Prakash,P N; Dr.Ramaiah,D(National Institute for Interdisciplinary Science and Technology,CSIR, December , 2008)
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Abstract:
Development of organic molecules that exhibit selective
interactions with different biomolecules has immense significance
in biochemical and medicinal applications. In this context, our main
objective has been to design a few novel functionaIized molecules
that can selectively bind and recognize nucleotides and DNA in the aqueous medium through non-covalent interactions. Our strategy
was to design novel cycIophane receptor systems based on the
anthracene chromophore linked through different bridging moieties
and spacer groups. It was proposed that such systems would have a
rigid structure with well defined cavity, wherein the aromatic
chromophore can undergo pi-stacking interactions with the guest
molecules. The viologen and imidazolium moieties have been
chosen as bridging units, since such groups, can in principle, could
enhance the solubility of these derivatives in the aqueous medium
as well as stabilize the inclusion complexes through electrostatic
interactions.We synthesized a series of water soluble novel functionalized
cyclophanes and have investigated their interactions with
nucleotides, DNA and oligonucIeotides through photophysical.
chiroptical, electrochemical and NMR techniques. Results indicate
that these systems have favorable photophysical properties and
exhibit selective interactions with ATP, GTP and DNA involving
electrostatic. hydrophobic and pi-stacking interactions inside the
cavity and hence can have potential use as probes in biology.
Akhil, K Nair; Dr.Ramaiah,D(Cochin University Of Science And Technology, October 3, 2013)
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Abstract:
Design and study of molecular receptors capable of mimicking
natural processes has found applications in basic research as well as in
the development of potentially useful technologies. Of the various
receptors reported, the cyclophanes are known to encapsulate guest
molecules in their cavity utilizing various non–covalent interactions
resulting in significant changes in their optical properties. This unique
property of the cyclophanes has been widely exploited for the
development of selective and sensitive probes for a variety of guest
molecules including complex biomolecules. Further, the incorporation of
metal centres into these systems added new possibilities for designing
receptors such as the metallocyclophanes and transition metal
complexes, which can target a large variety of Lewis basic functional
groups that act as selective synthetic receptors.
The ligands that form complexes with the metal ions, and are
capable of further binding to Lewis-basic substrates through open
coordination sites present in various biomolecules are particularly
important as biomolecular receptors. In this context, we synthesized a
few anthracene and acridine based metal complexes and novel
metallocyclophanes and have investigated their photophysical and
biomolecular recognition properties.
Description:
Photosciences and Photonics
Chemical Sciences and Technology Division
CSIR-National Institute for Interdisciplinary Science and
Technology (CSIR-NIIST), Trivandrum
Subhash, N; Dr.Sathianandan, K(Cochin University of Science And Technology, August , 1981)
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Abstract:
Laser engineering is an area in which developments in the
existing design concepts and technology appear at an alarming rate.
Now—a-days, emphasis has shifted from innovation to cost reduction
and system improvement. To a major extent, these studies are aimed
at attaining larger power densities, higher system efficiency and
identification of new lasing media and new lasing wavelengths. Todate
researchers have put to use all the ditferent Forms of matter as lasing
material. Laser action was observed For the first time in a gaseous
system - the He-Ne system. This was Followed by a variety of solidstate
and gas laser systems. Uarious organic dyes dissolved in suitable
solvents were found to lase when pumped optically. Broad band
emission characteristics of these dye molecules made wavelength tuning
possible using optical devices. Laser action was also observed in
certain p-n junctions of semiconductor materials and some of these
systems are also tunable. The recent addition to this list was the
observation of laser action from certain laser produced plasmas.
The purpose of this investigation was to examine the design
and Fabrication techniques of pulsed Nitrogen lasers and high power
Nd: Glass laserso Attempt was also made to put the systems developed
into certain related experiments
Description:
Department of Physics, Cochin University of Science and Technology
Divya, Thomas; Girish Kumar, K(Cochin University Of Science And Technology, May 27, 2015)
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Abstract:
Chemical sensors have growing interest in the determination of food
additives, which are creating toxicity and may cause serious health concern,
drugs and metal ions. A chemical sensor can be defined as a device that
transforms chemical information, ranging from the concentration of a
specific sample component to total composition analysis, into an analytically
useful signal. The chemical information may be generated from a chemical
reaction of the analyte or from a physical property of the system investigated.
