The well charge balanced or efficient materials are established by varying the feed ratios of acceptor mol % in the donor polymers. Moreover, the emission colors of the copolymers are tuned from blue to green and blue to red in case of polyfluorene and polycarbazole, respectively. The PLEDs are fabricated with these new materials that exhibited excellent device properties. The AIEE active monomers are synthesized based on the mono-substituted dibenzofulvene (M-DBF) derivatives and their photophysical properties are further investigated. White light emitting polymers are synthesized by incorporating AIEE active monomers as orange or red emitting dopants into polyfluorene host. The newly developed materials showed high solubility, which is very important parameter to obtain better film forming properties during the device fabrication. In addition, to the incorporation of the AIEE active monomers into the polymer host, the voltage independent EL spectra is easily achieved. This can be attributed to the non-planarity of the AIEE active molecules which can effectively reduce the intermolecular interactions in the condense state. Another set of AIEE active monomers are synthesized based donor and acceptor units by changing the bridge (Thiophene & Phenyl) between donor and acceptor. The thiophene substituted monomers displayed the AIEE active nature and remaining phenyl substituted monomers exhibited weak or AIE inactive nature. Also, the heavy atom effect is successfully studied. The detailed theoretical studies are performed to support the experimental results. Overall new organic materials with improved optical properties are developed and utilized for OLED applications as well as AIE properties.
Design and fabrication of rylene diimide based active materials, devices and applications
(2017) Kalita, Anamika
The thesis entitled “Design and Fabrication of Rylene Diimide Based Active Materials, Devices and Applications” deals with synthesis of various Rylene Diimide based derivatives following a simple one step condensation reaction route. The derivatives N, N'-bis(cyclohexyl)naphthalene diimide (NDI-CY2) and N, N'-bis(methylcyclohexane)naphthalene diimide (NMeCy2) were successfully employed for the OFETs application using simple, cost effective fabrication techniques and demonstrating the influence of various combinations of inorganic/polymeric dielectric layers on device performances. The conjugated perylene diimide derivative appended with histidine side group, PDI-HIS was utilized for the detection of ammonia (NH3) vapors via fabricating a simple two terminal sensor device. A new derivative of cationic naphthalene diimide, N, N′-bis(3-imidazolium-1-ylpropyl)-naphthalenediimide diiodide (NDMI) was developed for its application in detection of nitroexplosive picric acid (PA) both in aqueous and vapor phase. Furthermore, an economical and portable electronic prototype was established for visual and on-site detection of PA vapors under exceptionally realistic conditions.
Device Engineering of organic field effect transistors for sensing applications
(2017) Dey, Anamika
Considering the demand of future technology, the thesis entitled “Device Engineering of Organic Field Effect Transistors for Sensing Applications” introduces important methodologies which have been developed for improving the performances of OFET. The thesis mainly focuses to modify the gate dielectric layer to reduce the operational voltage of both p-type and n-type OFETs and use them for various sensing applications. By modulating gate dielectric layer with the combinations of a high-k inorganic and two low-k organic dielectric materials, the operational voltage of OFET was effectively reduced from 50 V to 7 V, which was later used for photo-sensing application. Again, by using the combination of two inorganic and one organic dielectric material layer, the operational voltage of OFET was further successfully reduced from 7 V to 2 V and the same device architecture was used for bio-sensing application. This thesis mainly described very simple, unique and robust methodologies for lowering the operational voltage of OFETs up to 2 V, which can be further used as very effective and stable platforms in the next generation of portable electronics.
Design, development and fabrication of thiophene and benzothiadiazole based conjugated polymers for photovoltaics
(2018) Ratha, Radhakrishna
The content of this synopsis report entitled "Design, development and fabrication of thiophene and benzothiadiazole based conjugated polymers for photovoltaics" is divided into five chapters. In chapter 1 the respective research area, where design synthesis and fabrication of conjugated polymers, along with the scope and significance of the subsequent chapters are discussed. In chapter 2 photostability enhancement of P3HT-PCBM by using appropriate ratio of MWCNT in ambient conditions have been discussed. Chapter 3 discusses about synthesis of poly(ortho-arylene-vinylene) type of polymer alternating at 5,6-position of BT namely PI and P2 in the polymer main chain. Chapter 4 demonstrates that on functionalization of methyl acetate group at 5,6-positions of BT red-shift absorbance, lowered the LUMOOptical improves phase separation in active layer of PSC and hence improves solar cell performance compared to its methyl counterpart. Chapter 5 results in synthesis of newer napthothiadiazole (NT) based D-A polymer and their BHJ solar cell performance.
