On-chip extrusion of lipid vesicles and tubes through microsized apertures

Microfluidics-mediated Liposomal Nanoparticles for Cancer Therapy: Recent Developments on Advanced Devices and Technologies

Liposomes, spherical particles with phospholipid double layers, have been extensively studied over the years as a means of drug administration. Conventional manufacturing techniques like thin-film hydration and extrusion have limitations in controlling liposome size and distribution. Microfluidics enables superior tuning of parameters during the self-assembly of liposomes, producing uniform populations. This review summarizes microfluidic methods for engineering liposomes, including hydrodynamic flow focusing, jetting, micro mixing, and double emulsions. The precise control over size and lamellarity afforded by microfluidics has advantages for cancer therapy. Liposomes created through microfluidics and designed to encapsulate chemotherapy drugs have exhibited several advantageous properties in cancer treatment. They showcase enhanced permeability and retention effects, allowing them to accumulate specifically in tumor tissues passively. This passive targeting of tumors results in improved drug delivery and efficacy while reducing systemic toxicity. Promising results have been observed in pancreatic, lung, breast, and ovarian cancer models, making them a potential breakthrough in cancer therapy. Surface-modified liposomes, like antibodies or carbohydrates, also achieve active targeting. Overall, microfluidic fabrication improves reproducibility and scalability compared to traditional methods while maintaining drug loading and biological efficacy. Microfluidics-engineered liposomal formulations hold significant potential to overcome challenges in nanomedicine-based cancer treatment.

Fabrication, modification and application of lipid nanotubes

The potential application of high aspect-ratio nanomaterials motivates the development of the fabrication and modification of lipid nanotubes(LNTs). To date, diverse fabricate processes and elaborate template procedures have produced suitable tubular architectures with definite dimensions and complex structures for expected functions and applications. Herein, we comprehensively summarize the fabrication of LNTs in vitro and discuss the progress made on the micro/nanomaterials fabrication using LNTs as a template, as well as the functions and possible application of a wide range of LNTs as fundamental or derivative material. In addition, the characteristics, advantages, and disadvantages of different fabrication, modification methods, and development prospects of LNTs were briefly summarized.

Fabrication of Biomaterials and Biostructures Based On Microfluidic Manipulation

Biofabrication technologies are of importance for the construction of organ models and functional tissue replacements. Microfluidic manipulation, a promising biofabrication technique with micro-scale resolution, can not only help to realize the fabrication of specific microsized structures but also build biomimetic microenvironments for biofabricated tissues. Therefore, microfluidic manipulation has attracted attention from researchers in the manipulation of particles and cells, biochemical analysis, tissue engineering, disease diagnostics, and drug discovery. Herein, biofabrication based on microfluidic manipulation technology is reviewed. The application of microfluidic manipulation technology in the manufacturing of biomaterials and biostructures with different dimensions and the control of the microenvironment is summarized. Finally, current challenges are discussed and a prospect of microfluidic manipulation technology is given. The authors hope this review can provide an overview of microfluidic manipulation technologies used in biofabrication and thus steer the current efforts in this field.

Synthetic cells in biomedical applications

Synthetic cells are engineered vesicles that can mimic one or more salient features of life. These features include directed localization, sense-and-respond behavior, gene expression, metabolism, and high stability. In nanomedicine, many of these features are desirable capabilities of drug delivery vehicles but are difficult to engineer. In this focus article, we discuss where synthetic cells offer unique advantages over nanoparticle and living cell therapies. We review progress in the engineering of the above life-like behaviors and how they are deployed in nanomedicine. Finally, we assess key challenges synthetic cells face before being deployed as drugs and suggest ways to overcome these challenges. This article is categorized under: Therapeutic Approaches and Drug Discovery > Emerging Technologies Biology-Inspired Nanomaterials > Lipid-Based Structures.

Self-assembled mRNA vaccines

mRNA vaccines have evolved from being a mere curiosity to emerging as COVID-19 vaccine front-runners. Recent advancements in the field of RNA technology, vaccinology, and nanotechnology have generated interest in delivering safe and effective mRNA therapeutics. In this review, we discuss design and self-assembly of mRNA vaccines. Self-assembly, a spontaneous organization of individual molecules, allows for design of nanoparticles with customizable properties. We highlight the materials commonly utilized to deliver mRNA, their physicochemical characteristics, and other relevant considerations, such as mRNA optimization, routes of administration, cellular fate, and immune activation, that are important for successful mRNA vaccination. We also examine the COVID-19 mRNA vaccines currently in clinical trials. mRNA vaccines are ready for the clinic, showing tremendous promise in the COVID-19 vaccine race, and have pushed the boundaries of gene therapy.

