Permeation of nanoparticles across the intestinal lipid membrane: dependence on shape and surface chemistry studied through molecular simulations

Molecular insights reveal how the glycolipids in cell membrane mitigates nanomaterial's invasion

Nanomaterial-cellular membrane interaction is crucial for the cytotoxicity of such materials in theoretical investigations. However, previous research often used cellular membrane models with one or few lipid types, which deviates significantly from realistic membrane compositions. Here, employing molecular dynamics (MD) simulations, we investigate the impact of a typical nanomaterial, boron nitride (BN), on a cellular membrane model based on the realistic small intestinal epithelial cell (SIEC) membrane. This membrane contains a complex composition, including abundant glycolipids. Our MD simulations reveal that BN nanosheet can partially insert into the SIEC membrane, maintaining a stable binding conformation without causing obvious structural changes. Dynamic analyses suggest that van der Waals (vdW) interactions drive the binding process between BN and the SIEC membrane. Further simulation of the interaction between BN nanosheet and deglycosylated SIEC membrane confirms that BN nanosheet cause significant structural damage to deglycosylated SIEC membranes, completely inserting into the membrane, extracting lipids, and burying some lipid hydrophilic heads within the membrane interior. Quantitative analyses of mean squared displacements (MSD) of membranes, membrane thicknesses, area per lipid, and order parameters indicate that BN nanosheet causes more substantial damage to deglycosylated SIEC membrane than to intact SIEC membrane. This comparison suggests the molecular mechanism involved in mitigating BN invasion by SIEC membrane that the polysaccharide heads of glycolipids in the SIEC membrane form a significant steric hindrance on membrane surface, not only hindering the insertion of BN, but also resisting the lipid extraction by BN. Free energy calculations further support this conclusion. Overall, our MD simulations not only shed new light into the reduced impact of BN nanosheet on the realistic SIEC membrane but also highlight the importance of glycolipids in protecting cell membranes from nanomaterial invasion, contributing to a deeper understanding of nanomaterial-realistic cell membrane interactions.

Formulation and Evaluation of Meloxicam Hybrid nano Particles

The goal of the present study was to prepare meloxicam (MX) entrapped hybrid particles (HPs) to enhance intestinal permeation and anti-inflammatory activity. MX-HPs were prepared by nanoprecipitation method using lipid, chitosan, poloxamer, and TPGS. The formulations (MX-HPs1, MX-HPs2, MX-HPs3) were evaluated for particle size, entrapment efficiency, and drug release to select the optimized composition and further evaluated for permeation study, stability study, morphology, interaction study, and anti-inflammatory activity by carrageenan-induced rat paw edema test. The prepared MX-HPs showed nano sized particles (198.5 ± 3.7 to 223.8 ± 2.1 nm) and PDI (<0.3), zeta potential (16.5 ± 2.7 to 29.1 ± 3.6 mV), and high entrapment efficiency (75.1 ± 4.7 to 88.5 ± 3.9%). The surface morphology was assessed by transmission electron microscopy and showed non-aggregated particles. Infra-red (IR) spectroscopy of pure MX as well as formulation revealed no drug-polymer interaction and X-ray diffraction confirmed the conversion of crystalline MX into amorphous form. The release study data revealed prolonged MX release for 24 h. The selected optimized hybrid particles (MX-HPs2) revealed a 2.3-fold improved enhancement ratio than free MX. The storage stability and gastrointestinal stability data demonstrated a stable formulation in SIF as well as SGF. The anti-inflammatory activity showed better therapeutic action than pure MX dispersion. From the study, it can be concluded that the prepared MX-HPs may be a promising delivery system for MX in treating inflammatory disorders.

Impact of mechanical cues on key cell functions and cell-nanoparticle interactions

In recent years, it has been recognized that mechanical forces play an important regulative role in living organisms and possess a direct impact on crucial cell functions, ranging from cell growth to maintenance of tissue homeostasis. Advancements in mechanobiology have revealed the profound impact of mechanical signals on diverse cellular responses that are cell type specific. Notably, numerous studies have elucidated the pivotal role of different mechanical cues as regulatory factors influencing various cellular processes, including cell spreading, locomotion, differentiation, and proliferation. Given these insights, it is unsurprising that the responses of cells regulated by physical forces are intricately linked to the modulation of nanoparticle uptake kinetics and processing. This complex interplay underscores the significance of understanding the mechanical microenvironment in shaping cellular behaviors and, consequently, influencing how cells interact with and process nanoparticles. Nevertheless, our knowledge on how localized physical forces affect the internalization and processing of nanoparticles by cells remains rather limited. A significant gap exists in the literature concerning a systematic analysis of how mechanical cues might bias the interactions between nanoparticles and cells. Hence, our aim in this review is to provide a comprehensive and critical analysis of the existing knowledge regarding the influence of mechanical cues on the complicated dynamics of cell-nanoparticle interactions. By addressing this gap, we would like to contribute to a detailed understanding of the role that mechanical forces play in shaping the complex interplay between cells and nanoparticles.

De novo design of a nanoregulator for the dynamic restoration of ovarian tissue in cryopreservation and transplantation

The cryopreservation and transplantation of ovarian tissue underscore its paramount importance in safeguarding reproductive capacity and ameliorating reproductive disorders. However, challenges persist in ovarian tissue cryopreservation and transplantation (OTC-T), including the risk of tissue damage and dysfunction. Consequently, there has been a compelling exploration into the realm of nanoregulators to refine and enhance these procedures. This review embarks on a meticulous examination of the intricate anatomical structure of the ovary and its microenvironment, thereby establishing a robust groundwork for the development of nanomodulators. It systematically categorizes nanoregulators and delves deeply into their functions and mechanisms, meticulously tailored for optimizing ovarian tissue cryopreservation and transplantation. Furthermore, the review imparts valuable insights into the practical applications and obstacles encountered in clinical settings associated with OTC-T. Moreover, the review advocates for the utilization of microbially derived nanomodulators as a potent therapeutic intervention in ovarian tissue cryopreservation. The progression of these approaches holds the promise of seamlessly integrating nanoregulators into OTC-T practices, thereby heralding a new era of expansive applications and auspicious prospects in this pivotal domain.

Effect of GM1 concentration change on plasma membrane: molecular dynamics simulation and analysis

Ganglioside GM1 is a class of glycolipids predominantly located in the nervous system. Comprising a ceramide anchor and an oligosaccharide chain containing sialic acid, GM1 plays a pivotal role in various cellular processes, including signal transduction, cell adhesion, and membrane organization. Moreover, GM1 has been implicated in the pathogenesis of several neurological disorders, such as Parkinson's disease, Alzheimer's disease, and stroke. In this study, by creating a neural cell model membrane simulation system and employing rigorous molecular models, we utilize a coarse-grained molecular dynamics approach to explore the structural and dynamic characteristics of multi-component neuronal plasma membranes at varying GM1 ganglioside concentrations. The simulation results reveal that as GM1 concentration increases, a greater number of hydrogen bonds form between GM1 molecules, resulting in the formation of larger clusters, which leads to reduced membrane fluidity, increased lipid ordering, decreased membrane thickness and surface area and higher levels of GM1 dissociation. Through a meticulous analysis, while considering GM1's structural attributes, we offer valuable insights into the structural and dynamic traits of the cell membrane. This study provides a robust methodology for exploring membrane characteristics and enhances our comprehension of GM1 molecules, serving as a resource for both experimental and computational researchers in this field.

