Liposomes as drug deposits in multilayered polymer films

Engineering the liposomal formulations from natural peanut phospholipids for pH and temperature sensitive release of folic acid, levodopa and camptothecin

The present study demonstrates the extraction and identification of phospholipids (PLs) from peanut seed for formulation of liposomes for pH and thermo-sensitive delivery and release of folic acid (FA), levodopa (DOPA) and, camptothecin (CPT). The TLC, FTIR and GC-MS based characterization of extracted peanut PLs showed phosphatidylethanolamine, cardiolipin and phosphatidic acid as major PLs and palmitic acid and oleic acid as major fatty acids. Liposomes (LSMs) of size 1-2 μm formulated by optimized thin-film hydration method were found to entrap FA, DOPA and CPT with 58, 61.4 and 52.12% efficiency, respectively with good stability. The effect of external stimuli like pH and temperature on the release pattern of FA, DOPA and CPT indicated that FA was optimally released at pH 10 and 57 °C, DOPA at pH 2 and 37 °C, while CPT was best released at pH 6 and 47 °C. When tested for the in vitro activity, DOPA released by DOPA@LSMs showed lower toxicity to 3T3 than to SH-SY5Y cells. Similarly, CPT released by CPT@LSMs showed remarkable anticancer activity against MCF-7 cells with an IC50 value of 17.99 μg/mL. Thus peanut PLs can be efficiently used for liposomal formulations for pH and thermo-sensitive release of drugs.

Polymeric Drug Delivery Systems Bearing Cholesterol Moieties: A Review

This review aims to provide an overview of polymers comprising cholesterol moiety/ies designed to be used in drug delivery. Over the last two decades, there have been many papers published in this field, which are summarized in this review. The primary focus of this article is on the methods of synthesis of polymers bearing cholesterol in the main chain or as side chains. The data related to the composition, molecular weight, and molecular weight distribution of polymers are presented. Moreover, other aspects, such as forms of carriers, types of encapsulated drugs, encapsulation efficiency and capacity, are also included.

Multicompartment Microreactors Prevent Excitotoxic Dysfunctions In Rat Primary Cortical Neurons

Excitotoxicity is a cellular phenomenon that comprises the consequences of toxic actions of excitatory neurotransmitters, such as glutamate. This process is usually related to overproduction of reactive oxygen species (ROS) and ammonia (NH₄ ⁺ ) toxicity. Platinum nanoparticle (Pt-NP)-based microreactors able to degrade hydrogen peroxide (H₂ O₂ ) and NH₄ ⁺ , are previously described as a novel therapeutical approach against excitotoxicity, conferring protection to neuroblasts. Now, it is demonstrated that these microreactors are compatible with rat primary cortical neurons, show high levels of neuronal membrane interaction, and are able to improve cell survival and neuronal activity when neurons are exposed to H₂ O₂ or NH₄ ⁺ . Additionally, more complex microreactors are assembled, including enzyme-loaded liposomes containing glutamate dehydrogenase and glutathione reductase, in addition to Pt-NP. The in vitro activity of these microreactors is characterized and they are compared to the Pt-NP-based microreactors in terms of biological activity, concluding that they enhance cell viability similarly or more extensively than the latter. Extracellular electrophysiological recordings demonstrate that these microreactors rescue neuronal functionality lost upon incubation with H₂ O₂ or NH₄ ⁺ . This study provides more evidence for the potential application of these microreactors in a biomedical context with more complex cellular environments.

Facile and Versatile Strategy for Construction of Anti-Inflammatory and Antibacterial Surfaces with Polydopamine-Mediated Liposomes Releasing Dexamethasone and Minocycline for Potential Implant Applications

