Surface engineering of liposomes for stealth behavior

Antibody-Nanoparticle Conjugates in Therapy: Combining the Best of Two Worlds

Monoclonal antibodies (mAbs) and antibody fragments have revolutionized medicine as highly specific binding agents and inhibitors. At the same time, several types of nanomaterials, including liposomes, lipid nanoparticles (NPs), polymersomes, metal and metal oxide NPs, and protein nanostructures, are increasingly utilized and explored for therapeutic potential due to their versatility, chemical and physical properties, and tunability. However, nanomaterials alone often lack specificity, leading to relatively low efficacy and/or high toxicity. To address this problem, a rapidly emerging area is antibody-nanomaterial conjugates (ANCs), which combine the precise targeting specificity of antibodies with the effector functionality of the nanomaterial. In this review, we give a brief introduction to mAbs and major conjugation techniques, describe major classes of nanomaterials being studied for therapeutic potential, and review the literature on ANCs of each class. Special focus is given to emerging applications including ANCs addressing the blood-brain barrier, ANCs delivering nucleic acids, and light-activated ANCs. While many disease targets are related to cancer, ANCs are also under development to address autoimmune, neurological, and infectious diseases. While important challenges remain, ANCs are poised to become a next-generation therapeutic technology.

Next-Gen Cancer Treatment: Nanotechnology-Driven siRNA Delivery Solutions

RNA interference through small interfering RNA (siRNA) has shown great promise as a potential cancer treatment strategy in recent years. However, the delivery of siRNA to target cancer cells efficiently remains a significant challenge. This review aims to highlight the recent advances in nanotechnology-enabled siRNA delivery for cancer treatment, bridging the gap between bench research and clinical application. A comprehensive literature search was conducted to identify recent studies focused on the utilization of nanotechnology for siRNA delivery in cancer treatment. Key databases, including PubMed, Scopus, and Web of Science, were used, and relevant articles were screened. Several nanotechnology-based platforms for siRNA delivery have emerged in recent years, providing enhanced selectivity, improved stability, and controlled release profiles. The primary types of nanocarriers discussed include lipid-based nanoparticles, inorganic nanoparticles, polymeric nanoparticles, and exosomes. Nanotechnology-based siRNA delivery systems represent a promising avenue for cancer treatment. Although significant progress has been made in preclinical studies, translating these findings to clinical applications poses several challenges, including scale-up production, safety, and targeted delivery. Nevertheless, the recent developments in this field hold great promise in revolutionizing cancer therapy, providing hope for more effective and personalized treatment options in the future.

Development, Characterization, and Antimicrobial Evaluation of Hybrid Nanoparticles (HNPs) Based on Phospholipids, Cholesterol, Colistin, and Chitosan Against Multidrug-Resistant Gram-Negative Bacteria

Background: Colistin, a lipopeptide antibiotic usually used as a last resort against multidrug-resistant bacterial strains, has also begun to address the challenge of antimicrobial resistance. Objective: this study evaluates whether hybrid nanoparticles (HNPs) composed of Phospholipon® 90G, cholesterol, and colistin can enhance its effectiveness against resistant clinical isolates of Klebsiella pneumoniae, a clinically significant Gram-negative bacterium. Methods: HNPs were developed using the ethanol injection method and coated with chitosan through a layer-by-layer technique. HNP characterization included measurements of particle size, polydispersity index (PDI), and zeta potential, along with thermal (DSC) and spectrophotometric (FT-IR) analyses. Ultrafiltration and ATR-FTIR were employed to assess colistin's association and release efficiencies. The biological evaluation followed CLSI guidelines. Results: uncoated hybrid nanoparticles (U-HNP) and chitosan-coated hybrid nanoparticles (Ch-HNP) described monodisperse populations, with respective PDI values of ~0.124 and ~0.150, Z-averages of ~249 nm and ~250 nm, and zeta potential values of +17 mV and +20 mV. Colistin's association and release efficiencies were approximately 79% and 10%, respectively. Regarding antimicrobial activity, results showed that colistin as part of HNPs is poorly effective against this microorganism. However, in the most resistant strain, colistin activity increased slightly when the HNP was coated with chitosan. Conclusions: HNPs described high stability against disaggregation, limiting the colistin release and, therefore, affecting antimicrobial performance.

The modification of conventional liposomes for targeted antimicrobial delivery to treat infectious diseases

Some of the most crucial turning points in the treatment strategies for some major infectious diseases including AIDS, malaria, and TB, have been reached with the introduction of antimicrobials and vaccines. Drug resistance and poor effectiveness are key limitations that need to be overcome. Conventional liposomes have been explored as a delivery system for infectious diseases bioactives to treat infectious diseases to provide an efficient approach to maximize the therapeutic outcomes, drug stability, targetability, to reduce the side-effects of antimicrobials, and enhance vaccine performance where necessary. However, as the pathological understanding of infectious diseases become more known, the need for more advanced liposomal technologies was born to continue having a profound effect on targeted chemotherapy for infectious diseases. This review therefore provides a concise incursion into the most recent and vogue liposomal formulations used to treat infectious diseases. An appraisal of immunological, stimuli-responsive, biomimetic and functionalized liposomes and other novel modifications to conventional liposomes is assimilated in sync with mutations of resistant pathogens.

FRET-based mesoporous organosilica nanoplatforms for in vitro and in vivo anticancer two-photon photodynamic therapy

We report the synthesis of multifunctional periodic mesoporous organosilica nanoparticles (PMO NPs) with substantial two-photon absorption properties and targeting capability for two-photon excitation fluorescence (TPEF) and photodynamic therapy (TPE-PDT). Prepared using an adapted sol-gel synthesis, the nanoplatforms integrated two silylated chromophores in their three-dimensional matrix to maximize non-radiative Förster resonance energy transfer from a high two-photon absorption fluorophore donor to a porphyrin derivative acceptor, leading to an enhanced generation of reactive oxygen species. Combinations of biodegradable and non-biodegradable bis(triethoxysilyl)alkoxysilanes were employed for the synthesis of the NPs, and the corresponding photophysical studies revealed high efficiency levels of FRET. Next, the cellular uptake and toxicities of pristine and functionalized NPs were evaluated on breast cancer cell lines upon TPEF and TPE-PDT. Notably, the use of TPE-PDT treatment led to high levels of phototoxicity on MCF-7 and MDA-MB-231 cancer cells with substantial effects when compared to one-photon excitation (OPE)-PDT treatment. Preliminary in vivo data on selective and biodegradable NPs showed a significant phototoxicity towards MDA-MB-231 on zebrafish xenograft embryos, making these advanced nanoplatforms promising candidates for future TPE-PDT-based cancer treatments.

Enhancing Gene Therapy through Ultradeformable Vesicles for Efficient siRNA Delivery

Gene therapy is a revolutionary approach aimed at treating various diseases by manipulating the expression of specific genes. The composition and formulation of ultra-deformable vesicles play a crucial role in determining their properties and performance as siRNA delivery vectors. In the development of ultra-deformable vesicles for siRNA delivery, careful lipid selection and optimization are crucial for achieving desirable vesicle characteristics and efficient siRNA encapsulation and delivery. The stratum corneum acts as a protective barrier, limiting the penetration of molecules, including siRNA, into the deeper layers of the skin. Ultradeformable vesicles offer a promising solution to overcome this barrier and facilitate efficient siRNA delivery to target cells in the skin. The stratum corneum, the outermost layer of the skin, acts as a significant barrier to the penetration of siRNA.These engineering approaches enable the production of uniform and well-defined vesicles with enhanced deformability and improved siRNA encapsulation efficiency. Looking ahead, advancements in ultra-deformable vesicle design and optimization, along with continued exploration of combination strategies and regulatory frameworks, will further drive the field of ultra-deformable vesicle-based siRNA delivery.

