Multiscale approach to investigate self-assembly of telodendrimer based nanocarriers for anticancer drug delivery

Nonbonded Molecular Interaction Controls Aggregation Kinetics of Hydrophobic Molecules in Water

Molecular aggregation frequently occurs during material synthesis, cellular processes, and drug delivery systems, often resulting in decreased performance and efficiency. One major reason for such aggregation in an aqueous solution is hydrophobicity. While the basic understanding of the aggregation process of hydrophobic molecules from a thermodynamic standpoint is known, the present literature lacks a connection between the aggregation kinetics and the molecular basis of hydrophobicity. This study explores how various fluorescent probes (rhodamine dyes) aggregate in an aqueous solution due to their hydrophobicity. The method employs a combination of modeling and characterization to comprehend the aggregation process by examining the nonbonded intermolecular interactions. The aggregation kinetics was analyzed by measuring the average diffusivity of the molecules using fluorescent correlation spectroscopy and NMR diffusion measurements. Through all-atom molecular dynamics (MD) simulations, it has been observed that the level of hydrophobicity is strongly correlated to the total number of hydrogen bonds between water molecules and dyes. In addition, the aggregation frequency of colliding species, which depends on the concentration, is inversely related to hydrogen bonding and the diffusivity of the molecules. This study of small molecules was applied to predict protein aggregation rates, demonstrating strong alignment with the existing literature. The study has also helped to identify and understand the concentration at which a hydrophobic molecule does not aggregate in an aqueous solution. The method developed here could help investigate the aggregation process and its root causes at the molecular level in aqueous systems to develop strategies to control it.

Toward the Integration of Machine Learning and Molecular Modeling for Designing Drug Delivery Nanocarriers

The pioneering work on liposomes in the 1960s and subsequent research in controlled drug release systems significantly advances the development of nanocarriers (NCs) for drug delivery. This field is evolved to include a diverse array of nanocarriers such as liposomes, polymeric nanoparticles, dendrimers, and more, each tailored to specific therapeutic applications. Despite significant achievements, the clinical translation of nanocarriers is limited, primarily due to the low efficiency of drug delivery and an incomplete understanding of nanocarrier interactions with biological systems. Addressing these challenges requires interdisciplinary collaboration and a deep understanding of the nano-bio interface. To enhance nanocarrier design, scientists employ both physics-based and data-driven models. Physics-based models provide detailed insights into chemical reactions and interactions at atomic and molecular scales, while data-driven models leverage machine learning to analyze large datasets and uncover hidden mechanisms. The integration of these models presents challenges such as harmonizing different modeling approaches and ensuring model validation and generalization across biological systems. However, this integration is crucial for developing effective and targeted nanocarrier systems. By integrating these approaches with enhanced data infrastructure, explainable AI, computational advances, and machine learning potentials, researchers can develop innovative nanomedicine solutions, ultimately improving therapeutic outcomes.

Manufacturing process of liposomal Formation: A coarse-grained molecular dynamics simulation

A method of producing liposomes has been previously developed using a continuous manufacturing technology that involves a co-axial turbulent jet in co-flow. In this study, coarse-grained molecular dynamics (CG-MD) simulations were used to gain a deeper understanding of how the self-assembly process of liposomes is affected by the material attributes (such as the concentration of ethanol) and the process parameters (such as temperature), while also providing detailed information on a nano-scale molecular level. Specifically, the CG-MD simulations yield a comprehensive internal view of the structure and formation mechanisms of liposomes containing DPPC, DPPG, and cholesterol molecules. The importance of this work is that structural details on the molecular level are proposed, and such detail is not possible to obtain through experimental studies alone. The assessment of structural properties, including the area per lipid, diffusion coefficient, and order parameters, indicated that a thicker bilayer was observed at higher ethanol concentrations, while a thinner bilayer was present at higher temperatures. These conditions led to more water penetrating the interior of the bilayer and an unstable structure, as indicated by a larger contact area between lipids and water, and a higher coefficient of lipid lateral diffusion. However, stable liposomes were found through these evaluations at lower ethanol concentrations and/or lower process temperatures. Furthermore, the CG-MD model was further compared and validated with experimental and computational data including liposomal bilayer thickness and area per lipid measurements.

