Abstract

Functionalized magnetic nanoparticles are important components as magnetic labels for biorecognition and medical diagnostics. Here, I will review of my group’s contribution to the manipulation and detection of magnetic particles for point of care medical diagnostics with emphasis on the development of one the world’s first biosensing protocols based on InSb and GaAs/AlGaAs Hall devices with integrated gold current strips for high sensitivity and rapid detection of superparamagnetic beads.

For the detection of sub-200 nm magnetic beads we exploited the magnetically induced capture of micrometer sized ‘probe beads’ by nanometer sized ‘target beads’ enabling detection of small concentrations of beads as small as 8 nm in ‘planar’ microcapillary systems.

We have also developed a ‘label-less homogenous’ procedure—magneto-optical transmission sensing—where the optical transmission of a solution containing rotating chains of magnetic of nanobeads was used to detect biomolecules with pM-level sensitivity with a dynamic range of more than four orders of magnitude.

Porous silicon also offers a simple method for monitoring biomolecular interaction, and I will describe the results of biosensing based on a protocol consisting of porous silicon and magnetic nanoparticle labels.

I will conclude by describing biosensing based on magnetically induced self-assembly of superparamagnetic beads and nonmagnetic beads (Fig.1) a magnetorheological fluid solutions.

CV

Dr Adarsh Sandhu is deputy director of the Electronics-Inspired Interdisciplinary Research Institute (EIIRIS), Toyohashi University of Technology. Other responsibilities at Toyohashi include advisor to the president and head of international public relations.

He came to Japan in 1985 after receiving a Monbusho Scholarship to study at the Tokyo Institute of Technology and University of Tokyo. Then, in 1986 after completing his doctoral thesis at the University of Manchester, England, he joined Fujitsu Laboratories Ltd., Atsugi, as their first foreign researcher with a permanent position. At Fujitsu he developed molecular beam epitaxy systems for the growth of III-V compound semiconductor heterostructures and quantum effect electron devices. Major breakthroughs included the fabrication of the world’s first carbon doped base heterojunction bipolar transistor using gas source MBE and ultra-high resolution magnetic field sensors based on HEMT heterostructures.

In 1992 Dr Sandhu took a sabbatical as a visiting scholar at the Cavendish Laboratory, Cambridge University, where he conducted experiments on the transport properties of semiconductor and superconductor interfaces. In April 1995, he left Fujitsu to take up a tenured faculty position at a private university, where he continued to work on condensed matter physics and initiated research on magnetic imaging of ferromagnetic domains by scanning Hall probe microscopy (SHPM). In August 2002, Dr Sandhu accepted a tenured position at the Quantum Nanoelectronics Research Centre, Tokyo Institute of Technology, where his research activities include nano-scanning Hall probe microscopy and development of biosensors based on magnetic labels for rapid medical diagnosis.

Dr Sandhu is a visiting professor at universities including Tsinghua University (Beijing) and IIT Delhi, and has collaborative projects with several major Japanese corporations.

He is a member of several important Japanese academic societies including the 162 and 175 committee’s the Japan Society for the Promotion of Science (JSPS); Japan Society of Applied Physics (JSAP); and Magnetic Society of Japan (MSJ). Dr Sandhu is the founder of the ‘JSAP International’ newsletter and has authored numerous articles on science and education for Japanese journals. He has rare distinction of being is a member of the Foreign Correspondents Club of Japan (FCCJ), and FCCJ Toastmasters.

Dr Sandhu is fluent in Japanese—spoken and written—giving lectures on solid-state physics and electromagnetism in the Japanese. He enjoys most sports and outdoor activities and writing about scientific developments in the Asia Pacific region. Dr Sandhu’s travels in Asia and observations of the impact of science and technology in this part of the world form a backdrop to his first novel—scheduled for completion in 2012—set in Beijing, Delhi, and Tokyo.

Dr Sandhu has served as Editorial Consultant for Nature Nanotechnology, and Nature Photonics and Editor of Research Highlights for NPG Asia Materials. He is currently the editor of IOP Asia Pacific website, which is dedicated to highlighting scientific developments in Asia Pacific.