Multi-scale modeling of folic acid-functionalized TiO2 nanoparticles for active targeting of tumor cells

Optimizing Polyethylene Glycol Coating for Stealth Nanodiamonds

Nanodiamonds (NDs) have emerged as potential candidates for versatile platforms in nanomedicine, offering unique properties that enhance their utility in drug delivery, imaging, and therapeutic applications. To improve their biocompatibility and nanomedical applicability, NDs are coated with organic polymer chains, such as poly(ethylene glycol) (PEG), which are well known to prolong their blood-circulating lifetime by reducing the surface adsorption of serum proteins. Theoretical simulations are useful tools to define, at the atomic level, the optimal parameters that guide the presentation of the coating chains in the biological environment and the interaction of coated NDs with proteins. In this work, we perform atomistic molecular dynamics (MD) simulations of several PEGylated spherical ND models immersed in a realistic physiological medium. In particular, we evaluate the effect of the polymer chain's terminal group, length, grafting density, and the ND core dimension on both the structural properties of the PEG coating and the interaction of the nanoconjugates with the aqueous phase. Moreover, we investigate the role played by the chemical nature of the core material through a comparative analysis with a PEGylated spherical titanium dioxide (TiO2) nanoparticle (NP). Among all the parameters evaluated, we find that the PEG grafting density, the PEG chain length, and the NP core material are key factors in determining the dynamic behavior of PEGylated nanosystems in solution, whereas the PEG terminal group and the ND dimension only play a marginal role. These factors can be strategically adjusted to identify the optimal conditions for enhanced clinical performance. Finally, we prove that the PEG coating prevents the aggregation of two ND particles. We believe that this computational study will provide valuable insights to the experimental community, supporting the rational design of polymer-coated inorganic NPs for more efficient nanomedical applications.

Dual-Targeted Drug Delivery to Myeloid Leukemia Cells via Complement- and Transferrin-Based Protein Corona

Although traditionally regarded as an impediment, the protein corona can facilitate the advancement of targeted drug delivery systems. This study presents an innovative approach for targeting acute myeloid leukemia (AML) using nanoparticles with agglutinated protein (NAPs). Agglutinated transferrin and C3b in NAPs selectively bind to CD71 and CD11b, receptors that are overexpressed on myeloid leukemic cells compared to nonmalignant cells. In vitro, NAPs achieved a 73.9% doxorubicin (DOX) uptake in leukemic cells, compared to 6.19% for the free drug, while significantly reducing off-target accumulation in normal cells from 42.9% to 5.76%. In vivo, the distribution of NAPs correlated to the organ infiltration pattern of leukemic cells. NAPs demonstrated antileukemic activity in both in vitro and in vivo NSG mouse models, inducing cell death via apoptosis and ferroptosis. In conclusion, NAP-mediated targeted drug delivery represents a promising therapeutic strategy for AML, enhancing treatment efficacy and minimizing off-target effects.

Mechanistic Insights into Toxicity of Titanium Dioxide Nanoparticles at the Micro- and Macro-levels

Titanium oxide nanoparticles (TiO2 NPs) have been regarded as a legacy nanomaterial due to their widespread usage across multiple fields. The TiO2 NPs have been and are still extensively used as a food and cosmetic additive and in wastewater and sewage treatment, paints, and industrial catalysis as ultrafine TiO2. Recent developments in nanotechnology have catapulted it into a potent antibacterial and anticancer agent due to its excellent photocatalytic potential that generates substantial amounts of highly reactive oxygen radicals. The method of production, surface modifications, and especially size impact its toxicity in biological systems. The anatase form of TiO2 (<30 nm) has been found to exert better and more potent cytotoxicity in bacteria as well as cancer cells than other forms. However, owing to the very small size, anatase particles are able to penetrate deep tissue easily; hence, they have also been implicated in inflammatory reactions and even as a potent oncogenic substance. Additionally, TiO2 NPs have been investigated to assess their toxicity to large-scale ecosystems owing to their excellent reactive oxygen species (ROS)-generating potential compounded with widespread usage over decades. This review discusses in detail the mechanisms by which TiO2 NPs induce toxic effects on microorganisms, including bacteria and fungi, as well as in cancer cells. It also attempts to shed light on how and why it is so prevalent in our lives and by what mechanisms it could potentially affect the environment on a larger scale.