Lipid Bilayer-Modified Nanofluidic Channels of Sizes with Hundreds of Nanometers for Characterization of Confined Water and Molecular/Ion Transport

Water inside and between cells with dimensions on the order of 10¹-10³ nm such as synaptic clefts and mitochondria is thought to be important to biological functions, such as signal transmissions and energy production. However, the characterization of water in such spaces has been difficult owing to the small size and complexity of cellular environments. To this end, we proposed and fabricated a biomimetic nanospace exploiting nanofluidic channels with defined dimensions of hundreds of nanometers and controlled environments. A method of modifying a glass nanochannel with a unilamellar lipid bilayer was developed. We revealed that 2.1-5.6 times higher viscosity of water arises in a 200 nm sized biomimetic nanospace by interactions between water molecules and the lipid bilayer surface and significantly affects the molecular/ion transport that is required for the biological functions. The proposed method provides both a technical breakthrough and new findings to the fields of physical chemistry and biology.

Acoustofluidic Synthesis of Particulate Nanomaterials

Synthesis of nanoparticles and particulate nanomaterials with tailored properties is a central step toward many applications ranging from energy conversion and imaging/display to biosensing and nanomedicine. While existing microfluidics-based synthesis methods offer precise control over the synthesis process, most of them rely on passive, partial mixing of reagents, which limits their applicability and potentially, adversely alter the properties of synthesized products. Here, an acoustofluidic (i.e., the fusion of acoustic and microfluidics) synthesis platform is reported to synthesize nanoparticles and nanomaterials in a controllable, reproducible manner through acoustic-streaming-based active mixing of reagents. The acoustofluidic strategy allows for the dynamic control of the reaction conditions simply by adjusting the strength of the acoustic streaming. With this platform, the synthesis of versatile nanoparticles/nanomaterials is demonstrated including the synthesis of polymeric nanoparticles, chitosan nanoparticles, organic-inorganic hybrid nanomaterials, metal-organic framework biocomposites, and lipid-DNA complexes. The acoustofluidic synthesis platform, when incorporated with varying flow rates, compositions, or concentrations of reagents, will lend itself unprecedented flexibility in establishing various reaction conditions and thus enable the synthesis of versatile nanoparticles and nanomaterials with prescribed properties.

Synthesis of Biomaterials Utilizing Microfluidic Technology

Recently, microfluidic technologies have attracted an enormous amount of interest as potential new tools for a large range of applications including materials synthesis, chemical and biological detection, drug delivery and screening, point-of-care diagnostics, and in-the-field analysis. Their ability to handle extremely small volumes of fluids is accompanied by additional benefits, most notably, rapid and efficient mass and heat transfer. In addition, reactions performed within microfluidic systems are highly controlled, meaning that many advanced materials, with uniform and bespoke properties, can be synthesized in a direct and rapid manner. In this review, we discuss the utility of microfluidic systems in the synthesis of materials for a variety of biological applications. Such materials include microparticles or microcapsules for drug delivery, nanoscale materials for medicine or cellular assays, and micro- or nanofibers for tissue engineering.

Advances in microfluidics for lipid nanoparticles and extracellular vesicles and applications in drug delivery systems

Lipid-based nanobiomaterials as liposomes and lipid nanoparticles (LNPs) are the most widely used nanocarriers for drug delivery systems (DDSs). Extracellular vesicles (EVs) and exosomes are also expected to be applied as DDS nanocarriers. The performance of nanomedicines relies on their components such as lipids, targeting ligands, encapsulated DNA, encapsulated RNA, and drugs. Recently, the importance of the nanocarrier sizes smaller than 100nm is attracting attention as a means to improve nanomedicine performance. Microfluidics and lab-on-a chip technologies make it possible to produce size-controlled LNPs by a simple continuous flow process and to separate EVs from blood samples by using a surface marker, ligand, or electric charge or by making a mass or particle size discrimination. Here, we overview recent advances in microfluidic devices and techniques for liposomes, LNPs, and EVs and their applications for DDSs.