Unravel the Tangle: Atomistic Insight into Ultrahigh Curcumin-Loaded Polymer Micelles

Amphiphilic ABA-triblock copolymers, comprised of poly(2-oxazoline) and poly(2-oxazine), can solubilize poorly water-soluble molecules in a structure-dependent manner forming micelles with exceptionally high drug loading. All-atom molecular dynamics simulations are conducted on previously experimentally characterized, curcumin-loaded micelles to dissect the structure-property relationships. Polymer-drug interactions for different levels of drug loading and variation in polymer structures of both the inner hydrophobic core and outer hydrophilic shell are investigated. In silico, the system with the highest experimental loading capacity shows the highest number of drug molecules encapsulated by the core. Furthermore, in systems with lower loading capacity outer A blocks show a greater extent of entanglement with the inner B blocks. Hydrogen bond analyses corroborate previous hypotheses: poly(2-butyl-2-oxazoline) B blocks, found experimentally to have reduced loading capacity for curcumin compared to poly(2-propyl-2-oxazine), establish fewer but longer-lasting hydrogen bonds. This possibly results from different sidechain conformations around the hydrophobic cargo, which is investigated by unsupervised machine learning to cluster monomers in smaller model systems mimicking different micelle compartments. Exchanging poly(2-methyl-2-oxazoline) with poly(2-ethyl-2-oxazoline) leads to increased drug interactions and reduced corona hydration; this suggests an impairment of micelle solubility or colloidal stability. These observations can help driving forward a more rational a priori nanoformulation design.

Molecular recognition of bio-active triterpenoids from Swertia chirayita towards hepatitis Delta antigen: a mechanism through docking, dynamics simulation, Gibbs free energy landscape

Medicinal plants the underpinning of indigenous herbal serve, are the possible source of key compounds for the development of new drugs. Hepatitis D, one of the most widespread infectious diseases associated with global public health issues. Therefore, we aim to screen natural compounds to find out potent inhibitor towards hepatitis delta antigen. Through ADMET investigation, we have screened twenty phytochemicals for this study. Additionally, using molecular docking, these phytochemicals were docked with the HDV protease which signifies the phytochemicals beta-amyrin, chiratenol, episwertenol and swertanone have a significant capability to bind with hepatitis D virus protein. The docking study was further accompanied by analyzes RMSD, RMSF, Rg, SASA, Hbond number, and principal component analysis through 100 ns MD simulations. Based on our principal component analysis, beta-amyrin, chiratenol, episwertenol and swertanone phytochemicals can be a potential drug candidates for inhibition of hepatitis D. The above observation is also supported by our Gibbs free energy landscape study. The potential therapeutic characteristics of the phytochemicals against hepatitis D inhibition offer additional support for the in vitro and in vivo studies in future.

Coarse-Grained Molecular Dynamics Simulations of Paclitaxel-Loaded Polymeric Micelles