Liposomal Formulations: A Recent Update

Liposome-based drug delivery technologies have showed potential in enhancing medication safety and efficacy. Innovative drug loading and release mechanisms highlighted in this review of next-generation liposomal formulations. Due to poor drug release kinetics and loading capacity, conventional liposomes have limited clinical use. Scientists have developed new liposomal carrier medication release control and encapsulation methods to address these limits. Drug encapsulation can be optimized by creating lipid compositions that match a drug's charge and hydrophobicity. By selecting lipids and adding co-solvents or surfactants, scientists have increased drug loading in liposomal formulations while maintaining stability. Nanotechnology has also created multifunctional liposomes with triggered release and personalized drug delivery. Surface modification methods like PEGylation and ligand conjugation can direct liposomes to disease regions, improving therapeutic efficacy and reducing off-target effects. In addition to drug loading, researchers have focused on spatiotemporal modulation of liposomal carrier medication release. Stimuli-responsive liposomes release drugs in response to bodily signals. Liposomes can be pH- or temperature-sensitive. To improve therapeutic efficacy and reduce systemic toxicity, researchers added stimuli-responsive components to liposomal membranes to precisely control drug release kinetics. Advanced drug delivery technologies like magnetic targeting and ultrasound. Pro Drug, RNA Liposomes approach may improve liposomal medication administration. Magnetic targeting helps liposomes aggregate at illness sites and improves drug delivery, whereas ultrasound-mediated drug release facilitates on-demand release of encapsulated medicines. This review also covers recent preclinical and clinical research showing the therapeutic promise of next-generation liposomal formulations for cancer, infectious diseases, neurological disorders and inflammatory disorders. The transfer of these innovative liposomal formulations from lab to clinical practice involves key difficulties such scalability, manufacturing difficulty, and regulatory limits.

Microfluidic post-insertion of polyethylene glycol lipids and KK or RGD high functionality and quality lipids in milk-derived extracellular vesicles

To achieve the desired delivery effect, extracellular vesicles (EVs) must bypass rapid clearance from circulation and exhibit affinity for target cells; however, it is difficult to simultaneously incorporate two materials into EVs. Post-insertion is a general modification method that can be performed by simply mixing different solutions. Previously, we have developed a microfluidic post-insertion method that supported fast and upscaled modification of EVs using KK-modified high-functionality and -quality (HFQ) lipids. Here, we used microfluidic post-insertion to achieve simultaneous incorporation of polyethylene glycol (PEG) lipids and KK or RGD-modified HFQ lipids into milk-derived EVs to avoid uptake from the reticuloendothelial system and increase the uptake into target cells. PEG lipid and HFQ lipids were formulated to produce micelles and subsequently mixed with EV solution using a microfluidic device. Compared to bulk mixing, microfluidic post-insertion showed higher cellular association. Altered cellular association capacities and endocytic pathways indicated simultaneous incorporation. The cellular association of modified EVs can be adjusted by altering the ratio of (EK)4-KK in micelles with slight changes in physicochemical properties. Furthermore, microfluidic post-insertion is also suitable for (SG)5-RGD, which is insoluble in phosphate-buffered saline (PBS). Our results may be valuable for the development and manufacture of functional EVs as drug delivery systems for clinical applications.

Injectable Genetic Engineering Hydrogel for Promoting Spatial Tolerance of Transplanted Kidney in Situ

The establishment of a tolerant space to realize the co-stimulation of cytokines and contact-dependent molecules remain challenging in allotransplant. Here, an injectable genetically engineered hydrogel (iGE-Gel) is reported, which developed with a multivalent network of FOXP3 engineered extracellular vesicles (Foe-EVs) through the hydrophobic interaction between stearic acid modified hyaluronic acid (HASA) and the membrane phospholipids of extracellular vesicles (EVs). The iGE-Gel exhibited self-healing properties, injectability and biocompatibility. It is revealed that iGE-Gel displayed with abundant regulatory cytokines and coinhibitory contact molecules, promoting the formation of immune tolerance in situ. The multiplex immunohistofluorescence confirmed tolerant niches is dominated by FOXP3+ Tregs and PDL1+ cells in the allograft, which reduced the drainage of alloantigens to subcapsular sinus of lymph nodes, and suppressed the formation of germinal centers. Remarkably, the proportion of alloreactive T cells (IFN-γ/IL-2) and B cells (IgG1/IgG2a/IgG3) as well as the serum titers of donor specific antibody (DSA) is decreased by iGE-Gel. In murine allogeneic transplantation, the injection of iGE-Gel significantly alleviated immune cell infiltration and complement damage in the graft, preserved the structure and function of renal cells and prolonged recipient survival period from 30.8 to 79.3 days, highlighting the potential of iGE-Gel as a transformative treatment in allotransplant.

Calcein release from DPPC liposomes by phospholipase A2 activity: Effect of cholesterol and amphipathic copolymers

In this study, we evaluated the impact of incorporating diblock and triblock amphiphilic copolymers, as well as cholesterol into DPPC liposomes on the release of a model molecule, calcein, mediated by exogenous phospholipase A2 activity. Our findings show that calcein release slows down in the presence of copolymers at low concentration, while at high concentration, the calcein release profile resembles that of the DPPC control. Additionally, calcein release mediated by exogenous PLA2 decreases as the amount of solubilized cholesterol increases, with a maximum between 18 mol% and 20 mol%. At concentrations higher than 24 mol%, no calcein release was observed. Studies conducted on HEK-293 and HeLa cells revealed that DPPC liposomes reduced viability by only 5% and 12%, respectively, after 3 hours of incubation, while DPPC liposome in presence of 33 mol% of Cholesterol reduced viability by approximately 11% and 23%, respectively, during the same incubation period. For formulations containing copolymers at low and high concentrations, cell viability decreased by approximately 20% and 40%, respectively, after 3 hours of incubation. Based on these preliminary results, we can conclude that the presence of amphiphilic copolymers at low concentration can be used in the design of new DPPC liposomes, and together with cholesterol, they can modulate liposome stabilization. The new formulations showed low cytotoxicity in HEK-293 cells, and it was observed that calcein release depended entirely on PLA2 activity and the presence of calcium ions.

Innovative Approaches to Enhancing the Biomedical Properties of Liposomes

Liposomes represent a promising class of drug delivery systems that enhance the therapeutic efficacy and safety of various pharmaceutical agents. Also, they offer numerous advantages compared to traditional drug delivery methods, including targeted delivery to specific sites, controlled release, and fewer side effects. This review meticulously examines the methodologies employed in the preparation and characterization of liposomal formulations. With the rising incidence of adverse drug reactions, there is a pressing need for innovative delivery strategies that prioritize selectivity, specificity, and safety. Nanomedicine promises to revolutionize diagnostics and treatments, addressing current limitations and improving disease management, including cancer, which remains a major global health challenge. This paper aims to conduct a comprehensive study on the interest of biomedical research regarding nanotechnology and its implications for further applications.

Nanomedicine in HNSCC therapy-a challenge to conventional therapy

Squamous cell carcinoma of the head and neck (HNSCC) is a difficult-to-treat cancer and treatment is challenging due to recurrence or metastasis. Therefore, there is an urgent need to explore more effective targeted therapies to improve the clinical outcomes and survival of HNSCC patients. The nanomedicine is emerging as a promising strategy to achieve maximal anti-tumor effect in cancer therapy. In this review, we summarize some important signaling pathways and present the current and potential roles of various nanomaterial drug-delivery formulations in HNSCC treatment, aiming to understand the pathogenesis of HNSCC and further improve the therapeutic efficacy of nanomaterial HNSCC. This article seeks to highlight the exciting potential of novel nanomaterials for targeted cancer therapy in HNSCC and thus provide motivation for further research in this field.

