Electrodes designed for the detection of molecules instead of ions
Biosensor: A biosensor is an analytical device which converts the biological signal into a measurable electrical signal.
Professor Leland C Clark is the father of Biosenor. Professor Leland C Clark 1918–2005
Potential measurements of electrochemical cells
Ion selective methods
Reference electrode
Indicator electrode
Potential measuring device
Reference electrode
Indicator electrodes
Ion specific electrodes
Potentiometric measurements
Known half-cell
Insensitive to solution under examination
Reversible and obeys Nernst equation
Constant potential
Returns to original potential
Calomel electrode
Hg in contact with Hg(I) chloride
Ag/AgCl
Potential measurements of electrochemical cells
Ion selective methods
Reference electrode
Indicator electrode
Potential measuring device
Reference electrode
Indicator electrodes
Ion specific electrodes
Potentiometric measurements
Known half-cell
Insensitive to solution under examination
Reversible and obeys Nernst equation
Constant potential
Returns to original potential
Calomel electrode
Hg in contact with Hg(I) chloride
Ag/AgCl
Potentiometry is an electrochemical method of Analysis deals with the measurement of electric potential or emf of an electrolyte solution under the condition of constant current.
Potentiometry is the measurement of electrical potential of an electrolyte solution to determine its concentration.
The principle is based on the fact that the potential of the given sample is directly proportional to the concentration of its electro active ions or its activity (pH)
When the pair of electrodes is placed in the sample solution it shows the potential difference by the addition of the titrant or by the change in the concentration of the ions.
The theory of potentiometry is based on the nernst equation.It gives the basic relationship between the potential generated by an electrochemical cell and the concentration of the ions.
The potential E ( Half cell potential) of any electrode is given by nernst equation
A sensor that integrates a biological element with a physiochemical transducer to produce an electronic signal proportional to a single analyze which is then conveyed to a detector.
Potentiometry is an electrochemical method of Analysis deals with the measurement of electric potential or emf of an electrolyte solution under the condition of constant current.
Potentiometry is the measurement of electrical potential of an electrolyte solution to determine its concentration.
The principle is based on the fact that the potential of the given sample is directly proportional to the concentration of its electro active ions or its activity (pH)
When the pair of electrodes is placed in the sample solution it shows the potential difference by the addition of the titrant or by the change in the concentration of the ions.
The theory of potentiometry is based on the nernst equation.It gives the basic relationship between the potential generated by an electrochemical cell and the concentration of the ions.
The potential E ( Half cell potential) of any electrode is given by nernst equation
A sensor that integrates a biological element with a physiochemical transducer to produce an electronic signal proportional to a single analyze which is then conveyed to a detector.
A biosensor is an independently integrated receptor transducer device, which is capable of providing selective quantitative or semi-quantitative analytical information using a biological recognition element.(IUPAC recommendations 1999)
Professor Leland c Clark junior (1918-2005) is called the father of biosensor. The inventor of the Clark electrode, a device used for measuring oxygen in blood, water and other liquids.
Biosensors play a part in the field of environmental quality, medicine and industry mainly by identifying material and the degree of concentration present.
Biotechnology is challenging subject to teach and understand also..its a very interesting subject in pharmacy..all the power point is made as per your syllabus with point to point discussion.
thank you
The ionic strength of a solution is a measure of the concentration of ions in that solution. Ionic compounds, when dissolved in water, dissociate into ions. The total electrolyte concentration in solution will affect important properties such as the dissociation constant or the solubility of different salts
What can you tell us about the chemical reactions that go into a fireworks display?
Traditionally, three reagents, potassium nitrate, carbon, and sulfur, make gunpowder. You're doing a combustion reaction out of those types of materials that create
this detonation explosion.
MOFs are ideal candidates as gas-sensing materials and have been widely used to detect oxygen, water vapor, toxic and hazardous gases, special air pollutants, and VOCs.
