Disha NEET Physics Guide for classes 11 and 12.pdf
Rapid detection systems
1. Rapid detection of food
borne pathogens &
Biosensors.
Dawrul Islam
M.Tech (FSQM)
313004
2. Introduction
• Biological defense and security applications demand
rapid, sensitive detection of bacterial pathogens.
• Standard culture methods for identifying pathogenic
bacteria cannot provide fast results in an emergency
situation such as a biological attack.
• Advanced techniques are designed for detection of
pathogens through gene identifications and biomarker
signature.
3. The Issue of Food Safety
• 48 million people get sick annually
due to food borne diseases.
• 128,000 hospitalizations
• 5,000 deaths
• According to the CDC-
• Bacterial contamination accounts
for 91% of total foodborne
diseases.
Annually
4. Needs for detection
• Food borne diseases cost
billions of dollars annually
• The food industry is the main
party concerned with the
presence of pathogenic
microorganisms, where failure
to detect a pathogen may lead
to a dreadful effect.
• Pathogens may enter the food
through many different ways
• To minimize time and human
error.
5. Today we will discuss….
• Conventional detection techniques.
• What are biosensors , there types and applications ?
• Current Research in Biosensors.
8. Rapid Methods – Food borne Pathogens
• 4.Antibody-based Assays
Highly specific interactions of antigen-antibody used for detection of
pathogens.
ELISA
Immunoprecipitation
• 5. Nucleic acid-basedAssays
These include the methods based on the use of nucleic acids for detection
of pathogens
DNA hybridization
DNA Microarray
PCR: sensitive and reliable
-Real time PCR
10. Biosensors
What Is a Biosensor?
The bio-receptor is a biomolecule that
recognizes the target analyte whereas the
transducer converts the recognition event into a
measurable signal.
11. Block Diagram of a Biosensor
a) Target+Bioreceptor
b) Transducer
c) Amplifier
d) Processor
e) Monitor
12.
13. Types of Biosensor in pathogen
Detection
• Whole-cell-based biosensors
Genetically engineered yeast or
bacteria cells to bear the luc or lux
gene operon, expressing
luminescence proteins as the green
fluorescence protein (GFP).
-Bacterial Bioluminescence.
Detects 100 cells/hr.
• Amperometric Biosensors
• Amperometric biosensor are the
most common electrochemical
biosensor which has been used for
pathogen detection.
• Detection of Ecoli 0157 &
Salmonella .
14. Types of Biosensor in pathogen
Detection
• Enzyme-based biosensors
• An enzyme biosensor is an analytical
device that combines an enzyme
with a transducer to produce signal
proportional to target analyte
concentration.
• Enzyme sensor array by model
recognition using an artificial neural
network .
• This type of test is generally applied
to analysis of dairy products, fish
etc.
• Optical biosensors
• These types of sensors are based
on measuring responses to light
emission.
• Optical biosensors are based on
well founded methods including
fluorescence, light absorbance,
photothermal techniques, etc.
These technical usages have been
demonstrated to detect the presence
of allergens, particularly peanuts,
during food production.
15. Research in Biosensors
• CARBON NANOTUBES
The significant sensitivity of CNT conductivity to the surface adsorbates allows
the use of CNT as highly sensitive Nano-scale sensors
- Amperometric Nanobiosensors
• Immunomagnetic Separation of BacterialTarget
The electrically active NPs were conjugated with antibodies by direct physical
adsorption of magnetic NP and confirmed in Polyclonal anti-Bacillus antibodies
17. Conclusions
• As a rapid method is used more frequently, its benefits and at the same time,
its limitations also become more apparent.
• Lastly, technology continues to advance at a great pace and next generation
assays, such as biosensors and DNA chips already are being developed that
has the potential capability for near real-time and on-line monitoring of
multiple pathogens in foods.
Mostly the FB epidemic is associated with bacteria stain eg. Shigella , Salmonella etcBioterrorism , Epidemic and Health impacts , Industrial and economical losses , detailed analysis shows biosensor are much better for accuracy , lets see what are the basic diffrences are there in conventional and advanced techniques and how development of designer biosensor with multiply testing ability can be produced.Gene id : (fim A) salmonella , (afa- ecoli 0157)
Bioterrisom, advancement of genetically modified strains, Most of them are Salmonella sp. ,Escherichia coli, Listeria monocytogenes, Staphylococcus aureus, were found to be main source of bacterial contaminations in our food supply.
2. Thousands of product samples would be recalled and dumped for minimization of food borne epidemics & would lower the brand value .3. It can enter though pre harvesting , cultivation , post harvesting or at place its being served.4. In colony counting there is high risk of human error.
How rapid detection methods are developed and , were these are applicable 3. How they are faster then conv. Methods
Culturing the sample , then observed for pathogen though plate counting methods , and are subseptable to human error.Are based on ab-ag interactions – eg ELISA , Imunoprecipitation. Are Hybridization techniques , faster and reliable then above
BROAD CLASSIFICATION OF IDENTIFICATIONBiochemical identifiers like specific enzyme , Fatty acid compostionIn a study that was done in year 2007 ,they selected a specific monoclonal antibody (mouse IgG1) against L. monocytogenes, and also attempted to detect it directly.
DNA hy- similar to the sandwich ‘elisa’ but instead enzyme conjugates with the ab which forms color.Probes are labelled with radioactive labels for detection.Autoradiography is then used to detect the probe-target complexesDNA microarray- advanced technique which are extensively used for analysis of genetic constraint , also analyses level of expression of toxic gene or protiens
Complex carbohydrates , hormones etc
These are the following types of recognition elements which binds to biosensor and produces quantifiable results.Calorimetric biosensors – food quality analysis , Heat based detection .
Those sensors based on eitherthe fusion of the lux operon to result in detectable amount of bioluminanceBact.Biolum.Capable of detecting 100 cells/hrAmperometric detection of micro-organisms involvesthe measurement of the current generated through electrooxidation/reduction catalysed by their enzymesAmp-E. coli O157:H7 |81cfu| ( 6 min ) Salmonella 1–5 6hL. monocytogenes, and C. jejuni 10 cells/mL.Another study on detection of the freshness; based on L-lactate detection in tomato paste and infant food or by using a continuous measurement format of enzyme flow reactors [Baeumner et al. 2003]Phytotoxins,especially those produced by algae and found in seafoodwere of interest in Baeumner study 2003
Enzyme based--simultaneous determination of the three biogenic amines (putrescine, histamine and Tyramine).A monoamine oxidase, a diamine oxidase (with specific activities adequate for rapid detection)Mycotoxins, such as aflatoxin B1, have been currently used as targets for analysis performed with screen-printed immunosensor devices.Biosensor kit: Cobas IDA BC : EnterobacteriaMicroID : BC: Listeria Riboprinter – Nucliec acid – Salmonella , stplycocus, EcoliBactometer- salmonella
CNT-oxi-The accelerated electron transfer reaction of hydrogen peroxide at the CNT-based paste electrode offered a rapid low-potential (0.10 V) detection of the substrate
The electrically active NPs were conjugated with antibodies by direct physical adsorption as described and confirmed in Polyclonal anti-Bacillus antibodies The bio-modified particles (immuno-c/sNPs) were magnetically separated to remove any unbound antibody in the supernatant, washed twice with blocking buffer, re-suspended in phosphate buffer.GE healthcare Genequant 100
Because of the complex designs and formats of these tests, coupled with the difficulties of testing foods, users must exercise caution when selecting rapid methods and to also evaluate these tests thoroughly, as some may be more suitable than others for distinct testing situations or for assaying certain types of food
