The detection of low-molecular-weight biomarkers is essential for diagnosing and managing various diseases, including neurodegenerative conditions such as Alzheimer’s disease. A biomarker’s low molecular weight a challenge label-free optical modalities, the phase change they detect directly proportional to mass bound on sensor’s surface. To address this challenge, we used resonant Young’s slit interferometer geometry implemented several innovations, noise matching optimisation fringe...

It is clear that a crowded environment influences the structure, dynamics, and interactions of biological molecules, but complexity this phenomenon demands development new experimental theoretical approaches. Here we use two complementary single-molecule FRET techniques to show kinetics DNA base pairing unpairing, which are fundamental both role its technological applications, strongly modulated by environment. We directly observed single hairpins, excellent model systems for studying...

Optical tweezers have had a major impact on bioscience research by enabling the study of biological particles with high accuracy. The focus so far has been trapping individual particles, ranging from cellular to molecular level. However, biology is intrinsically heterogeneous; therefore, access variations within same population and species necessary for rigorous understanding system. demonstrated ability multiple targets in parallel; however, multiplexing capability becomes challenge when...

The explosive growth of single-molecule techniques is transforming our understanding biology, helping to develop new physics inspired by emergent biological processes, and leading emerging areas nanotechnology. Key chemical processes can now be probed with levels detail, one molecule at a time, from the nanoscopic dynamics nature's molecular machines an ever-expanding range exciting applications across multiple length time scales. Their common feature ability render underlying distribution...

A major hallmark of Alzheimer's disease is the misfolding and aggregation amyloid- β peptide (Aβ). While early research pointed towards large fibrillar- plaque-like aggregates as being most toxic species, recent evidence now implicates small soluble Aβ oligomers orders magnitude more harmful. Techniques capable characterizing oligomer stoichiometry assembly are thus critical for a deeper understanding earliest stages neurodegeneration rationally testing next-generation inhibitors....

Membrane solubilization by sodium dodecyl sulfate (SDS) is indispensable for many established biotechnological applications, including viral inactivation and protein extraction. Although the ensemble thermodynamics have been thoroughly explored, underlying molecular dynamics remained inaccessible, owing to major limitations of traditional measurement tools. Here, we integrate multiple advanced biophysical approaches gain multiangle insight into time-dependence fundamental kinetic steps...

The fluorescence response of the Thioflavin-T (ThT) dye and derivatives has become standard tool for detecting β-amyloid aggregates (Aβ) in solution. However, it is accepted that ThT-based methods suffer from important drawbacks. Some these are due to cationic structure ThT, which limits its application at slightly acidic conditions; whereas some limitations related general use an extrinsic-dye sensing strategy intrinsic requirement formation a sensor-binding site during aggregation process....

The solubilization of lipid membranes by Tween-20 is crucial for a number biotechnological applications, but the mechanistic details remain elusive. Evidence from ensemble assays supports model that encompasses surfactant association with membrane and release mixed micelles to solution, whether this process also involves intermediate transitions between regimes unanswered. In search origins, increasing focus placed on identifying interactions controllable mimetics. Here, we employed...

Abstract Single pass cell surface receptors regulate cellular processes by transmitting ligand-encoded signals across the plasma membrane via changes to their extracellular and intracellular conformations. This transmembrane signaling is generally initiated ligand binding in monomeric form. While subsequent receptor-receptor interactions are established as key aspects of signaling, contribution has been challenging isolate due complexity ligand-dependence these interactions. By combining...

The solubilization of membranes by detergents is critical for many technological applications and has become widely used in biochemistry research to induce cell rupture, extract constituents, purify, reconstitute crystallize membrane proteins. thermodynamic details have been extensively investigated, but the kinetic aspects remain poorly understood. Here we a combination single-vesicle Förster resonance energy transfer (svFRET), fluorescence correlation spectroscopy quartz-crystal...

