This document provides an overview of fluorescence spectroscopy. It defines luminescence as the emission of photons from electronically excited states. There are two main types of luminescence: fluorescence from singlet excited states and phosphorescence from triplet excited states. The document discusses instrumentation for fluorescence spectroscopy including light sources, wavelength selection devices like filters and monochromators, and detectors. It also covers factors that affect fluorescence intensity such as molecular structure, concentration, temperature, and pH.
This presentation gives you thorough knowledge about the IR Spectroscopy. This include basic principle, type of vibrations, factors influencing vibrational frequency, instrumentation and applications of IR Spectroscopy. This is the most widely used technique for identifying unknown functional group depending on the vibrational frequency.
In this slide contains Interference In Atomic Absorption Spectroscopy and applications.
Presented by: Shaik Gouse ul azam. ( department of pharmaceutical analysis.)
RIPER, anantpur.
IR SPECTROSCOPY, INTRODUCTION, PRINCIPLE, THEORY, FATE OF ABSORBED RADIATION, FERMI RESONANCE, FINGERPRINT REGION, VIBRATIONS, FACTORS AFFECTING ABSORPTION OF IR RADIATION, SAMPLING TECHNIQUES, APPLICATIONS OF IR SPECTROSCOPY.
This presentation gives you thorough knowledge about the IR Spectroscopy. This include basic principle, type of vibrations, factors influencing vibrational frequency, instrumentation and applications of IR Spectroscopy. This is the most widely used technique for identifying unknown functional group depending on the vibrational frequency.
In this slide contains Interference In Atomic Absorption Spectroscopy and applications.
Presented by: Shaik Gouse ul azam. ( department of pharmaceutical analysis.)
RIPER, anantpur.
IR SPECTROSCOPY, INTRODUCTION, PRINCIPLE, THEORY, FATE OF ABSORBED RADIATION, FERMI RESONANCE, FINGERPRINT REGION, VIBRATIONS, FACTORS AFFECTING ABSORPTION OF IR RADIATION, SAMPLING TECHNIQUES, APPLICATIONS OF IR SPECTROSCOPY.
Introduction, theoretical principle, quantum efficiency of fluorescence, molecular structure of
fluorescence, instrumentation, factors influencing the intensity of fluorescence, comparison of
fluorometry with spectrophotometry, application of fluorometry in pharmaceutical analysis
Introduction, theoretical principle, quantum efficiency of fluorescence, molecular structure of
fluorescence, instrumentation, factors influencing the intensity of fluorescence, comparison of fluorometry with spectrophotometry, application of fluorometry in pharmaceutical analysis
Introduction, theoretical principle, quantum efficiency of fluorescence, molecular structure of
fluorescence, instrumentation, factors influencing the intensity of fluorescence, comparison of
fluorometry with spectrophotometry, application of fluorometry in pharmaceutical analysis
A brief information about the SCOP protein database used in bioinformatics.
The Structural Classification of Proteins (SCOP) database is a comprehensive and authoritative resource for the structural and evolutionary relationships of proteins. It provides a detailed and curated classification of protein structures, grouping them into families, superfamilies, and folds based on their structural and sequence similarities.
Seminar of U.V. Spectroscopy by SAMIR PANDASAMIR PANDA
Spectroscopy is a branch of science dealing the study of interaction of electromagnetic radiation with matter.
Ultraviolet-visible spectroscopy refers to absorption spectroscopy or reflect spectroscopy in the UV-VIS spectral region.
Ultraviolet-visible spectroscopy is an analytical method that can measure the amount of light received by the analyte.
This pdf is about the Schizophrenia.
For more details visit on YouTube; @SELF-EXPLANATORY;
https://www.youtube.com/channel/UCAiarMZDNhe1A3Rnpr_WkzA/videos
Thanks...!
Introduction:
RNA interference (RNAi) or Post-Transcriptional Gene Silencing (PTGS) is an important biological process for modulating eukaryotic gene expression.
It is highly conserved process of posttranscriptional gene silencing by which double stranded RNA (dsRNA) causes sequence-specific degradation of mRNA sequences.
dsRNA-induced gene silencing (RNAi) is reported in a wide range of eukaryotes ranging from worms, insects, mammals and plants.
This process mediates resistance to both endogenous parasitic and exogenous pathogenic nucleic acids, and regulates the expression of protein-coding genes.
What are small ncRNAs?
micro RNA (miRNA)
short interfering RNA (siRNA)
Properties of small non-coding RNA:
Involved in silencing mRNA transcripts.