Biomaterials for Protein Delivery: Opportunities and Challenges to Clinical Translation

The development of biomaterials for protein delivery is an emerging field that spans materials science, bioengineering, and medicine. In this review, we highlight the immense potential of protein-delivering biomaterials as therapeutic options and discuss the multifaceted challenges inherent to the field. We address current advancements and approaches in protein delivery that leverage stimuli-responsive materials, harness advanced fabrication techniques like 3D printing, and integrate nanotechnologies for greater targeting and improved stability, efficacy, and tolerability profiles. We also discuss the demand for highly complex delivery systems to maintain structural integrity and functionality of the protein payload. Finally, we discuss barriers to clinical translation, such as biocompatibility, immunogenicity, achieving reliable controlled release, efficient and targeted delivery, stability issues, scalability of production, and navigating the regulatory landscape for such materials. Overall, this review summarizes insights from a survey of the current literature and sheds light on the interplay between innovation and the practical implementation of biomaterials for protein delivery.

The use of a complex tetra-culture alveolar model to study the biological effects induced by gold nanoparticles with different physicochemical properties

A substantial increase in engineered nanoparticles in consumer products has been observed, heightening human and environmental exposure. Inhalation represents the primary route of human exposure, necessitating a focus on lung toxicity studies. However, to avoid ethical concerns the use of in vitro models is an efficient alternative to in vivo models. This study utilized an in vitro human alveolar barrier model at air-liquid-interface with four cell lines, for evaluating the biological effects of different gold nanoparticles. Exposure to PEGylated gold nanospheres, nanorods, and nanostars did not significantly impact viability after 24 h, yet all AuNPs induced cytotoxicity in the form of membrane integrity impairment. Gold quantification revealed cellular uptake and transport. Transcriptomic analysis identified gene expression changes, particularly related to the enhancement of immune cells. Despite limited impact, distinct effects were observed, emphasizing the influence of nanoparticles physicochemical parameters while demonstrating the model's efficacy in investigating particle biological effects.

Cholesterols Induced Distinctive Entry of the Graphene Nanosheet into the Cell Membrane

Graphene nanosheets are highly valued in the biomedical field due to their potential applications in drug delivery, biological imaging, and biosensors. Their biological effects on mammalian cells may be influenced by cholesterols, which are crucial components in cell membranes that take part in many vital processes. Therefore, it is particularly important to investigate the effect of cholesterols on the transport mechanism of graphene nanosheets in the cell membrane as well as the final stable configuration of graphene, which may have an impact on cytotoxicity. In this paper, the molecular details of a graphene nanosheet interacting with a 1,2-dipalmitoyl-sn-glycero-3-phosphorylcholine (DPPC) membrane with cholesterols were studied using molecular dynamics simulations. Results showed that the structure of the graphene nanosheet transits from the cut-in state in a pure DPPC membrane to being sandwiched between two DPPC leaflets when cholesterols reach a certain concentration. The underlying mechanism showed that cholesterols are preferentially adsorbed on the graphene nanosheet, which causes a larger disturbance to the nearby DPPC tails and thus guides the graphene nanosheet into the core of lipid bilayers to form a sandwiched structure. Our results are helpful for understanding the fundamental interaction mechanism between the graphene nanosheet and cell membrane and to explore the potential applications of the graphene nanosheet in biomedical sciences.

Digestion of lipid micelles leads to increased membrane permeability

Lipid-based drug carriers are an attractive option to solubilise poorly water soluble therapeutics. Previously, we reported that the digestion of a short tail PC lipid (2C6PC) by the PLA2 enzyme has a significant effect on the structure and stability of the micelles it forms. Here, we studied the interactions of micelles of varying composition representing various degrees of digestion with a model ordered (70 mol% DPPC & 30 mol% cholesterol) and disordered (100% DOPC) lipid membrane. Micelles of all compositions disassociated when interacting with the two different membranes. As the percentage of digestion products (C6FA and C6LYSO) in the micelle increased, the disassociation occurred more rapidly. The C6FA inserts preferentially into both membranes. We find that all micelle components increase the area per lipid, increase the disorder and decrease the thickness of the membranes, and the 2C6PC lipid molecules have the most significant impact. Additionally, there is an increase in permeation of water into the membrane that accompanies the insertion of C6FA into the DOPC membranes. We show that the natural digestion of lipid micelles result in molecular species that can enhance the permeability of lipid membranes that in turn result in an enhanced delivery of drugs.

Combination of Backbone Rigidity and Richness in Aryl Structures Enables Direct Membrane Translocation of Polymer Scaffolds for Efficient Gene Delivery

The development of cell-penetrating polymers with endocytosis-independent cell uptake pathways has emerged as a prominent strategy to enhance the transfection efficiency. Inspired by the rigid α-helical structure that endows polypeptides with cell-penetrating ability, we propose that a rigid backbone can facilitate the corresponding polymer vector's performance in gene delivery by bypassing the difficult endosomal escape process. Meanwhile, the installation of aromatic domains, as a way to promote gene transfection efficiency, is employed through the construction of a poly(benzyl ether) (PBE)-based scaffold in this work. We demonstrate that the direct membrane translocation capability of the synthesized PBE contributes to its enhanced transfection performance and excellent biocompatibility profile, rendering the imidazolium-functionalized PBE scaffold with higher activity and biocompatibility. Molecular details of the PBE-lipid interaction are also revealed in molecular dynamics simulations, indicating the important roles of individual structural elements on the polymeric scaffold in the membrane penetration process.

Enhancing the Gene Transfection of Poly(β-amino ester)/DNA Polyplexes by Modular Manipulation of Amphiphilicity

Poly(β-amino ester)s (PAEs) have been widely developed for gene delivery, and hydrophobic modification can further enhance their gene transfection efficiency. However, systematic manipulation of amphiphilicity of PAEs through copolymerization with hydrophobic monomers is time-consuming and, to some extent, uncontrollable. Here, a modular strategy is developed to manipulate the amphiphilicity of the PAE/DNA polyplexes. A hydrophobic polymer (DD-C12-122) and a hydrophilic polymer (DD-90-122) are synthesized separately and used as a hydrophobic module and a hydrophilic module, respectively. The amphiphilicity of polyplexes could be manipulated by changing the ratio of the hydrophobic module and hydrophilic module. Using the modular strategy, the PAE/DNA polyplexes with the highest gene transfection efficiency and safety profile as well as possible mechanisms are identified. The modular strategy provides a novel way to engineer the hydrophobicity of PAEs to improve their gene transfection and can be easily generalized and potentially extended to other polymeric gene delivery systems.

Emerging non-viral vectors for gene delivery

Gene therapy holds great promise for treating a multitude of inherited and acquired diseases by delivering functional genes, comprising DNA or RNA, into targeted cells or tissues to elicit manipulation of gene expression. However, the clinical implementation of gene therapy remains substantially impeded by the lack of safe and efficient gene delivery vehicles. This review comprehensively outlines the novel fastest-growing and efficient non-viral gene delivery vectors, which include liposomes and lipid nanoparticles (LNPs), highly branched poly(β-amino ester) (HPAE), single-chain cyclic polymer (SCKP), poly(amidoamine) (PAMAM) dendrimers, and polyethyleneimine (PEI). Particularly, we discuss the research progress, potential development directions, and remaining challenges. Additionally, we provide a comprehensive overview of the currently approved non-viral gene therapeutics, as well as ongoing clinical trials. With advances in biomedicine, molecular biology, materials science, non-viral gene vectors play an ever-expanding and noteworthy role in clinical gene therapy.