The siEGFR nanoplexes for the enhanced brain glioma treatment: Endoplasmic reticulum biomimetic strategy to induce homing effect and non-degradable intracellular transport

The epidermal growth factor receptor (EGFR) plays a pivotal role in tumor progression and is an essential therapeutic target for treating malignant gliomas. Small interfering RNA (siRNA) has the potential to selectively degrade EGFR mRNA, yet its clinical utilization is impeded by various challenges, such as inefficient targeting and limited escape from lysosomes. Our research introduces polyethylene glycol (PEG) and endoplasmic reticulum membrane-coated siEGFR nanoplexes (PEhCv/siEGFR NPs) as an innovative approach to brain glioma therapy by overcoming several obstacles: 1) Tumor-derived endoplasmic reticulum membrane modifications provide a homing effect, facilitating targeted accumulation and cellular uptake; 2) Endoplasmic reticulum membrane proteins mediate a non-degradable "endosome-Golgi-endoplasmic reticulum" transport pathway, circumventing lysosomal degradation. These nanoplexes demonstrated significantly enhanced siEGFR gene silencing in both in vitro and in vivo U87 glioma models. The findings of this study pave the way for the advanced design and effective application of nucleic acid-based therapeutic nanocarriers.

Liposomes delivery systems of functional substances for precision nutrition

Natural bioactive compounds with antioxidant, antimicrobial, anticancer, and other biological activities are vital for maintaining the body's physiological functions and enhancing immunity. These compounds have great potential as nutritional therapeutic agents, but they can be limited due to their poor flavor, color, unstable nature, and poor water solubility, and degradation by gastrointestinal enzymes. Liposomes, as ideal carriers, can encapsulate both water-soluble and fat-soluble nutrients, enhance the bioavailability of functional substances, promote the biological activity of functional substances, and control the release of nutrients. Despite their potential, liposomes still face obstacles in nutrient delivery. Therefore, the design of liposomes for special needs, optimization of the liposome preparation process, enhancement of liposome encapsulation efficiency, and industrial production are key issues that must be addressed in order to develop food-grade liposomes. Moreover, the research on surface-targeted modification and surface functionalization of liposomes is valuable for expanding the scope of application of liposomes and achieving the release of functional substances from liposomes at the appropriate time and site. The establishment of in vivo and in vitro digestion models of nutrient-loaded liposomes, in-depth study of gastrointestinal digestive behavior after liposome ingestion, targeted nutrient release, and deciphering the nutritional intervention of human diseases and positive health promotion are promising fields with broad development prospects.

A Concise Review on Effect of PEGylation on the Properties of Lipid-Based Nanoparticles

Nanoparticle-based drug delivery systems have emerged as promising platforms for enhancing therapeutic efficacy while minimizing off-target effects. Among various strategies employed to optimize these systems, polyethylene glycol (PEG) modification, known as PEGylation-the covalent attachment of PEG to nanoparticles, has gained considerable attention for its ability to impart stealth properties to nanoparticles while also extending circulation time and improving biocompatibility. PEGylation extends to different drug delivery systems, in specific, nanoparticles for targeting cancer cells, where the concentration of drug in the cancer cells is improved by virtue of PEGylation. The primary challenge linked to PEGylation lies in its confirmation. Numerous research findings provide comprehensive insights into selecting PEG for various PEGylation methods. In this review, we have endeavored to consolidate the outcomes concerning the choice of PEG and diverse PEGylation techniques.

Targeted Liposomal Drug Delivery: Overview of the Current Applications and Challenges

In drug development, it is not uncommon that an active substance exhibits efficacy in vitro but lacks the ability to specifically reach its target in vivo. As a result, targeted drug delivery has become a primary focus in the pharmaceutical sciences. Since the approval of Doxil® in 1995, liposomes have emerged as a leading nanoparticle in targeted drug delivery. Their low immunogenicity, high versatility, and well-documented efficacy have led to their clinical use against a wide variety of diseases. That being said, every disease is accompanied by a unique set of physiological conditions, and each liposomal product must be formulated with this consideration. There are a multitude of different targeting techniques for liposomes that can be employed depending on the application. Passive techniques such as PEGylation or the enhanced permeation and retention effect can improve general pharmacokinetics, while active techniques such as conjugating targeting molecules to the liposome surface may bring even further specificity. This review aims to summarize the current strategies for targeted liposomes in the treatment of diseases.

The Chemical Reactivity of Membrane Lipids

It is well-known that aqueous dispersions of phospholipids spontaneously assemble into bilayer structures. These structures have numerous applications across chemistry and materials science and form the fundamental structural unit of the biological membrane. The particular environment of the lipid bilayer, with a water-poor low dielectric core surrounded by a more polar and better hydrated interfacial region, gives the membrane particular biophysical and physicochemical properties and presents a unique environment for chemical reactions to occur. Many different types of molecule spanning a range of sizes, from dissolved gases through small organics to proteins, are able to interact with membranes and promote chemical changes to lipids that subsequently affect the physicochemical properties of the bilayer. This Review describes the chemical reactivity exhibited by lipids in their membrane form, with an emphasis on conditions where the lipids are well hydrated in the form of bilayers. Key topics include the following: lytic reactions of glyceryl esters, including hydrolysis, aminolysis, and transesterification; oxidation reactions of alkenes in unsaturated fatty acids and sterols, including autoxidation and oxidation by singlet oxygen; reactivity of headgroups, particularly with reactive carbonyl species; and E/Z isomerization of alkenes. The consequences of reactivity for biological activity and biophysical properties are also discussed.

Synergistic vesicle-vector systems for targeted delivery

With the immense progress in drug delivery systems (DDS) and the rise of nanotechnology, challenges such as target specificity remain. The vesicle-vector system (VVS) is a delivery system that uses lipid-based vesicles as vectors for a targeted drug delivery. When modified with target-probing materials, these vesicles become powerful vectors for drug delivery with high target specificity. In this review, we discuss three general types of VVS based on different modification strategies: (1) vesicle-probes; (2) vesicle-vesicles; and (3) genetically engineered vesicles. The synthesis of each VVS type and their corresponding properties that are advantageous for targeted drug delivery, are also highlighted. The applications, challenges, and limitations of VVS are briefly examined. Finally, we share a number of insights and perspectives regarding the future of VVS as a targeted drug delivery system at the nanoscale.

Targeted Nano-Based Systems for the Anti-Obesity Agent's Delivery

Obesity is a global health concern and a chronic disease that is accompanied by excessive fat storage in adipose and nonadipose tissues. An increase in the body-mass index (BMI) is directly proportional to the 2- to 3.9-fold increase in all-cause mortality in obesity. If left untreated for a longer period, obesity-related metabolic, cardiovascular, inflammatory, and malignant diseases reduce life expectancy. Currently, most of the anti-obesity drugs have failed and fallen into disrepute, either due to their ineffectiveness or adverse effects. In this review, depending on their enhanced pharmacokinetic and biodistribution profiles, whether nanocarriers alter the basic properties and bioactivity of anti-obesity drugs used in clinical practice are debated. First, nanocarriers can improve the safety of still-used anti-obesity drugs by lowering their systemic toxicity through increasing targeting efficacy and preventing drug carrier toxicity. Second, when the micro-ribonucleic acids (miRNAs), which are aberrantly expressed in obesity and obesity-related diseases, are encapsulated into nanoparticles, they are effective in multiple obesity-related metabolic pathways and gene networks. Finally, a synergistic anti-obesity effect with low dose and low toxicity can be obtained with the combinatory therapy applied by encapsulating the anti-obesity drug and gene in the same nanocarrier delivery vehicle.