A continuous manufacturing technology based on coaxial turbulent jet in coflow was previously developed to produce paclitaxel-loaded polymeric micelles. Herein, coarse-grained molecular dynamics (CG-MD) simulations were implemented to better understand the effect of the material attributes (i.e., the drug-polymer ratio and the ethanol concentration) and process parameters (i.e., temperature) on the self-assembly process of polymeric micelles as well as to provide molecular details on micelle instability. An all-atom (AA) poly (ethylene glycol)-poly (lactic acid) (PEG-PLA) polymer model was developed as the reference for parameterizing a coarse-grained (CG) model, and the AA polymer model was further validated with experimental glass transition temperature (T_g). The model transferability was verified by comparing structural properties between the AA and CG models. The CG model was further validated with experimental data, including micelle particle size measurements and drug encapsulation efficiency. Furthermore, the encapsulation of paclitaxel into the polymeric micelles was included in the simulations, taking into consideration the interactions between the paclitaxel and the polymers. The results from various points of view demonstrated a strong dependence of the shape of the micelles on the drug encapsulation, with micelles transitioning from spherical to ellipsoidal structures with an increasing paclitaxel amount. Simulation data were also used to identify the critical aggregation number (i.e., the number of polymer and drug molecules required for transition from one shape to another). Improved micellar structural stability was found with a larger micellar size and less solvent accessibility. Lastly, an evaluation was performed on the micellar dissociation free energy using a steered molecular dynamics simulation over a range of temperatures and ethanol concentrations. These simulations revealed that at higher ethanol and temperature conditions, micelles become destabilized, resulting in greater paclitaxel release. The increased drug release was determined to originate from the solvation of the hydrophobic core, which promoted micellar swelling and an associated reduction in hydrophobic interactions, leading to a loosely packed micellar structure.

The Martini Model in Materials Science

The Martini model, a coarse-grained force field initially developed with biomolecular simulations in mind, has found an increasing number of applications in the field of soft materials science. The model's underlying building block principle does not pose restrictions on its application beyond biomolecular systems. Here, the main applications to date of the Martini model in materials science are highlighted, and a perspective for the future developments in this field is given, particularly in light of recent developments such as the new version of the model, Martini 3.

Understanding the Synergistic Correlation between the Spatial Distribution of Drug-Loaded Mixed Micellar Systems and In Vitro Behavior via Experimental and Computational Approaches

To better promote the application of polymeric mixed micelles (PMMs), a coarse-grained molecular dynamics simulation (CGMD) has been employed to investigate the factors controlling the spatial distribution within the PMMs and predict their drug-loading properties, meanwhile, combined with experimental methods to validate and examine it. In this study, the snapshots obtained from CGMD and the results of proton nuclear magnetic resonance (¹H NMR) and transmission electron microscopy (TEM) provide new insights into the distribution principle that the spatial distribution depends on the hydrophobic compatibility of drugs with the regions within PMMs. Docetaxel (DTX) is located within the interior or near the core-corona interface of the HS15 hydrophobic core inside FS/PMMs (PMMs fabricated from a nonionic triblock copolymer (F127)) and a nonionic surfactant (HS15), and therefore, the system with a high HS15 ratio, such as system I, is more suitable for loading DTX. In contrast, the more water-soluble puerarin (PUE) is more likely to be solubilized in the "secondary hydrophobic area," mainly formed by the hydrophobic part of F127 within FS/PMMs. However, when the initial feeding concentration of the drug is increased or the FS mixing ratios are changed, an inappropriate distribution would occur and hence influence the drug-loading stability. Also, this impact was further elucidated by the calculated parameters (solvent-accessible surface area (SASA), the radius of gyration (R_g), and energy landscape), and the analysis of the drug leakage, concluding that inappropriate distribution of the drug would lower the stability of the drug in the PMMs. These results combined together provide new insights into the distribution principle that the spatial distribution of drugs within PMMs depends on the hydrophobic compatibility of drugs with the regions formed by micellar materials. Additionally, in vitro drug release yielded a consistent picture with the above conclusions and provides evidence that both the location of the drug within the systems and the stability of the drug-loading system have a great influence on the drug release behavior. Accordingly, this work demonstrates that we can tune the drug-loading stability and drug release behavior via the drug-PMM interaction and drug location study, and CGMD technology would be a step forward in the search for suitable drug-delivery PMMs.

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.

Telodendrimers: Promising Architectural Polymers for Drug Delivery

Architectural complexity has played a key role in enhancing the efficacy of nanocarriers for a variety of applications, including those in the biomedical field. With the continued evolution in designing macromolecules-based nanoparticles for drug delivery, the combination approach of using important features of linear polymers with dendrimers has offered an advantageous and viable platform. Such nanostructures, which are commonly referred to as telodendrimers, are hybrids of linear polymers covalently linked with different dendrimer generations and backbones. There is considerable variety in selection from widely studied linear polymers and dendrimers, which can help tune the overall composition of the resulting hybrid structures. This review highlights the advances in articulating syntheses of these macromolecules, and the contributions these are making in facilitating therapeutic administration. Limited progress has been made in the design and synthesis of these hybrid macromolecules, and it is through an understanding of their physicochemical properties and aqueous self-assembly that one can expect to fully exploit their potential in drug delivery.