Selective and vertical microfabrication of lipid tubule arrays on glass substrates using template-guided gentle hydration

Generally, asymmetric tubular lipid structures have been formed under the specific condition of gentle hydration or by using hydrodynamic and/or electrical elongation of vesicular lipid structures. Small-size lipid tubes are, however, very difficult to allocate or align in the vertical direction on the specific site of the substrate and, therefore, the ability to produce them selectively and in large quantities as an array form is limited. Herein, we propose an easy and novel method to fabricate selective and vertical lipid tube arrays using template-guided gentle hydration of dried lipid films without any external forces. A lipid solution was drop-dispensed onto a porous membrane and dried to form a lipid film. Then, the lipid-coated porous membrane was transferred to a glass substrate by using a UV-cured polymer layer to achieve tight bonding. Upon swelling with an appropriate buffer, expansion forces due to osmotic pressure during the gentle hydration process were highly constrained to confined pores, thereby resulting in the nucleation of tube-like lipid structures through the pores. Interestingly, according to the aspect ratio of pores (AR_pore, pore length/pore diameter), different shapes of lipid structures, including vesicular, oval, and tube-like, were generated, which indicates the importance of the AR_pore, as well as the pore diameter, during fabrication of tubular lipid structures. Also, this approach was easily modified with 1% chitosan to enhance the stability of the lipid tubes (>30 min in life time), by lipid coating twice and by using unsaturated lipids to increase tube length (>30 μm in length). Therefore, in the future, the simple but robust template-guided gentle hydration method will be a useful tool for fabricating addressable and engineered lipid tube arrays as a sensory unit.

Designing liposomal adjuvants for the next generation of vaccines

Liposomes not only offer the ability to enhance drug delivery, but can effectively act as vaccine delivery systems and adjuvants. Their flexibility in size, charge, bilayer rigidity and composition allow for targeted antigen delivery via a range of administration routes. In the development of liposomal adjuvants, the type of immune response promoted has been linked to their physico-chemical characteristics, with the size and charge of the liposomal particles impacting on liposome biodistribution, exposure in the lymph nodes and recruitment of the innate immune system. The addition of immunostimulatory agents can further potentiate their immunogenic properties. Here, we outline the attributes that should be considered in the design and manufacture of liposomal adjuvants for the delivery of sub-unit and nucleic acid based vaccines.

Microfluidic and lab-on-a-chip preparation routes for organic nanoparticles and vesicular systems for nanomedicine applications

In recent years, advancements in the fields of microfluidic and lab-on-a-chip technologies have provided unique opportunities for the implementation of nanomaterial production processes owing to the miniaturisation of the fluidic environment. It has been demonstrated that microfluidic reactors offer a range of advantages compared to conventional batch reactors, including improved controllability and uniformity of nanomaterial characteristics. In addition, the fast mixing achieved within microchannels, and the predictability of the laminar flow conditions, can be leveraged to investigate the nanomaterial formation dynamics. In this article recent developments in the field of microfluidic production of nanomaterials for drug delivery applications are reviewed. The features that make microfluidic reactors a suitable technological platform are discussed in terms of controllability of nanomaterials production. An overview of the various strategies developed for the production of organic nanoparticles and colloidal assemblies is presented, focusing on those nanomaterials that could have an impact on nanomedicine field such as drug nanoparticles, polymeric micelles, liposomes, polymersomes, polyplexes and hybrid nanoparticles. The effect of microfluidic environment on nanomaterials formation dynamics, as well as the use of microdevices as tools for nanomaterial investigation is also discussed.

Microfluidic methods for forming liposomes

Liposome structures have a wide range of applications in biology, biochemistry, and biophysics. As a result, several methods for forming liposomes have been developed. This review provides a critical comparison of existing microfluidic technologies for forming liposomes and, when applicable, a comparison with their analogous macroscale counterparts. The properties of the generated liposomes, including size, size distribution, lamellarity, membrane composition, and encapsulation efficiency, form the basis for comparison. We hope that this critique will allow the reader to make an informed decision as to which method should be used for a given biological application.