Two main steps involved in the functioning of a chemical sensor are
recognition and transduction. Chemical sensors employ specific transduction
techniques to yield analyte information. The most widely used techniques
employed in chemical sensors are optical absorption, luminescence, redox
potential etc. According to the operating principle of the transducer, chemical
sensors may be classified as electrochemical sensors, optical sensors, mass
sensitive sensors, heat sensitive sensors etc.
Electrochemical sensors are devices that transform the effect of the
electrochemical interaction between analyte and electrode into a useful
signal. They are very widespread as they use simple instrumentation, very
good sensitivity with wide linear concentration ranges, rapid analysis time and
simultaneous determination of several analytes. These include voltammetric,
potentiometric and amperometric sensors.
Fluorescence sensing of chemical and biochemical analytes is an active
area of research. Any phenomenon that results in a change of fluorescence
intensity, anisotropy or lifetime can be used for sensing. The fluorophores are
mixed with the analyte solution and excited at its corresponding wavelength.
The change in fluorescence intensity (enhancement or quenching) is directly
related to the concentration of the analyte. Fluorescence quenching refers to any
process that decreases the fluorescence intensity of a sample. A variety of molecular rearrangements, energy transfer, ground-state complex formation
and collisional quenching. Generally, fluorescence quenching can occur by two
different mechanisms, dynamic quenching and static quenching.
The thesis presents the development of voltammetric and fluorescent
sensors for the analysis of pharmaceuticals, food additives metal ions. The developed sensors were successfully applied for the determination
of analytes in real samples.
Chemical sensors have multidisciplinary applications. The development
and application of voltammetric and optical sensors continue to be an
exciting and expanding area of research in analytical chemistry. The
synthesis of biocompatible fluorophores and their use in clinical analysis,
and the development of disposable sensors for clinical analysis is still a
challenging task. The ability to make sensitive and selective measurements and
the requirement of less expensive equipment make electrochemical and
fluorescence based sensors attractive.
Pearl,Augustine; Dr.Girish Kumar, K(Cochin University of Science and Technology, June , 2008)
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Abstract:
The quality of a drug is determined after establishing its authenticity by testing its purity and quality of the pure substance in the drug and its formulations.Ion selective sensors have become one of the most effective and powerful means for analytical scientists in the determination of drug substances and are playing an increasing role in pharmaceutical analysis.ISEs are cost effective,easy to prepare and can be rapidly manipulated . Potentiometric ion selective sensors have been developed for six drugs namely trimethoprim, ketoconazole, lamivudine, domperidon, nimesulide and Lomefloxacin. The sensors fabricated include both PVC membrane sensor as well as carbon paste sensor. A total of sixteen different sensors have been developed. The response parameters of all the sensors have been studied and the sensors were applied to the determination of the drugs in pharmaceutical formulations and also in real samples like urine.
Description:
Department of Applied Chemistry,Cochin University of Science and Technology
Renjini, Joseph; Dr.Girish Kumar, K(Cochin University of Science & Technology, January , 2012)
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Abstract:
The development of electrochemical sensors is currently one of the active areas of research in analytical chemistry.Voltammetric sensors as an important class of electrochemical sensors are extensively used in pharmaceutical applications.In voltammetric analysis,many active compounds in dosage forms,in contrast to excipients,can be readily oxidised or reduced at the electrode surface by applying a potential.Chemically modified electrodes have great significance in the electrochemical determination of pharmaceuticals.The modification of electrode results in efficient determination of electroactive species at very lower potential without any major interferences.The present study involves the fabrication of 8 voltammetric sensors for the drugs Metronidazole Benzoate,
Sulfamethoxazole,
Acyclovir,
Pam Chloride ,
Trimethoprim ,
Tamsulosin Hydrochloride and
Ceftriaxone Sodium.Two sensors were developed for the drug tamsulosin hydrochloride while one sensor each was developed for the other drugs.