Recent Progress in the Characterization, Synthesis, Delivery Procedures, Treatment Strategies, and Precision of Antimicrobial Peptides

Infectious diseases are constantly evolving to bypass antibiotics or create resistance against them. There is a piercing alarm for the need to improve the design of new effective antimicrobial agents such as antimicrobial peptides which are less prone to resistance and possess high sensitivity. This would guard public health in combating and overcoming stubborn pathogens and mitigate incurable diseases; however, the emergence of antimicrobial peptides' shortcomings ranging from untimely degradation by enzymes to difficulty in the design against specific targets is a major bottleneck in achieving these objectives. This review is aimed at highlighting the recent progress in antimicrobial peptide development in the area of nanotechnology-based delivery, selectivity indices, synthesis and characterization, their doping and coating, and the shortfall of these approaches. This review will raise awareness of antimicrobial peptides as prospective therapeutic agents in the medical and pharmaceutical industries, such as the sensitive treatment of diseases and their utilization. The knowledge from this development would guide the future design of these novel peptides and allow the development of highly specific, sensitive, and accurate antimicrobial peptides to initiate treatment regimens in patients to enable them to have accommodating lifestyles.

Design, Synthesis, and Comparison of PLA-PEG-PLA and PEG-PLA-PEG Copolymers for Curcumin Delivery to Cancer Cells

Curcumin (CUR) has potent anticancer activities, and its bioformulations, including biodegradable polymers, are increasingly able to improve CUR's solubility, stability, and delivery to cancer cells. In this study, copolymers comprising poly (L-lactide)-poly (ethylene glycol)-poly (L-lactide) (PLA-PEG-PLA) and poly (ethylene glycol)-poly (L-lactide)-poly (ethylene glycol) (PEG-PLA-PEG) were designed and synthesized to assess and compare their CUR-delivery capacity and inhibitory potency on MCF-7 breast cancer cells. Molecular dynamics simulations and free energy analysis indicated that PLA-PEG-PLA has a higher propensity to interact with the cell membrane and more negative free energy, suggesting it is the better carrier for cell membrane penetration. To characterize the copolymer synthesis, Fourier transform-infrared (FT-IR) and proton nuclear magnetic resonance (¹H-NMR) were employed, copolymer size was measured using dynamic light scattering (DLS), and their surface charge was determined by zeta potential analysis. Characterization indicated that the ring-opening polymerization (ROP) reaction was optimal for synthesizing high-quality polymers. Microspheres comprising the copolymers were then synthesized successfully. Of the two formulations, PLA-PEG-PLA experimentally exhibited better results, with an initial burst release of 17.5%, followed by a slow, constant release of the encapsulated drug up to 80%. PLA-PEG-PLA-CUR showed a significant increase in cell death in MCF-7 cancer cells (IC₅₀ = 23.01 ± 0.85 µM) based on the MTT assay. These data were consistent with gene expression studies of Bax, Bcl2, and hTERT, which showed that PLA-PEG-PLA-CUR induced apoptosis more efficiently in these cells. Through the integration of nano-informatics and in vitro approaches, our study determined that PLA-PEG-PLA-CUR is an optimal system for delivering curcumin to inhibit cancer cells.

Flowing through Gastrointestinal Barriers with Model Nanoparticles: From Complex Fluids to Model Human Intestinal Epithelium Permeation

Most nanomaterial-based medicines are intravenously applied since oral administration comprises challenging-related biological obstacles, such as interactions with distinct digestive fluids and their transport through the intestinal barrier. Moreover, there is a lack of nanoparticle-based studies that faithfully consider the above-cited obstacles and boost oral-administered nanomedicines' rational design. In this study, the physicochemical stability of fluorescent model silica nanoparticles (f-SiO₂NPs) passing through all simulated gastrointestinal fluids (salivary, gastric, and intestinal) and their absorption and transport across a model human intestinal epithelium barrier are investigated. An aggregation/disaggregation f-SiO₂NPs process is identified, although these particles remain chemically and physically stable after exposure to digestive fluids. Further, fine imaging of f-SiO₂NPs through the absorption and transport across the human intestinal epithelium indicates that nanoparticle transport is time-dependent. The above-presented protocol shows tremendous potential for deciphering fundamental gastrointestinal nanoparticles' evolution and can contribute to rational oral administration-based nanomedicine design.

Elucidating collective translocation of nanoparticles across the skin lipid matrix: a molecular dynamics study

The top layer of skin, the stratum corneum, provides a formidable barrier to the skin. Nanoparticles are utilized and further explored for personal and health care applications related to the skin. In the past few years, several researchers have studied the translocation and permeation of nanoparticles of various shapes, sizes, and surface chemistry through cell membranes. Most of these studies focused on a single nanoparticle and a simple bilayer system, whereas skin has a highly complex lipid membrane architecture. Moreover, it is highly unlikely that a nanoparticle formulation applied on the skin will not have multiple nanoparticle-nanoparticle and skin-nanoparticle interactions. In this study, we have utilized coarse-grained MARTINI molecular dynamics simulations to assess the interactions of two types (bare and dodecane-thiol coated) of nanoparticles with two models (single bilayer and double bilayer) of skin lipid membranes. The nanoparticles were found to be partitioned from the water layer to the lipid membrane as an individual entity as well as in the cluster form. It was discovered that each nanoparticle reached the interior of both single bilayer and double bilayer membranes irrespective of the nanoparticle type and concentration, though coated particles were observed to efficiently traverse across the bilayer when compared with bare particles. The coated nanoparticles also created a single large cluster inside the membrane, whereas the bare nanoparticles were found in small clusters. Both the nanoparticles exhibited preferential interactions with cholesterol molecules present in the lipid membrane as compared to other lipid components of the membrane. We have also observed that the single membrane model exhibited unrealistic instability at moderate to higher concentrations of nanoparticles, and hence for translocation study, a minimum double bilayer model should be employed.

Stochastic Approximation to MBAR and TRAM: Batchwise Free Energy Estimation

The dynamics of molecules are governed by rare event transitions between long-lived (metastable) states. To explore these transitions efficiently, many enhanced sampling protocols have been introduced that involve using simulations with biases or changed temperatures. Two established statistically optimal estimators for obtaining unbiased equilibrium properties from such simulations are the multistate Bennett acceptance ratio (MBAR) and the transition-based reweighting analysis method (TRAM). Both MBAR and TRAM are solved iteratively and can suffer from long convergence times. Here, we introduce stochastic approximators (SA) for both estimators, resulting in SAMBAR and SATRAM, which are shown to converge faster than their deterministic counterparts, without significant accuracy loss. Both methods are demonstrated on different molecular systems.

Polymeric nanoparticles and nanomicelles of hydroxychloroquine co-loaded with azithromycin potentiate anti-SARS-CoV-2 effect

The outbreak of coronavirus (COVID-19) has put the world in an unprecedented scenario. To reestablish the world routine as promote the effective treatment of this disease, the world is looking for new (and old) drug that can efficiently kill the virus. In this study, we have developed two nanosystems: polymeric nanoparticles and nanomicelles-based on hydroxychloroquine and azithromycin. The nanosystem was fully characterized by AFM and DLS techniques. Also, the nanosystems were radiolabeled with ^99mTc and pulmonary applied (installation) in vivo to evaluate the biological behavior. The toxicity of both nanosystem were evaluated in primary cells (FGH). Finally, both nanosystems were evaluated in vitro against the SARS-CoV-2. The results demonstrated that the methodology used to produce the nanomicelles and the nanoparticle was efficient, the characterization showed a nanoparticle with a spherical shape and a medium size of 390 nm and a nanomicelle also with a spherical shape and a medium size of 602 nm. The nanomicelles were more efficient (~ 70%) against SARS-CoV-2 than the nanoparticles. The radiolabeling process with ^99mTc was efficient (> 95%) in both nanosystems and the pulmonary application demonstrated to be a viable route for both nanosystems with a local retention time of approximately, 24 h. None of the nanosystems showed cytotoxic effect on FGH cells, even in high doses, corroborating the safety of both nanosystems. Thus, claiming the benefits of the nanotechnology, especially with regard the reduced adverse we believe that the use of nanosystems for COVID-19 treatment can be an optimized choice.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s40097-022-00476-3.

