Design and application of stimulus-responsive droplets and bubbles stabilized by phospholipid monolayers

Abstract

Biomimetic colloidal particles are promising agents for biosensing, but current technologies fall far short of Nature's capabilities for sensing, assessing, and responding to stimuli. Phospholipidcontaining cell membranes are capable of binding and responding to an enormous variety of biomolecules by virtue of membrane organization and the presence of receptor proteins. By tuning the composition and functionalization of simulated membranes, soft colloids such as droplets and bubbles can be designed to respond to various stimuli. Moreover, because lipid monolayers can surround almost any hydrophobic phase, the interior of the colloid can be selected to provide a sensitive readout, for example in the form of optical microscopy or acoustic detection. In this work, we review some advances made by our group and others in the formulation of lipid-coated particles with different internal phases such as fluorocarbons, hydrocarbons, or liquid crystals. In some cases, binding or displacement of stabilizing lipids gives rise to conformational changes or disruptions in local membrane geometry, which can be amplified by the interior phase. In other cases, multivalent analytes can promote aggregation or even membrane fusion, which can be utilized for optical or acoustic readout. By highlighting a few recent examples, we hope to show that lipid monolayers represent an extremely versatile biosensing platform that can react to and detect biomolecules by leveraging the unique capabilities of phospholipid membranes.

Therapeutic oxygen delivery by perfluorocarbon-based colloids

“…Phase-shift NEs that can reversibly switch from liquid NE droplets to gaseous MBs (Scheme 1) when activated by heat, sound or light after having been positioned in target tissues currently draw considerable attention [102,130,[145][146][147][148][149][150][151][152][153][154][155][156][157][158][159][160]. P-SNEs benefit from the small initial size and relatively long intravascular circulation half-life (up to a few days) of NE droplets, allowing extravasation and retention in tumor tissue (the still debated EPR effect) [161,162], and, after vaporization, acquire the responsiveness of MBs to US (resonance, inertial cavitation and destruction) needed for on-demand, site-selected delivery of O 2 and other therapeutics (Table 6, Scheme 4).…”

Effects of the Molecular Structure of Malodor Substances and Their Masking on 1,2-Dioleoyl-sn-glycero-3-phosphocholine Molecular Layers

“…On the basis of the experimental results mentioned above and related papers, ,− we discuss the characteristic responses of TS molecules to the DOPC molecular layer. Π for all of the samples utilized, that is, NE, NA, DE, DA, BA, and CA, was maintained at zero for A > 15 Å 2 molecule –1 (Figure S4 of the Supporting Information).…”

“…The phospholipid artificial membrane is used as a model cell membrane to investigate the mechanism of cell response because it is difficult to factor out intrinsic elements and their nature on the mechanism of chemical sensation in living organisms as a result of their complexity. − Indeed, interactions between chemical species and functional groups in phospholipid artificial membranes have been reported to be associated with barrier homeostasis of cellular membranes in skin . It has also been reported that membrane fluidity of liposomes is affected by ODs. − We recently evaluated the interaction between OD molecules and phospholipid molecular layers based on the spectroscopies and surface pressure ( Π )–area ( A ) isotherms .…”

Comprehensive review on ultrasound-responsive theranostic nanomaterials: mechanisms, structures and medical applications

“…Like many other NPs applied intravenously, PVA-based MBs are also prone to become uptaken by the reticuloendothelial system; however, they stay in the blood circulation long enough to act as an efficient contrast agent [ 219 ]. Some novel nanosystems that have been developed are composed of liquid PFCs, perfluorohexane (PFH), PFP, phosphatidylethanolamine, and halocarbons as probes for US molecular imaging applications and as carriers for drug/gene delivery [ 129 , 171 , 220 ].…”