Molecular imaging is rapidly developing as a powerful tool in research and medical diagnostic. By integrating complementary signal reporters into a single nanoparticulate contrast agent, multimodal molecular imaging can be performed as scalable images with high sensitivity, resolution and specificity. In this review, multifunctional nanoparticles (MFNPs) are classified into four types: conjugation, encapsulation, core/shell, and co-doping. Further, new constructs of MFNPs were reported recently which have used nanoparticulate contrast agent such as quantum dots (QDs), iron oxide nanoparticles (IONPs), Upconversion nanoparticles (UCNPs), carbon based nanoparticles, gold nanoparticles (Au-NPs), Metal-Organic Frameworks (MOFs), dendrimers and porphyrins based nanoparticles. Different surface modification strategies were also developed as well as ligands are attached to those NPs to render the biocompatibility and enable specific targeting. These new development in MFNPs are expected to introduce a paradigm shift in multi-modal molecular imaging and thereby opening up an era of personalized medicine and new diagnostic medical imaging tools.

Amyloid is defined as insoluble, extracellular, proteinous aggregates formed by misfolding of proteins or peptides which are normally soluble. In the human body, amyloid is toxic and can cause cell death. Therefore, the presence of amyloid is linked with several diseases, including Alzheimer's disease (AD), spongiform encephalopathies and type II diabetes, which are also referred as amyloidosis. AD is one of the most well-known amyloidoses. In AD, the amyloid aggregates appear predominantly in the patients' brain, composed by a certain group of peptides known as amyloid beta (Aβ) peptides. Current clinical diagnoses of AD are primarily based on cognitive symptoms. However, it is often too late for intervention when the symptoms are detectable and there is no effective treatment for AD. On the other hand, the onset of amyloid aggregation may start years before the appearance of AD symptoms. Therefore, the detection and intervention of AD related amyloid at the molecular level are expected to be developed as powerful diagnostic and therapeutic methods for AD. Nanoparticle facilitated therapy and diagnosis have recently achieved impressive success in biomedical researches, especially in oncology studies. Compared to small molecule based probes and drugs, nanoparticles are capable to generate more comprehensive diagnosis, enhanced therapeutic effect, and better specific targeting. However, the reported applications of nanoparticles for AD research are still limited. In this context, by identifying the aforementioned research gap, this thesis aims to investigate the potential of nanoparticles for the early detection, imaging, and intervention of amyloid. To fulfill this objective, three nanoparticles: gold nanoparticles (AuNPs), carbon dots (C-dots) and iron oxide nanoparticles (IONPs), have been selected due to their unique physiochemical properties.