Evaluation of the photo-degradation of Alzheimer's amyloid fibrils with a label-free approach

Recent Advances in Fluorescent Theranostics for Alzheimer's Disease: A Comprehensive Survey on Design, Synthesis, and Properties

Alzheimer's disease (AD) is the most common form of neurodegenerative dementia that is rapidly becoming a major health problem, especially in developed countries because of their increasing life expectancy. Two main problems are often associated with the disease: (i) the absence of a widely accessible "gold-standard" for early diagnosis and (ii) lack of effective therapies with disease-modifying effects. The recent success of the monoclonal antibody lecanemab played an important role not only in clarifying a possible druggable pathway but also in spelling the revival of small molecule drug discovery. Unlike bulky biologics, small molecules are structurally less complex, generally cheaper, and compatible with at-home oral consumption, making it feasible for people to start their drug regimen early and stay on it longer. In this sense, small-molecule near-infrared fluorescent theranostics have been gaining more and more attention from the scientific community, as they have the potential to simultaneously provide diagnostic outputs and deliver therapeutic action, paving the way toward personalized medicine in AD patients. They also have the potential to shift the diagnostic "status-quo" from expensive and limited-access PET radiotracers toward inexpensive and handy imaging tools widely available for primary patient screening and preclinical animal studies. Herein, we review the most recent advances in the field of fluorescent theranostics for Alzheimer's disease, detailing their design strategies, synthetic approaches and imaging and therapeutic properties in vitro and in vivo. With this Review, we intend to provide a milestone in the acquired knowledge in the field of AD theranostics, encouraging the future development of properly designed theranostic compounds with improved chances to reach clinical applications.

Recent developments in biosensing methods for extracellular vesicle protein characterization

Research into extracellular vesicles (EVs) has grown significantly over the last few decades with EVs being widely regarded as a source of biomarkers for human health and disease with massive clinical potential. Secreted by every cell type in the body, EVs report on the internal cellular conditions across all tissue types. Their presence in readily accessible biofluids makes the potential of EV biosensing highly attractive as a noninvasive diagnostic platform via liquid biopsies. However, their small size (50-250 nm), inherent heterogeneity, and the complexity of the native biofluids introduce challenges for effective characterization, thus, limiting their clinical utility. This has led to a surge in the development of various novel EV biosensing techniques, with capabilities beyond those of conventional methods that have been directly transferred from cell biology. In this review, key detection principles used for EV biosensing are summarized, with a focus on some of the most recent and fundamental developments in the field over the last 5 years. This article is categorized under: Diagnostic Tools > Biosensing Diagnostic Tools > In Vitro Nanoparticle-Based Sensing.

Structural conversion of human islet amyloid polypeptide aggregates under an electric field

Electric fields (EFs) in biological systems are well known, and their presence implies the activity of protein ion channels and pumps in various cells. The aggregation of islet amyloid polypeptides (IAPP) was recently found in human brain tissue, and this was related to the electrical activity of neurons and caused neuronal loss. However, the association between amyloid formation and the electric field is still unknown. Herein a direct method to stimulate the formation of the hIAPP peptide under an EF is reported.

Application of QCM in Peptide and Protein-Based Drug Product Development

AT-cut quartz crystals vibrating in the thickness-shear mode (TSM), especially quartz crystal resonators (QCRs), are well known as very efficient mass sensitive systems because of their sensitivity, accuracy, and biofunctionalization capacity. They are highly reliable in the measurement of the mass of deposited samples, in both gas and liquid matrices. Moreover, they offer real-time monitoring, as well as relatively low production and operation costs. These features make mass sensitive systems applicable in a wide range of different applications, including studies on protein and peptide primary packaging, formulation, and drug product manufacturing process development. This review summarizes the information on some particular implementations of quartz crystal microbalance (QCM) instruments in protein and peptide drug product development as well as their future prospects.

Nanochaperone-Based Strategies to Control Protein Aggregation Linked to Conformational Diseases

The generation of highly organized amyloid fibrils is associated with a wide range of conformational pathologies, including primarily neurodegenerative diseases. Such disorders are characterized by misfolded proteins that lose their normal physiological roles and acquire toxicity. Recent findings suggest that proteostasis network impairment may be one of the causes leading to the accumulation and spread of amyloids. These observations are certainly contributing to a new focus in anti-amyloid drug design, whose efforts are so far being centered on single-target approaches aimed at inhibiting amyloid aggregation. Chaperones, known to maintain proteostasis, hence represent interesting targets for the development of novel therapeutics owing to their potential protective role against protein misfolding diseases. In this minireview, research on nanoparticles that can either emulate or help molecular chaperones in recognizing and/or correcting protein misfolding is discussed. The nascent concept of "nanochaperone" may indeed set future directions towards the development of cost-effective, disease-modifying drugs to treat several currently fatal disorders.

Inhibition and disaggregation of amyloid β protein fibrils through conjugated polymer–core thermoresponsive micelles

The micelles (CPMs) have a thermoresponsive surface and reactive oxygen species (ROS) generating core. At 37 °C, CPMs captured Aβ aggregates to inhibit and disaggregate aggregates under white-light irradiation, reducing Aβ-induced cytotoxicity.

Photodegradation of porphyrin-bound hIAPP(1–37) fibrils

Amyloid deposits in pancreatic islets of type 2 diabetes mellitus (T2DM) are mainly comprised of human islet amyloid polypeptide (hIAPP), the degradation of hIAPP fibrils by photoactive porphyrin could be a preventive strategy against T2DM.

Advances in Molecularly Imprinting Technology for Bioanalytical Applications

In recent years, along with the rapid development of relevant biological fields, there has been a tremendous motivation to combine molecular imprinting technology (MIT) with biosensing. In this situation, bioprobes and biosensors based on molecularly imprinted polymers (MIPs) have emerged as a reliable candidate for a comprehensive range of applications, from biomolecule detection to drug tracking. Unlike their precursors such as classic immunosensors based on antibody binding and natural receptor elements, MIPs create complementary cavities with stronger binding affinity, while their intrinsic artificial polymers facilitate their use in harsh environments. The major objective of this work is to review recent MIP bioprobes and biosensors, especially those used for biomolecules and drugs. In this review, MIP bioprobes and biosensors are categorized by sensing method, including optical sensing, electrochemical sensing, gravimetric sensing and magnetic sensing, respectively. The working mechanism(s) of each sensing method are thoroughly discussed. Moreover, this work aims to present the cutting-edge structures and modifiers offering higher properties and performances, and clearly point out recent efforts dedicated to introduce multi-sensing and multi-functional MIP bioprobes and biosensors applicable to interdisciplinary fields.

Deformation of stable and toxic hIAPP oligomers by liposomes with distinct nanomechanical features and reduced cytotoxicity

Nanoliposomes can induce hIAPP oligomers to undergo fibrillation with distinct mechanical properties and reduced cytotoxicity.