Reducing early nonbacterial inflammation induced by implanted materials and infection resulting from bacterial contamination around the implant-abutment interface could greatly decrease implant failure rates, which would be of clinical significance. In this work, we presented a facile and versatile strategy for the construction of anti-inflammatory and antibacterial surfaces. Briefly, the surfaces of polystyrene culture plates were first coated with polydopamine and then decorated with dexamethasone plus minocycline-loaded liposomes (Dex/Mino liposomes), which was validated by contact angle goniometry, quartz crystal microbalance, and fluorescence microscopy. Dex/Mino liposomes were dispersed on functional surfaces and the drug release kinetics exhibited the sustained release of dexamethasone and minocycline. Our results demonstrated that the Dex/Mino liposome-modified surfaces had good biocompatibility. Additionally, liposomal dexamethasone reduced proinflammatory mediator expression (particularly IL-6 and TNF-α) in lipopolysaccharide-stimulated human gingival fibroblasts and human mesenchymal stem cells. Moreover, liposomal minocycline prevented the adhesion and proliferation of Porphyromonas gingivalis (Gram-negative bacteria) and Streptococcus mutans (Gram-positive bacteria). These findings demonstrate that an anti-inflammatory and antibacterial surface was developed, using dopamine as a medium and combining a liposomal delivery device, which has potential for use to reduce implant failure rates. Accordingly, the surface modification strategy presented could be useful in biofunctionalization of implant materials.

Mucopenetrating micelles with a PEG corona

Crossing the intestinal mucus layer is a long-standing challenge for orally delivered nanoparticles carrying therapeutic cargo. We report the assembly of mucopenetrating cargo-loaded micelles using block copolymers consisting of either linear poly(ethylene glycol) (PEG) or bottle-brush poly(oligo(ethylene glycol)methacrylate) (PEG_b) as the hydrophilic block and poly(caprolactone) (PCL) or poly(cholesteryl methacrylate) (PCMA) as the hydrophobic extension. The micelles were shown to preserve their stability and retain ∼50% of their cargo in simulated gastric fluid. The ability of micelles to diffuse through reconstituted porcine mucus was assessed in a microfluidic set-up. Finally, the delivery of Nile Red as a hydrophobic model cargo across a mucus layer produced by epithelial cells was demonstrated. These engineered mucopenetrating micelles have potential to be developed into efficient absorption enhancers, contributing a nanotechnology solution to oral drug delivery.

Planar and Cell Aggregate-Like Assemblies Consisting of Microreactors and HepG2 Cells

The assembly of microreactors has made considerable progress toward the fabrication of artificial cells. However, their characterization remains largely limited to buffer solution-based assays in the absence of their natural role model-the biological cells. Herein, the combination of microreactors with HepG2 cells either in planar cell cultures or in the form of cell aggregates is reported. Alginate (Alg)-based microreactors loaded with catalase are assembled by droplet microfluidics, and their activity is confirmed. The acceptance of polymer-coated ∼40 μm Alg particles by proliferating HepG2 cells is depending on the terminating polymer layer. When these functional microreactors are cocultured with HepG2 cells, they can be employed for detoxification, that is, hydrogen peroxide removal, and by doing so, they assist the cells to survive. This report is among the first successful combination of microreactors with biological cells, that is, HepG2 cells, contributing to the fundamental understanding of integrating synthetic and biological partners toward the maturation of this semisynthetic concept for biomedical applications.

Nanoparticle as a novel tool in hyperthermic intraperitoneal and pressurized intraperitoneal aerosol chemotheprapy to treat patients with peritoneal carcinomatosis

The treatment of peritoneal surface malignances has changed considerably over the last thirty years. Unfortunately, the palliative is the only current treatment for peritoneal carcinomatosis (PC). Two primary intraperitoneal chemotherapeutic methods are used. The first is combination of cytoreductive surgery (CRS) and Hyperthermic IntraPEritoneal Chemotherapy (HIPEC), which has become the gold standard for many cases of PC. The second is Pressurized IntraPeritoneal Aerosol Chemotheprapy (PIPAC), which is promising direction to minimally invasive as safedrug delivery. These methods were improved through multicenter studies and clinical trials that yield important insights and solutions. Major method development has been made through nanomedicine, specifically nanoparticles. Here, we are presenting the latest advances of nanoparticles and their application to precision diagnostics and improved treatment strategies for PC. These advances will likely develop both HIPEC and PIPAC methods that used for in vitro and in vivo studies. Several benefits of using nanoparticles will be discussed including: 1) Nanoparticles as drug delivery systems; 2) Nanoparticles and Near Infrred (NIR) Irradiation; 3) use of nanoparticles in perioperative diagnostic and individualized treatment planning; 4) use of nanoparticles as anticancer dressing's, hydrogels and as active beeds for optimal reccurence prevention; and 5) finally the curent in vitro and in vivo studies and clinical trials of nanoparticles. The current review highlighted use of nanoparticles as novel tools in improving drug delivery to be effective for treatment patients with peritoneal carcinomatosis.