In eukaryotes, intracellular physico-chemical properties like macromolecular crowding and cytoplasmic viscoelasticity influence key processes such as metabolic activities, molecular diffusion protein folding. However, mapping in living cells remains challenging. One approach uses passive rheology which of exogenous fluorescent particles internalized is tracked inferred from derived mean square displacement relations. Recently, the crGE2.3 Förster resonance energy transfer biosensor was...

Up-regulation of Hsp20 protein levels in response to amyloid fibril formation is considered a key protective against the onset Alzheimer's disease (AD). Indeed, physical interaction between and Aβ known prevent oligomerisation protects neuronal cells from mediated toxicity, however, details molecular mechanism regulatory cell signalling events behind this process have remained elusive. Using both conventional MTT end-point assays novel real time measurement impedance, we show that human...

A major pathogenic hallmark of Alzheimer's disease is the presence neurotoxic plaques composed amyloid beta (Aβ) peptides in patients' brains. The pathway plaque formation remains elusive, though some clues appear to lie dominant Aβ1 - 42 these despite Aβ1-40 making up approximately 90% Aβ pool. We hypothesize that this asymmetry driven by hydrophobicity two extra amino acids are incorporated Aβ1-42. To investigate hypothesis at level single molecules, we have developed a molecular...

Abstract The first single‐molecule fluorescence detection of a structurally‐defined synthetic carbohydrate is reported: heparan sulfate (HS) disaccharide fragment labeled with Alexa488. Single molecules have been measured whilst freely diffusing in solution and controlled encapsulation surface‐tethered lipid vesicles has allowed extended observations down to the level. diverse dynamic nature HS–protein interactions means that new tools investigate pure HS fragments at molecular level would...

A characteristic property of colloidal semiconductor nanocrystal quantum dots (QDs) is their emission intermittency. Although a unifying theory QD photoprocesses remains elusive, the importance charged states clear. We now report new approach to directly study role surface charge on by adding metal ions individual, core-only QDs immobilized in aqueous solution an agarose gel. The CdTe show very stable absence but dramatic and reversible increase blinking due presence trivalent ions. Our...

Lipid vesicles are valuable mesoscale molecular confinement vessels for studying membrane mechanics and lipid-protein interactions, they have found utility among bio-inspired technologies, including drug delivery vehicles. While vesicle morphology can be modified by changing the lipid composition introducing fusion or pore-forming proteins detergents, influence of extramembrane crowding on has remained under-explored owing to a lack experimental tools capable capturing morphological changes...

A major hallmark of Alzheimer's disease (AD) is the formation toxic aggregates β-amyloid peptide (Aβ). Given that Aβ peptides are known to localise within mitochondria and interact with 17β-HSD10, a mitochondrial protein expressed at high levels in AD brains, we investigated inhibitory potential 17β-HSD10 against aggregation under range physiological conditions. Fluorescence self-quenching (FSQ) Aβ(1-42) labelled HiLyte Fluor 555 was used evaluate effect conditions established grow distinct...

Abstract Extracellular vesicles (EVs) are very promising biomarkers for the diagnosis of various diseases, including cardiovascular, infectious and neurodegenerative disorders. Of particular relevance is their importance in cancer liquid biopsy, where they play a key role early detection monitoring tumour. A number technologies have recently been developed to improve performance current EV methods, but technique that can provide high resolution, accuracy multiplexing capability several...

The epidermal growth factor receptor (EGFR) is critical to normal cellular signaling pathways. Moreover, it has been implicated in a range of pathologies, including cancer. As result, the primary target many anticancer drugs. One limitation design and development these drugs lack molecular-level information about interactions conformational dynamics EGFR. To overcome this limitation, work reports construction characterization functional, fluorescently labeled, full-length EGFR model membrane...

A rapid, sensitive and selective optical readout of the presence gadolinium(iii) ions would have a wide range applications for clinical environmental monitoring. We demonstrate that water-soluble CdTe quantum dots (QDs) are induced to aggregate by Gd3+ in aqueous solution. By using combination photoluminescence spectroscopy, dynamic light scattering fluorescence correlation spectroscopy (FCS) monitor dot aggregation kinetics, we correlate efficiency self-quenching process with degree across...