Confined synthesis and integration of functional materials in sub-nanoliter volumes

We present a novel microchip-based approach to combine the synthesis, characterization, and utilization of different functional materials on a single platform. A two-layer microfluidic device comprising 10 parallel actuated reaction chambers with volumes of a few hundred picoliters is used to localize and confine the synthesis, while the surfaces of the reaction chambers comprise an electrode array for direct integration and further characterization of the created crystalline assemblies without the need for further manipulation or positioning devices. First we visualized and evaluated the dynamics of our method by monitoring the formation of a fluorescent metal-organic complex (Zn(bix)). Next, we induced the site-specific growth of two types of organic conductive crystals, AuTTF and AgTCNQ, directly onto the electrode arrays in one- and two-step reactions, respectively. The performance of the created AgTCNQ crystals as memory elements was thoroughly examined. Moreover, we proved for first time that AuTTF composites can be used as label-free sensing elements.

Directed self-assembly of lipid nanotubes from inverted hexagonal structures

Conventional lipid-tube formation is based on either a tube phase of certain lipids or the shape transformation of lamellar structures by applying a point load. In the present study, lipid blocks in inverted hexagonal phase made of 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE) were shown to protrude lipid nanotubes upon a fluid-dynamic flow on polyelectrolyte-functionalized surfaces in physiological buffer solution. The outer diameter of the tubes is 19.1 ± 4.5 nm and their lengths are up to several hundred micrometers. The method described enables the alignment and patterning of lipid nanotubes into various (including curvy) shapes with a microfluidic system.

Microfluidic fabrication of complex-shaped microfibers by liquid template-aided multiphase microflow

This study presents a simple microfluidic approach to the rapid fabrication of complex-shaped microfibers (e.g., single hollow, double hollow, and microbelt), with highly uniform structures, based on a combination of the spontaneous formation of polymeric jet streams and in situ photopolymerization. Two laminar flows of a photocurable fluid and a liquid template (nonpolymerizing fluid) spontaneously form jet streams in equilibrium states in microfluidic channels because of the minimization of the interfacial energy between the two fluids. The formation of the jet streams strongly depends on the spreading coefficients and the evolution time along the downstream of the microfluidic system. Thus, the simple control of the spreading coefficients can guide microfibers into various shapes. The sizes of the core and shell of the hollow fibers can also be readily manipulated by the flow rates of the polymerizing fluid and the liquid template phase. Asymmetric hollow fibers can also be produced in different evolutionary states in the microfluidic system. The microfluidic approach shown here represents a significant step toward the easy fabrication of microfibers with readily controllable structures and geometries. We anticipate that this novel fabrication approach and the prediction method based on spreading coefficients presented in this work can be applied to produce a wide variety of functional microfibrous materials.

Preparation of monodisperse block copolymer vesicles via flow focusing in microfluidics

We demonstrate that microfluidic flow devices enable a rapid, continuous, well-reproducible and size-controlled preparation of unilamellar block copolymer vesicles. The PDMS-based microfluidic device consists of perpendicularly crossed channels allowing hydrodynamic flow focusing of an ethanolic block copolymer solution in a stream of water. By altering the flow rate ratio in the water and ethanolic inlet channels, the vesicle size can be tuned over a large size range from 40 nm to 2 microm without subsequent processing steps manipulating size and shell characteristics. The ability of tuning the vesicle mean size over a range of several orders of magnitude with the possibility of in situ encapsulation of active ingredients creates new opportunities for the preparation of tailored drug delivery systems in science, medicine and industry.

Microfluidic mixing and the formation of nanoscale lipid vesicles

We investigate the formation of unilamellar lipid vesicles (liposomes) with diameters of tens of nanometers by controlled microfluidic mixing and nanoparticle determination (COMMAND). Our study includes liposome synthesis experiments and numerical modeling of our microfluidic implementation of the batch solvent injection method. We consider microfluidic liposome formation from the perspective of fluid interfaces and convective-diffusive mixing, as we find that bulk fluid flow parameters including hydrodynamically focused alcohol stream width, final alcohol concentration, and shear stress do not primarily determine the vesicle formation process. Microfluidic device geometry in conjunction with hydrodynamic flow focusing strongly influences vesicle size distributions, providing a coarse method to control liposome size, while total flow rate allows fine-tuning the vesicle size in certain focusing regimes. Although microfluidic liposome synthesis is relatively simple to implement experimentally, numerical simulations of the mixing process reveal a complex system of fluid flow and mass transfer determining the formation of nonequilibrium vesicles. These results expand our understanding of the microfluidic environment that controls liposome self-assembly and yield several technological advances for the on-chip synthesis of nanoscale lipid vesicles.