Ideal Conductor Model: An Analytical Finite-Size Correction for Nonequilibrium Molecular Dynamics Simulations of Ion Transport through Nanoporous Membranes

Modulating ion transport through nanoporous membranes is critical to many important chemical and biological separation processes. The corresponding transport timescales, however, are often too long to capture accurately using conventional molecular dynamics (MD). Recently, path sampling techniques, such as forward-flux sampling (FFS), have emerged as attractive alternatives for efficiently and accurately estimating arbitrarily long ionic passage times. Here, we use non-equilibrium MD and FFS to explore how the kinetics and mechanisms of pressure-driven chloride transport through a nanoporous graphitic membrane are affected by its lateral dimensions. We not only find ionic passage times and free energy barriers to decrease dramatically upon increasing the membrane surface area but also observe an abrupt and discontinuous change in the locus of the transition state. These strong finite size effects arise due to the cumulative effect of the periodic images of the leading ion entering the pore on the distribution of the induced excess charge at the membrane surface in the feed. By assuming that the feed is an ideal conductor, we analytically derive a finite size correction term that can be computed from the information obtained from a single simulation and successfully use it to obtain corrected free energy profiles with no dependence on the system size. We then estimate ionic passage times in the thermodynamic limit by assuming an Eyring-type dependence of rates on barriers with a size-independent prefactor. This approach constitutes a universal framework for removing finite size artifacts in molecular simulations of ion transport through nanoporous membranes and biological channel proteins.

Surface and Structure of Phosphatidylcholine Membranes Reconstructed with CoFe2O4 Nanoparticles

Structural changes in phosphatidylcholine lipid membranes caused by the introduction of insoluble CoFe₂O₄ nanoparticles (NPs) are analyzed. Changes in nuclear magnetic resonance spectrum, infrared spectrum, and ionic conductivity of membranes are observed with the addition of NPs. The presence of NPs in membranes is proved by atomic force and magnetic force microscopy. Structural changes in the membranes in the vicinity of the lipid C-O bonds caused by NPs are observed by Scanning near-field optical microscopy. Analysis of nuclear magnetic resonance (NMR) spectra allowed us to identify the affected atomic groups in the membrane surface layers. Conductivity measurements of the bilayer membranes were performed in DC as well as in time-resolved modes. Hydrophobic NPs stimulate surface distortion and creation of pores, which depending on NP concentration leads to an increase in the ionic conductivity of membranes. Concentration dependence demonstrating percolation threshold was analyzed in the frame of the fractal theory approach.

Ethyl lauroyl arginate-based hydrophobic ion pair complex in lipid nanocapsules: A novel oral delivery approach of rosmarinic acid for enhanced permeability and bioavailability

Limited oral bioavailability due to high hydrophilicity restricts the beneficial use of Rosmaranic acid (RM) that is characterized by many biological and pharmacological effects. The present work was addressed to extract RM from Rosmarinus officinalis L. leaves and then increase its lipophilicity and permeability through the application of hydrophobic ion pair (HIP) approach using ethyl lauroyl arginate (ELA) as a novel counter-ion. Different RM:ELA ratios were screened to optimize HIP formation process. The encapsulation of the optimized HIP into lipid nanocapsules (LNCs) was then achieved to facilitate oral administration. The results of % transmittance, % complexation efficiency (87.32 ± 0.19%) and partition coefficient revealed the successful formation of the HIP complex occurred at RM:ELA molar ratio of 1:2. The formed HIP was successfully loaded into spherical small sized (39.32 ± 0.18 nm) LNCs. The ex vivo permeability studies across porcine intestine showed that the cumulative RM amount permeated/area after 6 h from HIP and LNCs were 3.79 ± 0.57 and 5.71 ± 0.32 µg/cm², respectively. Pharmacokinetic study results showed that the maximum RM concentrations in plasma (C_max) can be arranged in a descending manner as follows; 61.33 ± 8.89 < 42.13 ± 11.22 < 20.96 ± 3.12 ng/ml attained after 4.80, 8.00 and 10.40 h in case of LNC, HIP and solution, respectively. Moreover, the HIP and LNC formulae showed higher total drug amounts in plasma reaching 1.46 and 1.88-fold relative to RM solution, respectively. In conclusion, the HIP complex and HIP loaded LNCs prosper in enhancing the permeability and absorption of the low permeable drugs.

A Core-Shell Approach for Systematically Coarsening Nanoparticle-Membrane Interactions: Application to Silver Nanoparticles

The continuous release of engineered nanomaterial (ENM) into the environment may bring about health concerns following human exposure. One important source of ENMs are silver nanoparticles (NPs) that are extensively used as anti-bacterial additives. The introduction of ENMs into the human body can occur via ingestion, skin uptake or the respiratory system. Therefore, evaluating how NPs translocate over bio-membranes is essential in assessing their primary toxicity. Unfortunately, data regarding membrane-NP interaction is still scarce, as is theoretical and in silico insight into what governs adhesion and translocation for the most relevant NPs and membranes. Coarse-grained (CG) molecular descriptions have the potential to alleviate this situation, but are hampered by the absence of a direct link to NP materials and membrane adhesion mechanisms. Here, we interrogate the relationship between the most common NP representation at the CG level and the adhesion characteristics of a model lung membrane. We find that this representation for silver NPs is non-transferable, meaning that a proper CG representation for one size is not suited for other sizes. We also identify two basic types of primary adhesion-(partial) NPs wrapping by the membrane and NP insertion into the membrane-that closely relate to the overall NP hydrophobicity and significantly differ in terms of lipid coatings. The proven non-transferability of the standard CG representation with size forms an inspiration for introducing a core-shell model even for bare NPs that are uniform in composition. Using existing all-atom molecular dynamics (MD) data as a reference, we show that this extension does allow us to reproduce size-dependent NP adhesion properties and lipid responses to NP binding at the CG level. The subsequent CGMD evaluation for 10 nm Ag NPs provides new insight into membrane binding for relevant NP sizes and into the role of water in trapping NPs into defected mixed monolayer-bilayer states. This development will be instrumental for simulating NP-membrane adhesion towards more experimentally relevant length and time scales for particular NP materials.

Generic prediction of exocytosis rate constants by size-based surface energies of nanoparticles and cells

Nanotechnology brings benefits in fields such as biomedicine but nanoparticles (NPs) may also have adverse health effects. The effects of surface-modified NPs at the cellular level have major implications for both medicine and toxicology. Semi-empirical and mechanism-based models aid to understand the cellular transport of various NPs and its implications for quantitatively biological exposure while avoiding large-scale experiments. We hypothesized relationships between NPs-cellular elimination, surface functionality and elimination pathways by cells. Surface free energy components were used to characterize the transport of NPs onto membranes and with lipid vesicles, covering both influences by size and hydrophobicity of NPs. The model was built based on properties of neutral NPs and cells, defining Van de Waals forces, electrostatic forces and Lewis acid-base (polar) interactions between NPs and vesicles as well as between vesicles and cell membranes. We yielded a generic model for estimating exocytosis rate constants of various neutral NPs by cells based on the vesicle-transported exocytosis pathways. Our results indicate that most models are well fitted (R² ranging from 0.61 to 0.98) and may provide good predictions of exocytosis rate constants for NPs with differing surface functionalities (prediction errors are within 2 times for macrophages). Exocytosis rates differ between cancerous cells with metastatic potential and non-cancerous cells. Our model provides a reference for cellular elimination of NPs, and intends for medical applications and risk assessment.