Advances in the Delivery and Development of Epigenetic Therapeutics for the Treatment of Cancer

Gene expression at the transcriptional level is altered by epigenetic modifications such as DNA methylation, histone methylation, and acetylation, which can upregulate, downregulate, or entirely silence genes. Pathological dysregulation of epigenetic processes can result in the development of cancer, neurological problems, metabolic disorders, and cardiovascular diseases. It is of promising therapeutic interest to find medications that target these epigenetic alterations. Despite the enormous amount of work that has been done in this area, very few molecules have been approved for clinical purposes. This article provides a comprehensive review of recent advances in epigenetic therapeutics for cancer, with a specific focus on emerging delivery and development strategies. Various delivery systems, including pro-drugs, conjugated molecules, nanoparticles (NPs), and liposomes, as well as remedial strategies such as combination therapies, and epigenetic editing, are being investigated to improve the efficacy and specificity of epigenetic drugs (epi-drugs). Furthermore, the challenges associated with available epi-drugs and the limitations of their translation into clinics have been discussed. Target selection, isoform selectivity, physiochemical properties of synthesized molecules, drug screening, and scalability of epi-drugs from preclinical to clinical fields are the major shortcomings that are addressed. This Review discusses novel strategies for the identification of new biomarkers, exploration of the medicinal chemistry of epigenetic modifiers, optimization of the dosage regimen, and design of proper clinical trials that will lead to better utilization of epigenetic modifiers over conventional therapies. The integration of these approaches holds great potential for improving the efficacy and precision of epigenetic treatments, ultimately benefiting cancer patients.

Development of an apolipoprotein E mimetic peptide-lipid conjugate for efficient brain delivery of liposomes

Liposomes are versatile carriers that can encapsulate various drugs; however, for delivery to the brain, they must be modified with a targeting ligand or other modifications to provide blood-brain barrier (BBB) permeability, while avoiding rapid clearance by reticuloendothelial systems through polyethylene glycol (PEG) modification. BBB-penetrating peptides act as brain-targeting ligands. In this study, to achieve efficient brain delivery of liposomes, we screened the functionality of eight BBB-penetrating peptides reported previously, based on high-throughput quantitative evaluation methods with in vitro BBB permeability evaluation system using Transwell, in situ brain perfusion system, and others. For apolipoprotein E mimetic tandem dimer peptide (ApoEdp), which showed the best brain-targeting and BBB permeability in the comparative evaluation of eight peptides, its lipid conjugate with serine-glycine (SG)5 spacer (ApoEdp-SG-lipid) was newly synthesized and ApoEdp-modified PEGylated liposomes were prepared. ApoEdp-modified PEGylated liposomes were effectively associated with human brain capillary endothelial cells via the ApoEdp sequence and permeated the membrane in an in vitro BBB model. Moreover, ApoEdp-modified PEGylated liposomes accumulated in the brain 3.9-fold higher than PEGylated liposomes in mice. In addition, the ability of ApoEdp-modified PEGylated liposomes to localize beyond the BBB into the brain parenchyma in mice was demonstrated via three-dimensional imaging with tissue clearing. These results suggest that ApoEdp-SG-lipid modification is an effective approach for endowing PEGylated liposomes with the brain-targeting ability and BBB permeability.

Nanoliposomes for Controlled Release of Cannabinodiol at Relevant Gastrointestinal Conditions

Cannabidiol (CBD) has significant therapeutic potential; nevertheless, its advance as an effective drug by the pharmaceutical business is hindered by its inherent characteristics, such as low bioavailability, low water solubility, and variable pharmacokinetic profiles. This research aimed to develop nanoliposomes using an easy and low-cost method to improve the hydrosolubility of CBD and achieve a controlled delivery of the active principle under relevant physiological conditions from the mouth to the intestine; the cytotoxic and antitumor activities were also evaluated. To achieve the objective, core-shell nanoliposomes based on CBD were synthesized in three easy steps and characterized in terms of shape, size, surface chemistry, thermal capacity, and surface charge density through transmission electron microscopy (TEM), dynamic light scattering (DLS), Fourier transform infrared (FTIR), thermogravimetric analysis (TGA), and potential charge (PZ), respectively. CBD-controlled delivery trials were carried out under simulated mouth-duodenal conditions and fitted to Korsmeyer-Peppas and Noyes-Whitney models to conclude about the pharmacokinetics of CBD from nano-CBD. Cytotoxicity studies on nonmalignant human keratinocytes (HaCaT) were carried out to evaluate its safety and the recommended consumption dose, and finally, the antiproliferative capacity of nano-CBD on human colon carcinoma cells (SW480) was determined as beginning proposal for cancer treatment. The characterization results verified the water solubility for the CBD nanoencapsulated, the core-shell structure, the size in the nanometric regime, and the presence of the synthesis components. The dissolution rate at duodenal conditions was higher than that in buccal and stomach environments, respectively, and this behavior was associated with the shell (lecithin) chemical structure, which destabilizes at pH above 7.2, allowing the release by non-Fickian diffusion of CBD as corroborated by the Korsmeyer-Peppas model. In vitro biological tests revealed the innocuousness and cyto-security of nano-CBD up to 1000 mg·L-1 when evaluated on HaCaT cells and concentrations higher than 1000 mg·L-1 showed antitumor activity against human colon carcinoma cells (SW480) taking the first step as a chemotherapeutic proposal. These results are unprecedented and propose a selective delivery system based on nano-CBD at low cost and that provides a new form of administration and chemo treatment.

α-Tocopherol Polyethylene Glycol 1000 Succinate-Based Cationic Liposome for the Intracellular Delivery of Doxorubicin in MDA-MB-231 Triple-Negative Breast Cancer Cell Line

Present research work reports the development of doxorubicin (DOX) loaded α-tocopherol polyethylene glycol 1000 succinate (TPGS)-coated cationic liposomes. The developed formulation was evaluated for its anticancer potential and intracellular uptake against the MDA-MB-231 breast cancer cell line. Moreover, hemocompatibility studies were also done on human blood red blood cells for the determination of blood compatibility. The prepared doxorubicin-loaded TPGS liposomes (DOX-LIPO-TPGS) and doxorubicin-loaded cationic liposomes (DOX-LIPO+-TPGS) reveal vesicle size (177.5 ± 2.5 and 201.7 ± 2.3 nm), polydispersity index (0.189 ± 0.01 and 0.218 ± 0.02), zeta potential (-36.9 ± 0.7 and 42 ± 0.9 mv), and % entrapment efficiency (65.88% ± 3.7% and 74.5% ± 3.9%). Furthermore, in vitro, drug release kinetics of the drug alone and drug from formulation shows sustained release behavior of developed formulation with 99.98% in 12 h and 80.98% release of the drug in 72 h, respectively. In addition, cytotoxicity studies and cellular DOX uptake on the MDA-MB-231 breast cancer cell line depict higher cytotoxic and drug uptake potential with better hemocompatibility of DOX-LIPO+-TPGS with respect to DOX. The data from the study revealed that TPGS plays an important role in enhancing the formulation's quality attributes like stability, drug release, cytotoxicity, and hemocompatibility behavior. This may serve that TPGS-coated cationic liposome as a vital candidate for the treatment of cancer and drug delivery in case of breast cancer.