Called “small” because they are usually only about 21-24 nucleotides long.
Synthesized by first cutting up longer precursor sequences (like the 61nt one that Lee discovered).
Silence an mRNA by base pairing with some sequence on the mRNA.
Discovery of siRNA?
The first small RNA:
In 1993 Rosalind Lee (Victor Ambros lab) was studying a non- coding gene in C. elegans, lin-4, that was involved in silencing of another gene, lin-14, at the appropriate time in the
development of the worm C. elegans.
Two small transcripts of lin-4 (22nt and 61nt) were found to be complementary to a sequence in the 3' UTR of lin-14.
Because lin-4 encoded no protein, she deduced that it must be these transcripts that are causing the silencing by RNA-RNA interactions.
Types of RNAi ( non coding RNA)
MiRNA
Length (23-25 nt)
Trans acting
Binds with target MRNA in mismatch
Translation inhibition
Si RNA
Length 21 nt.
Cis acting
Bind with target Mrna in perfect complementary sequence
Piwi-RNA
Length ; 25 to 36 nt.
Expressed in Germ Cells
Regulates trnasposomes activity
MECHANISM OF RNAI:
First the double-stranded RNA teams up with a protein complex named Dicer, which cuts the long RNA into short pieces.
Then another protein complex called RISC (RNA-induced silencing complex) discards one of the two RNA strands.
The RISC-docked, single-stranded RNA then pairs with the homologous mRNA and destroys it.
THE RISC COMPLEX:
RISC is large(>500kD) RNA multi- protein Binding complex which triggers MRNA degradation in response to MRNA
Unwinding of double stranded Si RNA by ATP independent Helicase
Active component of RISC is Ago proteins( ENDONUCLEASE) which cleave target MRNA.
DICER: endonuclease (RNase Family III)
Argonaute: Central Component of the RNA-Induced Silencing Complex (RISC)
One strand of the dsRNA produced by Dicer is retained in the RISC complex in association with Argonaute
ARGONAUTE PROTEIN :
1.PAZ(PIWI/Argonaute/ Zwille)- Recognition of target MRNA
2.PIWI (p-element induced wimpy Testis)- breaks Phosphodiester bond of mRNA.)RNAse H activity.
MiRNA:
The Double-stranded RNAs are naturally produced in eukaryotic cells during development, and they have a key role in regulating gene expression .
2. LUMINESCENCE SPECTROSCOPY
•The emissionof radiation from a species after that species has absorbed radiation.
LUMINESCENCEFLUORESCENCEPHOSPHORESCENCESPECTROSCOPYCHEMILUMINESCENCE
2
3. What is luminescence ?
Luminescenceistheemissionofphotonsfromelectronicallyexcitedstate.
Luminescenceisdividedintotwotypes,dependinguponthenatureofthegroundandtheexcitedstates.
Inasingletexcitedstate,theelectroninthehigherenergyorbitalhastheoppositespinorientationasthesecondelectroninthelowerorbital.Thesetwoelectronsaresaidtobepaired.Returntothegroundstatefromanexcitedsingletstatedoesnotrequireanelectrontochangeitsspinorientation.
Inatripletstatetheseelectronsareunpaired,thatis,theirspinshavethesameorientation.Achangeinspinorientationisneededforatripletstatetoreturntothesingletgroundstate.
diamagnetic S1
paramagnetic T1
So
5. Types of luminescence
(classification according to the means by which energy is supplied to excite the luminescent molecule)
1)Photoluminescence: Molecules are excited by interaction with photons of radiation.
Fluorescence:
Prompt fluorescence: S1S0 + h
The release of electromagnetic energy is immediate or from the singlet state.
Delayed fluorescence: S1T1S1S0 + h
This results from two intersystem crossings, first from the singlet to the triplet,
then from the triplet to the singlet.
Phospholuminescence:T1S0+ h
A delayed release of electromagnetic energy from the triplet state.
2) Chemiluminescence: The excitation energy is obtained from the chemical energy of
reaction.
3) Bioluminescence: Chemiluminescence from a biological system: firefly, sea pansy, jellyfish, bacteria, protozoa, crustacea.
4)Triboluminescence: A release of energy when certain crystals, such as sugar, are broken.
5)Cathodoluminescence: A release of energy produced by exposure to cathode rays
6)Thermoluminescence: When a material existing in high vibrational energy levels emits energy at a temperature below red heat, after being exposed to small amounts of thermal energy.