Advancements in mitochondrial-targeted nanotherapeutics: overcoming biological obstacles and optimizing drug delivery

In recent decades, nanotechnology has significantly advanced drug delivery systems, particularly in targeting subcellular organelles, thus opening new avenues for disease treatment. Mitochondria, critical for cellular energy and health, when dysfunctional, contribute to cancer, neurodegenerative diseases, and metabolic disorders. This has propelled the development of nanomedicines aimed at precise mitochondrial targeting to modulate their function, marking a research hotspot. This review delves into the recent advancements in mitochondrial-targeted nanotherapeutics, with a comprehensive focus on targeting strategies, nanocarrier designs, and their therapeutic applications. It emphasizes nanotechnology's role in enhancing drug delivery by overcoming biological barriers and optimizing drug design for specific mitochondrial targeting. Strategies exploiting mitochondrial membrane potential differences and specific targeting ligands improve the delivery and mitochondrial accumulation of nanomedicines. The use of diverse nanocarriers, including liposomes, polymer nanoparticles, and inorganic nanoparticles, tailored for effective mitochondrial targeting, shows promise in anti-tumor and neurodegenerative treatments. The review addresses the challenges and future directions in mitochondrial targeting nanotherapy, highlighting the need for precision, reduced toxicity, and clinical validation. Mitochondrial targeting nanotherapy stands at the forefront of therapeutic strategies, offering innovative treatment perspectives. Ongoing innovation and research are crucial for developing more precise and effective treatment modalities.

Computer-aided nanodrug discovery: recent progress and future prospects

Nanodrugs, which utilise nanomaterials in disease prevention and therapy, have attracted considerable interest since their initial conceptualisation in the 1990s. Substantial efforts have been made to develop nanodrugs for overcoming the limitations of conventional drugs, such as low targeting efficacy, high dosage and toxicity, and potential drug resistance. Despite the significant progress that has been made in nanodrug discovery, the precise design or screening of nanomaterials with desired biomedical functions prior to experimentation remains a significant challenge. This is particularly the case with regard to personalised precision nanodrugs, which require the simultaneous optimisation of the structures, compositions, and surface functionalities of nanodrugs. The development of powerful computer clusters and algorithms has made it possible to overcome this challenge through in silico methods, which provide a comprehensive understanding of the medical functions of nanodrugs in relation to their physicochemical properties. In addition, machine learning techniques have been widely employed in nanodrug research, significantly accelerating the understanding of bio-nano interactions and the development of nanodrugs. This review will present a summary of the computational advances in nanodrug discovery, focusing on the understanding of how the key interfacial interactions, namely, surface adsorption, supramolecular recognition, surface catalysis, and chemical conversion, affect the therapeutic efficacy of nanodrugs. Furthermore, this review will discuss the challenges and opportunities in computer-aided nanodrug discovery, with particular emphasis on the integrated "computation + machine learning + experimentation" strategy that can potentially accelerate the discovery of precision nanodrugs.

The effect of polymer coating on nanoparticles' interaction with lipid membranes studied by coarse-grained molecular dynamics simulations

Nanoparticles' (NPs) permeation through cell membranes, whether it happens via passive or active transport, is an essential initial step for their cellular internalization. The NPs' surface coating impacts the way they translocate through the lipid bilayer and the spontaneity of the process. Understanding the molecular details of NPs' interaction with cell membranes allows the design of nanosystems with optimal characteristics for crossing the lipid bilayer: computer simulations are a powerful tool for this purpose. In this work, we have performed coarse-grained molecular dynamics simulations and free energy calculations on spherical titanium dioxide NPs conjugated with polymer chains of different chemical compositions. We have demonstrated that the hydrophobic/hydrophilic character of the chains, more than the nature of their terminal group, plays a crucial role in determining the NPs' interaction with the lipid bilayer and the thermodynamic spontaneity of NPs' translocation from water to the membrane. We envision that this computational work will be helpful to the experimental community in terms of the rational design of NPs for efficient cell membrane permeation.

Chemiluminescent Conjugated Polymer Nanoparticles for Deep-Tissue Inflammation Imaging and Photodynamic Therapy of Cancer

Deep-tissue optical imaging and photodynamic therapy (PDT) remain a big challenge for the diagnosis and treatment of cancer. Chemiluminescence (CL) has emerged as a promising tool for biological imaging and in vivo therapy. The development of covalent-binding chemiluminescence agents with high stability and high chemiluminescence resonance energy transfer (CRET) efficiency is urgent. Herein, we design and synthesize an unprecedented chemiluminescent conjugated polymer PFV-Luminol, which consists of conjugated polyfluorene vinylene (PFV) main chains and isoluminol-modified side chains. Notably, isoluminol groups with chemiluminescent ability are covalently linked to main chains by amide bonds, which dramatically narrow their distance, greatly improving the CRET efficiency. In the presence of pathologically high levels of various reactive oxygen species (ROS), especially singlet oxygen (1O2), PFV-Luminol emits strong fluorescence and produces more ROS. Furthermore, we construct the PFV-L@PEG-NPs and PFV-L@PEG-FA-NPs nanoparticles by self-assembly of PFV-Luminol and amphiphilic copolymer DSPE-PEG/DSPE-PEG-FA. The chemiluminescent PFV-L@PEG-NPs nanoparticles exhibit excellent capabilities for in vivo imaging in different inflammatory animal models with great tissue penetration and resolution. In addition, PFV-L@PEG-FA-NPs nanoparticles show both sensitive in vivo chemiluminescence imaging and efficient chemiluminescence-mediated PDT for antitumors. This study paves the way for the design of chemiluminescent probes and their applications in the diagnosis and therapy of diseases.