Quantitative and functional characterisation of extracellular vesicles after passive loading with hydrophobic or cholesterol-tagged small molecules

Extracellular vesicles (EVs) are nanosized intercellular messengers that bear enormous application potential as biological drug delivery vehicles. Much progress has been made for loading or decorating EVs with proteins, peptides or RNAs using genetically engineered donor cells, but post-isolation loading with synthetic drugs and using EVs from natural sources remains challenging. In particular, quantitative and unambiguous data assessing whether and how small molecules associate with EVs versus other components in the samples are still lacking. Here we describe the systematic and quantitative characterisation of passive EV loading with small molecules based on hydrophobic interactions - either through direct adsorption of hydrophobic compounds, or by membrane anchoring of hydrophilic ligands via cholesterol tags. As revealed by single vesicle imaging, both ligand types bind to CD63 positive EVs (exosomes), however also non-specifically to other vesicles, particles, and serum proteins. The hydrophobic compounds Curcumin and Terbinafine aggregate on EVs with no apparent saturation up to 106-107 molecules per vesicle as quantified by liquid chromatography - high resolution mass spectrometry (LC-HRMS). For both compounds, high density EV loading resulted in the formation of a population of large, electron-dense vesicles as detected by quantitative cryo-transmission electron microscopy (TEM), a reduced EV cell uptake and a toxic gain of function for Curcumin-EVs. In contrast, cholesterol tagging of a hydrophilic mdm2-targeted cyclic peptide saturated at densities of ca 104-105 molecules per vesicle, with lipidomics showing addition to, rather than replacement of endogenous cholesterol. Cholesterol anchored ligands did not change the EVs' size or morphology, and such EVs retained their cell uptake activity without inducing cell toxicity. However, the cholesterol-anchored ligands were rapidly shed from the vesicles in presence of serum. Based on these data, we conclude that (1) both methods allow loading of EVs with small molecules but are prone to unspecific compound binding or redistribution to other components if present in the sample, (2) cholesterol anchoring needs substantial optimization of formulation stability for in vivo applications, whereas (3) careful titration of loading densities is warranted when relying on hydrophobic interactions of EVs with hydrophobic compounds to mitigate changes in physicochemical properties, loss of EV function and potential cell toxicity.

Specific surface modification of liposomes for gut targeting of food bioactive agents

Liposomes have become a research hotspot in recent years as food delivery systems with attractive properties, including the bilayer structure assembled like the cell membrane, reducing the side-effect and improving environmental stability of cargos, controlling release, extending duration of functional ingredients, and high biodegradable and biocompatible abilities in the body. However, the conventional liposomes lack stability during storage and are weak in targeted absorption in the gastrointestinal track. At present, surface modification has been approved to be an effective platform to shield these barricades and help liposomes deliver the agents safely and effectively to the ideal site. In this review, the gastrointestinal stability of conventional liposomes, cargo release models from liposomes, and the biological fate of the core materials after release were emphasized. Then, the strategies in both physical and chemical perspectives to improve the stability and utilization of liposomes in the gastrointestinal tract, and the emerging approaches for improving gut targeting by specifically modified liposomes and the intestinal receptors relative to liposomes/cargos absorption were highlighted. Last but not the least, the safety, challenges, and opportunities for the improvement of liposomal bioavailability were also discussed to inspire new applications of liposomes as oral carriers.

Poly(vinyl pyrrolidone) derivatives as PEG alternatives for stealth, non-toxic and less immunogenic siRNA-containing lipoplex delivery

The recent approval of Onpattro® and COVID-19 vaccines has highlighted the value of lipid nanoparticles (LNPs) for the delivery of genetic material. If it is known that PEGylation is crucial to confer stealth properties to LNPs, it is also known that PEGylation is responsible for the decrease of the cellular uptake and endosomal escape and for the production of anti-PEG antibodies inducing accelerated blood clearance (ABC) and hypersensitivity reactions. Today, the development of PEG alternatives is crucial. Poly(N-vinyl pyrrolidone) (PNVP) has shown promising results for liposome decoration but has never been tested for the delivery of nucleic acids. Our aim is to develop a series of amphiphilic PNVP compounds to replace lipids-PEG for the post-insertion of lipoplexes dedicated to siRNA delivery. PNVP compounds with different degrees of polymerization and hydrophobic segments, such as octadecyl, dioctadecyl and 1,2-distearoyl-sn-glycero-3-phosphoethanolamine (DSPE), were generated. Based on the physicochemical properties and the efficiency to reduce protein corona formation, we showed that the DSPE segment is essential for the integration into the lipoplexes. Lipoplexes post-grafted with 15% DSPE-PNVP30 resulted in gene silencing efficiency close to that of lipoplexes grafted with 15% DSPE-PEG. Finally, an in vivo study in mice confirmed the stealth properties of DSPE-PNVP30 lipoplexes as well as a lower immune response ABC effect compared to DSPE-PEG lipoplexes. Furthermore, we showed a lower immune response after the second injection with DSPE-PNVP30 lipoplexes compared to DSPE-PEG lipoplexes. All these observations suggest that DSPE-PNVP30 appears to be a promising alternative to PEG, with no toxicity, good stealth properties and lower immunological response.

Design, strategies, and therapeutics in nanoparticle-based siRNA delivery systems for breast cancer

Utilizing small interfering RNA (siRNA) as a treatment for cancer, a disease largely driven by genetic aberrations, shows great promise. However, implementing siRNA therapy in clinical practice is challenging due to its limited bioavailability following systemic administration. An attractive approach to address this issue is the use of a nanoparticle (NP) delivery platform, which protects siRNA and delivers it to the cytoplasm of target cells. We provide an overview of design considerations for using lipid-based NPs, polymer-based NPs, and inorganic NPs to improve the efficacy and safety of siRNA delivery. We focus on the chemical structure modification of carriers and NP formulation optimization, NP surface modifications to target breast cancer cells, and the linking strategy and intracellular release of siRNA. As a practical example, recent advances in the development of siRNA therapeutics for treating breast cancer are discussed, with a focus on inhibiting cancer growth, overcoming drug resistance, inhibiting metastasis, and enhancing immunotherapy.

Exosome-Based Drug Delivery: Translation from Bench to Clinic

Exosome-based drug delivery is emerging as a promising field with the potential to revolutionize therapeutic interventions. Exosomes, which are small extracellular vesicles released by various cell types, have attracted significant attention due to their unique properties and natural ability to transport bioactive molecules. These nano-sized vesicles, ranging in size from 30 to 150 nm, can effectively transport a variety of cargoes, including proteins, nucleic acids, and lipids. Compared to traditional drug delivery systems, exosomes exhibit unique biocompatibility, low immunogenicity, and reduced toxicity. In addition, exosomes can be designed and tailored to improve targeting efficiency, cargo loading capacity, and stability, paving the way for personalized medicine and precision therapy. However, despite the promising potential of exosome-based drug delivery, its clinical application remains challenging due to limitations in exosome isolation and purification, low loading efficiency of therapeutic cargoes, insufficient targeted delivery, and rapid elimination in circulation. This comprehensive review focuses on the transition of exosome-based drug delivery from the bench to clinic, highlighting key aspects, such as exosome structure and biogenesis, cargo loading methods, surface engineering techniques, and clinical applications. It also discusses challenges and prospects in this emerging field.