8. Concept of singlet and triplet state
Singlet and triplet states
•Ground state –two electrons per orbital; electrons have opposite spin and are paired
•Singlet excited state
Electron in higher energy orbital has the opposite spin orientation relative to electron in the lower orbital
•Triplet excited state
The excited valence electron may spontaneously reverse its spin (spin flip). This process is called intersystem crossing. Electrons in both orbitals now have same spin orientation
12. Principle of fluorimetry
•Amoleculeabsorbsincidentelectromagneticradiationsandgetexcited.
•Itisunstableinitsexcitedstateandtendstoreturntothegroundstatebyemittingradiation.
•Fluorescencecanbereferredastheradiationsemittedfromanexcitedmoleculeintransitionfromsingletexcitedstatetosingletgroundstate.
•Influorimetry,radiationsemittedareoflongerwavelengththanabsorbedradiations.Thisisbecause,whentheradiationsfallonthemolecule,vibrationoccurs(in10-13seconds),andhasanaveragelifeof10-9seconds.Duringthevibrationperiod,lossofenergyoccursduetointermolecularcollisionsandsomeenergyislosttosolventmolecules(moleculesofthesolventusedforthedissolutionofthesampleinfluorimetry).Hencetheemittedradiationsareoflongerwavelengthandhavelessenergy.(sinceEαc/λ)
12
13. •Orbital changes can be explained as:
1.Fluorescence:
Singlet state Singlet excited state singlet ground state
pp* (No change in spin)
2. Phosphorescence:
Singlet state Singlet excited state Triplet state (2 unpaired electrons) singlet ground state
pp* (No change in spin) Change in spin
•In either fluorescence or phosphorescence the frequency of the emitted radiation is less than the frequency of incident radiation. The relationship is ;
0> fluor> phos
Where, = frequency 13
14. Fluorescence related to concentration
ThefluorescenceradiantpowerFisproportionaltotheabsorbedradiantpower.
F=(Po–P)
where=fluorescenceefficiency,Po=incidentpower,P=transmittedpower
TherelationshipbetweentheabsorbedradiantpowerandconcentrationcanbeobtainedfromBeer’slaw.
P/Po=10–A=10–bCor,P=Po10–bC
or,F=Po(1–10–bC)------------(1)
This is the fluorescence law.
WhenexpandingtheexponentialtermsandassumingbCtobe0.05orless, onlythefirsttermintheseriesissignificantandequationcanbewrittenas
F=Po(lnbC)=kbC-----------(2)
23. Instrumentation for fluorescence spectroscopy
Power
supply
Source
Excitation monochromator
Emission monochromator
Detector
Sample cell
Slit
Data processor
General layout of fluorescence spectrophotometer
25. 1) Light sources
a. Gas discharge lamps :
Xenon arc lamp
High pressure mercury vapor lamp
b. Incandescent lamps : Tungsten wire filament lamp
c. Laser : tunable dye laser
d. X-ray source for X-ray fluorescence
2) Wavelength selection devices
a. Filters :
Absorption filters ---tinted glass or gelatin containing dyes sandwiched between glass
Interference filters ---thin transparent layer of CF2or MgF2sandwiched two parallel,
partially refelecting metal films
b. Monochromators :
Gratings
Prism
28. 3) Sample compartment
Cuvettes or cells with area of 1 cm2 .Usually made up of;
Quarz or fused silica ----200 nm~ 800 nm
Glass or plastic ----300 nm~
4) Detectors
Photomultiplier tube
30. Types of Fluorescent Molecules
•Experimentallyitisfoundthatfluorescenceisfavouredinrigidmolecules,eg.,phenolphthaleinandfluoresceinarestructurallysimilarasshownbelow.However,fluoresceinshowsafargreaterfluorescencequantumefficiencybecauseofitsrigidity.
• phenolphthalein
31. Types of Fluorescent Molecules
•ItisthoughtthattheextrarigidityimpartedbythebridgingoxygengroupinFluoresceinreducestherateofnonradiativerelaxationsothatemissionbyfluorescencehassufficienttimetooccur.
Fluorescein
32. Application
1.Analysis of medicinal compound:
•A number of drugs can be estimated using fluorimetry.
•Fluorescence is made to produce from non- fluorogenicdrugs by following ways:
(a) Some drugs are capable of exhibiting fluorescence in an appropriate solvent.
e.g. Quinine in 0.1 N Sulfuric acid, Riboflavin in 1% tartaric acid, Aminocrinein 0.1 N HCl.
32