Filgrastim loading in PLGA and SLN nanoparticulate system: a bioinformatics approach

OBJECTIVE

In this research work, we hypothesized to predict the nanoparticulate system, best suited for targeted delivery of filgrastim. Significance: Targeted delivery of filgrastim to bone marrow is required to decrease the incidence of neutropenia/febrile neutropenia. This is achieved by nanoparticulate systems, duly designed by bioinformatics approach.

METHOD

The targeted delivery of filgrastim in nanoparticulate system was achieved by molecular dynamics (MD) simulation studies. Two matrices comprising PLGA and SLN (tripalmitin, core component of SLN system) were modeled separately with proposed drug filgrastim. Energy minimization of all systems was done using the steepest descent method. PLGA and tripalmitin systems were equalized at 310 °C, at 1 bar pressure with Berendsen barostat for 200 ps using a v-rescale thermostat for 100 ps. Atomistic MD simulations of four model system and mass density of interacting systems were calculated.

RESULTS

The mass density maps of each nanoparticle system, that is, PLGA and tripalmitin showed an increase in density toward the end of the simulation. The contact numbers attained equilibria with the average number of approx.. 1500 contacts in case of tripalmitin-filgrastim system. While PLGA-filgrastim system shows lesser contacts as compared to tripalmitin with average contacts of approx. 1000.The binding free energy was predicted to be -1104 kJ/mol in tripalmitin-filgrastim complex and -421 kJ/mol in PLGA-filgrastim system.

CONCLUSION

Findings of study revealed that both nanoparticle systems assumed to be good model for drug-carrier systems. Though SLN systems were thought to be more appropriate than PLGA, still the in vivo findings could ascertain this hypothesis in futuristic work.

Coarse-Grained Molecular Dynamic and Experimental Studies on Self-Assembly Behavior of Nonionic F127/HS15 Mixed Micellar Systems

The self-assembly of a nonionic triblock copolymer (F127) and a nonionic surfactant (HS15) has been investigated due to favorable changes in properties in their mixtures. The effect of the mixing ratio on the self-assembly process and on the structural stability of the mixtures was studied by coarse-grained molecular dynamic simulation (CGMD) and experimental measurements (transmission electron microscopy, dynamic light scattering measurement, drug loading stability analysis, and fluorescence spectroscopy measurement). The CGMD provided the information on self-assembly behavior. The microstructure and micellar stability are affected by different proportions of F127/HS15. Pure HS15 molecules (system I) can rapidly form stable aggregates driven by strong hydrophobic force, including two steps: the formation of seed clusters and the fusion of them. At low F127 ratio (system II), the self-assembly process is dynamic unstable, and a volatile "coil/cluster-like" aggregate is formed under the single "binding" effect. As the ratio of added F127 increase, such as system III, stable "lotus-seedpod-like" aggregates form under the double effects of "binding plus wrapping". Its dynamic equilibrium can be achieved rapidly. The experimental results approved the assumption of "different mixing ratio with different structural stability" and even different loading stability of F127/HS15 systems for drugs with different log P, such as PUE and DTX, which means different loading area for them in the micellar systems at different mixing ratios because of less hydrophobic microdomains with the increase of F127 molecules.