Mechanism of RGD-conjugated nanodevice binding to its target protein integrin αVβ3 by atomistic molecular dynamics and machine learning

Active targeting strategies have been proposed to enhance the selective uptake of nanoparticles (NPs) by diseased cells, and recent experimental findings have proven the effectiveness of this approach. However, no mechanistic studies have yet revealed the atomistic details of the interactions between ligand-activated NPs and integrins. As a case study, here we investigate, by means of advanced molecular dynamics simulations (MD) and machine learning methods (namely equilibrium MD, binding free energy calculations and training of self-organized maps), the interaction of a cyclic-RGD-conjugated PEGylated TiO2 NP (the nanodevice) with the extracellular segment of integrin αVβ3 (the target), the latter experimentally well-known to be over-expressed in several solid tumors. Firstly, we proved that the cyclic-RGD ligand binding to the integrin pocket is established and kept stable even in the presence of the cumbersome realistic model of the nanodevice. In this respect, the unsupervised machine learning analysis allowed a detailed comparison of the ligand/integrin binding in the presence and in the absence of the nanodevice, which unveiled differences in the chemical features. Then, we discovered that unbound cyclic RGDs conjugated to the NP largely contribute to the interactions between the nanodevice and the integrin. Finally, by increasing the density of cyclic RGDs on the PEGylated TiO2 NP, we observed a proportional enhancement of the nanodevice/target binding. All these findings can be exploited to achieve an improved targeting selectivity and cellular uptake, and thus a more successful clinical outcome.

Folic Acid-Decorated Chitosan-PLGA Nanobiopolymers for Targeted Drug Delivery to Acute Lymphoblastic Leukemia Cells: In Vitro Studies

OBJECTIVES

This study developed a drug delivery system (DDS) using folic acid (FA)-functionalized chitosan (CS) and poly (lactic-co-glycolic acid) (PLGA) nanocarriers for targeted sodium butyrate (NB) delivery to leukemia cells (NALM6). The goal was to enhance NB's therapeutic efficacy while reducing its cytotoxicity to non-malignant cells.

METHODS

FA-CS-PLGA nanocarriers were synthesized and characterized using Fourier-transform infrared spectroscopy (FT-IR), dynamic light scattering (DLS), zeta potential analysis, transmission electron microscopy (TEM), and thermogravimetric analysis (TGA). Encapsulation efficiency, release kinetics, cytotoxicity, and apoptosis induction were assessed using MTT assays and flow cytometry in NALM6 cells.

RESULTS

The FA-CS-PLGA nanocarriers had a surface charge of 34.2 ± 0.12 mV and a size range of 40-60 nm. Encapsulation efficiency was 16%, with 16% of NB released within the first 4 h. MTT assays showed a reduction in leukemia cell viability to 26% after 24 h with 400 nM FA-CS-PLGA-NB, compared to over 50% viability with pure NB. The IC50 was around 300 nM. Flow cytometry revealed that FA-CS-PLGA-NB induced apoptosis in over 20% of leukemia cells, far exceeding the 5% induced by unmodified NB.

CONCLUSION

FA-CS-PLGA nanocarriers show significant promise as a targeted DDS for leukemia therapy, enhancing NB delivery to leukemia cells and improving therapeutic efficacy while minimizing off-target toxicity. These results support further in vivo studies and potential clinical applications.

Dual Responsive Magnetic Drug Delivery Nanomicelles with Tumor Targeting for Enhanced Cancer Chemo/Magnetothermal Synergistic Therapy

Introduction

Stimulus-responsive nanocarrier systems are promising in cancer treatment. They improve drug stability and facilitate controlled drug release. However, single-responsive nanocarriers still face insufficient tumor targeting and low efficacy.