Time-resolved tracking of a minimum gene expression system reconstituted in giant liposomes

Individual expression: We describe a method that allows the observation of real-time gene expression in a large number of individual giant liposomes encapsulating identical genetic material. We followed the gene expression profiles from DNA and mRNA templates coding for different proteins. Although the average profiles of individual liposomes were similar to those measured in bulk solution, strong variability between individual liposomes was observed at both transcription and translation.

Massively parallel production of lipid microstructures

In this paper we describe a simple and inexpensive microfluidic system for the production of lipid tubules and vesicles. The system incorporates a central microporous membrane for interfacing lipid films with aqueous flows. Hydrodynamic drag was used for the parallel elongation of high axial ratio lipid tubules with uniform 1.5 +/- 0.5 microm diameters. Alternatively, electrokinetic operation was used for the rapid and continuous production of vast numbers of lipid vesicles with diameters ranging from 1 to 3 microm.

Lipid nanotubule fabrication by microfluidic tweezing

There is currently great interest in the development of lipid enclosed systems with complex geometrical arrangements that mimic cellular compartments. With biochemical functionalization, these soft matter devices can be used to probe deeper into life's transport dominated biochemical operations. In this paper, we present a novel tool for machining lipid nanotubules by microfluidic tweezing. A bilayer poly(dimethylsiloxane) (PDMS) device was designed with a lipid reservoir that was loaded by capillary action for lipid film deposition. The lipid reservoir is vertically separated from an upper flow for controlled material wetting and the formation of giant tubule bodies. Three fluidic paths are interfaced for introduction of the giant tubules into the high velocity center of a parabolic flow profile for exposure to hydrodynamic shear stresses. At local velocities approximating 2 mm s (-1), a 300-500 nm diameter jet of lipid material was tweezed from the giant tubule body and elongated with the flow. The high velocity flow provides uniform drag for the rapid and continuous fabrication of lipid nanotubules with tremendous axial ratios. Below a critical velocity, a remarkable shape transformation occurred and the projected lipid tubule grew until a constant 3.6 mum diameter tubule was attained. These lipid tubules could be wired for the construction of advanced lifelike bioreactor systems.

Novel method for obtaining homogeneous giant vesicles from a monodisperse water-in-oil emulsion prepared with a microfluidic device

A novel technique called the "lipid-coated ice droplet hydration method" is presented for the preparation of giant vesicles with a controlled size between 4 and 20 microm and entrapment yields for water-soluble molecules of up to about 30%. The method consists of three main steps. In the first step, a monodisperse water-in-oil emulsion with a predetermined average droplet diameter between 4 and 20 microm is prepared by microchannel emulsification, using sorbitan monooleate (Span 80) and stearylamine as emulsifiers and hexane as oil. In the second step, the water droplets of the emulsion are frozen and separated from the supernatant hexane solution by precipitation, followed by a removal of the supernatant and followed by the replacement of Span 80 by using a hexane solution containing egg yolk phosphatidylcholine, cholesterol, and stearylamine (5:5:1, molar ratio). This procedure is performed at -10 degrees C to keep the water droplets of the emulsion in a frozen state and thereby to avoid extensive water droplet coalescence. In the third step, hexane is evaporated at -4 to -7 degrees C and an external water phase is added to the remaining mixture of lipids and water droplets to form giant vesicles that have an average size in the range of that of the initial emulsion droplets (4-20 microm). The entrapment yield and the lamellarity of the vesicles obtained depend on the lipid/water droplet ratio and on the composition of the external water phase. At high lipid/water droplet ratio, the giant vesicles have a thicker membrane (indicating multilamellarity) and a higher entrapment yield than in the case of a low lipid/water droplet ratio. The highest entrapment yield ( approximately 35%) is obtained if the added external water phase contains preformed unilamellar egg phosphatidylcholine vesicles with an average diameter of 50 nm. The addition of these small vesicles minimizes the water droplet coalescence during the third step of the vesicle preparation, thereby decreasing the extent of release of water-soluble molecules originally present in the water droplets. The GVs prepared can be extruded through polycarbonate membranes to yield large unilamellar vesicles with about 100 nm diameter. This size reduction, however, leads to a decrease in the entrapment yield to about 12% due to solute leakage from the vesicles during the extrusion process.