Computational Nanoscopy of Tight Junctions at the Blood-Brain Barrier Interface

The selectivity of the blood-brain barrier (BBB) is primarily maintained by tight junctions (TJs), which act as gatekeepers of the paracellular space by blocking blood-borne toxins, drugs, and pathogens from entering the brain. The BBB presents a significant challenge in designing neurotherapeutics, so a comprehensive understanding of the TJ architecture can aid in the design of novel therapeutics. Unraveling the intricacies of TJs with conventional experimental techniques alone is challenging, but recently developed computational tools can provide a valuable molecular-level understanding of TJ architecture. We employed the computational methods toolkit to investigate claudin-5, a highly expressed TJ protein at the BBB interface. Our approach started with the prediction of claudin-5 structure, evaluation of stable dimer conformations and nanoscale assemblies, followed by the impact of lipid environments, and posttranslational modifications on these claudin-5 assemblies. These led to the study of TJ pores and barriers and finally understanding of ion and small molecule transport through the TJs. Some of these in silico, molecular-level findings, will need to be corroborated by future experiments. The resulting understanding can be advantageous towards the eventual goal of drug delivery across the BBB. This review provides key insights gleaned from a series of state-of-the-art nanoscale simulations (or computational nanoscopy studies) performed on the TJ architecture.

Synthetic routes to nanomaterials containing anthracyclines: noncovalent systems

Chemotherapy still constitutes a basic treatment for various types of cancer. Anthracyclines are effective antineoplastic drugs that are widely used in clinical practice. Unfortunately, they are characterized by high systemic toxicity and lack of tumour selectivity. A promising way to enhance treatment effectiveness and reduce toxicity is the synthesis of systems containing anthracyclines either in the form of complexes for the encapsulation of active drugs or their covalent conjugates with inert carriers. In this respect nanotechnology offers an extensive spectrum of possible solutions. In this review, we discuss recent advances in the development of anthracycline prodrugs based on nanocarriers such as copolymers, lipids, DNA, and inorganic systems. The review focuses on the chemical architecture of the noncovalent nanocarrier-drug systems.

The effect of surface poly(ethylene glycol) length on in vivo drug delivery behaviors of polymeric nanoparticles

Engineering nanoparticles of reasonable surface poly(ethylene glycol) (PEG) length is important for designing efficient drug delivery systems. Eliminating the disturbance by other nanoproperties, such as size, PEG density, etc., is crucial for systemically investigating the impact of surface PEG length on the biological behavior of nanoparticles. In the present study, nanoparticles with different surface PEG length but similar other nanoproperties were prepared by using poly(ethylene glycol)-block-poly(ε-caprolactone) (PEG-b-PCL) copolymers of different molecular weights and incorporating different contents of PCL₃₅₀₀ homopolymer. The molecular weight of PEG block in PEG-PCL was between 3400 and 8000 Da, the sizes of nanoparticles were around 100 nm, the terminal PEG density was controlled at 0.4 PEG/nm² (or the frontal PEG density was controlled at 0.16 PEG/nm²). Using these nanoproperties well-designed nanoparticles, we demonstrated PEG length-dependent changes in the biological behaviors of nanoparticles and exhibited nonmonotonic improvements as the PEG molecular weight increased from 3400 to 8000 Da. Moreover, under the experimental conditions, we found nanoparticles with a surface PEG length of 13.8 nm (MW = 5000 Da) significantly decreased the absorption with serum protein and interaction with macrophages, which led to prolonged blood circulation time, enhanced tumor accumulation and improved antitumor efficacy. The present study will help to establish a relatively precise relationship between surface PEG length and the in vivo behavior of nanoparticles.

Computational modelling of drug delivery to solid tumour: Understanding the interplay between chemotherapeutics and biological system for optimised delivery systems

Drug delivery to solid tumour involves multiple physiological, biochemical and biophysical processes taking place across a wide range of length and time scales. The therapeutic efficacy of anticancer drugs is influenced by the complex interplays among the intrinsic properties of tumours, biophysical aspects of drug transport and cellular uptake. Mathematical and computational modelling allows for a well-controlled study on the individual and combined effects of a wide range of parameters on drug transport and therapeutic efficacy, which would not be possible or economically viable through experimental means. A wide spectrum of mathematical models has been developed for the simulation of drug transport and delivery in solid tumours, including PK/PD-based compartmental models, microscopic and macroscopic transport models, and molecular dynamics drug loading and release models. These models have been used as a tool to identify the limiting factors and for optimal design of efficient drug delivery systems. This article gives an overview of the currently available computational models for drug transport in solid tumours, together with their applications to novel drug delivery systems, such as nanoparticle-mediated drug delivery and convection-enhanced delivery.