Multimodal propulsion of synthetic microbots
(2018) Singh, Amit Kumar
The recent quest for miniaturization has inspired researchers to design and develop micro or nanorobots suitable for multifarious applications. The present thesis reports the fabrication of a host of micromotors composed of iron nanoparticles (FeNPs) aggregates, FeNPs coated on polymeric materials, paper, and agglomerates of pollutant carbon soot. These fabricated micromotors were employed for pH sensing, cargo transport, hydrogen generation and water detoxification applications. The Chapter 1 introduces the general introduction and basic concepts related to the self-propulsion of synthetic micro/nanoswimmers. The Chapter 2 reports a controlled migration of an iron nanoparticle (FeNP) coated polymer micromotor. The self-propulsion owing to the asymmetric catalytic decomposition of peroxide fuel was directed through a pH gradient imposed across the motor-surface, while the magnetic field induced an external control on the movement and the speed of the motor. The Chapter 3 demonstrates the design and development of a self-propelling ferrobot composed of a collection of iron nanoparticles (FeNPs). While the propulsive thrust required for the chemotactic migration of the ferrobots was generated through the ejection of hydrogen bubbles due to the reaction of aqueous formic acid (FA) with FeNP clusters on the motor surface, presence of ferromagnetic FeNPs assured “on-the-fly” remote guidance using an external magnetic field. The experiments uncovered the potential of the proposed ferrobots not only for the on-demand power supply to the portable devices but also as a single-step commercial process to produce pure hydrogen under ambient condition and devoid of greenhouse gas emission. In the Chapter 4, the self-propulsion of paper-based microjets, namely paperbots has been explored, which has multimodal chemical and magnetic controls on the motion. The Chapter 5 shows fabrication of multifunctional chemically-powered carbon soot-based microbots, namely CARBOts, by heterogeneous deposition of catalytic platinum (Pt) and magnetic nickel (Ni) nanofilms on the airborne contaminant carbon soot (CS) for environmental remediation. These magneto-catalytic CARBOts demonstrated efficient catalytic degradation of methylene blue (MB) dye in the presence of 10% (v/v) H2O2 fuel under ambient conditions. The intrinsic oleophillic nature of the CARBOts facilitated successful oil-motor interaction, which led to efficient on-the-fly capturing of oil droplets. The Chapter 6 concludes with the thesis summary and a concise discussion on the future prospects of micromotors discussed in this thesis work.
Luminescent gold and copper nanoclusters for theranostic applications
(2018) Goswami, Upashi
The present thesis entitled “Luminescent Gold and Copper Nanoclusters for Theranostic Applications” emphasizes on synthesis and development of different types of metal nanoclusters (Au and Cu) and their potential applications. The thesis is organized in five chapters where Chapter 1 provides introduction and insights of luminescent metal nanoclusters, and it’s various applications in the field of bacterial detection, enumeration, distinction of antibiotic resistant strains, white light emission, electro chemical biosensing, bioimaging, therapeutics, and in the fields of theranostics for cancer therapy.Chapter 2 begins with a new facile method of synthesis of luminescent gold nanoclusters (Au NCs) taking bacteria as template where the luminescence property of the as-synthesized Au NCs was probed for bacterial detection and counting, offering a quick method to enumerate the number of bacteria present in the samples. Additionally, the method was employed for distinction between the Gram strains and for detection of bacterial contaminants from water sources and kanamycin resistant strains rapidly.Chapter 3, introduced the concept of white light emission from a unicellular living organism functionalized with gold nanoclusters Au NCs. The bacterial cell wall with Au NCs synthesized on it, emitted white light associated with high quantum yield and chemical stability.Further, in Chapter 4 spherical luminescent drug encapsulated composite nanoparticles (PEG-Au NC-NaB-NPs) were synthesized for synergy of action and the mechanism of cell death was also studied in detail along with inspired trials for in vivo mice bearing Dalton’s lymphoma ascites (DLA) tumors.Chapter 5 demonstrates novel synthesis of blue emitting transferrin stabilized copper nanoclusters, which were further formulated into spherical transferrin copper nanocluster-doxorubicin nanoparticles (Tf-CuNC-Dox-NPs) or nanodrug for efficacious targeted delivery. The uptake and release of Dox from the nanoparticulate system was monitored by Förster resonance energy transfer (FRET) assisted bioimaging.The Tf-CuNC-Dox-NPs evinced synergistic anticancer activity involving Tf-CuNCs and Dox where mechanism of its action was also elucidated in details. The work was complemented with detailed in vivo studies on TfR positive DLA mice model.
