A pH-responsive asymmetric lipid vesicle as drug carrier

Towards a biomimetic cellular structure and physical morphology with liposome-encapsulated agarose sol systems

The cytoplasm, serving as the primary hub of cellular metabolism, stands as a pivotal cornerstone for the harmonious progression of life. The ideal artificial cell should not only have a biomembrane structure system similar to that of a cell and the function of carrying genetic information, but also should have an intracellular environment. In this pursuit, we employed a method involving the incorporation of glycerol into agarose, resulting in the formation of agarose-glycerol mixed sol (AGs). This dynamic sol exhibited fluidic properties at ambient temperature, closely mimicking the viscosity of authentic cytoplasm. Harnessing the electroformation technique, AGs was encapsulated within liposomes, enabling the efficient creation of artificial cells that closely resembled native cellular dimensions through meticulous parameter adjustments of the alternating current (AC) field. Subsequently, artificial cells harboring AGs were subjected to diverse electrolyte and non-electrolyte solutions, enabling a comprehensive exploration of their deformation phenomena, encompassing both inward and outward budding. This study represents a significant stride forward in addressing one of the most fundamental challenges in the construction of artificial cytoplasm. It is our fervent aspiration that this work shall offer invaluable insights and guidance for future endeavors in the realm of artificial cell construction.

Formulation optimization of pH-sensitive liposomes based drug delivery of Carboplatin and anti-proliferative evaluation against A549 (human lung carcinoma) cell lines

The developments of pH–sensitive liposomes which are stable at physiological pH i.e. (6.8–7.4) have not explored much up until now. These lipid vesicles will go through destabilization and attain fusogenic properties in acidic conditions leading to liberation of aqueous contents. Carboplatin, included in the family of alkylating agent was found to exhibit adverse effects like myelo suppression, ion thrombocytopenia and leucopenia. Therefore, in order to circumvent these effects, carboplatin pH-sensitive liposomes for specific delivery is the ideal criteria and it poses a great challenge since the water-soluble drugs exhibited very low entrapment efficiency. The essential portion of study was evaluated using the Design Expert software 8. The pH-sensitive liposomes were optimized using Central composite design and one factor Response surface model design method and were prepared by film hydration method. Two formulation variables like drug: lipid ratio (X1) and volume of hydration media (X2) used to vary at three different levels and the other three variables viz. temperature, speed of rotation and vacuum applied were kept constant. The Response surface and contour plots were figured to elicit the effects of interaction of variables on the overall entrapment efficiency. pH-sensitive liposomes of carboplatin have been regarded as a promising delivery systematic approach in order to target tumor tissue as evaluated by the pre-clinical studies in both in vitro and ex-vivo conditions.

Microfluidic Nanoparticles for Drug Delivery

Nanoparticles (NPs) have attracted tremendous interest in drug delivery in the past decades. Microfluidics offers a promising strategy for making NPs for drug delivery due to its capability in precisely controlling NP properties. The recent success of mRNA vaccines using microfluidics represents a big milestone for microfluidic NPs for pharmaceutical applications, and its rapid scaling up demonstrates the feasibility of using microfluidics for industrial-scale manufacturing. This article provides a critical review of recent progress in microfluidic NPs for drug delivery. First, the synthesis of organic NPs using microfluidics focusing on typical microfluidic methods and their applications in making popular and clinically relevant NPs, such as liposomes, lipid NPs, and polymer NPs, as well as their synthesis mechanisms are summarized. Then, the microfluidic synthesis of several representative inorganic NPs (e.g., silica, metal, metal oxide, and quantum dots), and hybrid NPs is discussed. Lastly, the applications of microfluidic NPs for various drug delivery applications are presented.

The fabrication of phospholipid vesicle-based artificial cells and their functions

Phospholipid vesicles as artificial cells are used to simulate the cellular structure and function.

Floating and Diving Loops of ABA Triblock Copolymers in Lipid Bilayers and Stability Enhancement for Asymmetric Membranes

Hybrid membranes of lipids and A_xB_yA_z triblock copolymers can possess better biocompatibility and mechanical stability. In this work, triblock copolymer conformations and stability of asymmetric membranes are explored by dissipative particle dynamics. The triblock copolymers in the membranes exhibit either the bridge or loop conformation. As hydrophobic B-blocks interact attractively with lipid heads, bridge-shaped copolymers are significantly inhibited and loop-shaped copolymers prefer to stay at the interface between hydrophilic and hydrophobic layers. This floating loop has a flattened conformation, consistent with the experimental findings. In contrast, for repulsive interactions between B-blocks and lipid heads, bridge-shaped copolymers are abundant and loop-shaped copolymers tend to plunge into the hydrophobic layer. This diving loop displays a random coil conformation. The asymmetric membrane in which the fractions of loop-shaped copolymers in the upper and lower leaflets are different is thermodynamically unstable. Two approaches are proposed to acquire kinetically stable asymmetric membranes. First, membrane symmetrization is arrested by eliminating bridge-shaped copolymers, which is achieved by B-block/lipid head attraction and B-block/lipid tail repulsion. Second, asymmetric triblock copolymers (x ≠ z) are used to prevent the passage of the long A-block through the hydrophobic layer.