Dynamics of OmpF Trimer Formation in the Bacterial Outer Membrane of Escherichia coli

The self-assembly of outer membrane protein F (OmpF) in the outer membrane of Escherichia coli Gram-negative bacteria was studied using multiscale molecular dynamics simulations. To accommodate the long time scale required for protein assembly, coarse-grained parametrization of E. coli outer membrane lipids was first developed. The OmpF monomers formed stable dimers at specific protein-protein interactions sites irrespective of the lipid membrane environment. The dimer intermediate was asymmetric but provided a template to form a symmetric trimer. Superposition analysis of the self-assembled trimer with the X-ray crystal structure of the trimer available in the protein data bank showed excellent agreement with global root-mean-square deviation of less than 2.2 Å. The free energy change associated with dimer formation was -26 ± 1 kcal mol^-1, and for a dimer to bind to a monomer and to form a trimer yielded -56 ± 4 kcal mol^-1. Based on thermodynamic data, an alternate path to trimer formation via interaction of two dimers is also presented.

The role of hydrophobic modification on hyaluronic acid dynamics and self-assembly

The advent of nanomedicine has rejuvenated the need for increased understanding of the fundamental physicochemical properties of polymeric amphiphiles. Hyaluronic acid (HA) is a hydrophilic polysaccharide that is frequently conjugated to hydrophobic moieties and then used to entrap dyes and therapeutics. Here, we develop computational models to examine the effects of the hydrophobic modification on supramolecular behavior among three systematically designed HA derivatives substituted with alkyl chains of increasing length. Our simulations coalesce with experimentally obtained results to demonstrate the dependence of supramolecular behavior on intramolecular forces. We show that the formation of clearly defined hydrophobic domains in samples of octadecylamine-modified HA compared to HA conjugates with shorter alkyl chains is a result of more favorable hydrophobic interactions. Trends in hydrodynamic radius and polydispersity are observed in experimental results that coalesce with theoretical calculations, suggesting that supramolecular properties are dependent on the physicochemical characteristics of individual polymer strands.

Riboflavin-containing telodendrimer nanocarriers for efficient doxorubicin delivery: High loading capacity, increased stability, and improved anticancer efficacy

We have developed two linear-dendritic telodendrimers (TDs) with rational design using amphiphilic riboflavin (Rf) as building blocks for efficient doxorubicin (DOX) delivery. Micellar TD nanoparticles (NPs) are composed of a hydrophilic polyethylene glycol (PEG) shell and a Rf-containing affinitive core for DOX encapsulation. Strong DOX-Rf interactions and amphiphilic Rf structure render these nanocarriers with an ultra-high DOX loading capacity (>1/1, DOX/TD, w/w), ∼100% loading efficiency, the sustained drug release and the optimal particle sizes (20-40 nm) for efficient tumor-targeted drug delivery. These nanoformulations significantly prolonged DOX circulation time in the blood without the accelerated clearance observed after multiple injections. DOX-TDs target several types of tumors efficiently in vivo, e.g. Raji lymphoma, MDA-MB-231 breast cancer, and SKOV-3 ovarian cancer. In vivo maximum tolerated dose (MTD) of DOX was increased by 2-2.5 folds for the nanoformulations in mice relative to those of free DOX and Doxil^®. These nanoformulations significantly inhibited tumor growth and prolonged survival of mice bearing SKOV-3 ovarian cancer xenografts. In summary, Rf-containing nanoformulations with high DOX loading capacity, improved stability and efficient tumor targeting lead to superior antitumor efficacy, which merit the further development for clinical application.

