Quantitative accounting of dye leakage and photobleaching in single lipid vesicle measurements: Implications for biomacromolecular interaction analysis

Lipid Membrane Interface Viewpoint: From Viral Entry to Antiviral and Vaccine Development

Membrane-enveloped viruses are responsible for most viral pandemics in history, and more effort is needed to advance broadly applicable countermeasures to mitigate the impact of future outbreaks. In this Perspective, we discuss how biosensing techniques associated with lipid model membrane platforms are contributing to improving our mechanistic knowledge of membrane fusion and destabilization that is closely linked to viral entry as well as vaccine and antiviral drug development. A key benefit of these platforms is the simplicity of interpreting the results which can be complemented by other techniques to decipher more complicated biological observations and evaluate the biophysical functionalities that can be correlated to biological activities. Then, we introduce exciting application examples of membrane-targeting antivirals that have been refined over time and will continue to improve based on biophysical insights. Two ways to abrogate the function of viral membranes are introduced here: (1) selective disruption of the viral membrane structure and (2) alteration of the membrane component. While both methods are suitable for broadly useful antivirals, the latter also has the potential to produce an inactivated vaccine. Collectively, we emphasize how biosensing tools based on membrane interfacial science can provide valuable information that could be translated into biomedicines and improve their selectivity and performance.

Biophysical Measurement Strategies for Antiviral Drug Development: Recent Progress in Virus-Mimetic Platforms Down to the Single Particle Level

The rapid growth in the global human population has increased the prevalence of emerging infectious diseases, which poses a major risk to public health. In search of effective clinical solutions, the acquisition of knowledge and understanding of biomolecular processes associated with viral pathogens represents a prerequisite. In this context, biophysical engineering approaches are particularly promising since they can resolve biomolecular interactions systematically by circumventing the complexities associated with experiments involving natural biological systems. The engineering approaches encompass the design and construction of biomimetic platforms that simulate the physiological system. This approach enables us to characterize, measure, and quantitatively analyze biomolecular interactions.In this Account, we summarize biophysical measurements that our group has successfully adopted to develop broad-spectrum antiviral drugs based on the lipid envelope antiviral disruption (LEAD) strategy, targeting the structural integrity of the outer viral membrane to abrogate viral infectivity. We particularly focus on the engineering aspects related to the design and construction of the tethered lipid vesicle platform, which closely mimics the viral membrane. We first outline the development of the LEAD agents screening platform that integrates soft matter design components with biomaterials and surface functionalization strategies to facilitate parallel measurements tracking peptide-induced destabilization of nanoscale, virus-mimicking vesicles with tunable size and composition. Then, we describe how this platform can be effectively employed to gain insights into the membrane curvature dependency of certain peptides. The fundamental knowledge acquired through this systematic process is crucial in the identification and subsequent development of antiviral drug candidates. In particular, we highlight the development of curvature-sensitive α-helical (AH) peptides as a broad-spectrum antiviral agent that has been demonstrated as an effective therapeutic treatment against multiple enveloped viruses. Also, we introduce a tethered cluster of vesicles to mimic clusters of enveloped viruses, exhibiting higher infectivity levels in the biological system. Then, we discuss key considerations, including experimental artifacts, namely dye leakage and imaging-related photobleaching, and corresponding corrective measures to improve the accuracy of quantitative interpretation. With the ongoing development and application of the tethered lipid vesicle platform, there is a compelling opportunity to explore fundamental biointerfacial science and develop a new class of broad-spectrum antiviral agents to prepare for the future membrane-enveloped viral pandemics.

Photoswitchable Conjugated Oligoelectrolytes for a Light-Induced Change of Membrane Morphology

The synthesis of a new conjugated oligoelectrolyte (COE), namely DSAzB, is described, which contains a conjugated core bearing a diazene moiety in the center of its electronically delocalized structure. Similar to structurally related phenylenevinylene-based COEs, DSAzB readily intercalates into model and natural lipid bilayer membranes. Photoinduced isomerization transforms the linear trans COE into a bent or C-shape form. It is thereby possible to introduce DSAzB into the bilayer of a cell and disrupt its integrity by irradiation with light. This leads to controlled permeabilization of membranes, as demonstrated by the release of calcein from DMPG/DMPC vesicles and by propidium iodide influx experiments on S. epidermidis. Both experiments support that the permeabilization is selective for the light stimulus, highly efficient, and repeatable. Target-selective and photoinduced actions demonstrated by DSAzB may have broad applications in biocatalysis and related biotechnologies.