# Presentation: 941724

## NANOMATERIAL-BASED MICROCHIP  ENVIRONMENTAL ASSAYS

- Joe Wang
- SensoChip Lab,
- NMSU, Las Cruces

- (Towards the Nano/Micro Interface)

##   Why Microchips?

** ****IMPROVED PERFORMANCE**
** ****HIGH DEGREE OF INTEGRATION**
- Sample Cleanup (filters, extraction etc.)
- Preconcentration (beads, membranes)
- Mixing/Reactions (Derivatization)
- Separation
- Detection
** ****HIGH SPEED**
** ****MINIATURIZATION / PORTABILITY**
** ****NEGLIGIBLE WASTE AND SAMPLE / REAGENT CONSUMPTION**
** ****AUTOMATION**
** ****PARALLEL ASSAYS**
** ****LOW COST**

- The dramatic downscaling and integration of chemical assays** **hold considerable promise for faster and simpler on-site monitoring of priority pollutants and  make these analytical microsystems particularly attractive as ‘green analytical chemistry’ screening tools.

**MICROCHIPS FOR ENVIRONMENTAL  MONITORING**

##   Electrochemical (EC) Detectors for   

**  ****Microseparation chips**

** ****REMARKABLY HIGH SENSITIVITY**
** ****PORTABILITY (Inherent miniaturization and integration of both the     ****	****	****   detector and  control instrumentation)**
** ****COMPATIBITLITY WITH MICROFABRICATION TECHNOLOGIES**
** ****LOW COST**
** ****LOW POWER REQUIREMENTS**
** ****INDEPENDENCE OF OPTICAL PATHLENGTH AND SAMPLE **
**  ****TURBIDITY**

## The inherent miniaturization and complete integration of electrochemical detection make it extremely attractive for creating truly portable (and possibly disposable) stand-alone microsystems. Optical detection systems, in contrast, are still relatively large, hence compromising the benefits of miniaturization. 

**Towards Self-Contained Portable Monitoring Microsystems**

##  NMSU ‘Lab-on-a-Chip’ Microsystem

**Pocket PC **

**Power Supply **

**μChip **

**Hand-held Analyzer**
**(‘PalmSens’)**

##   CE/EC MICROCHIPS:   TOWARDS E NVIRONMENTAL MONITORING

- PHENOLIC  COMPOUNDS
- HYDRAZINES
- NITROAROMATIC EXPLOSIVES
- PESTICIDES AND NERVE  AGENTS

## CE-Microchip with Amperometic Detector

- Assays of multiple contaminants in short time scales

## Slide 9

## μ CZE-EC Detection of Explosives

**Time/s**

**0**

**100**

**200**

**50**

**150**

**250**

**Current**

**TNT**

**DNB**

**2,4-DNT**

**2,6-DNT**

**4-NT**

**5 **

**nA**

**μ** **CZE-EC Detection of Explosives**

**TOTAL**

*Anal. Chem. 74 (2002) 1187.*

**   **

**INDIVIDUAL**

- 0

- 50

- 100

- 150

- 10 nA

**TNB**

**4-Am-2,6-DNT**

- Time (s)

- Current

- Current

**DNB**

**TNT**

**2,4-DNT**

**2-Am-4,6-DNT**

- 100 nA

- 0

- 50

- 100

- 150

**MICROCHIP  SWITCHING  BETWEEN **
**RAPID SCREENING AND  DETAILED  IDENTIFICATION**

## NANOMATERIAL-BASED MICROCHIP

**Nanotechnology is defined as the creation of functional materials, **
**devices and systems through control of matter at the 1-100 nm scale. **
**The use of nanomaterials in  Analytical Chemistry has taken off **
**rapidly and will surely continue to expand. The unique properties of **
**nanoparticles, nanotubes and nanowires**** offer great prospects for **
**enhancing the performance of CE microchips and  for developing**
**novel nanomaterial-based electrical detection strategies.**

-   ENVIRONMENTAL ASSAYS

## INTEGRATION OF  MULTIPLE  FUNCTIONS

**ON A “LAB-ON-A-CHIP” DEVICE**

**Nanomaterials can be used to facilitate each of these processes**

- Detection

- Separation

- Reaction

- Pre-concentration

## Pd Nanoparticles for Electrocatalytic Detection

## Carbon Nanotubes

- What are they?
- Graphite sheets rolled  into a cylinder to form nanometer tubes
- Preparation
- Arc evaporation (non-catalytic)
- Chemical Vapor Deposition (CVD)
- Multi-wall and single-wall

**MWCNT**

**SWCNT**

**Armchair**
**Zigzag**
**Chiral**

## WHY  CARBON  NANOTUBES?

**CARBON  NANOTUBES  POSSESS   REMARKABLE**
**ELECTRONIC, MECHANICAL  AND  CHEMICAL**
**PROPERTIES  WHICH   MAKES  THEM   EXTREMELY  ATTRACTIVE   FOR  VARIOUS  SENSING   DEVICES.**
**CARBON NANOTUBES  WERE  SHOWN   USEFUL TO**
**PROMOTE  ELECTRON-TRANSFER  REACTIONS**
**AND  IMPARTS  HIGHER  RESISTANCE  TO SURFACE  FOULING**

## Electropherograms at the bare and 

**CNT-modified detectors **

- Anal. Chem. 2004

- The electrocatalytic activity and resistance to surface fouling of CNT
-  materials lead to improved sensitivity, stability and resolution
- compared to common carbon-electrode detectors.