Permeation of flavonoid loaded human serum albumin nanoparticles across model membrane bilayers

The rapid growth in the applications of nanoparticles (NPs) in biomedical and pharmaceutical fields requires an understanding of the interactions with the lipid bilayer membrane for further in vivo studies. Zwitterionic 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC), negatively charged 1,2-dioleoyl-sn-glycero-3-phospho-l-serine (DOPS) and positively charged 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE) have been used to prepare model lipid membranes and the ability of flavonoid loaded nanoparticles to cross the membranes investigated. The lipid vesicles have been prepared by a freeze-thaw method followed by an extrusion technique and characterised by dynamic light scattering (DLS) and high-resolution transmission electron microscopy (HRTEM). The synthesized model lipid membranes exhibited a bilayer spherical type of morphology with an average diameter of less than 150 nm. A calcein leakage assay and fluorescence anisotropy measurement indicated that the membranes are permeable to the flavonoid (fisetin/morin/epicatechin) loaded human serum albumin nanoparticles. This implies that drug/compound encapsulated nanoparticles are able to effectively cross the lipid bilayer thus permitting the design and development of new compounds that may be encapsulated for safe and potential use in biomedical applications.

Enhanced Oral Absorption and Liver Distribution of Polymeric Nanoparticles through Traveling the Enterohepatic Circulation Pathways of Bile Acid

The intestinal epithelium is known to be a main hindrance to oral delivery of nanoparticles. Even though surface ligand modification can enhance cellular uptake of nanoparticles, the "easy entry and hard across" was frequently observed for many active targeting nanoparticles. Here, we fabricated polymeric nanoparticles relayed by bile acid transporters with monomethoxy poly(ethylene glycol)-poly(D,l-lactide) and deoxycholic acid-conjugated poly(2-ethyl-2-oxazoline)-poly(D,l-lactide) based on structural characteristics of intestine epithelium and the absorption characteristics of endogenous substances. As anticipated, deoxycholic acid-modified polymeric nanoparticles featuring good stability in simulated gastrointestinal fluid could notably promote the internalization of their payload by Caco-2 cells through mediation of apical sodium-dependent bile acid transporter (ASBT) and transmembrane transport of the nanoparticles across Caco-2 cell monolayers via relay-guide of ASBT, ileal bile acid-binding protein, and the heteromeric organic solute transporter (OSTα-OSTβ) along with multidrug resistance-associated protein 3 (MRP3) evidenced by competitive inhibition and fluorescence immunoassay, which was further visually confirmed by the stronger fluorescence from C6-labeled nanoparticles inside enterocytes and the basal side of the intestinal epithelium of mice. The transcellular transport of deoxycholic acid-modified nanoparticles in an intact form was mediated by caveolin/lipid rafts and clathrin with intracellular trafficking trace of endosome-lysosome-ER-Golgi apparatus and bile acid transport route. Furthermore, the increased uptake by HepG2 cells compared with unmodified nanoparticles evidenced the target ability of deoxycholic acid-modified nanoparticles to the liver, which was further supported by ex vivo imaging of excised major organs of mice. Thus, this study provided a feasible and potential strategy to further enhance transepithelial transport efficiency and liver-targeted ability of nanoparticles by means of the specific enterohepatic circulation pathways of bile acid.

Harnessing Lipid Polymer Hybrid Nanoparticles for Enhanced Oral Bioavailability of Thymoquinone: In Vitro and In Vivo Assessments

The clinical application of phytochemicals such as thymoquinone (THQ) is restricted due to their limited aqueous solubility and oral bioavailability. Developing mucoadhesive nanocarriers to deliver these natural compounds might provide new hope to enhance their oral bioavailability. Herein, this investigation aimed to develop THQ-loaded lipid-polymer hybrid nanoparticles (THQ-LPHNPs) based on natural polymer chitosan. THQ-LPHNPs were fabricated by the nanoprecipitation technique and optimized by the 3-factor 3-level Box−Behnken design. The optimized LPHNPs represented excellent properties for ideal THQ delivery for oral administration. The optimized THQ-LPHNPs revealed the particles size (PS), polydispersity index (PDI), entrapment efficiency (%EE), and zeta potential (ZP) of <200 nm, <0.25, >85%, and >25 mV, respectively. THQ-LPHNPs represented excellent stability in the gastrointestinal milieu and storage stability in different environmental conditions. THQ-LPHNPs represented almost similar release profiles in both gastric as well as intestinal media with the initial fast release for 4 h and after that a sustained release up to 48 h. Further, the optimized THQ-LPHNPs represent excellent mucin binding efficiency (>70%). Cytotoxicity study revealed much better anti-breast cancer activity of THQ-LPHNPs compared with free THQ against MDA-MB-231 and MCF-7 breast cancer cells. Moreover, ex vivo experiments revealed more than three times higher permeation from the intestine after THQ-LPHNPs administration compared to the conventional THQ suspension. Furthermore, the THQ-LPHNPs showed 4.74-fold enhanced bioavailability after oral administration in comparison with the conventional THQ suspension. Therefore, from the above outcomes, mucoadhesive LPHNPs might be suitable nano-scale carriers for enhanced oral bioavailability and therapeutic efficacy of highly lipophilic phytochemicals such as THQ.

Selective membrane wrapping on differently sized nanoparticles regulated by clathrin assembly: A computational model

Nanoparticles (NPs) enter cells via multiple pathways, all of which are NP size dependent. Previous studies indicated that the clathrin-mediated endocytosis has different selectivity for the NP size, but the regulatory mechanism remains unclear and difficult to study at the molecular scale in vivo. By means of computer simulation, here we design membrane wrapping on differently sized NPs with mimic clathrin assembly at the opposite membrane side. With relatively large NPs readily wrapped by a pure membrane as manifested, clathrin modulates the process and tunes the size selectivity. Although finite curvature can be generated by cage-like clathrin assembly to facilitate membrane wrapping on relatively small NPs, the clathrin assemblage has a certain range of size, which is mismatched with larger NPs. Besides, the local membrane patch is rigidified by clathrin to increase the barrier of membrane wrapping on larger NPs. Competition of these items determines whether membrane wrapping on NPs is promoted or suppressed, and can be tuned by the NP-membrane adhesion strength, clathrin concentration, and inter-NP distance. Our results highlight the significance of complex environment in altering the nature of NP interaction with cell membranes, and are expected to help design NPs for biomedical applications requiring precise control of NP uptake or cell membrane attachment.

Advances in oral peptide drug nanoparticles for diabetes mellitus treatment

Peptide drugs play an important role in diabetes mellitus treatment. Oral administration of peptide drugs is a promising strategy for diabetes mellitus because of its convenience and high patient compliance compared to parenteral administration routes. However, there are a series of formidable unfavorable conditions present in the gastrointestinal (GI) tract after oral administration, which result in the low oral bioavailability of these peptide drugs. To overcome these challenges, various nanoparticles (NPs) have been developed to improve the oral absorption of peptide drugs due to their unique in vivo properties and high design flexibility. This review discusses the unfavorable conditions present in the GI tract and provides the corresponding strategies to overcome these challenges. The review provides a comprehensive overview on the NPs that have been constructed for oral peptide drug delivery in diabetes mellitus treatment. Finally, we will discuss the rational application and give some suggestions that can be utilized for the development of oral peptide drug NPs. Our aim is to provide a systemic and comprehensive review of oral peptide drug NPs that can overcome the challenges in GI tract for efficient treatment of diabetes mellitus.