Multicompartment Artificial Organelles Conducting Enzymatic Cascade Reactions inside Cells

Cell organelles are subcellular structures entrapping a set of enzymes to achieve a specific functionality. The incorporation of artificial organelles into cells is a novel medical paradigm which might contribute to the treatment of various cell disorders by replacing malfunctioning organelles. In particular, artificial organelles are expected to be a powerful solution in the context of enzyme replacement therapy since enzymatic malfunction is the primary cause of organelle dysfunction. Although several attempts have been made to encapsulate enzymes within a carrier vehicle, only few intracellularly active artificial organelles have been reported to date and they all consist of single-compartment carriers. However, it is noted that biological organelles consist of multicompartment architectures where enzymatic reactions are executed within distinct subcompartments. Compartmentalization allows for multiple processes to take place in close vicinity and in a parallel manner without the risk of interference or degradation. Here, we report on a subcompartmentalized and intracellularly active carrier, a crucial step for advancing artificial organelles. In particular, we develop and characterize a novel capsosome system, which consists of multiple liposomes and fluorescent gold nanoclusters embedded within a polymer carrier capsule. We subsequently demonstrate that encapsulated enzymes preserve their activity intracellularly, allowing for controlled enzymatic cascade reaction within a host cell.

A facile supramolecular approach to fabricate multifunctional upconversion nanoparticles as a versatile platform for drug loading, in vivo delivery and tumor imaging

Multifunctional upconversion nanoparticles (UCNPs) that can be implemented in theranostic applications are particularly attractive scaffolds for precise drug delivery. However, most of the current methods for drug formulation are technically complicated, thereby impeding their use in the clinic. Here, we report on the preparation of a lipophilic cytotoxic prodrug-integrated and polyethylene glycol (PEG)-cloaked UCNPs scaffold through a facile one-pot supramolecular approach. By choosing 7-ethyl-10-hydroxycamptothecin (SN38)-derived prodrug 1 as a model chemotherapeutic, we show that this lipophilic prodrug can be feasibly self-assembled onto the surface of UCNPs, which are cooperatively solubilized by PEGylated phospholipids. The resulting SN38 prodrug 1-encapsulated UCNPs (designated 1@pUCNPs) produce a stable colloidal system in aqueous solution, making it suitable for intravenous injection. The SN38 drug loading capacity in pUCNPs is as high as ∼12.3 wt%, and a sustained drug release profile is observed, indicating that the drug payloads can be transported to targeted tumor sites via the enhanced permeability and retention (EPR) effect. Upconversion luminescence (UCL) imaging, including in vivo and ex vivo imaging, suggests that the drug-loaded pUCNPs remain stable in tumors over a long time and preferentially accumulate in tumors presumably via the EPR effect. Furthermore, the 1@pUCNPs show superior therapeutic outcomes compared with the clinically approved SN38 prodrug CPT-11 in the Bcap-37 mouse model of breast cancer. Collectively, our results demonstrate that pUCNPs facilely constructed in a one-pot self-assembly manner may be used as a versatile platform, enabling synchronous in vivo delivery of poorly water-soluble drugs and tumor imaging.

Liposome-Loaded Cell Backpacks

Cell backpacks, or micron-scale patches of a few hundred nanometers in thickness fabricated by layer-by-layer (LbL) assembly, are potentially useful vehicles for targeted drug delivery on the cellular level. In this work, echogenic liposomes (ELIPs) containing the anticancer drug doxorubicin (DOX) are embedded into backpacks through electrostatic interactions and LbL assembly. Poly(allylamine hydrochloride)/poly(acrylic acid) (PAH/PAA)n , and poly(diallyldimethylammonium chloride)/poly(styrene sulfonate) (PDAC/SPS)n film systems show the greatest ELIP incorporation of the films studied while maintaining the structural integrity of the vesicles. The use of ELIPs for drug encapsulation into backpacks facilitates up to three times greater DOX loading compared to backpacks without ELIPs. Cytotoxicity studies reveal that monocyte backpack conjugates remain viable even after 72 h, demonstrating promise as drug delivery vehicles. Because artificial vesicles can load many different types of drugs, ELIP containing backpacks offer a unique versatility for broadening the range of possible applications for cell backpacks.

