This document outlines a nanosensor for detecting nitroaromatic explosives like TNT. It begins with an introduction to nanobiosensors and describes different types of nanosensors including optical, chemical, physical, and biological nanosensors. It then discusses various nanomaterials that can be used for explosive detection sensors, including carbon nanomaterials, metals, and nanoparticles. As an application, it describes a hybrid nanosensor that uses both the electrochemical reduction of TNT and interactions with a conducting polymer to detect TNT vapors sensitively and selectively. Remaining challenges include developing sensors that can effectively sample and detect explosives in various environments while discriminating against interferents.

1. Nanosensors for trace
nitroaromatic explosive
detection
by Melike Şeyma
Kadayıfçı

2. Outlines
 Introduction
Types of Nanosensors
Nanomaterial-based sensors for nitroaromatic explosive detection
Application:A Hybrid Nanosensor for TNT Vapor Detection
Challanges in moving toward practical applications
 Conclusions

3. Introduction
What is a Nanobiosensors ?
A biosensor is a measurement system for the detection of an analyte that
combines biological compenent with a physicochemical detector, and a
nanobiosensor is a biosensor that on the nano-scale size (1).
Figure 1: Image of a biosensor

4. Biosensor system
Figure 2: Components of biosensor system

5. Types of Nanosensors
NanoSensors
Optical
Nanosensors
Ambient Light
Nanosensors
Proximity
Nanosensors
Biological
Nanosensor
Antibody/Antige
n Interaction
DNA
Interaction
Enzymatic
Interaction
Chemical
Nanosensors
Chemical
Composition
Molecular
Concentratio
n
Physical
Nanosensors
Pressure
Force
Mass
Displacement

6. Nanomaterial-based sensors for nitroaromatic explosive
detection:
Carbon-based nanomaterials
Metal-based nanomaterials
Nanoporous materials
Quantom dot-based nanomaterials
Hybrid nanomaterials : Pt nanoparticles ensembled on
graphene hybrid nanosheet (2)

7. Application: A Hybrid Nanosensor for TNT Vapor Detection
 A hybrid nanosensor based on the electrochemical reduction of TNT and the interaction
of the reduction products with conducting polymer nanojunctions in an ionic liquid.
The sensor simultaneously measures the electrochemical current from the reduction of TNT
and the conductance change of the polymer nanojunction caused from the reduction product.(3)
Figure 4

8. A Hybrid Nanosensor for TNT Vapor Detection
Researchers have also compared the effects of the same interferents on the
electrochemical detection (Figure 3b). They found that the electrochemical detection
alone is more prone to interferents, which underscores the importance of the
integrated nanojunction and electrochemical sensor on the same chip (4).
Figure 5

9. Challanges in moving toward practical applications
Creating a sensor that is both sensitive and selective is only the first part of the
challenge.
 The second part involves bringing explosives from the environment to the
sensor element.(5)
Discrimate the analytes from various interferents in variable enviroments.
Sample collection; because nitroaromatics have extremly low vapor pressures(e.
g TNT)
Since explosive molecules stick to surfaces, delivery lines and other
components need to be maintained at a higher temperature. Operating at higher
temperatures decreases sensitivity.

10. Conclusion
Nano scale materials often possess unique optical and electrical
characteristics, which could enhance the sensitivity and selectivity with incorporation
of some existing techniques.
As new nanomaterials with specific characteristics are developing, analytical chemists
try to apply them for analytical purposes. Efforts in developing new sensors derive
from one goal and that is producing fast, sensitive, selective, and low cast sensors.
In the application part, Researchers have demonstrated an integrated electrochemical and
electrical nanosensor for sensitive and selective detection of nitroaromatic explosives
vapors. The sensor utilizes both the electrochemical signatures of the reduction of the
analytes and specific interactions of the reduction products with the polymer nanojunction to
achieve excellent selectivity.

11. References
1) http://www.deu.edu.tr/ders-katalog/2014-2015/eng/en_132_9665_4800.html
2) Farhad Akhgari, Hassan Fattahi, Yones Mosaei Oskoei, Recent advances in
nanomaterial-based sensors for detection of trace nitroaromatic explosives, Sensors
and Actuators B 221 (2015) 867–878
3-4) Alvaro Dı´az Aguilar,Erica S. Forzani,Mathew Leright,Francis Tsow,Avi Cagan,
Rodrigo A. Iglesias,Larry A. Nagahara,Islamshah Amlani,Raymond Tsui,And N. J. Tao, A
Hybrid Nanosensor for TNT Vapor Detection, DOI: 10.1021/nl902382s |Nano
Lett.2010,10, 380-384
5) Larry Senesac and Thomas G. Thundat, Nanosensors for trace explosive detection, march
2008 |volume11 | number 3