•Oral administration of peptide drugs is a promising strategy for diabetes mellitus treatment

•A series of formidable unfavorable conditions in gastrointestinal tract result in the low oral bioavailability of peptide drugs

•Nanoparticles can improve the oral bioavailability of peptide drugs

Molecular insights into the resistance of phospholipid heads to the membrane penetration of graphene nanosheets

The interaction between nanomaterials and phospholipid membranes underlies many emerging biological applications. To what extent hydrophilic phospholipid heads shield the bilayer from the integration of hydrophobic nanomaterials remains unclear, and this open question contains important insights for understanding biological membrane physics. Here, we present molecular dynamics (MD) simulations to clarify the resistance of phospholipid heads to the membrane penetration of graphene nanosheets. With 130 simulation trials, we observed that ∼22% graphene nanosheets penetrate the POPC bilayer. Sharp corners of the nanosheets should have a lower energy barrier than nanosheet edges, but interestingly, the membrane penetration mainly starts from the edge-approaching orientation. We thoroughly analyzed the pentration pathway and propulsion, indicating that the membrane penetration of graphene nanosheets is dominated by the joint effects of nanosheet edges and corners. Furthermore, the molecular origin of the resistance is clarified by evaluating the bilayers of different phospholipids, which successfully correlates the penetration resistance of phospholipid heads with the correlated motions of neighboring phospholipids for the first time. These results are expected to inspire future studies on the dynamic behavior of phospholipids, bio-nano interfaces, and design of biological nanomaterials.

Protective Effect of Nanoparticles from Platycladi Cacumen Carbonisata on 2,4,6-Trinitrobenzene Sulfonic Acid (TNBS)-Induced Colitis in Rats

Aim: To evaluate the protective effects of Platycladi Cacumen Carbonisata-derived nanoparticles (PCC-NPs) against 2,4,6-trinitrobenzenesulfonic acid (TNBS)-induced ulcerative colitis (UC) in rats. Methods: This study developed and characterized novel PCC-NPs synthesized by a green and simple pyrolysis process using Platycladi Cacumen (PC) as the sole precursor. The UC model prepared with rectal instillation of TNBS was used to evaluate the potential efficacy of PCC-NPs, and the underlying mechanisms were preliminarily explored from the perspective of anti-inflammatory and antioxidative stress for the first time. Results: PCC-NPs exhibited low cytotoxicity, good dispersibility and copious surface functional groups. Nanoparticles with diameters ranging from 40-60 nm mainly manifested a therapeutic effect by downregulating tumour necrosis factor-α (TNF-α), interleukin-6 (IL-6) and upregulating interleukin-10 (IL-10). In addition, PCC-NPs relieved colon injury by inhibiting myeloperoxidase (MPO) activity, limiting the release of malondialdehyde (MDA) and increasing the activity of superoxide dismutase (SOD). Conclusion: Green synthetic PCC-NPs is a potential candidate as a complementary drug for intestinal inflammation of inflammatory bowel disease, and its regulatory mechanisms may be to balance the levels of pro-/anti-inflammatory cytokines and improve resistance to oxidative stress.

Complex nanoemulsion for vitamin delivery: droplet organization and interaction with skin membranes

Lipid nanoemulsions are promising nanomaterials for drug delivery applications in food, pharmaceutical and cosmetic industries. Despite the noteworthy commercial interest, little is known about their supramolecular organization, especially about how such multicomponent formulations interact with cell membranes. In the present work, coarse-grained molecular dynamics simulations have been employed to study the self-assembly of a 15-component lipid nanoemulsion droplet containing vitamins A and E for skin delivery. Our results display aspects of the unique "onion-like" agglomeration between the chemical constituents in the different layers of the lipid nanodroplet. Vitamin E molecules are more concentrated in the center of the droplet together with other hydrophobic constituents such as the triglycerides with long tails. On the other hand, vitamin A occupies an intermediate layer between the core and the co-emulsifier surface of the nanodroplet, together with lecithin phospholipids. Coarse-grained molecular dynamics simulations were also performed to provide insight into the first steps involved in absorption and penetration of the nanodroplet through skin membrane models, representing an intracellular (hair follicle infundibulum) and intercellular pathway (stratum corneum) through the skin. Our data provide a first view on the complex organization of commercial nanoemulsion and its interaction with skin membranes. We expect our results to open the way towards the rational design of such nanomaterials.

A generic model based on the properties of nanoparticles and cells for predicting cellular uptake

Nanoparticles (NPs) are widely used in industry and technology due to their small size and versatility, which makes them easy to enter organisms and pose threats to human and ecological health. Given the particularity and complex structure of NPs, statistical models alone cannot reliably predict uptake. Hence, we developed a generic model for predicting the cellular uptake of NPs with organic coatings, based on physicochemical interactions underlying uptake. The model utilized the concentration, experimental conditions and properties of NPs viz. size, surface coating and coverage. These parameters were converted to surface energy components and surface potentials, and combined with the components and potential for a cell membrane. For NPs uptake, we constructed energetic profiles and barriers for adsorption and permeation onto/through cell membranes. The relationships derived were compared to experimental uptake data. The model provided accurate and robust uptake estimates for neutrally charged unhalogenated NPs and six different cell types. We envision that the model provides a reference for cellular accumulation of neutral NPs and (ecological/human) risk assessment of NPs or microparticles.

Polymers for Biomedical Applications: The Importance of Hydrophobicity in Directing Biological Interactions and Application Efficacy

The past decades have seen significant research effort in the field of polymers for a range of biomedical applications, driven by the promising prospect of these materials for realizing next generation therapeutics in the clinic. In this regard, it is widely accepted that polymer properties such as chemistry, charge, and block composition, as well as properties of their self-assemblies including size, shape, surface chemistry, and biodegradation, all influence and direct their interactions with cells and biological membranes. In particular, polymer hydrophobicity is a property of interest, with growing evidence demonstrating the significant impact that hydrophobic interactions with lipid membranes and proteins can have on biomaterial application efficacy within the body. However, to date, this phenomenon has been relatively underexplored, and therefore there exists no clear universal understanding to direct polymer design. In this Perspective, we highlight important contributions to this field, focusing on seminal studies which investigate experimentally and theoretically how incorporation of hydrophobic moieties within polymer systems can influence their ultimate properties when used in biomedical applications. In this way, we aim to signify future directions in the design of highly performing polymers for biomedicine, making a case for the importance of standardized computational modeling to achieve widely applicable conclusions and facilitate future translational efforts.

Rod-shaped nintedanib nanocrystals improved oral bioavailability through multiple intestinal absorption pathways

Nintedanib (BIBF) is a biopharmaceutical classification system II (BCS II) drug that has a good therapeutic effect for the treatment of nonsmall cell lung cancer; however, it shows poor oral bioavailability due to low dissolution and intestinal absorption. This study aims to fabricate rod-shaped nanocrystals to enhance oral bioavailability by improving the dissolution and absorption of BIBF in the intestine. By prescription screening, BIBF nanocrystals (BIBF-NCs) with a particle size of 325.30 ± 1.03 nm and zeta potential of 32.70 ± 1.24 mV were fabricated by an antisolvent precipitation-ultrasound approach with a stabilizer of sodium carboxyl methyl cellulose (CMC-Na). BIBF-NCs exhibited a rod-shaped morphology by transmission electron microscopy (TEM). The results of powder X-ray diffraction (PXRD) and differential scanning calorimetry (DSC) showed that the crystal form of BIBF in BIBF-NCs was altered. The BIBF-NCs remarkably improved the saturation solubility and dissolution of BIBF compared with BIBF powder. According to the results of in situ single-pass intestinal perfusion (SPIP), BIBF-NCs showed improved absorption and membrane permeability, with K_a and P_app values in the jejunum of 0.21 ± 0.01 min^-1 and (4.34 ± 0.11) × 10^-4 cm/min, respectively. Further, the K_a and P_app values of BIBF-NCs were all reduced significantly after the addition of inhibitors colchicine, chlorpromazine and indomethacin, which demonstrated that BIBF-NCs could be absorbed by endocytosis mediated by caveolae and clathrin and micropinocytosis in the intestine. The cell evaluation results showed that BIBF-NCs could be taken up by macrophages and transported from Caco-2 monolayers. The in vivo pharmacokinetic results showed that the bioavailability of the BIBF-NCs was 2.51-fold higher than that of the BIBF solution (BIBF-Sol) after oral administration with a longer T_max (4.50 ± 1.00 h vs. 2.60 ± 1.92 h). In summary, rod-shaped BIBF-NCs could significantly improve oral bioavailability through multiple intestinal absorption pathways.