Telodendrimers for Physical Encapsulation and Covalent Linking of Individual or Combined Therapeutics

New therapeutics for glioblastoma multiforme and our ability to deliver them using efficient nanocarriers constitute topical areas of research. We report a comparative study of temozolomide and quercetin in the treatment of glioblastoma (GBM) in three-dimensions, and their incorporation into micelles obtained from synthetically articulated architectural copolymers, and a commercially available linear polymer poly(ethylene glycol)-poly(lactic-co-glycolic acid) (PEG-PLGA). A versatile synthetic methodology to telodendrimers, which can be easily adapted to the needs of other therapeutic interventions, is presented. These dendritic block copolymers self-assemble into micelles and offer a platform for single or combination drug therapy. Telodendrimer micelles loaded with quercetin did not exhibit superior cell killing effect over the free drug, but acetazolamide, an inhibitor carbonic anhydrase IX, significantly reduced GBM cell viability in 3D spheroids. Results from these studies show that high loading of drugs into telodendrimer micelles requires a physical fit between the biologically active agent and telodendrimer nanocarrier, and points toward new possibilities for incorporation of chemotherapeutic and other agents to enhance their effectiveness.

Quantitative computational models of molecular self-assembly in systems biology

Molecular self-assembly is the dominant form of chemical reaction in living systems, yet efforts at systems biology modeling are only beginning to appreciate the need for and challenges to accurate quantitative modeling of self-assembly. Self-assembly reactions are essential to nearly every important process in cell and molecular biology and handling them is thus a necessary step in building comprehensive models of complex cellular systems. They present exceptional challenges, however, to standard methods for simulating complex systems. While the general systems biology world is just beginning to deal with these challenges, there is an extensive literature dealing with them for more specialized self-assembly modeling. This review will examine the challenges of self-assembly modeling, nascent efforts to deal with these challenges in the systems modeling community, and some of the solutions offered in prior work on self-assembly specifically. The review concludes with some consideration of the likely role of self-assembly in the future of complex biological system models more generally.

Optically Active Helical Polyacetylene Self-Assembled into Chiral Micelles Used As Nanoreactor for Helix-Sense-Selective Polymerization

Chiral micelles have been drawing ever-increasing attention because of their potentials in mimicking the unique stereochemical effects of enzymes. This article reports on the first success in preparing chiral micelles through self-assembly of helical polyacetylene bearing cholic acid pendants. The micelles were further used as chiral nanoreactor, in which achiral acetylenic monomer smoothly underwent helix-sense-selective polymerization (HSSP). The HSSPs directly established optically active core/shell nanoparticles whose shell and core both were constructed by helical polymers. The shells (or micelles) provided a protective effect for the preferably induced one-handed helical polymer chains in the cores. The present work provides insights into the self-assembly of chiral helical polymers, and also provides a powerful strategy for constructing novel chiral polymer nanoarchitectures.

Drug-Specific Design of Telodendrimer Architecture for Effective Doxorubicin Encapsulation

Designing a versatile nanocarrier platform that can be tailored to deliver specific drug payloads is challenging. In general, effective drug encapsulation, high drug-loading capacity, uniform shape and size distribution, and enhanced stability are among the fundamental attributes of a successful nanocarrier design. These physiochemical features of the nanocarriers are intimately tied to the specific drug payload that they are tasked to deliver. The molecular architecture of the nanocarrier's scaffold often needs to be tuned for each drug, especially if the target drugs are structurally and chemically distinct as in the case of doxorubicin (DOX) and paclitaxel (PTX). Starting from our previously reported telodendrimeric block copolymer platform optimized for PTX, we analyze three generations of telodendrimer architectures to arrive at the design that is capable of encapsulating another important chemotherapeutic drug, DOX. Multiple long-time-scale self-assembly simulations were performed both in atomistic and coarse-grained resolutions to generate equilibrated DOX-encapsulated nanocarriers. The results show how subtle changes in the molecular architecture of the telodendrimer head groups have profound effects on the nanocarrier size, morphology, and asphericity. The simulation results are in agreement with the experimental data for DOX-encapsulated nanocarriers. This work emphasizes the increasing role of molecular simulations in the rational design of nanocarriers, thereby eliminating the trial and error method that has been prevalent in experimental synthesis. The molecular-level insights gained from the simulations will be used to design the next generation of drug-specific nanocarriers.