Methods

In this study, we synthesized folate-modified DSPE-PEOz nanomicelles with PEG chains and loaded them with magnetic iron particles and doxorubicin (DOX). Folic acid (FA) was employed as a ligand to target cancer cells actively. The nanomicelles are biocompatible and acid-sensitive drug carriers. Magnetic field-responsive nanoparticles enable moderately controlled magnetothermal therapy of tumors regardless of tumor location. The pH/magnetic field dual-responsive nanomicelles shed their PEG layer in response to tumor tissue acidity and react to magnetic fields through magnetothermal effects.

Results

In vitro and in vivo experiments demonstrated that the nanomicelles could efficiently target cancer cells, release drugs in response to pH changes, and enhance drug uptake through magnetothermal effects.

Discussion

The dual-responsive magnetic nanomicelles are expected to enhance the anti-cancer efficacy of chemo/magnetothermal synergistic therapy.

Molecular Dynamics for the Optimal Design of Functionalized Nanodevices to Target Folate Receptors on Tumor Cells

Atomistic details on the mechanism of targeting activity by biomedical nanodevices of specific receptors are still scarce in the literature, where mostly ligand/receptor pairs are modeled. Here, we use atomistic molecular dynamics (MD) simulations, free energy calculations, and machine learning approaches on the case study of spherical TiO2 nanoparticles (NPs) functionalized with folic acid (FA) as the targeting ligand of the folate receptor (FR). We consider different FA densities on the surface and different anchoring approaches, i.e., direct covalent bonding of FA γ-carboxylate or through polyethylene glycol spacers. By molecular docking, we first identify the lowest energy conformation of one FA inside the FR binding pocket from the X-ray crystal structure, which becomes the starting point of classical MD simulations in a realistic physiological environment. We estimate the binding free energy to be compared with the existing experimental data. Then, we increase complexity and go from the isolated FA to a nanosystem decorated with several FAs. Within the simulation time framework, we confirm the stability of the ligand-receptor interaction, even in the presence of the NP (with or without a spacer), and no significant modification of the protein secondary structure is observed. Our study highlights the crucial role played by the spacer, FA protonation state, and density, which are parameters that can be controlled during the nanodevice preparation step.

Bottom-up on-surface synthesis based on click-functionalized peptide bundles

On-surface synthesis is a modern technique for the preparation of atomically low-dimensional molecular nanostructures. However, most nanomaterials grow horizontally on the surface, and the step-by-step longitudinally controllable covalent bonding reaction on the surface is rarely reported. Here, we successfully achieved bottom-up on-surface synthesis by using coiled-coil homotetrameric peptide bundles called 'bundlemers' as building blocks. Rigid nano-cylindrical bundlemer with two click-reactive functionalities at each end can be grafted vertically onto the surface or another bundlemer with complementary clickable groups by click reaction at one end, thus enabling the longitudinal bottom-up synthesis of rigid rods with an exact number of bundlemers (up to 6) on the surface. Moreover, we can graft linear poly(ethylene glycol) (PEG) to one terminal of rigid rods to obtain rod-PEG hybrid nanostructures that can be released from the surface under specific conditions. Interestingly, rod-PEG nanostructures consisting of different numbers of bundles can self-assemble in water into different nano-hyperstructures. In general, the bottom-up on-surface synthesis strategy presented here can provide a simple and accurate method to manufacture a variety of nanomaterials.

Surface modification of TiO2 nanoparticles with organic molecules and their biological applications

In recent years, titanium(IV) dioxide nanoparticles (TiO₂NPs) have shown promising potential in various biological applications such as antimicrobials, drug delivery, photodynamic therapy, biosensors, and tissue engineering. For employing TiO₂NPs in these fields, their nanosurface must be coated or conjugated with organic and/or inorganic agents. This modification can improve their stability, photochemical properties, biocompatibility, and even surface area for further conjugation with other molecules such as drugs, targeting molecules, polymers, etc. This review describes the organic-based modification of TiO₂NPs and their potential applications in the mentioned biological fields. In the first part of this review, around 75 recent publications (2017-2022) are mentioned on the common TiO₂NP modifiers including organosilanes, polymers, small molecules, and hydrogels, which improve the photochemical features of TiO₂NPs. In the second part of this review, we presented 149 recent papers (2020-2022) about the use of modified TiO₂NPs in biological applications, in which specific bioactive modifiers are introduced in this part with their advantages. In this review, the following information is presented: (1) the common organic modifiers for TiO₂NPs, (2) biologically important modifiers and their benefits, and (3) recent publications on biological studies on the modified TiO₂NPs with their achievements. This review shows the paramount significance of the organic-based modification of TiO₂NPs to enhance their biological effectiveness, paving the way toward the development of advanced TiO₂-based nanomaterials in nanomedicine.