Conductometric titration is a type of titration in which the electrolytic conductivity of the reaction mixture is continuously monitored as one reactant is added. The equivalence point is the point at which the conductivity undergoes a sudden change. ... Example: titration of an HCl solution with the strong base NaOH.
When you design your product, you put a lot of money, energy and consideration into achieving the best possible function, good appearance and high reliability. Corrosion, wear and fatigue resistance may not be the first factors you consider.
However, material selection is crucial to obtain a long service life and to avoid damage such as operation failure – for instance due to inadequate mechanical strength - or unacceptable appearance due to corrosion products.
If you choose the correct materials for your product from the beginning, you can prevent damage deriving from corrosion, wear and mechanical impact. In many cases, you may completely avoid corrosion by choosing a resistant material for its actual application environment.
Lithium aluminium hydride (LiAlH4) is widely used in organic chemistry as a reducing agent. ... Often as a solution in diethyl ether and followed by an acid workup, it will convert esters, carboxylic acids, acyl chlorides, aldehydes, and ketones into the corresponding alcohols.
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 .
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.
Observation of Io’s Resurfacing via Plume Deposition Using Ground-based Adapt...Sérgio Sacani
Since volcanic activity was first discovered on Io from Voyager images in 1979, changes
on Io’s surface have been monitored from both spacecraft and ground-based telescopes.
Here, we present the highest spatial resolution images of Io ever obtained from a groundbased telescope. These images, acquired by the SHARK-VIS instrument on the Large
Binocular Telescope, show evidence of a major resurfacing event on Io’s trailing hemisphere. When compared to the most recent spacecraft images, the SHARK-VIS images
show that a plume deposit from a powerful eruption at Pillan Patera has covered part
of the long-lived Pele plume deposit. Although this type of resurfacing event may be common on Io, few have been detected due to the rarity of spacecraft visits and the previously low spatial resolution available from Earth-based telescopes. The SHARK-VIS instrument ushers in a new era of high resolution imaging of Io’s surface using adaptive
optics at visible wavelengths.
Richard's entangled aventures in wonderlandRichard Gill
Since the loophole-free Bell experiments of 2020 and the Nobel prizes in physics of 2022, critics of Bell's work have retreated to the fortress of super-determinism. Now, super-determinism is a derogatory word - it just means "determinism". Palmer, Hance and Hossenfelder argue that quantum mechanics and determinism are not incompatible, using a sophisticated mathematical construction based on a subtle thinning of allowed states and measurements in quantum mechanics, such that what is left appears to make Bell's argument fail, without altering the empirical predictions of quantum mechanics. I think however that it is a smoke screen, and the slogan "lost in math" comes to my mind. I will discuss some other recent disproofs of Bell's theorem using the language of causality based on causal graphs. Causal thinking is also central to law and justice. I will mention surprising connections to my work on serial killer nurse cases, in particular the Dutch case of Lucia de Berk and the current UK case of Lucy Letby.
Earliest Galaxies in the JADES Origins Field: Luminosity Function and Cosmic ...Sérgio Sacani
We characterize the earliest galaxy population in the JADES Origins Field (JOF), the deepest
imaging field observed with JWST. We make use of the ancillary Hubble optical images (5 filters
spanning 0.4−0.9µm) and novel JWST images with 14 filters spanning 0.8−5µm, including 7 mediumband filters, and reaching total exposure times of up to 46 hours per filter. We combine all our data
at > 2.3µm to construct an ultradeep image, reaching as deep as ≈ 31.4 AB mag in the stack and
30.3-31.0 AB mag (5σ, r = 0.1” circular aperture) in individual filters. We measure photometric
redshifts and use robust selection criteria to identify a sample of eight galaxy candidates at redshifts
z = 11.5 − 15. These objects show compact half-light radii of R1/2 ∼ 50 − 200pc, stellar masses of
M⋆ ∼ 107−108M⊙, and star-formation rates of SFR ∼ 0.1−1 M⊙ yr−1
. Our search finds no candidates
at 15 < z < 20, placing upper limits at these redshifts. We develop a forward modeling approach to
infer the properties of the evolving luminosity function without binning in redshift or luminosity that
marginalizes over the photometric redshift uncertainty of our candidate galaxies and incorporates the
impact of non-detections. We find a z = 12 luminosity function in good agreement with prior results,
and that the luminosity function normalization and UV luminosity density decline by a factor of ∼ 2.5
from z = 12 to z = 14. We discuss the possible implications of our results in the context of theoretical
models for evolution of the dark matter halo mass function.
