From King Abdulla University of Science and Technology جامعة الملك عبد الله للعلوم] [والتقنيةه‎: “Sensors get a laser shape up”

From King Abdulla University of Science and Technology جامعة الملك عبد الله للعلوم] [والتقنيةه‎

2020-11-15

Laser writing breathes life into high-performance sensing platforms.

A simple method developed at KAUST uses laser beams to create graphene electrodes that have better performance than those produced through older methods.

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The LDG/MIP-based electrochemical sensor sensitively and selectively detects BPA in water samples. © 2020 KAUST.

Electrodes consisting of graphene, an atypical form of carbon, may transform the way electroactive substances are detected and measured in numerous fields ranging from food safety and clinical diagnosis to environmental monitoring.

Graphene comprises multiple ultrathin and highly ordered sheets of interconnected honeycomb-shaped rings of carbon atoms. This multilayered architecture provides the material with exceptional electronic properties, especially electrical conductivity and electrocatalytic activity, as well as physical features that are useful for making electrochemical sensors.


Exciting New Technology Makes BPA Water Testing More Efficient
The LDG/MIP-based electrochemical sensor sensitively and selectively detects BPA in water samples.

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Graphene electrodes can be fabricated on various substrates using a CO2 laser beam (© 2020 Elsevier B.V. Ref. 1, Fig 1A) © 2020 Elsevier B.V. Ref. 1, Fig 1A.

Typically, graphene electrodes are produced by peeling off individual sheets from graphite or depositing a reactive gaseous mixture of precursors onto a substrate. However, these approaches involve time-consuming, multistep synthesis and isolation processes; plus, they struggle to control stacking and oxidation of the sheets.

To improve on technically challenging and expensive approaches, researchers from Khaled Salama’s lab, in collaboration with others, developed a simple and scalable method that converts polymer or carbon precursor films into graphene electrodes using a laser beam. This mask-free method produces uniform, three-dimensional multilayered electrodes that combine high porosity and surface area, necessary for next-generation electrochemical sensor and biosensor platforms.

Salama’s team and collaborators from the Hassan II University of Casablanca, Morocco, incorporated laser-derived graphene (LDG) electrodes in sensing platforms for major sources of antioxidants called phenolic compounds and related electroactive biomolecules².

All tested compounds showed higher electrocatalytic activity on the graphene-based platforms than on conventional systems using carbon electrodes.

“The graphene-based platforms showed excellent performance for detecting paracetamol, a common drug,” says Abdellatif Ait Lahcen, a postdoc from Salama’s Lab. They also distinguished paracetamol in a commercially available tablet that combines the drug with the antioxidant ascorbic acid, which often produces interferences in typical electrochemical analyses.

An evaluation of the electrochemical behavior of a set of hormones and neurotransmitters called catecholamines also provided insight into the mechanisms of oxidation–reduction reactions of these compounds.

There are many electrode modification approaches that can boost sensor performance. Biological receptors, such as enzymes, nucleic acids and antibodies, provide target-specific sensors, but they require complex surface immobilization techniques.

Potential alternatives are emerging for these natural receptors. Synthetic polymers known as molecularly imprinted polymers (MIPs) are durable and easy to prepare. KAUST researchers plan to optimize the fabrication of the sensors and expand their applications to other biomolecules and disease biomarkers. “We are developing MIP-modified biomimetic sensors for the early detection of breast cancer biomarkers,” Ait Lahcen says.

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Sensing platforms using laser-derived graphene electrodes (LSGEs) exhibit higher electrochemical performances than conventional systems using carbon electrodes (SPCE) for the detection of sulfur-containing compounds, drugs, antioxidants, vitamins, catecholamines and their precursor, L-Dopa. © 2020 KAUST.

The researchers modified LDG electrodes with MIPs to fabricate a cheap sensor for the detection of bisphenol A (BPA) in water and plastic samples³. The modification involved synthesizing polypyrrole under applied voltage in the presence of BPA molecules, which acted as templates and left imprints in the polymer when removed. The sensor displayed higher sensitivity and selectivity toward BPA than similar substances, such as estradiol, epinephrine and bisphenol F.

“Combining LDG electrodes with MIPs will lead to new highly sensitive and selective electrochemical sensors,” says Tutku Beduk, a Ph.D. student from Salama’s lab.

Salama believes that these MIP-based sensors will help ensure that water remains clean, pure and toxin-free.

References

Lahcen, A.A., Rauf, S., Beduk, T., Durmus, C., Aljedaibi, A., Timur, S., Alshareef, H.N., Amine, A., Wolfbeis, O.S. & Salama, K.N. Electrochemical sensors and biosensors using laser-derived graphene: a comprehensive review. Biosensors and Bioelectronics(2020).|
Ghanam, A., Lahcen, A.A., Beduk, T., Alshareef, H.N., Amine, A. & Salama, K.N. Laser scribed graphene: a novel platform for highly sensitive detection of electroactive biomolecules. Biosensors and Bioelectronics (2020).

Beduk, T., Lahcen, A.A., Tashkandi, N. & Salama, K.N. One-step electrosynthesized molecularly imprinted polymer on laser scribed graphene bisphenol a sensor. Sensors and Actuators B: Chemical 314, 128026 (2020).

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King Abdullah University of Science and Technology (KAUST) (جامعة الملك عبد الله للعلوم و التقنية ) is a private research university located in Thuwal, Saudi Arabia. Founded in 2009, the university provides research and graduate training programs in English as the official language of instruction.

KAUST is the first mixed-gender university campus in Saudi Arabia. In 2013, the university was among the 500 fastest growing research and citation records in the world. In the 2016 Nature Index Rising Stars, the university ranked 19th in the world of the fastest rising universities for high quality research output. In 2019 KAUST is ranked 8th fastest rising young universities (aged 50 and under) for their research output since 2015, as measured by fractional count (FC).

In 2006, Ali Al-Naimi chaired a Saudi Aramco team to undertake the building and planning of the academics. Nadhmi Al-Nasr was chosen to lead the project. They employed the Washington Advisory Group’s Frank H. T. Rhodes and Frank Press to design the academic structure, SRI International to develop the four research institutes, and the architectural firm of HOK for the campus master plan, which included wind towers and solar panels. The location of the campus at Thuwal included 16.4 sq km on land and 19.6 sq km of marine sanctuary offshore. Ground breaking took place in Oct. 2007, and 178 scholarships were awarded in Jan. 2008.[1]

KAUST officially opened on September 23, 2009 at an inauguration ceremony, where King Abdullah Bin Abdulaziz Al Saud gave a speech where he stated that places like the University that “embrace all people are the first line of defence against extremists”. The University initially received a $10 billion endowment. Upon opening, the University admitted 400 students from over 60 countries and 70 faculty. The campus is home to Shaheen, Asia’s fastest supercomputer.

Shaheen II Cray XC-40 supercomputer at KAUST