Alnawaz Rehemtulla

Fluorescent Pebble Nano-Sensors and Nanoexplorers for Real-Time Intracellular and Biomedical Applications

PEBBLEs (Probes Encapsulated By Biologically Localized Embedding) are sub-micron sized optical sensors specifically designed for minimally invasive analyte monitoring in viable, single cells with applications for real time analysis of drug, toxin, and environmental effects on cell function. PEBBLE nanosensor is a general term that describes a family of matrices and nano-fabrication techniques used to miniaturize many existing optical sensing technologies. The main classes of PEBBLE nanosensors are based on matrices of cross-linked polyacrylamide, cross-linked poly(decyl methacrylate), and sol-gel silica. These matrices have been used to fabricate sensors for H+, Ca2+, K+, Na+, Mg2+, Zn2+, Cu2+, Cl−, O2, NO, and glucose that range from 20 nm to 600 nm in diameter. A number of delivery techniques have been used successfully to deliver PEBBLE nanosensors into mouse oocytes, rat alveolar macrophages, rat C6-glioma, and human neuroblastoma cells. For majority of this chapter, we will focus on the fabrication, characterization and applications of all the different kinds of PEBBLE sensors developed up to date. In the remainder of the chapter, we will introduce a new family of PEBBLEs with several emerging directions in PEBBLE design and applications, from intracellular imaging to in-vivo actuating and targeting.

PET and SPECT Imaging of Tumor Angiogenesis

Positron Emission Tomography (PET) and Single Photon Emission Computed Tomography (SPECT) based functional imaging utilize radiolabeled tracers to provide information for real time visualization of physiological or biological processes in live animals or humans. Disease-related biomarkers involved in initiation and/or progression of a pathological condition are imaged by these nuclear imaging technologies which lead to early detection of abnormalities prior to the appearance of morphological changes visualized by other imaging modalities such as CT or MRI (1-3). Additional advantages of nuclear imaging approaches are high sensitivity of detection and high spatial resolution. Further they are either nonor minimally invasive and highly quantitative (4). Together, these characteristics of PET and SPECT make them an invaluable technique for monitoring some diseases and disorders.

DW-MRI Assessment of Cancer Response to Chemoradiation

MR imaging is widely used in the radiological diagnosis of oncology patients as it provides excellent soft tissue differentiation using routine anatomical MR imaging. A variety of MR acquisition sequences are available which can yield images of biophysical, physiological, metabolic, or functional properties of tissues. Imaging of response to oncological treatments has traditionally used single or multidirectional measurements of tumour dimensions following completion of therapy. Development of an MR imaging biomarker that would allow for early prediction of tumour response to therapeutic intervention would be a significant achievement as it could individualize clinical management of cancer patients in a timely fashion and improve outcome. This goal is very important as standard risk factors currently used in patient assessment cannot account for the variable and unpredictable treatment responses encountered by patients with similar risk profiles. This chapter will overview the use of diffusion-weighted MR imaging (DW-MRI) as a method of providing a potentially early surrogate marker of response to therapy in oncological imaging.