Cancer cell metabolism: special Reference to Lactate PathwayAADYARAJPANDEY1
Normal Cell Metabolism:
Cellular respiration describes the series of steps that cells use to break down sugar and other chemicals to get the energy we need to function.
Energy is stored in the bonds of glucose and when glucose is broken down, much of that energy is released.
Cell utilize energy in the form of ATP.
The first step of respiration is called glycolysis. In a series of steps, glycolysis breaks glucose into two smaller molecules - a chemical called pyruvate. A small amount of ATP is formed during this process.
Most healthy cells continue the breakdown in a second process, called the Kreb's cycle. The Kreb's cycle allows cells to “burn” the pyruvates made in glycolysis to get more ATP.
The last step in the breakdown of glucose is called oxidative phosphorylation (Ox-Phos).
It takes place in specialized cell structures called mitochondria. This process produces a large amount of ATP. Importantly, cells need oxygen to complete oxidative phosphorylation.
If a cell completes only glycolysis, only 2 molecules of ATP are made per glucose. However, if the cell completes the entire respiration process (glycolysis - Kreb's - oxidative phosphorylation), about 36 molecules of ATP are created, giving it much more energy to use.
IN CANCER CELL:
Unlike healthy cells that "burn" the entire molecule of sugar to capture a large amount of energy as ATP, cancer cells are wasteful.
Cancer cells only partially break down sugar molecules. They overuse the first step of respiration, glycolysis. They frequently do not complete the second step, oxidative phosphorylation.
This results in only 2 molecules of ATP per each glucose molecule instead of the 36 or so ATPs healthy cells gain. As a result, cancer cells need to use a lot more sugar molecules to get enough energy to survive.
Unlike healthy cells that "burn" the entire molecule of sugar to capture a large amount of energy as ATP, cancer cells are wasteful.
Cancer cells only partially break down sugar molecules. They overuse the first step of respiration, glycolysis. They frequently do not complete the second step, oxidative phosphorylation.
This results in only 2 molecules of ATP per each glucose molecule instead of the 36 or so ATPs healthy cells gain. As a result, cancer cells need to use a lot more sugar molecules to get enough energy to survive.
introduction to WARBERG PHENOMENA:
WARBURG EFFECT Usually, cancer cells are highly glycolytic (glucose addiction) and take up more glucose than do normal cells from outside.
Otto Heinrich Warburg (; 8 October 1883 – 1 August 1970) In 1931 was awarded the Nobel Prize in Physiology for his "discovery of the nature and mode of action of the respiratory enzyme.
WARNBURG EFFECT : cancer cells under aerobic (well-oxygenated) conditions to metabolize glucose to lactate (aerobic glycolysis) is known as the Warburg effect. Warburg made the observation that tumor slices consume glucose and secrete lactate at a higher rate than normal tissues.