Advances in lipid-based carriers for cancer therapeutics: Liposomes, exosomes and hybrid exosomes

Cancer has recently surpassed heart disease as the leading cause of deaths worldwide for the age group 45-65 and has been the primary focus for biomedical researchers. Presently, the drugs involved in the first-line cancer therapy are raising concerns due to high toxicity and lack of selectivity to cancer cells. There has been a significant increase in research with innovative nano formulations to entrap the therapeutic payload to enhance efficacy and eliminate or minimize toxic effects. Lipid-based carriers stand out due to their unique structural properties and biocompatible nature. The two main leaders of lipid-based drug carriers: long known liposomes and comparatively new exosomes have been well-researched. The similarity between the two lipid-based carriers is the vesicular structure with the core's capability to carry the payload. While liposomes utilize chemically derived and altered phospholipid components, the exosomes are naturally occurring vesicles with inherent lipids, proteins, and nucleic acids. More recently, researchers have focused on developing hybrid exosomes by fusing liposomes and exosomes. Combining these two types of vesicles may offer some advantages such as high drug loading, targeted cellular uptake, biocompatibility, controlled release, stability in harsh conditions and low immunogenicity.

Milk Exosomes: Next-Generation Agents for Delivery of Anticancer Drugs and Therapeutic Nucleic Acids

Exosomes are nanovesicles 40-120 nm in diameter secreted by almost all cell types and providing humoral intercellular interactions. Given the natural origin and high biocompatibility, the potential for loading various anticancer molecules and therapeutic nucleic acids inside, and the surface modification possibility for targeted delivery, exosomes are considered to be a promising means of delivery to cell cultures and experimental animal organisms. Milk is a unique natural source of exosomes available in semi-preparative and preparative quantities. Milk exosomes are highly resistant to the harsh conditions of the gastrointestinal tract. In vitro studies have demonstrated that milk exosomes have an affinity to epithelial cells, are digested by cells by endocytosis mechanism, and can be used for oral delivery. With milk exosome membranes containing hydrophilic and hydrophobic components, exosomes can be loaded with hydrophilic and lipophilic drugs. This review covers a number of scalable protocols for isolating and purifying exosomes from human, cow, and horse milk. Additionally, it considers passive and active methods for drug loading into exosomes, as well as methods for modifying and functionalizing the surface of milk exosomes with specific molecules for more efficient and specific delivery to target cells. In addition, the review considers various approaches to visualize exosomes and determine cellular localization and bio-distribution of loaded drug molecules in tissues. In conclusion, we outline new challenges for studying milk exosomes, a new generation of targeted delivery agents.

Micro and nanotechnologies: The little formulations that could

The first publication of micro- and nanotechnology in medicine was in 1798 with the use of the Cowpox virus by Edward Jenner as an attenuated vaccine against Smallpox. Since then, there has been an explosion of micro- and nanotechnologies for medical applications. The breadth of these micro- and nanotechnologies is discussed in this piece, presenting the date of their first report and their latest progression (e.g., clinical trials, FDA approval). This includes successes such as the recent severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccines from Pfizer, Moderna, and Janssen (Johnson & Johnson) as well as the most popular nanoparticle therapy, liposomal Doxil. However, the enormity of the success of these platforms has not been without challenges. For example, we discuss why the production of Doxil was halted for several years, and the bankruptcy of BIND therapeutics, which relied on a nanoparticle drug carrier. Overall, the field of micro- and nanotechnology has advanced beyond these challenges and continues advancing new and novel platforms that have transformed therapies, vaccines, and imaging. In this review, a wide range of biomedical micro- and nanotechnology is discussed to serve as a primer to the field and provide an accessible summary of clinically relevant micro- and nanotechnology platforms.

Polysarcosine-based lipid formulations for intracranial delivery of mRNA

Messenger RNA (mRNA) is revolutionizing the future of therapeutics in a variety of diseases, including neurological disorders. Lipid formulations have shown to be an effective platform technology for mRNA delivery and are the basis for the approved mRNA vaccines. In many of these lipid formulations, polyethylene glycol (PEG)-functionalized lipid provides steric stabilization and thus plays a key role in improving the stability both ex vivo and in vivo. However, immune responses towards PEGylated lipids may compromise the use of those lipids in some applications (e.g., induction of antigen specific tolerance), or within sensitive tissues (e.g., central nervous system (CNS)). With respect to this issue, polysarcosine (pSar)-based lipopolymers were investigated as an alternative to PEG-lipid in mRNA lipoplexes for controlled intracerebral protein expression in this study. Four polysarcosine-lipids with defined sarcosine average molecular weight (M_n = 2 k, 5 k) and anchor diacyl chain length (m = 14, 18) were synthesized, and incorporated into cationic liposomes. We found that the content, pSar chain length and carbon tail lengths of pSar-lipids govern the transfection efficiency and biodistribution. Increasing carbon diacyl chain length of pSar-lipid led up to 4- and 6-fold lower protein expression in vitro. When the length of either pSar chain or lipid carbon tail increased, the transfection efficiency decreased while the circulation time was prolonged. mRNA lipoplexes containing 2.5% C14-pSar2k resulted in the highest mRNA translation in the brain of zebrafish embryos through intraventricular injection, while C18-pSar2k-liposomes showed a comparable circulation with DSPE-PEG2k-liposomes after systemic administration. To conclude, pSar-lipid enable efficient mRNA delivery, and can substitute PEG-lipids in lipid formulations for controlled protein expression within the CNS.

Preparation, Drug Distribution, and In Vivo Evaluation of the Safety of Protein Corona Liposomes for Liraglutide Delivery

The development of oral drug delivery systems is challenging, and issues related to the mucus layer and low intestinal epithelial permeability have not yet been surmounted. The purpose of this study was to develop a promising formulation that is more adapted to in vivo absorption and to facilitate the administration of oral liraglutide. Cationic liposomes (CLs) linked to AT-1002 were prepared using a double-emulsion method, and BSA was adsorbed on the surface of the AT-CLs, resulting in protein corona cationic liposomes with AT-1002 (Pc-AT-CLs). The preparation method was determined by investigating various process parameters. The particle size, potential, and encapsulation efficiency (EE%) of the Pc-AT-CLs were 202.9 ± 12.4 nm, 1.76 ± 4.87 mV, and 84.63 ± 5.05%, respectively. The transmission electron microscopy (TEM) imaging revealed a nearly spherical structure of the Pc-AT-CLs, with a recognizable coating. The circular dichroism experiments confirmed that the complex preparation process did not affect the secondary structure of liraglutide. With the addition of BSA and AT-1002, the mucosal accumulation of the Pc-AT-CLs was nearly two times lower than that of the AT-CLs, and the degree of enteric metaplasia was 1.35 times higher than that of the PcCLs. The duration of the intestinal absorption of the Pc-AT-CLs was longer, offering remarkable biological safety.

Microfluidic Post-Insertion Method for the Efficient Preparation of PEGylated Liposomes Using High Functionality and Quality Lipids

Introduction

Targeted liposomes using ligand peptides have been applied to deliver therapeutic agents to the target sites. The post-insertion method is commonly used because targeted liposomes can be prepared by simple mixing of ligand peptide-lipid and liposomes. A large-scale preparation method is required for the clinical application of ligand-peptide-modified liposomes. Large-scale preparation involves an increase in volume and a change in the preparation conditions. Therefore, the physicochemical properties of liposomes may change owing to large alterations in the preparation conditions. To address this issue, we focused on a microfluidic device and developed a novel ligand peptide modification method, the microfluidic post-insertion method.

Methods

We used integrin αvβ3-targeted GRGDS (RGD) and cyclic RGDfK (cRGD)-modified high functionality and quality (HFQ) lipids, which we had previously developed. First, the preparation conditions of the total flow rate in the microfluidic device for modifying HFQ lipids to polyethylene glycol (PEG)-modified (PEGylated) liposomes were optimized by evaluating the physicochemical properties of the liposomes. The targeting ability of integrin αvβ3-expressing colon 26 murine colorectal carcinoma cells was evaluated by comparing the cellular association properties of the liposomes prepared by the conventional post-insertion method.