Description:
Dept.of Applied Chemistry,Cochin University of Science and Technology
Sobhana, Mathew; Dr.Girish Kumar, K(Cochin University of Science and Technology, March , 2012)
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Abstract:
Electroanalytical techniques represent a class of powerful and versatile
analytical method which is based on the electrical properties of a solution of
the analyte when it is made part of an electrochemical cell. They offer high
sensitivity, accuracy, precision and a large linear dynamic range. The cost of
instrumentation is relatively low compared to other instrumental methods of
analysis. Many solid state electrochemical sensors have been commercialised
nowadays. Potentiometry is a very simple electroanalytical technique with
extraordinary analytical capabilities. Since valinomycin was introduced as an
ionophore for K+, Ion Selective Electrodes have become one of the best
studied and understood analytical devices. It can be used for the
determination of substances ranging from simple inorganic ions to complex
organic molecules. It is a very attractive option owing to the wide range of
applications and ease of the use of the instruments employed. They also
possess the advantages of short response time, high selectivity and very low
detection limits. Moreover, analysis by these electrodes is non-destructive and
adaptable to small sample volumes. It has become a standard technique for
medical researchers, biologists, geologists and environmental specialists.
This thesis presents the synthesis and characterisation of five
ionophores. Based on these ionophores, nine potentiometric sensors are
fabricated for the determination of ions such as Pb2+, Mn2+, Ni2+, Cu2+ and
Sal- ion (Salicylate ion). The electrochemical characterisation and analytical
application studies of the developed sensors are also described. The thesis is
divided into eight chapters
Description:
Department of Applied Chemistry, Cochin University of Science and Technology
Kishore,V C; Dr.Sudha Kartha,C; Dr. Sreekumar, K(Cochin University of Science & Technology, June , 2008)
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Abstract:
This Thesis discussed molecules suitable for photorefractive effect. Out
of the molecules studied, only one system was used to make photorefractive polymers system. Other molecules, especially, the electro-optic
polymer, Poly(3-methacrloyl-1-(4'-nitro-4-azo-1'-phenyl)phenylalanine-co-
methyl methacrylate) can be subjected to more detailed studies to explore
the possibilities of using them for electro-optic applications. Though not included in the thesis, the efficient photoconductor, Poly(6-tert-butyl-3-
phenyl-3,4-dihydro-2H-1,3-benzoxazine) sensitized with C60, which was described in Chapter 3 showed a low magnitude photovoltaic effect. This
hints at the possibility of using this system for organic solar cells also. The thesis presented the initial observation of photorefractive effect in
a polybenzoxazine based polymer system. A detailed analysis of the effect of C60, ECZ and DR1 can be carried out to check for the possibility of a high efficiency photorefractive system.
Description:
Applied Optics Division, Department of Physics, Cochin University of Science and Technology
Sanal, K C; Dr.Jayaraj, M K(Cochin University of Science And Technology, January 27, 2014)
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Abstract:
Semiconductor physics has developed significantly in the field of re-
search and industry in the past few decades due to it’s numerous
practical applications. One of the relevant fields of current interest in
material science is the fundamental aspects and applications of semi-
conducting transparent thin films. Transparent conductors show the
properties of transparency and conductivity simultaneously. As far
as the band structure is concerned, the combination of the these two
properties in the same material is contradictory. Generally a trans-
parent material is an insulator having completely filled valence and
empty conduction bands. Metallic conductivity come out when the
Fermi level lies within a band with a large density of states to provide
high carrier concentration. Effective transparent conductors must nec-
essarily represent a compromise between a better transmission within the visible spectral range and a controlled but useful electrical con-
ductivity [1–6]. Generally oxides like In2O3, SnO2, ZnO, CdO etc,
show such a combination. These materials without any doping are
insulators with optical band gap of about 3 eV. To become a trans-
parent conductor, these materials must be degenerately doped to lift
the Fermi level up into the conduction band. Degenerate doping pro-
vides high mobility of extra carriers and low optical absorption. The
increase in conductivity involves an increase in either carrier concen-
tration or mobility. Increase in carrier concentration will enhance the
absorption in the visible region while increase in mobility has no re-
verse effect on optical properties. Therefore the focus of research for
new transparent conducting oxide (TCO) materials is on developing
materials with higher carrier mobilities.
Description:
Department of Physics
Cochin University of Science and Technology