AN INCISIVE REVIEW OF NANOSENSORS

ABOUT AUTHORS
Inderjeet Kaur, Navneet Kaur, Maninder Kaur
Department of Biotechnology, CT institute of Pharmaceutical Sciences, Shahpur, Jalandhar, Punjab

ABSTRACT
Nanosensors are increasing expanding consideration because of the need to distinguish and measure chemical and physical properties in hard to achieve biological and industrial systems that are in the nano-scale locale. An option is given in the fast improvement of nanosensors which have favorable position to recognize sustenance segments in a simple and brisk way. Different kinds of nanosensors are being produced to meet the diverse necessities in food inspection (nanosensors for identification of outside and interior conditions in food packaging, carbon nanotubes based electrochemical sensors for recognition of cations, anions and organic compounds in nourishment, different aptamers for identification of pesticides, anti-microbials, overwhelming metals, microbial cells and poisons).

INTRODUCTION
Nanotechnology guarantees the capacity to manufacture exact machine and parts of molecular size. In its unique sense, ‘nanotechnology’ refers to the anticipated capacity to build things from the base up, utilizing techniques and tools. In nanotechnology science nosensors are detecting tool with no less than one of their detecting measurements being not more prominent than 100 nm. In the field of nanotechnology, Nano sensors are instrumental for observing physical and chemical phenomenon in locales hard to achieve, biochemical are detect in cellular organelles, estimating nanoscopic particles in the industry as well as in environment. A sensor is an instrument that reacts to a physical stimulation (for example heat, light, sound, pressure and motion).The sensor is in charge of changing over some sort of physical phenomenon into an amount quantifiable by a data acquisition (DAQ) system.nanosensors are broadly three categories following are
1. optical nanosensors
2. electromagnetic nanosensors
3. mechanical and/or vibrational nanosensorss

Need for Nano sensors
• When particles are smaller and specific phenomena are characteristic length often new physics, chemistry which leads to properties of size
• The decrease in the size of the sensing part.
• Sensitivity can increase due to better conduction properties

Table 1: various types of nanosensors (Lim et al., 2006).

Nanosensor

type

Sub-category

Measured specimens or physical

Properties

Optical

Fiber optic

Benzopyrene tetrol, benzo[a]-

pyrene, caspase-9 (an apoptosis

protein), cytochrome c (a protein

involved in producing cellular

energy), pH, K+, Ca2+, NO,

NO2

−, Cl−, Na+

PEBBLE

(direct)

H+, Ca2+, Mg2+, Zn2+, glucose

and dissolved O2

PEBBLE

(ion-correlation)

K+, Na+, Cl−

Electromagnetic

Current

measurement

H2S, GOx, lactase oxidase,

dehydrogenase, peroxidase,

hydrogen peroxide, catalase,

organophosphorus pesticides,

organophosphorus substrates of

organophosphorus hydrolase,

DNA, ATP

Magnetism

measurement

Molecular interactions, oligonucleotide

sequences, enzymatic

activity, viral particles, magnetic

field, speed, position sensing

Mechanical

Vibrational

Resonance frequency, spring

Constant

Inertial

Pressure, acceleration, yaw rate

Current nanosensors devices can be divided into (Liu 2006):
* Nanostructured materials – e.g. porous silicon,
• Classification of porous silicon
• Nanoporous silicon – (features < 5nm)
• Mesoporous silicon – (features 5nm – 100nm)
• Macroporous silicon – (features > 100nm)
• Pores generated by electrical breakdown

Manufacturing Methods of porous silicon
• Electrochemical Etching
• Chemical Etching
• Spark Erosion
• Chemical Vapor Deposition
Properties
• Porosity
• Photoluminescence
• Electroluminescence
• Reflectivity
• Conduction
* Nanoparticles based sensors, Nanoprobes,
* Nanowire nanosensors, Nano systems: cantilevers, Nano-electromechanical systems (NEMS).

Table 2: Carbon Nanotubes based Nanosensors(Craig et al.,2013; Joyner et al.,2015)

System	Target species	Salient feature
Single wall nanotubes (SWNT)	NH3 and NO2	Sensitive to 200 ppm of NO2, and 1% of NH3.
Single wall nanotubes (SWNT)	N2, He, O2, and Ar	Gas concentrations as lowas 100 ppm can be detected
Multi-wall carbon nanotubes (MWCNTs)	NH3	Gas concentrations as lowas 10 ppm can be detected. The sensor showed a reversible response of few minutes.
Poly(o-anisidine) (POAS) coated CNT	HCl	Nine times increase in sensitivity compared to uncoated CNT
Single-walled carbon nanotube (SWNT)	β-D-glucose	Senses β-D-glucose in solution phase by two distinct mechanisms of signal transduction: fluorescence and charge transfer.
Poly(vinylferrocene) (PVF) derivatised MWCNTs	Glucose	Glucose concentration in real blood sample can be determined.