Multicompartmentalized vesosomes containing DOX loaded liposomes and 5FU loaded liposomes for synergistic tumor treatment

A multicompartmentalized vesosome drug delivery system was developed for enhanced cancer treatments.

A multifunctional biomimetic hybrid nanocarrier for the controlled delivery of chemotherapy drugs by near-infrared light

We have constructed a biocompatible magnetic nanoparticle-based nanocomposite material by integrating the features of Fe₃O₄ nanoparticles, mesoporous silica and lipid bilayer for the treatment of tumor.

Deformation of giant unilamellar vesicles under osmotic stress

Biological membrane plays an important role in maintaining an osmotic equilibrium between the cytoplasm and the extracellular solution of cells. Here, the giant unilamellar vesicles (GUVs) as cell models were used to investigate the effect of osmotic stress on phospholipid membranes. The deformation of GUVs, including inward budding and outward budding, was systematically investigated by the osmotic press from glucose, sucrose, LiCl, and KCl solutions. The permeability (P) of DMPC, DMPC/10 mol% Chol GUVs, DMPC/25 mol% Chol GUVs, and DMPC/40 mol% Chol GUVs in glucose, sucrose, LiCl, and KCl solutions were all obtained. The P value decreases with the addition of more cholesterol in the bilayer. The monovalent cations caused higher permeability of lipid bilayer membranes due to their combination with phospholipids. The molar flux of water (J) value was found to be the key factor for determining the deformation state from mainly inward budding to mainly outward budding. The findings in this paper may help us to understand cell transformation triggered with osmotic stress.

Liposome Crosslinked Polyacrylamide/DNA Hydrogel: a Smart Controlled-Release System for Small Molecular Payloads

A novel stimuli-responsive hydrogel system with liposomes serving as both noncovalent crosslinkers and functional small molecules carriers for controlled-release is developed. Liposomes can crosslink polyacrylamide copolymers functionalized with cholesterol-modified DNA motifs to yield a DNA hydrogel system, due to the hydrophobic interaction between cholesteryl groups and the lipid bilayer of liposomes. Functional information encoded DNA motifs on the polymer backbones endow the hydrogel with programmable smart responsive properties. In a model system, the hydrogel exhibits stimuli-responsive gel-to-sol transformation triggered by the opening of DNA motifs upon the presence of a restriction endonuclease enzyme, EcoR I, or temperature change, realizing the controlled-release of liposomes which are highly efficient carriers of active small molecules payloads. Two active molecules, 1,1-dioctadecyl-3,3,3,3-tetramethylindodicarbocyanine perchlorate (DiIC18(5)) and calcein, are chosen as the hydrophobic and hydrophilic model payloads, respectively, to address the feasibility of the releasing strategy. Moreover, the hydrogel exhibits injectable property as well as self-recovery behaviors.

Thylakoid Containing Artificial Cells for the Inhibition Investigation of Light-Driven Electron Transfer during Photosynthesis

The fabrication of artificial cells containing nature components is challenging. Herein we construct a thylakoid containing artificial cell (TA-cell) by forming multicompartmental structure inside giant unilamellar vesicles (GUVs) using osmotic stress. The thylakoids are selectively loaded inside each compartment in GUVs to mimic "chloroplast". The TA-cells are able to carry out photosynthesis upon light on. The TA-cells keep their 50% functionality of electron transfer for 12 days, which is twice of those of free thylakoids. Using TA-cells the inhibition of 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU) and heavy metal ions (Hg²⁺, Cu²⁺, Cd²⁺, Pb²⁺ and Zn²⁺) on the electron transfer process in TA-cells is systematically investigated. Their half maximal inhibitory concentration (IC₅₀) values are 36.23 ± 1.87, 0.02 ± 0.01, 0.42 ± 0.08, 0.82 ± 0.12, 1.97 ± 0.21, and 4.08 ± 0.18 μM, respectively. Hg²⁺ is the most toxic ion for the photosynthesis process among these five heavy metal ions. This biomimetic system can be expanded to study other processes during the photosynthesis. The TA-cells pave a way to fabricate more complicated nature component containing artificial cells.

Electroformation of double vesicles using an amplitude modulated electric field

Double vesicles are a promising model to mimic eukaryotic cells, yet effective preparation methods with high yields and stable double vesicles are scarce. Previously reported electroformation methods were mainly based on sinusoidal AC fields. Using a combination of sinusoidal and amplitude modulated (AM) electric fields lipid double vesicles could be produced for the first time by a simple electroformation process. First lipid domes formed in a sinusoidal AC field. The domes grew into tubes during the subsequent application of an AM field. These tubes deformed into double vesicles to minimize their free energy in accordance with the area-difference-elasticity model. Two forces are involved to explain the mechanism behind tube formation. The pulling force (F) is responsible to drag the domes into tubular vesicles, but has to overcome a critical force (F_c). The most important parameters of the electrical field were explored systematically. In our work, a maximum yield for double vesicles of 63% was achieved. These vesicles proved to be stable for one week at least. Hence our method could provide a way to fabricate novel cell models.