Molecule selective electrode system and bio sensor
1. SUBMITTED BY
MAYUR HARSUKHBHAI MARVANIYA
MSc CHEMISTRY(SEM-2)
20MSC01014
GUIDED BY
DR.VIRAJ BHANVADIA
ASSISTANT PROFESSOR
SOS,GSFC UNIVERSITY
2. MOLECULAR SELECTIVE ELECTRODE SYSTEM
i. Electrodes designed for the detection of molecules
instead of ions
ii. Gas sensing electrodes (or gas-sensing probes)
Typically based on ISE surrounded by electrolyte
solution
- Activity of ion measured is affected by dissolved
gas
- Gas enters interior solution from sample by
passing through a gas permeable membrane
3. Gas effuses through membrane:
CO2 (aq) » CO2 (g) » CO2 (aq)
External membrane internal
Solution pore solution
In internal solution, pH changes:
CO2 (aq) + H2O » HCO3
- + H+
which is detected by ISE probe
Overall reaction:
CO2 (aq) + H2O » H+ + HCO3
-
external internal
solution solution
Eind = c + 0.0592 log [CO2]ext
4. iii. Enzyme electrodes (or Biocatalytic Membrane
Electrodes)
-General approach is to use an immobilized enzyme.
- Enzyme converts a given molecular analyte into a
species that can be measured electrochemically.
Examples:
H+ pH electrode
CO2 CO2 Gas sensing electrode
NH3 NH4
+ Glass, pH
5. Principal: In presence of enzyme urease, urea (NH4)2CO is
hydrolyzed to give NH3 and H+
Monitor amount of NH3 produced using NH3 gas sensing
electrode
(NH4)2CO + 2H2O + H+ » 2NH4
+ + HCO3
- » 2NH3 + 2H+
6. BIO-SENSOR
Introduction
• A biosensor is an analytical device which converts the
biological signal into a measurable electrical signal.
• Professor Leland C Clark is the father of Biosenor.
Professor Leland C Clark 1918–2005
7. A GOOD BIOSENSOR
• It should provide accurate, precise, reproducible
results.
• It should be free from electrical noise.
• It should be cheap, small, portable and capable of
being used by semi-skilled operators.
• The reaction should be independent from physical
parameters ( pH and temperature
9. BIORECEPTOR
The bioreceptor is a biologically derived material
such as tissue, microorganisms, organelles, cell
receptors, enzymes, antibodies, nucleic acids, etc.
or Biomimetic component that binds or recognizes
the analyte of interest.
10. TRANSDUCER
When the analyte interacts with the bioreceptor,
change in biological signals such as change in
temperature, electrical charge occurs.
The transducer transforms these signal into
another signal which is easily measured and
quantified.
11. Based on the type of transducer the Bio-
sensors classified as
Biosensor
Calorimetric Optical Amperometric Piezoelectric Potentiometric
12. Calorimetric biosensors
The heat produced (or absorbed) by the reaction.
Potentiometric biosensors
Changes in the distribution of charges causing an electrical
potential.
Amperometric biosensors
Movement of electrons produced in a redox reaction.
Optical biosensors
Light output during the reaction or a light absorbance
difference between the reactants and products .
Piezo-electric biosensors
Effects due to the mass of the reactants or products .
13. SIGNAL PROSSESOR
Glucose monitoring device (for diabetes patients)
Monitor the glucose level in the blood
The enzyme glucose oxiadase is used by blood
glucose biosensor to break down of blood glucose.
First it oxidizes glucose and uses two electrons to
reduce the FAD (a component of the enzyme) to
FADH2 which in turn is oxidized by the electrode in a
number of steps.
The resulting current is a measure of the
concentration of glucose.
In this case, the electrode is the transducer and the
enzyme is the bioreceptor.
14. APPLICATION
There are numerous applications of biosensors with
various types. Some of them are used in
Monitoring blood glucose level of diabetes patients.
Detection of Environmental contamination e.g. the
detection of pesticides and heavy metals in river water.
Remote sensing of airborne pathogens durining
epidemic outbreaks
Determining levels of toxic substances before and after
bioremediation
Routine analytical measurement of folic acid, biotin,
vitamin B12
Drug discovery , Protein engineering.
Detection of toxic metabolites such as mycotoxins.