Molecular and mesoscale mechanism for hierarchical self-assembly of dipeptide and porphyrin light-harvesting system

Multiscale theoretical models are built to unravel the hierarchically ordered organization of dipeptide–porphyrin co-assemblies with different light-harvesting efficiencies.

Design of Nanoparticle-Based Carriers for Targeted Drug Delivery

Nanoparticles have shown promise as both drug delivery vehicles and direct antitumor systems, but they must be properly designed in order to maximize efficacy. Computational modeling is often used both to design new nanoparticles and to better understand existing ones. Modeled processes include the release of drugs at the tumor site and the physical interaction between the nanoparticle and cancer cells. In this article, we provide an overview of three different targeted drug delivery methods (passive targeting, active targeting and physical targeting), compare methods of action, advantages, limitations, and the current stage of research. For the most commonly used nanoparticle carriers, fabrication methods are also reviewed. This is followed by a review of computational simulations and models on nanoparticle-based drug delivery.

A drug-specific nanocarrier design for efficient anticancer therapy

The drug-loading properties of nanocarriers depend on the chemical structures and properties of their building blocks. Here, we customize telodendrimers (linear-dendritic copolymer) to design a nanocarrier with improved in vivo drug delivery characteristics. We do a virtual screen of a library of small molecules to identify the optimal building blocks for precise telodendrimer synthesis using peptide chemistry. With rationally designed telodendrimer architectures, we then optimize the drug binding affinity of a nanocarrier by introducing an optimal drug-binding molecule (DBM) without sacrificing the stability of the nanocarrier. To validate the computational predictions, we synthesize a series of nanocarriers and evaluate systematically for doxorubicin delivery. Rhein-containing nanocarriers have sustained drug release, prolonged circulation, increased tolerated dose, reduced toxicity, effective tumor targeting and superior anticancer effects owing to favourable doxorubicin-binding affinity and improved nanoparticle stability. This study demonstrates the feasibility and versatility of the de novo design of telodendrimer nanocarriers for specific drug molecules, which is a promising approach to transform nanocarrier development for drug delivery.

Fine-tuning vitamin E-containing telodendrimers for efficient delivery of gambogic acid in colon cancer treatment

Certain natural products such as gambogic acid (GA) exhibit potent antitumor effects. Unfortunately, administration of these natural products is limited by their poor solubility in conventional pharmaceutical solvents. In this study, a series of telodendrimers, composed of linear polyethylene glycol (PEG)-blocking-dendritic oligomer of cholic acid (CA) and vitamin E (VE), have been designed with architectures optimized for efficient delivery of GA and other natural anticancer compounds. Two of the telodendrimers with segregated CA and VE domains self-assembled into stable cylindrical and/or spherical nanoparticles (NPs) after being loaded with GA as observed under transmission electron microscopy (TEM), which correlated with the dynamic light scattering (DLS) analysis of sub-30 nm particle sizes. A very high GA loading capacity (3:10 drug/polymer w/w) and sustained drug release were achieved with the optimized telodendrimers. These novel nanoformulations of GA were found to exhibit similar in vitro cytotoxic activity against colon cancer cells as the free drug. Near-infrared fluorescence small animal imaging revealed preferential accumulation of GA-loaded NPs into tumor tissue. The optimized nanoformulation of GA achieved superior antitumor efficacy compared to GA-Cremophor EL formulation at equivalent doses in HT-29 human colon cancer xenograft mouse models. Given the mild adverse effects associated with this natural compound and the enhanced anticancer effects via tumor targeted telodendrimer delivery, the optimized GA nanoformulation is a promising alternative to the traditional chemotherapy in colon cancer treatment.