Springer, London/Berlin , İstanbul, 2019
The cell, the smallest living unit, interacts with its surroundings via cell membrane
and creates a unique biointerface that is vital for cellular processes and cell survival.
Better understanding of such a tiny yet complex system is not only crucial for
basic research, but also to design advanced platforms for a variety of applications,
particularly in medical field. Development of less complex model systems, i.e.,
biomimetic lipid membranes, is highly needed, but these models need to sustain
fluidity of the lipid bilayer and mimic native dynamic complexity to some extent
and retain their structure for the intended duration. Over the years, different
techniques have been proposed for the construction of the model systems (chapter
“Structural and Mechanical Characterization of Supported Model Membranes by
AFM”). In particular, atomic force microscopy (AFM), an elegant technology,
has enabled not only structural but also mechanical characterization of membrane
systems with different compositions at nanoscale resolution (chapter “Structural
and Mechanical Characterization of Supported Model Membranes by AFM”).
Biomimetic membranes also offer a platform for the reconstitution of membrane
proteins in vitro milieu, and AFM imaging has further enabled to probe various
membrane proteins in situ through their density and spatial distribution (chapter “To
Image the Orientation and Spatial Distribution of Reconstituted Na+,K+-ATPase
in Model Lipid Membranes”). Nevertheless, the existing biomimetic membrane
models are mostly insufficient to mimic all crucial properties on a single platform
and do not reflect the asymmetry present in actual biological membranes. Moreover,
the lipid content and distribution are essential in the structure and function of
most biological membranes. Recently, an intense effort has been focused on
deploying this asymmetry into model membrane systems (chapter “Asymmetric
Model Membranes: Frontiers and Challenges”). This emerging field has addressed
some of the challenges associated with production of asymmetric vesicles, and
thereby, more realistic biomimetic membranes could be constructed for practical
applications. As aforementioned, dynamics of biomimetic membranes is pivotal
in the function. The experimental techniques combined with computational tools
provide essential information and help researchers interpreting the experimental
data. Molecular dynamics methodology is mainly used for this purpose, and not
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only the membrane itself (chapter “Modeling of Cell Membrane Systems”), but
also its interactions with other structures, such as nanoparticles (chapter “Molecular
Dynamics Studies of Nanoparticle Transport Through Model Lipid Membranes”),
can be evaluated. In addition, model membranes are key tools to understand cell–cell
and cell–surface interactions, and when functionalized with bioactive molecules,
supported lipid membranes (SLBs) can be utilized to study membrane-mediated
cellular processes and to investigate cell behavior on various surfaces (chapter
“Investigation of Cell Interactions on Biomimetic Lipid Membranes”). For larger
transmembrane proteins spanning the lipid bilayer, SLBs are not adequate as they
are constructed directly on the surface and they lack of submembrane space,
leading to denaturation and malfunctioning of transmembrane proteins. In this
regard, tethered bilayer lipid membranes (tBLMs) offer a promising strategy to
leverage the lipid bilayer from the surface and precisely fine-tune the thickness
of this space, facilitating the construction of membrane proteins on the biosensor
platforms (chapter “Tethered Lipid Membranes as Platforms for Biophysical Studies
and Advanced Biosensors”). When integrated with immunoassays and microand nanoarray formats, SLBs, tBLMs, and liposomes have provided prominent
applications for clinical use (chapter “Biomedical Applications: Liposomes and
Supported Lipid Bilayers for Diagnostics, Theranostics, Imaging, Vaccine Formulation, and Tissue Engineering”). Owing to their native-like biophysical properties,
liposomes, on the other hand, carry their cargo like small lipid vesicles found
in cells, and when loaded with vaccines, contrast agents, or drugs, they become
very effective delivery vehicles (chapter “Biomedical Applications: Liposomes
and Supported Lipid Bilayers for Diagnostics, Theranostics, Imaging, Vaccine
Formulation, and Tissue Engineering”). While applying them into microfluidics
realm, dynamics and significant utility of SLBs and liposomes can be efficiently
investigated in a confined small volume. Furthermore, integrating bioprinting tools,
e.g., nozzles and spraying modules, with microfluidic-stemmed strategies creates
high throughput, automation, and scale-up for the future applications (chapter
“Lipid Bilayers and Liposomes on Microfluidics Realm: Techniques and Applications”). Biomimetic lipid membranes are also very powerful for designing drug
screening platforms since the majority of therapeutic agents interact with either
cell membranes or membrane proteins (chapter “Biomimetic Model Membranes
as Drug Screening Platform”). All these instances clearly point out the potential
of biomimetic lipid membranes in medical and pharmaceutical fields. Biomimetic
membranes are also being used in other distinct fields, including water filtration
and food and environmental pollutant monitoring. Aquaporins, membrane proteins
with unique selectivity toward water, embedded in biomimetic membranes have
been tested for water purification purposes (chapter “Biomimetic Membranes as
an Emerging Water Filtration Technology”), while their functionalization with
different biomolecules can be used in the detection of various analytes, including
phenols, pesticides, heavy metals, toxins, allergens, antibiotics, microorganisms,
hormones, dioxins, and genetically modified produce (chapter “Applications of
Lipid Membranes-based Biosensors for the Rapid Detection of Food Toxicants
and Environmental Pollutants”). In sum, the unique and admirable characteristics
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of biomimetic membranes have extended our fundamental knowledge on cell
membranes and their organization with milieu and ultimately opened new horizons
for other disciplines at the intersection of chemistry, physics, materials science,
engineering, biology, and medicine. Exclusively, their applications in the field of
medicine and other conjunctive realms have gained immense interest in recent
years by screening diseases and therapies, therefore expediting clinical management
through prevention studies. In the near future, further engineered biomimetic membranes, in combination with the existing developments, will spectacularly impact
greater than their current status in the health-care system through elucidating the
fundamental understanding of disease biology and mechanism, leading to synergetic
medical solutions to the real-world problems