Ionic Driven Embedment of Hyaluronic Acid Coated Liposomes in Polyelectrolyte Multilayer Films for Local Therapeutic Delivery

The ability to control the spatial distribution and temporal release of a therapeutic remains a central challenge for biomedical research. Here, we report the development and optimization of a novel substrate mediated therapeutic delivery system comprising of hyaluronic acid covalently functionalized liposomes (HALNPs) embedded into polyelectrolyte multilayer (PEM) platform via ionic stabilization. The PEM platform was constructed from sequential deposition of Poly-L-Lysine (PLL) and Poly(Sodium styrene sulfonate) (SPS) "(PLL/SPS)4.5" followed by adsorption of anionic HALNPs. An adsorption affinity assay and saturation curve illustrated the preferential HALNP deposition density for precise therapeutic loading. (PLL/SPS)2.5 capping layer on top of the deposited HALNP monolayer further facilitated complete nanoparticle immobilization, cell adhesion, and provided nanoparticle confinement for controlled linear release profiles of the nanocarrier and encapsulated cargo. To our knowledge, this is the first study to demonstrate the successful embedment of a translatable lipid based nanocarrier into a substrate that allows for temporal and spatial release of both hydrophobic and hydrophilic drugs. Specifically, we have utilized our platform to deliver chemotherapeutic drug Doxorubicin from PEM confined HALNPs. Overall, we believe the development of our HALNP embedded PEM system is significant and will catalyze the usage of substrate mediated delivery platforms in biomedical applications.

Janus subcompartmentalized microreactors

We report on Janus subcompartmentalized assemblies with enzyme loaded liposomes entrapped within a polymer carrier capsule - Janus subcompartmentalized microreactors. The concept is based on the use of Pickering emulsions and the subsequent deposition of interacting liposomes and polymer layers. We demonstrate the adjustment of the size of the Janus domains and the control over the amount of trapped liposomes using multiple liposome deposition steps. The obtained Janus capsosomes feature a distinct liposome domain within a closed polymeric hydrogel shell. The assembly of functional Janus microreactors using trypsin as cargo within the liposomal subcompartments is shown by performing locally confined enzymatic encapsulated catalysis. The presented assemblies with spatial control over the position of their liposomal subunits are a fascinating first step towards artificial cells with polarity.

Mixed poly(dopamine)/poly(L-lysine) (composite) coatings: from assembly to interaction with endothelial cells

Engineered polymer films are of significant importance in the field of biomedicine. Poly(dopamine) (PDA) is becoming more and more a key player in this context. Herein, we deposited mixed films consisting of PDA and poly(L-lysine) (PLL) of different molecular weights. The coatings were characterized by quartz crystal microbalance with dissipation monitoring, atomic force microscopy, and X-ray photoelectron spectroscopy. The protein adsorption to the mixed films was found to decrease with increasing amounts of PLL. PDA/PLL capsules were also successfully assembled. Higher PLL content in the membranes reduced their thickness while the ζ-potential increased. Further, endothelial cell adhesion and proliferation over 96 h were found to be independent of the type of coating. Using PDA/PLL in liposome-containing composite coatings showed that sequential deposition of the layers yielded higher liposome trapping compared to one-step adsorption except for negatively charged liposomes. Association/uptake of fluorescent cargo by adherent endothelial cells was found to be different for PDA and PDA/PLL films. Taken together, our findings illustrate the potential of PDA/PLL mixed films as coatings for biomedical applications.

