Mechanical properties of milk sphingomyelin bilayer membranes in the gel phase: Effects of naturally complex heterogeneity, saturation and acyl chain length investigated on liposomes using AFM

Quantitative atomic force microscopy provides new insight into matrix vesicle mineralization

“…Herein, we utilized recent innovations in AFM instrumentation, software, and probe nanofabrication to acquire topographical and quantitative nanomechanical characteristics of individual MVs in fluid at nanoscale resolution [16][17][18][19][20][21][22][23][24][25][26][27][28]41]. By using AFM-PFQNM, we provided direct experimental evidence of the changes in the morphology and physical properties of the NC induced by the accumulation of Ca 2+ in hydrated MVs.…”

“…Additionally, improved force control during imaging has enabled the study of fragile, hydrated biological samples with elastic moduli in the low kPa to MPa regime [16]. The nanomechanical characterization of structures enclosed by lipid bilayers has particularly benefited from these advancements: whole living cells [17][18][19][20][21], platelets [22], liposomes [23][24][25], and cell-derived vesicles, including synaptic vesicles [26] and exosomes [27,28], have been successfully characterized with modern fluid-based AFM methods. To date, MVs and MV mimetics, such as proteoliposomes, have been exclusively imaged in dried states using older AFM imaging methods [29,30].…”

Atomic force microscopy of food assembly: Structural and mechanical insights at the nanoscale and potential opportunities from other fields

“…In general, slightly higher moduli values were obtained from measurements taken on supported lipid bilayers than on liposomes, probably because of compression against the underlying substrate (Das, Sheikh, Olmsted, & Connell, 2010;Et-Thakafy et al, 2017;Picas, Rico, & Scheuring, 2012). Liposomes of milk sphingomyelin, involving a naturally complex composition of saturated and unsaturated molecules of varying chain lengths, show lower Young' modulus values than liposomes of single or binary composition (Et-Thakafy, Delorme, Guyomarc'h, & Lopez, 2018). Higher order polar lipid organization of simple liposomes may account for their relatively high Young's modulus values compared to those of complex biological samples (respectively tens of MPa vs hundreds of kPa - Fig.…”

Young modulus of supported lipid membranes containing milk sphingomyelin in the gel, fluid or liquid-ordered phase, determined using AFM force spectroscopy

“…Phase diagrams [85] or nanomechanical data [76] point to the complex, and sometimes unexpected, behavior of polar lipid mixtures with biological composition. In the same line, milk SM vesicles are significantly less stiff that vesicles of the single sphingomyelins, probably as a result of disorder in the packing of milk SM [86]. Research is still necessary to more closely investigate structures of the lipid phases actually existing in biological membranes and their role in the modulation of some of the cells functional properties [82,87].…”