The acoustic spectrophonometer: A novel bioanalytical technique based on multifrequency acoustic devices

The future: biomarkers, biosensors, neuroinformatics, and e-neuropsychiatry

The emergence of molecular biomarkers for psychological, psychiatric, and neurodegenerative disorders is beginning to change current diagnostic paradigms for this debilitating family of mental illnesses. The development of new genomic, proteomic, and metabolomic tools has created the prospect of sensitive and specific biochemical tests to replace traditional pen-and-paper questionnaires. In the future, the realization of biosensor technologies, point-of-care testing, and the fusion of clinical biomarker data, electroencephalogram, and MRI data with the patient's past medical history, biopatterns, and prognosis may create personalized bioprofiles or fingerprints for brain disorders. Further, the application of mobile communications technology and grid computing to support data-, computation- and knowledge-based tasks will assist disease prediction, diagnosis, prognosis, and compliance monitoring. It is anticipated that, ultimately, mobile devices could become the next generation of personalized pharmacies.

Magnetic acoustic resonance immunoassay (MARIA): a multifrequency acoustic approach for the non-labelled detection of biomolecular interactions

A unique sensing platform, comprising an electromagnetic field detector and an acoustic resonator, has been used as a wireless system for remote sensing of biorecognition events. The MARS (Magnetic Acoustic Resonator Sensor) technique has proven useful for detecting the formation of protein multilayers derived from specific binding phenomena. The technique enables multifrequency analysis, without the need of electrodes attached to the sensing element, and also facilitates the in situ surface modification of the substrate for antibody attachment. The MARS sensor was utilized as the platform on which a standard immunoassay was carried out. Two different conditions for the attachment of the first antibody to the quartz surface were tested: (i) Adsorption of the antibody onto the surface of a bare quartz disc; (ii) covalent immobilization of the antibody to a chemically modified quartz surface. Both methods can be successfully utilized for the 'label-less' detection of the biorecognition event between goat IgG and anti-goat IgG by analysis of the multifrequency spectrum. Covalent attachment of the primary antibody results in a more efficient immobilization, with higher surface density, and a consistently enhanced response for the binding of the secondary antibody. This approach will be of interest to life scientists and biochemists that require high performance assay methodologies that do not use chemical labels.

Acoustic microsensors—the challenge behind microgravimetry

Acoustic microsensors are commonly known as high-resolution mass-sensitive devices. This is a restricted view in many chemical and biosensor applications, especially in liquids. Sensitivity to non-gravimetric effects is a challenging feature of acoustic sensors. In this review we give an overview of recent developments in resonant sensors including micromachined devices and also list recent activity relating to the (bio)chemical interface of acoustic sensors. Major results from theoretical analysis of quartz crystal resonators, descriptive for all acoustic microsensors are summarized, and non-gravimetric contributions to the sensor signal from viscoelasticity and interfacial effects are discussed. We finally conclude with some future perspectives.