X-DNA origami-networked core-supported lipid stratum

DNA hydrogels are promising materials for various fields of research, such as in vitro protein production, drug carrier systems, and cell transplantation. For effective application and further utilization of DNA hydrogels, highly effective methods of nano- and microscale DNA hydrogel fabrication are needed. In this respect, the fundamental advantages of a core-shell structure can provide a simple remedy. An isolated reaction chamber and massive production platform can be provided by a core-shell structure, and lipids are one of the best shell precursor candidates because of their intrinsic biocompatibility and potential for easy modification. Here, we demonstrate a novel core-shell nanostructure made of gene-knitted X-shaped DNA (X-DNA) origami-networked gel core-supported lipid strata. It was simply organized by cross-linking DNA molecules via T4 enzymatic ligation and enclosing them in lipid strata. As a condensed core structure, the DNA gel shows Brownian behavior in a confined area. It has been speculated that they could, in the future, be utilized for in vitro protein synthesis, gene-integration transporters, and even new molecular bottom-up biological machineries.

Thiocoraline activates the Notch pathway in carcinoids and reduces tumor progression in vivo

Carcinoids are slow-growing neuroendocrine tumors (NETs) that are characterized by hormone overproduction; surgery is currently the only option for treatment. Activation of the Notch pathway has previously been shown to have a role in tumor suppression in NETs. The marine-derived thiodepsipeptide thiocoraline was investigated in vitro in two carcinoid cell lines (BON and H727). Carcinoid cells treated with nanomolar concentrations of thiocoraline resulted in a decrease in cell proliferation and an alteration of malignant phenotype evidenced by decrease of NET markers, ASCL-1, CgA, and NSE. Western blot analysis demonstrated the activation of Notch1 on the protein level in BON cells. Additionally, thiocoraline activated downstream Notch targets HES1, HES5, and HEY2. Thiocoraline effectively suppressed carcinoid cell growth by promoting cell cycle arrest in BON and H727 cells. An in vivo study demonstrated that thiocoraline, formulated with polymeric micelles, slowed carcinoid tumor progression. Thus, the therapeutic potential of thiocoraline, which induced activation of the Notch pathway, in carcinoid tumors was demonstrated.

Confined multiple enzymatic (cascade) reactions within poly(dopamine)-based capsosomes

The design of compartmentalized carriers as artificial cells is envisioned to be an efficient tool with potential applications in the biomedical field. The advent of this area has witnessed the assembly of functional, bioinspired systems attempting to tackle challenges in cell mimicry by encapsulating multiple compartments and performing controlled encapsulated enzymatic catalysis. Although capsosomes, which consist of liposomes embedded within a polymeric carrier capsule, are among the most advanced systems, they are still amazingly simple in their functionality and cumbersome in their assembly. We report on capsosomes by embedding liposomes within a poly(dopamine) (PDA) carrier shell created in a solution-based single-step procedure. We demonstrate for the first time the potential of PDA-based capsosomes to act as artificial cell mimics by performing a two-enzyme coupled reaction in parallel with a single-enzyme conversion by encapsulating three different enzymes into separated liposomal compartments. In the former case, the enzyme uricase converts uric acid into hydrogen peroxide, CO2 and allantoin, followed by the reaction of hydrogen peroxide with the reagent Amplex Ultra Red in the presence of the enzyme horseradish peroxidase to generate the fluorescent product resorufin. The parallel enzymatic catalysis employs the enzyme ascorbate oxidase to convert ascorbic acid into 2-L-dehydroascorbic acid.

Controlled lecithin release from a hierarchical architecture on blood-contacting surface to reduce hemolysis of stored red blood cells

Hemolysis of red blood cells (RBCs) caused by implant devices in vivo and nonpolyvinyl chloride containers for RBC preservation in vitro has recently gained much attention. To develop blood-contacting biomaterials with long-term antihemolysis capability, we present a facile method to construct a hydrophilic, 3D hierarchical architecture on the surface of styrene-b-(ethylene-co-butylene)-b-styrene elastomer (SEBS) with poly(ethylene oxide) (PEO)/lecithin nano/microfibers. The strategy is based on electrospinning of PEO/lecithin fibers onto the surface of poly [poly(ethylene glycol) methyl ether methacrylate] [P(PEGMEMA)]-modified SEBS, which renders SEBS suitable for RBC storage in vitro. We demonstrate that the constructed 3D architecture is composed of hydrophilic micro- and nanofibers, which transforms to hydrogel networks immediately in blood; the controlled release of lecithin is achieved by gradual dissolution of PEO/lecithin hydrogels, and the interaction of lecithin with RBCs maintains the membrane flexibility and normal RBC shape. Thus, the blood-contacting surface reduces both mechanical and oxidative damage to RBC membranes, resulting in low hemolysis of preserved RBCs. This work not only paves new way to fabricate high hemocompatible biomaterials for RBC storage in vitro, but provides basic principles to design and develop antihemolysis biomaterials for implantation in vivo.