Translocation of Endo-Functionalized Molecular Tubes across Different Lipid Bilayers: Atomistic Molecular Dynamics Simulation Study

Various artificial receptors, such as calixarenes, cyclodextrins, cucurbit[n]urils, and their acyclic compounds, pliiar[n]arenes, deep cavitands, and molecular tweezers, can permeate the lipid membranes and they are used as drug carriers to improve the drug solubility, stability, and bioavailability. Inspired by these, we have employed atomistic molecular dynamics simulation to examine the effects of endo-functionalized molecular tubes or naphthotubes (host-1a and host-1b) on seven different types of model lipid bilayers and the permeation properties of these receptors through these model lipid bilayers. Lipid types include six model lipid bilayers (POPC, POPE, DOPC, POPG, DPPE, POPE/POPG) and one realistic membrane (Yeast). We observe that these receptors are spontaneously translocated toward these model lipid bilayer head regions and do not proceed further into these lipid bilayer tail regions (reside at the interface between lipid head and lipid tail region), except for the DPPE-containing systems. In the DPPE model lipid bilayer-containing systems (1a-dppe and 1b-dppe), receptor molecules are only adsorbed on the bilayer surface and reside at the interface between lipid head and water. This finding is also supported by the biased free-energy profiles of these translocation processes. Passive transport of these receptors may be possible through these model lipid bilayers (due to low barrier height), except for DPPE bilayer-containing systems (that have a very high energy barrier at the center). The results from these simulations provide insight into the biocompatibility of host-1a or host-1b in microscopic detail. Based on this work, more research is needed to fully comprehend the role of these synthesized receptors as a prospective drug carrier.

Lipid-Based Ionic-Liquid-Mediated Nanodispersions as Biocompatible Carriers for the Enhanced Transdermal Delivery of a Peptide Drug

Lipid-based biocompatible ionic liquids (LBILs) have attracted attention as carriers in transdermal drug delivery systems (TDDSs) because of their lipophilic character. In this study, we report the formulation of a peptide-LBIL complex microencapsulated in an oil phase as a potential carrier for the transdermal delivery of leuprolide acetate as a model hydrophilic peptide. The peptide-LBIL complexes were prepared via a water-in-oil emulsion composed of 1,2-dimyristoyl-sn-glycerol-3-ethyl-phosphatidylcholine (EDMPC), a fatty acid (stearic, oleic, and linoleic acid)-based LBIL, and cyclohexane followed by freeze-drying to remove the water and cyclohexane. Then, the peptide-LBIL complexes were nanodispersed and stabilized in isopropyl myristate (IPM) using sorbitol laurate (Span-20). Ionic-liquid-in-oil nanodispersions (IL/O-NDs) were prepared with varying weight ratios of LBILs and Span-20 as the surfactant and the cosurfactant, respectively. Keeping the overall surfactant constant at 10 wt % in IPM, a 5:5 wt % ratio of surfactant (IL) and cosurfactant (Span-20) in the IL/O-NDs significantly (p < 0.0001) increased the physiochemical stability, drug-loading capacity, and drug encapsulation efficiency. The in vitro and in vivo peptide delivery across the skin was increased significantly (p < 0.0001) using IL/O-NDs, compared with non-IL-treated groups. Of all of the LBIL-based formulations, [EDMPC][Linoleate]/O-ND was considered the most preferable for a TDDS based on the pharmacokinetic parameters. The transdermal delivery flux with [EDMPC][Linoleate]/O-ND was increased 65-fold compared with the aqueous delivery vehicle. The IL/O-NDs were able to deform the lipid and protein arrangements of the skin layers to enhance the transdermal permeation of the peptide. In vitro and in vivo cytotoxicity studies of the IL/O-NDs revealed the biocompatibility of the LBIL-based formulations. These results indicated that IL/O-NDs are promising biocompatible carriers for lipid-peptide TDDSs.

Increasing the Power of Polyphenols through Nanoencapsulation for Adjuvant Therapy against Cardiovascular Diseases

Polyphenols play a therapeutic role in vascular diseases, acting in inherent illness-associate conditions such as inflammation, diabetes, dyslipidemia, hypertension, and oxidative stress, as demonstrated by clinical trials and epidemiological surveys. The main polyphenol cardioprotective mechanisms rely on increased nitric oxide, decreased asymmetric dimethylarginine levels, upregulation of genes encoding antioxidant enzymes via the Nrf2-ARE pathway and anti-inflammatory action through the redox-sensitive transcription factor NF-κB and PPAR-γ receptor. However, poor polyphenol bioavailability and extensive metabolization restrict their applicability. Polyphenols carried by nanoparticles circumvent these limitations providing controlled release and better solubility, chemical protection, and target achievement. Nano-encapsulate polyphenols loaded in food grade polymers and lipids appear to be safe, gaining resistance in the enteric route for intestinal absorption, in which the mucoadhesiveness ensures their increased uptake, achieving high systemic levels in non-metabolized forms. Nano-capsules confer a gradual release to these compounds, as well as longer half-lives and cell and whole organism permanence, reinforcing their effectiveness, as demonstrated in pre-clinical trials, enabling their application as an adjuvant therapy against cardiovascular diseases. Polyphenol entrapment in nanoparticles should be encouraged in nutraceutical manufacturing for the fortification of foods and beverages. This study discusses pre-clinical trials evaluating how nano-encapsulate polyphenols following oral administration can aid in cardiovascular performance.

Spectroscopy of model-membrane liposome-protein systems: complementarity of linear dichroism, circular dichroism, fluorescence and SERS

A range of membrane models have been developed to study components of cellular systems. Lipid vesicles or liposomes are one such artificial membrane model which mimics many properties of the biological system: they are lipid bilayers composed of one or more lipids to which other molecules can associate. Liposomes are thus ideal to study the roles of cellular lipids and their interactions with other membrane components to understand a wide range of cellular processes including membrane disruption, membrane transport and catalytic activity. Although liposomes are much simpler than cellular membranes, they are still challenging to study and a variety of complementary techniques are needed. In this review article, we consider several currently used analytical methods for spectroscopic measurements of unilamellar liposomes and their interaction with proteins and peptides. Among the variety of spectroscopic techniques seeing increasing application, we have chosen to discuss: fluorescence based techniques such as FRET (fluorescence resonance energy transfer) and FRAP (fluorescence recovery after photobleaching), that are used to identify localisation and dynamics of molecules in the membrane; circular dichroism (CD) and linear dichroism (LD) for conformational and orientation changes of proteins on membrane binding; and SERS (Surface Enhanced Raman Spectroscopy) as a rapidly developing ultrasensitive technique for site-selective molecular characterisation. The review contains brief theoretical basics of the listed techniques and recent examples of their successful applications for membrane studies.