Results

When the RGD-HFQ lipid was modified into PEGylated liposomes by varying the total flow rate (1, 6, and 12 mL/min) of the microfluidic device, as the total flow rate increased, the polydispersity index also increased, whereas the particle size did not change. Furthermore, the RGD- and cRGD-modified PEGylated liposomes prepared at a total flow rate of 1 mL/min showed high cellular association properties equivalent to those prepared by the conventional post-insertion method.

Conclusion

Microfluidic post-insertion method of HFQ lipids might be useful for clinical application and large-scale preparation of targeted liposomes.

PEGylation of Phosphatidylglycerol/Docosahexaenoic Acid Hexosomes with d-α-Tocopheryl Succinate Poly(ethylene glycol)2000 Induces Morphological Transformation into Vesicles with Prolonged Circulation Times

Considering the broad therapeutic potential of omega-3 polyunsaturated fatty acids such as docosahexaenoic acid (DHA), here we study the effect of PEGylation of DHA-incorporated hexosomes on their physicochemical characteristics and biodistribution following intravenous injection into mice. Hexosomes were formed from phosphatidylglycerol and DHA with a weight ratio of 3:2. PEGylation was achieved through the incorporation of either d-α-tocopheryl succinate poly(ethylene glycol)₂₀₀₀ (TPGS-mPEG₂₀₀₀) or 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-methoxy-poly(ethylene glycol)₂₀₀₀ (DSPE-mPEG₂₀₀₀) at a concentration of 1.5 wt %. Nanoparticle tracking analysis, synchrotron small-angle scattering, and cryo-transmission electron microscopy were employed to characterize the nanodispersions. The results show that PEGylated lipids induce a structural transition from an inverse hexagonal (H₂) phase inside the nanoparticles (hexosomes) to a lamellar (L_α) phase (vesicles). We also followed the effect of mouse plasma on the nanodispersion size distribution, number, and morphology because changes brought by plasma constituents could regulate the in vivo performance of intravenously injected nanodispersions. For comparative biodistribution studies, fluorescently labeled nanodispersions of equivalent quantum yields were injected intravenously into healthy mice. TPGS-mPEG₂₀₀₀-induced vesicles were most effective in avoiding hepatosplenic clearance at early time points. In an orthotopic xenograft murine model of glioblastoma, TPGS-mPEG₂₀₀₀-induced vesicles also showed improved localization to the brain compared with native hexosomes. We discuss these observations and their implications for the future design of injectable lyotropic nonlamellar liquid crystalline drug delivery nanosystems for therapeutic interventions of brain and liver diseases.

Perspectives of using microRNA-loaded nanocarriers for epigenetic reprogramming of drug resistant colorectal cancers

Epigenetic regulation by microRNAs (miRs) demonstrated a promising therapeutic potential of these molecules to regulate genetic activity in different cancers, including colorectal cancers (CRCs). The RNA-based therapy does not change genetic codes in tumor cells but can silence oncogenes and/or reactivate inhibited tumor suppressor genes. In many cancers, specific miRs were shown to promote or stop tumor progression. Among confirmed and powerful epigenetic regulators of colon carcinogenesis and development of resistance are onco-miRs, which include let-7, miR-21, miR-22, miR-23a, miR-27a, miR-34, miR-92, miR-96, miR-125b, miR-135b, miR-182, miR-200c, miR-203, miR-221, miR-421, miR-451, and others. Moreover, various tumor-suppressor miRs (miR-15b-5b, miR-18a, miR-20b, miR-22, miR-96, miR-139-5p, miR-145, miR-149, miR-197, miR-199b, miR-203, miR-214, miR-218, miR-320, miR-375-3p, miR-409-3p, miR-450b-5p, miR-494, miR-577, miR-874, and others) were found silenced in drug-resistant CRCs. Re-expression of tumor suppressor miR is complicated by the chemical nature of miRs that are not long-lasting compounds and require protection from the enzymatic degradation. Several recent studies explored application of miRs using nanocarrier complexes. This study critically describes the most successfully tested nanoparticle complexes used for intracellular delivery of nuclear acids and miRs, including micelles, liposomes, inorganic and polymeric NPs, dendrimers, and aptamers. Nanocarriers shield incorporated miRs and improve the agent stability in circulation. Attachment of antibodies and/or specific peptide or ligands facilitates cell-targeted miR delivery. Addressing in vivo challenges, a broad spectrum of non-toxic materials has been tested and indicated reliable advantages of lipid-based (lipoplexes) and polymer-based liposomes. Recent cutting-edge developments indicated that lipid-based complexes with multiple cargo, including several miRs, are the most effective approach to eradicate drug-resistant tumors. Focusing on CRC-specific miRs, this review provides a guidance and insights towards the most promising direction to achieve dramatic reduction in tumor growth and metastasis using miR-nanocarrier complexes.

Advances of engineered extracellular vesicles-based therapeutics strategy

Extracellular vesicles (EVs) are a heterogeneous population of lipid bilayer membrane-bound vesicles which encapsulate bioactive molecules, such as nucleic acids, proteins, and lipids. They mediate intercellular communication through transporting internally packaged molecules, making them attractive therapeutics carriers. Over the last decades, a significant amount of research has implied the potential of EVs servings as drug delivery vehicles for nuclear acids, proteins, and small molecular drugs. However, several challenges remain unresolved before the clinical application of EV-based therapeutics, including lack of specificity, stability, biodistribution, storage, large-scale manufacturing, and the comprehensive analysis of EV composition. Technical development is essential to overcome these issues and enhance the pre-clinical therapeutic effects. In this review, we summarize the current advancements in EV engineering which demonstrate their therapeutic potential.

Liposomal Entrapment or Chemical Modification of Relaxin2 for Prolongation of Its Stability and Biological Activity

Relaxin (RLX) is a protein that is structurally similar to insulin and has interesting biological activities. As with all proteins, preservation of RLX’s structural integrity/biological functionality is problematic. Herein, we investigated two methods for increasing the duration of relaxin-2’s (RLX2) biological activity: synthesis of a palmitoyl RLX2 conjugate (P-RLX2) with the use of a Palmitoyl-l-Glu-OtBu peptide modifier, and encapsulation into liposomes of P-RLX2, RLX2, and its oxidized form (O-RLX2). For liposomal encapsulation thin-film hydration and DRV methods were applied, and different lipid compositions were tested for optimized protein loading. RLX2 and O-RLX2 were quantified by HPLC. The capability of the peptides/conjugate to stimulate transfected cells to produce cyclic adenosine monophosphate (cAMP) was used as a measure of their biological activity. The stability and bioactivity of free and liposomal RLX2 types were monitored for a 30 d period, in buffer (in some cases) and bovine serum (80%) at 37 °C. The results showed that liposome encapsulation substantially increased the RLX2 integrity in buffer; PEGylated liposomes demonstrated a higher protection. Liposome encapsulation also increased the stability of RLX2 and O-RLX2 in serum. Considering the peptide’s biological activity, cAMP production of RLX2 was higher than that of the oxidized form and the P-RLX2 conjugate (which demonstrated a similar activity to O-RLX2 when measured in buffer, but lower when measured in the presence of serum proteins), while liposome encapsulation resulted in a slight decrease of bioactivity initially, but prolonged the peptide bioactivity during incubation in serum. It was concluded that liposome encapsulation of RLX2 and synthetic modification to P-RLX2 can both prolong RLX2 peptide in vitro stability; however, the applied chemical conjugation results in a significant loss of bioactivity (cAMP production), whereas the effect of liposome entrapment on RLX2 activity was significantly lower.