Liposome-containing polymer films and colloidal assemblies towards biomedical applications

Liposomes are important components for biomedical applications. Their unique architecture and versatile nature have made them useful carriers for the delivery of therapeutic cargo. The scope of this minireview is to highlight recent developments of biomimetic liposome-based multicompartmentalized assemblies of polymer thin films and colloidal carriers, and to outline a selection of recent applications of these materials in bionanotechnology.

A fluorescent perylene-assembled polyvinylpyrrolidone film: synthesis, morphology and nanostructure

A fluorescent polyvinylpyrrolidone (PVP) film with assembled nanostructures is successfully prepared in one pot by using perylene-3,4,9,10-tetracarboxylic acid dianhydride (PDA) as the fluorophore. The reactive anhydride groups in PDA play an important role in the covalent bonding of fluorescent molecules in the fluorescent PVP film, which has been demonstrated by a small-molecule model reaction. Interestingly, rod-like structures are found on the surface of the fluorescent film, which is attributed to the π-π interaction of PDA that occurred in the crosslinked PVP film. Further polarized optical microscopy (POM), X-ray diffraction (XRD) and optical analyses demonstrate the stable existence of π-conjugated nanostructures in the fluorescent PDA-based PVP film. The reactive anhydrides and the π-π interaction of perylene molecules are essential for the fabrication of the fluorescent perylene-assembled PVP film. This method could be extended to the preparation of the fluorescent PVP film with self-assembled nanostructures.

Biocatalytic polymer thin films: optimization of the multilayered architecture towards in situ synthesis of anti-proliferative drugs

We report on the assembly of multi-layered polyelectrolyte thin films containing an immobilized enzyme to perform conversion of externally administered prodrugs and achieve delivery of the resulting therapeutics to adhering cells. Towards this goal, multi-layered coatings were assembled using poly(sodium styrene sulfonate) and poly(allylamine hydrochloride). Activity of the incorporated enzyme was quantified as a function of the assembly conditions, position of the enzyme within the multi-layered architecture, concentration of the enzyme in the adsorption solution, and concentration of the administered prodrug. Biocatalytic coatings exhibited sustained levels of enzymatic activity over at least one week of incubation in physiological buffers without signs of loss of activity of the enzyme. Developed enzyme-containing polymer films afforded zero-order release of the in situ synthesized cargo with kinetics of synthesis (nM per hour) covering at least 3 orders of magnitude. Internalization of the synthesized product by adhering cells was visualized using a fluorogenic enzyme substrate. Therapeutic utility of biocatalytic coatings was demonstrated using a myoblast cell line and a prodrug for the anti-proliferative agent, 5-fluorouridine. Taken together, this work presents a novel approach to delivery of small molecule drugs using multi-layered polymer thin films with utility in surface-mediated drug delivery, assembly of therapeutic implantable devices, and tissue engineering.

Biocatalytic polymer coatings: on-demand drug synthesis and localized therapeutic effect under dynamic cell culture conditions

Biocatalytic surface coatings are prepared herein for localized synthesis of drugs and their on-demand, site-specific delivery to adhering cells. This novel approach is based on the incorporation of an enzyme into multilayered polymer coatings to accomplish enzyme-prodrug therapy (EPT). The build-up of enzyme-containing multilayered coatings is characterized and correlations are drawn between the multilayer film assembly conditions and the enzymatic activity of the resulting coatings. Therapeutic effect elicited by the substrate mediated EPT (SMEPT) strategy is investigated using a prodrug for an anticancer agent, SN-38. The performance of biocatalytic coatings under flow conditions is investigated and it is demonstrated that EPT allows synthesizing the drugs on-demand, at the time desired and in a controllable amount to suit particular applications. Finally, using cells cultured in sequentially connected flow chambers, it is demonstrated that SMEPT affords a site-specific drug delivery, that is, exerts a higher therapeutic effect in cells adhering directly to the biocatalytic coatings than in the cells cultured "downstream". Taken together, these data illustrate biomedical opportunities made possible by engineering tools of EPT into multilayered polymer coatings and present a novel, highly versatile tool for surface mediated drug delivery.