Direct printing of self-assembled lipid tubules on substrates

Lipid tubules formed by rolled-up bilayer sheets have shown promise in drug delivery systems, nanofluidics, and microelectronics. Here we report a method for directly printing lipid tubules on substrates. Preformed lipid tubules of 1,2-bis(tricosa-10,12-diynoyl)-sn-glycero-3-phosphocholine are aligned in the recessed channels of a thin poly(dimethylsiloxane) (PDMS) stamp. The aligned lipid tubules then serve as an "ink" for microcontact printing. We demonstrate that two-dimensional (2-D) arrays of aligned lipid tubules can be transferred onto planar, patterned, and curved substrates from the recessed channels of the PDMS stamp by bringing the tubule-inked PDMS stamp into contact with these substrates. We show that the 2-D array of aligned lipid tubules can be transcribed into a 2-D array of aligned silica cylinders through templated sol-gel condensation of tetraethoxysilane.

Entrapment of water by subunit c of ATP synthase

We consider an ancient protein, and water as a smooth surface, and show that the interaction of the two allows the protein to change its hydrogen bonding to encapsulate the water. This property could have made a three-dimensional microenvironment, 3-4 Gyr ago, for the evolution of subsequent complex water-based chemistry. Proteolipid, subunit c of ATP synthase, when presented with a water surface, changes its hydrogen bonding from an alpha-helix to beta-sheet-like configuration and moves away from its previous association with lipid to interact with water surface molecules. Protein sheets with an intra-sheet backbone spacing of 3.7A and inter-sheet spacing of 6.0 A hydrogen bond into long ribbons or continuous surfaces to completely encapsulate a water droplet. The resulting morphology is a spherical vesicle or a hexagonal crystal of water ice, encased by a skin of subunit c. Electron diffraction shows the crystals to be highly ordered and compressed and the protein skin to resemble beta-sheets. The protein skin can retain the entrapped water over a temperature rise from 123 to 223 K at 1 x 10(-4) Pa, whereas free water starts to sublime significantly at 153 K.

Electroformation of giant phospholipid vesicles on a silicon substrate: advantages of controllable surface properties

We introduce the use of silicon (Si) as a substrate for the electroformation of giant phospholipid vesicles. By taking advantage of the tunability of silicon surface properties, we varied the organization of the phospholipid film on the electrode and studied the consequences on vesicle formation. In particular, we investigated the effects of Si surface chemistry and microtopology on the organization of the phospholipid film and the properties of the final vesicles. We established correlations between chemical homogeneity, film defects, and resulting vesicle size distribution. By considering phospholipid films that are artificially fragmented by electrode microstructures, we showed that the characteristic size of vesicles decreases with a decrease in microstructure dimensions. We finally proposed a way to control the vesicle size distribution by using a micropatterned silicon dioxide layer on a Si substrate.

Engineering lipid tubules using nano-sized building blocks: the combinatorial self-assembly of vesicles

Nano-sized lipid vesicles with tailored properties have been used as building blocks to generate lipid tubules between two glass surfaces. The tubules formed not only have defined orientation, width, and length, but they can also grow to be as long as 13 mm under ambient conditions, without externally supplied flow, temperature control, or catalyzing agents. Tubule membrane and its internal aqueous content can be manipulated by controlling the combination of different vesicle's lipid composition and aqueous entrapment. This self-assembly process opens up new pathways for generating complicated and flexible architectures for use in biocompatible molecular and supramolecular engineering. We demonstrated these possibilities by generating tubules encapsulated with siRNA, tubules with multiple branches, and polymerized fluorescent tubules in a single-throughput self-assembly process.

Liposomes: technologies and analytical applications

Liposomes are structurally and functionally some of the most versatile supramolecular assemblies in existence. Since the beginning of active research on lipid vesicles in 1965, the field has progressed enormously and applications are well established in several areas, such as drug and gene delivery. In the analytical sciences, liposomes serve a dual purpose: Either they are analytes, typically in quality-assessment procedures of liposome preparations, or they are functional components in a variety of new analytical systems. Liposome immunoassays, for example, benefit greatly from the amplification provided by encapsulated markers, and nanotube-interconnected liposome networks have emerged as ultrasmall-scale analytical devices. This review provides information about new developments in some of the most actively researched liposome-related topics.