Developing gold nanocluster based cancer theranostics
(2018) Chatterjee, Bandhan
Nanotheranostic, a combination of diagnostic and therapeutic modalities at a nanoscale range offers a promising prospect in cancer therapeutics. Besides having the edges offered by the nanomaterials, it further refutes the need of separate units for individual modalities. The current thesis work is to develop novel nanoscale theranostic materials as potential candidates for their further clinical translation. The thesis is organised in six chapters. The first Chapter (Chapter 1) provides a holistic but comprehensive description about the need and basics of theranostics and current state of cancer theranostics. It also provides a comprehensive introduction of nanoclusters as majority of theranostic developed here are nanocluster based. The chapter also provides the background and objectives of the thesis. Chapter 2 describes the development of DNA (plasmid DNA) based smart theranostics for cancer therapy. The chapter entails the development of the DNA templated Au NCs and their further use in conjugation with cisplatin (anti-cancer drug) for developing composite NPs. Further these composite NPs were thoroughly characterized with various analytical instruments. The composite NPs were stable and had bright fluorescent with decent quantum yield. The composite NPs were readily taken up the HeLa cells and inflicted augmented cytotoxicity on the host cells while bioimaging them simultaneously. The composite NPs also have on demand loading capacity and pH dependent release profile. Chapter 3 deals with the synthesis of fluorescent gold nanocluster on dGTP, a small molecule. It should be borne here that whereas the previous work has gold nanocluster templated on DNA (have myriad of bases in it), this work is about stabilizing the gold nanocluster on a nucleotides (dGTP) rather the polymer of it. The dGTP templated Au NCs displayed impressive physical characteristics deemed of an imaging moiety and was further interacted with cisplatin to form theranostic composite NPs, which were further coated with PEG to provide a space for surface functionalization.The composite NPs were successful in the shuttling the drug efficiently into the treated cells while concurrently bioimaging it. Chapter 4 describes the development of a single unit theranostic. Here MTX (methotrexate), a commercial clinical drug is used as a template to synthesise gold nanoclusters. These single unit theranostics were extremely stable both in PBS and blood serum. They were brightly fluorescent, photostable and were efficiently taken by the cells. They inflicted highly augmented cytotoxicity on the host cells, also enabling the concurrent bioimaging the host cells. Chapter 5 entails the formation of a folic acid conjugated chitosan NP on which these MTX NCs were loaded. The purpose of the chapter is to study the feasibility of replacing the free drug with MTX NCs which have higher cytotoxicity and additional fluorescent properties in a drug delivery vehicle. The NPs were efficiently taken up by the cells and bioimaged it. The host cells also displayed an almost two-fold reduction in IC50 value of the drug when subjected to NPs in MTX NCs form. This augurs well for the further development of such single unit theranostics. Chapter 6 provides a comprehensive summary of the thesis and provides insight into the potential prospects of the thesis work
Multifunctional nanomoaterials for theranostic applications
(2018) Dutta, Deepanjalee
Multifunctional nanomaterials have been a point of attraction in cancer research due to its breadth of applications in imaging, therapeutics and targeting. Apart from imparting targeted diagnosis and therapy, these systems render the advantages of combinatorial therapeutic regime in alleviation of cancer. Particularly, biopolymer based nanoparticle delivery systems have been developed for anticancer treatments, wound healing and hydrogel based injection modules. They can achieve efficient conjugation, entrapment, absorption and encapsulation of drugs or imaging probes and enable the delivery of the same to the desired regions. In addition, small chemical molecules also have been modified towards development of theranostic agents for enhancing therapeutic potential and cell permeability. Imaging techniques involved in field of theranostic is mostly dependent on various types of contrast agents out of which luminescence probes acquire special attention. Such luminescence based imaging probes can be used to monitor the accumulation of nanomaterials in tissues and to track their multivalent interactions in intracellular domain. This dissertation focusses on biopolymer as well as small molecule based multifunctional nanomaterials in achieving the combined goal of in vitro therapy and diagnostics in a single module.The chapter 1 begins with an insight into the fascinating world of multifunctional nanomaterials. It traces back to the developmental junctures of theranostic nano-medicine and discusses the most recent progresses in the field. Some of the landmark findings have been highlighted to convey the importance of multifunctional nanomaterials in different arenas.

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