Frontiers in the treatment of glioblastoma: Past, present and emerging

Glioblastoma (GBM) is one of the most aggressive cancers of the brain. Despite extensive research over the last several decades, the survival rates for GBM have not improved and prognosis remains poor. To date, only a few therapies are approved for the treatment of GBM with the main reasons being: 1) significant tumour heterogeneity which promotes the selection of resistant subpopulations 2) GBM induced immunosuppression and 3) fortified location of the tumour in the brain which hinders the delivery of therapeutics. Existing therapies for GBM such as radiotherapy, surgery and chemotherapy have been unable to reach the clinical efficacy necessary to prolong patient survival more than a few months. This comprehensive review evaluates the current and emerging therapies including those in clinical trials that may potentially improve both targeted delivery of therapeutics directly to the tumour site and the development of agents that may specifically target GBM. Particular focus has also been given to emerging delivery technologies such as focused ultrasound, cellular delivery systems nanomedicines and immunotherapy. Finally, we discuss the importance of developing novel materials for improved delivery efficacy of nanoparticles and therapeutics to reduce the suffering of GBM patients.

An efficient approach to study membrane nano-inclusions: from the complex biological world to a simple representation

Membrane nano-inclusions (NIs) are of great interest in biophysics, materials science, nanotechnology, and medicine. We hypothesized that the NIs within a biological membrane bilayer interact via a simple and efficient interaction potential, inspired by previous experimental and theoretical work. This interaction implicitly treats the membrane lipids but takes into account its effect on the NIs micro-arrangement. Thus, the study of the NIs is simplified to a two-dimensional colloidal system with implicit solvent. We calculated the structural properties from Molecular Dynamics simulations (MD), and we developed a Scaling Theory to discuss their behavior. We determined the thermal properties through potential energy per NI and pressure, and we discussed their variation as a function of the NIs number density. We performed a detailed study of the NIs dynamics using two approaches, MD simulations, and Dynamics Theory. We identified two characteristic values of number density, namely a critical number density n c = 3.67 × 10-3 Å-2 corresponded to the apparition of chain-like structures along with the liquid dispersed structure and the gelation number density n g = 8.40 × 10-3 Å-2 corresponded to the jamming state. We showed that the aggregation structure of NIs is of fractal dimension d F < 2. Also, we identified three diffusion regimes of membrane NIs, namely, normal for n < n c, subdiffusive for n c ≤ n < n g, and blocked for n ≥ n g. Thus, this paper proposes a simple and effective approach for studying the physical properties of membrane NIs. In particular, our results identify scaling exponents related to the microstructure and dynamics of membrane NIs.

Not only in silico drug discovery: Molecular modeling towards in silico drug delivery formulations

The use of methods at molecular scale for the discovery of new potential active ligands, as well as previously unknown binding sites for target proteins, is now an established reality. Literature offers many successful stories of active compounds developed starting from insights obtained in silico and approved by Food and Drug Administration (FDA). One of the most famous examples is raltegravir, a HIV integrase inhibitor, which was developed after the discovery of a previously unknown transient binding area thanks to molecular dynamics simulations. Molecular simulations have the potential to also improve the design and engineering of drug delivery devices, which are still largely based on fundamental conservation equations. Although they can highlight the dominant release mechanism and quantitatively link the release rate to design parameters (size, drug loading, et cetera), their spatial resolution does not allow to fully capture how phenomena at molecular scale influence system behavior. In this scenario, the "computational microscope" offered by simulations at atomic scale can shed light on the impact of molecular interactions on crucial parameters such as release rate and the response of the drug delivery device to external stimuli, providing insights that are difficult or impossible to obtain experimentally. Moreover, the new paradigm brought by nanomedicine further underlined the importance of such computational microscope to study the interactions between nanoparticles and biological components with an unprecedented level of detail. Such knowledge is a fundamental pillar to perform device engineering and to achieve efficient and safe formulations. After a brief theoretical background, this review aims at discussing the potential of molecular simulations for the rational design of drug delivery systems.

Penetration and preferential binding of charged nanoparticles to mixed lipid monolayers: interplay of lipid packing and charge density

Designing of nanoparticles (NPs) for biomedical applications or mitigating their cytotoxic effects requires microscopic understanding of their interactions with cell membranes. Such insight is best obtained by studying model biomembranes which, however, need to replicate actual cell membranes, especially their compositional heterogeneity and charge. In this work we have investigated the role of lipid charge density and packing of phase separated Langmuir monolayers in the penetration and phase specificity of charged quantum dot (QD) binding. Using an ordered and anionic charged lipid in combination with uncharged but variable stiffness lipids we demonstrate how the subtle interplay of zwitterionic lipid packing and anionic lipid charge density can affect cationic nanoparticle penetration and phase specific binding. Under identical subphase pH, the membrane with higher anionic charge density displays higher NP penetration. We also observe coalescence of charged lipid rafts floating amidst a more fluidic zwitterionic lipid matrix due to the phase specificity of QD binding. Our results suggest effective strategies which can be used to design NPs for diverse biomedical applications as well as to devise remedial actions against their harmful cytotoxic effects especially against respiratory diseases.

Mechanistic Understanding From Molecular Dynamics Simulation in Pharmaceutical Research 1: Drug Delivery

In this review, we outline the growing role that molecular dynamics simulation is able to play as a design tool in drug delivery. We cover both the pharmaceutical and computational backgrounds, in a pedagogical fashion, as this review is designed to be equally accessible to pharmaceutical researchers interested in what this new computational tool is capable of and experts in molecular modeling who wish to pursue pharmaceutical applications as a context for their research. The field has become too broad for us to concisely describe all work that has been carried out; many comprehensive reviews on subtopics of this area are cited. We discuss the insight molecular dynamics modeling has provided in dissolution and solubility, however, the majority of the discussion is focused on nanomedicine: the development of nanoscale drug delivery vehicles. Here we focus on three areas where molecular dynamics modeling has had a particularly strong impact: (1) behavior in the bloodstream and protective polymer corona, (2) Drug loading and controlled release, and (3) Nanoparticle interaction with both model and biological membranes. We conclude with some thoughts on the role that molecular dynamics simulation can grow to play in the development of new drug delivery systems.

Molecular Dynamics Simulations Reveal Membrane Interactions for Poorly Water-Soluble Drugs: Impact of Bile Solubilization and Drug Aggregation

Molecular transport mechanisms of poorly soluble hydrophobic drug compounds to lipid membranes were investigated using molecular dynamics (MD) simulations. The model compound danazol was used to investigate the mechanism(s) by which bile micelles delivered it to the membrane. The interactions between lipid membrane and pure drug aggregates-in the form of amorphous aggregates and nanocrystals-were also studied. Our simulations indicate that bile micelles formed in the intestinal fluid may facilitate danazol incorporation into cellular membranes through two different mechanisms. The micelle may be acting as: i) a shuttle that presents the danazol directly to the membrane or ii) an elevator that moves the solubilized danazol with it as the colloidal structure itself becomes incorporated and solubilized within the membrane. The elevator hypothesis was supported by complementary lipid monolayer adsorption experiments. In these experiments, colloidal structures formed with simulated intestinal fluid were observed to rapidly incorporate into the monolayer. Simulations of membrane interaction with drug aggregates showed that both the amorphous aggregates and crystalline nanostructures incorporated into the membrane. However, the amorphous aggregates solubilized more quickly than the nanocrystals into the membrane, thereby improving the danazol absorption.