Recent progress of liposomes in nanomedicine

Liposome formulations are highlighted focusing on their chemical modification, interaction with cells, and use in substrate-mediated drug delivery and cell mimicry.

Cholesterol modification of (Bio)polymers using UV-Vis traceable chemistry in aqueous solutions

Cholesterol modification of synthetic and biological polymers is achieved using of thiocholesterol (TC) and thiol-disulfide exchange. TC is reacted with Ellman's reagent to produce a mixed disulfide (TC-ER) which is activated towards thiol-disulfide exchange. TC-ER is used to obtain an inclusion complex with methyl-β-cyclodextrin, which is then employed to achieve cholesterol functionalization of a model peptide, synthetic polymers, and physical hydrogels based on poly(vinyl alcohol). It is anticipated that the established techniques will significantly broaden the use of cholesterol in bio- and nanotechnology and specifically biomedicine.

Synthesis of apolipoprotein B lipoparticles to deliver hydrophobic/amphiphilic materials

To develop a drug delivery system (DDS), it is critical to address challenging tasks such as the delivery of hydrophobic and amphiphilic compounds, cell uptake, and the metabolic fate of the drug delivery carrier. Low-density lipoprotein (LDL) has been acknowledged as the human serum transporter of natively abundant lipoparticles such as cholesterol, triacylglycerides, and lipids. Apolipoprotein B (apo B) is the only protein contained in LDL, and possesses a binding moiety for the LDL receptor that can be internalized and degraded naturally by the cell. Therefore, synthetic/reconstituting apoB lipoparticle (rABL) could be an excellent delivery carrier for hydrophobic or amphiphilic materials. Here, we synthesized rABL in vitro, using full-length apoB through a five-step solvent exchange method, and addressed its potential as a DDS. Our rABL exhibited good biocompatibility when evaluated with cytotoxicity and cell metabolic response assays, and was stable during storage in phosphate-buffered saline at 4 °C for several months. Furthermore, hydrophobic superparamagnetic iron oxide nanoparticles (SPIONPs) and the anticancer drug M4N (tetra-O-methyl nordihydroguaiaretic acid), used as an imaging enhancer and lipophilic drug model, respectively, were incorporated into the rABL, leading to the formation of SPIONPs- and M4N- containing rABL (SPIO@rABL and M4N@rABL, respectively). Fourier transform infrared spectroscopy suggested that rABL has a similar composition to that of LDL, and successfully incorporated SPIONPs or M4N. SPIO@rABL presented significant hepatic contrast enhancement in T2-weighted magnetic resonance imaging in BALB/c mice, suggesting its potential application as a medical imaging contrast agent. M4N@rABL could reduce the viability of the cancer cell line A549. Interestingly, we developed solution-phase high-resolution transmission electron microscopy to observe both LDL and SPIO@rABL in the liquid state. In summary, our LDL-based DDS, rABL, has significant potential as a novel DDS for hydrophobic and amphiphilic materials, with good cell internalization properties and metabolicity.

Lipogels: surface-adherent composite hydrogels assembled from poly(vinyl alcohol) and liposomes

Drug-eluting engineered surface coatings are of paramount importance for many biomedical applications from implantable devices to tissue engineering. Herein, we present the assembly of lipogels, composite physical hydrogels assembled from poly(vinyl alcohol) and liposomes using thiol-disulfide exchange between end group modified PVA and thiocholesterol containing liposomes, and the response of adhering cells to these coatings. We demonstrate the controlled loading of liposomes into the polymer matrix and the preserved mechanical properties of the lipogels. Furthermore, the lipogels are successfully rendered cell adhesive by incorporation of poly(l-lysine) into the PVA polymer matrix or by poly(dopamine) coating of the lipogels. The successful lipid uptake from the lipogels by macrophages, hepatocytes, and myoblasts was monitored by flow cytometry. Finally, the delivery of active cargo, paclitaxel, to adherent myoblasts is shown, thus illustrating the potential of the lipogels as a drug eluting interface for biomedical applications.