- Enhanced performance by modifying the detector surface.

## Hydrodynamic voltammograms at screen-printed carbon electrode and carbon nanotube modified (CNT) screen-printed carbon electrode  

***Anal. Chem, 2004***

**Hydrodynamic voltammograms at screen-printed carbon electrode and carbon nanotube modified (CNT) screen-printed carbon electrode  **

**Carbon-Nanotube-based  Microchip Detection**

## Stability of the response to phenol and tyrosine at the carbon-nanotube modified and unmodified  electrodes 

**Stability of the response to phenol and tyrosine at the carbon-nanotube modified and unmodified  electrodes **

- Minimization of Surface Fouling

## 2,4-dichlorophenol

- CNT circumvents common surface fouling during
-     the phenol oxidation; the  redox process involves the formation of a surface-confined layer that promotes (rather than inhibits) the phenol oxidation.** **

**                 ****Bare GC                  CNT-GC                       CNT-GC**

## Calibration data for mixtures containing increasing levels of dopamine and catechol

**Calibration data for mixtures containing increasing levels of dopamine and catechol**

***AC, 1/2004***

## Carbon Nanotube/Copper Composite Electrode for Capillary Electrophoresis Microchip

**Carbon Nanotube/Copper Composite Electrode for Capillary Electrophoresis Microchip**

***Analyst, 2004***

## CE Microchip with a CNT/Cu Amperom. Detector

**CE Microchip with a CNT/Cu Amperom. Detector**

**Hydrodynamic voltammograms for different sugars**

***Analyst, 2004***

**Coupling of CNT with metal NP catalysts: Cu/CNT composites**

## CE Microchip with a CNT/Cu Amperom. Detector

**CE Microchip with a CNT/Cu Amperom. Detector**

## Effect of Composition (Oil:CNT:Cu):                                Synergitic Effect:

**Response at different paste formulations**

***Analyst, 2004***

## Analytical Performance:

**Analytical Performance:**
**Calibration Study**

## Carbon Nanotube/Copper Composite Electrode for the Detection of Amino Acids

***Analyst, 2004***

- Organophosphorus compounds
- neurotoxic

**OPH**

**CNT**

_**Optimized condition**_**: 5mg CNT; 0.5% Nafion; **
**48 IU/μL OPH**

**CNT  FOR ENHANCED  BIOSENSING OF  OP  PESTICIDES THROUGH CATALYTIC DETECTION OF THE p-NITROPHENOL  PRODUCT**

## Pesticides

**HDV for 10 μM paraoxon **
**Potential: +0.85 V**

**Calibration for 2 μM paraoxon **

**OPH/CNT-GC**

**OPH-GC**

**OPH/CNT-GC**

**OPH-GC**

## Anal. Chem.

- IMPROVED  MICROCHIP SEPARATIONS BY ADDING
- GOLD NANOPARTICLES TO RUN BUFFER

## Gold Nanoparticle-Enhanced Separation of Aminophenols 

***p*****-AP**

***o*****-AP**

***m*****-AP**

***Glass***

***PDADMAC ***
***Gold***

**Gold Nanoparticle-Enhanced Separation of Aminophenols **

## Gold Nanoparticle-Enhanced Separation of Aminophenols

**Gold Nanoparticle-Enhanced Separation of Aminophenols**

**Effect of Gold Nanoparticles on Separation Efficiency **

- (Doubling the Resolution and Plate Number)

## Sharp Microchip for Fast and Simple Sample Introduction

**Sharp Microchip for Fast and Simple Sample Introduction**
** ****for  CE Microsystems:**
**Towards ‘World-to-Chip’ Interface**

- Facilitates convenient electrokinetic loading of samples
- directly into the separation microchannel

- Analyst 2004

## Electropherograms for 80 alternative injections of

-  10 (a) and 5 (b) ppm TNT solutions.

- Analyst 2004

**Sharp Microchip for Fast and Simple Sample Introduction**
** ****for  CE Microsystems**

## A typical section of a polymer microchip produced at NMSU

**A typical section of a polymer microchip produced at NMSU**

- Anal. Chem. 04

- Towards Low-Cost (Disposable?) Microchips

##  MULTI-CHANNEL MICROCHIP  FOR

** ****MULTI-CHANNEL MICROCHIP  FOR**
**  ****PARALLEL ASSAYS  OF MAJOR CONTAMINANTS**

## CONCLUSIONS

**Such nanomaterials-based microchip devices are expected to have a major impact upon environmental monitoring and security surveillance. **

**Nanomaterials, such as nanotubes or nanoparticles offer great promise for enhancing the performance of microchip devices.**

## THANK  YOU !!!

## MULTICHANNEL CHIP  FOR PARALLEL ENVIRONMENTAL ASSAYS

## Carbon Nanotube/Copper Composite Electrode for the Detection of Glucose Family 

**Carbon Nanotube/Copper Composite Electrode for the Detection of Glucose Family **

***Analyst, 2004***