Nanomedicine and versatile therapies for cancer treatment

The higher prevalence of cancer is related to high rates of mortality and morbidity worldwide. By virtue of the properties of matter at the nanoscale, nanomedicine is proven to be a powerful tool to develop innovative drug carriers with greater efficacies and fewer side effects than conventional therapies. In this review, different nanocarriers for controlled drug release and their routes of administration have been discussed in detail, especially for cancer treatment. Special emphasis has been given on the design of drug delivery vehicles for sustained release and specific application methods for targeted delivery to the affected areas. Different polymeric vehicles designed for the delivery of chemotherapeutics have been discussed, including graft copolymers, liposomes, hydrogels, dendrimers, micelles, and nanoparticles. Furthermore, the effect of dimensional properties on chemotherapy is vividly described. Another integral section of the review focuses on the modes of administration of nanomedicines and emerging therapies, such as photothermal, photodynamic, immunotherapy, chemodynamic, and gas therapy, for cancer treatment. The properties, therapeutic value, advantages, and limitations of these nanomedicines are highlighted, with a focus on their increased performance versus conventional molecular anticancer therapies.

Stability of DMPC Liposomes Externally Conjugated with Branched Polyglycerol

Vesicles formed by DMPC liposomes externally conjugated with branched polyglycerol-dendrons as well as linear PEG in water solution were simulated using the DPD method. Such a structure of vesicles corresponds to the structure of polymer-grafted liposomes obtained experimentally by the post-insertion method, in which polymer chains are fixed on the outer surface of the liposome. The grafting density, generation number and spacer length of grafted dendrons were varied. It was shown that modification of the outer surface of liposomes due to grafting of hydrophilic dendrons has practically no effect on the size and shape of the vesicle, as well as on the morphology of the lipid membrane up to certain critical thresholds of grafting density, degree of polymerization, and generation number of grafted molecules. Exceeding the threshold values of these structural parameters leads to irreversible deformation of the lipid membrane. Diffusion through the membrane and the transition of grafted molecules from the outer surface of the liposome to the inner surface is not observed for dendrons with a generation number higher than one, even at high grafting densities. The critical values of the generation number and the characteristics of the molecular coating at these values were determined for various grafting densities and spacer lengths of the grafted chains. It was shown that the chemical potential of the grafted dendron can serve as a stability metric for the conjugated liposome. The chemical potential of grafted molecules was calculated using the mean field model of the spherical brush on the liposome surface. An analysis of the simulation data shows that, within the framework of the applicability of the mean field approach, the value of the chemical potential is a sufficient criterion for separating vesicles into stable and unstable forms. These results can be used as a guide for the experimental design of nanocontainers based on lipid vesicles with an external protective coating of branched macromolecules.

Effect of High-Frequency Ultrasound on Targeted Liposomes

Delivering highly toxic drugs inside a safe carrier to tumors while achieving controlled and effective drug release at the targeted sites represents an attractive approach to enhance drug efficiency while reducing its undesirable side effects. Functionalization of highly biocompatible nanocarriers such as liposomes conjugated with targeting moieties enhances their ability to target specific cancer cells overexpressing the targeted receptors. Furthermore, upon their accumulation at the target site, high-frequency ultrasound (HFUS) can be used to stimulate the controlled release of the loaded drugs. Here, the US-mediated drug release from calcein-loaded non-pegylated, pegylated as well as targeted-pegylated liposomes modified with human serum albumin (HSA) and transferrin (Tf) was investigated. HFUS at two different frequencies (1 MHz and 3 MHz) was found to trigger calcein release, with higher release rates recorded at the lower frequency (i.e., 1 MHz) compared to the higher frequency (i.e., 3 MHz) despite a higher power density. Pegylation was found to enhance liposomal sensitivity to HFUS. In addition, targeted pegylated liposomes were more susceptible to HFUS than non-targeted pegylated (control) liposomes. These findings show that pegylation and targeting moieties directly influence liposomal sensitivity to HFUS. Therefore, combining targeted-pegylated liposomes with HFUS represents a promising controlled and effective drug delivery system.

Inclusion Complex between Local Anesthetic/2-hydroxypropyl-β-cyclodextrin in Stealth Liposome

The drugs delivery system in the treatment of diseases has advantages such as reduced toxicity, increased availability of the drug, etc. Therefore, studies of the supramolecular interactions between local anesthetics (LAs) butamben (BTB) or ropivacaine (RVC) complexed with 2-hydroxypropyl-β-cyclodextrin (HP-βCD) and carried in Stealth liposomal (SL) are performed. ¹H-NMR nuclear magnetic resonance (DOSY and STD) were used as the main tools. The displacements observed in the ¹H-NMR presented the complexion between LAs and HP-βCD. The diffusion coefficients of free BTB and RVC were 7.70 × 10⁻¹⁰ m² s⁻¹ and 4.07 × 10⁻¹⁰ m² s⁻¹, and in the complex with HP-βCD were 1.90 × 10⁻¹⁰ m² s⁻¹ and 3.64 × 10⁻¹⁰ m² s⁻¹, respectively, which indicate a strong interaction between the BTB molecule and HP-βCD (98.3% molar fraction and Ka = 72.279 L/mol). With STD-NMR, the encapsulation of the BTB/HP-βCD and RVC/HP-βCD in SL vesicles was proven. Beyond the saturation transfer to the LAs, there is the magnetization transfer to the hydrogens of HP-βCD. BTB and RVC have already been studied in normal liposome systems; however, little is known of their behavior in SL.

pH-Sensitive Liposomes for Enhanced Cellular Uptake and Cytotoxicity of Daunorubicin in Melanoma (B16-BL6) Cell Lines

Daunorubicin (DNR) was delivered using a pH-sensitive liposomal system in B16-BL6 melanoma cell lines for enhanced cytotoxic effects. DNR was encapsulated within liposomes and CL as a component of the lipid bilayer. PEGylated pH-sensitive liposomes, containing CL, were prepared in the molar ratio of 40:30:5:17:8 for DOPE/cholesterol/DSPE-mPEG (2000)/CL/SA using the lipid film hydration method and loaded with DNR (drug: lipid ratio of 1:5). The CL liposomes exhibited high drug encapsulation efficiency (>90%), a small size (~94 nm), narrow size distribution (polydispersity index ~0.16), and a rapid release profile at acidic pH (within 1 h). Furthermore, the CL liposomes exhibited 12.5- and 2.5-fold higher cytotoxicity compared to DNR or liposomes similar to DaunoXome®. This study provides a basis for developing DNR pH-sensitive liposomes for melanoma treatment.

Unravelling Heterogeneities in Complement and Antibody Opsonization of Individual Liposomes as a Function of Surface Architecture

Coating nanoparticles with poly(ethylene glycol) (PEG) is widely used to achieve long-circulating properties after infusion. While PEG reduces binding of opsonins to the particle surface, immunogenic anti-PEG side-effects show that PEGylated nanoparticles are not truly "stealth" to surface active proteins. A major obstacle for understanding the complex interplay between opsonins and nanoparticles is the averaging effects of the bulk assays that are typically applied to study protein adsorption to nanoparticles. Here, a microscopy-based method for directly quantifying opsonization at the single nanoparticle level is presented. Various surface coatings are investigated on liposomes, including PEG, and show that opsonization by both antibodies and complement C3b is highly dependent on the surface chemistry. It is further demonstrated that this opsonization is heterogeneous, with opsonized and non-opsonized liposomes co-existing in the same ensemble. Surface coatings modify the percentage of opsonized liposomes and/or opsonin surface density on the liposomes, with strikingly different patterns for antibodies and complement. Thus, this assay provides mechanistic details about opsonization at the single nanoparticle level previously inaccessible to established bulk assays.