Advances in active targeting of ligand-directed polymeric nanomicelles via exploiting overexpressed cellular receptors for precise nanomedicine

Many of the utilized drugs which already exist in the pharmaceutical sector are hydrophobic in nature. These drugs are characterized by being poorly absorbed and difficult to formulate in aqueous environments with low bioavailability, which could result in consuming high and frequent doses in order to fulfil the required therapeutic effect. As a result, there is a decisive demand to find modern alternatives to overcome all these drawbacks. Self-assembling polymeric nanomicelles (PMs) with their unique structure appear to be a fascinating choice as a pharmaceutical carrier system for improving the solubility & bioavailability of many drugs. PMs as drug carriers have many advantages including suitable size, high stability, prolonged circulation time, elevated cargo capacity and controlled therapeutic release. Otherwise, the pathological features of some diseased cells, like cancer, allow PMs with particle size <200 nm to be passively uptaken via enhanced permeability and retention phenomenon (EPR). However, the passive targeting approach was proven to be insufficient in many cases. Consequently, the therapeutic efficiency of these PMs can be further reinforced by enhancing their cellular internalization via incorporating targeting ligands. These targeting ligands can enhance the assemblage of loaded cargos in the intended tissues via receptor-mediated endocytosis through exploiting receptors robustly expressed on the exterior of the intended tissue while minimizing their toxic effects. In this review, the up-to-date approaches of harnessing active targeting ligands to exploit certain overexpressed receptors will be summarized concerning the functionalization of the exterior of PMs for ameliorating their targeting potential in the scope of nanomedicine.

Design and evaluation of nanoscale materials with programmed responsivity towards epigenetic enzymes

Self-assembled materials capable of modulating their assembly properties in response to specific enzymes play a pivotal role in advancing 'intelligent' encapsulation platforms for biotechnological applications. Here, we introduce a previously unreported class of synthetic nanomaterials that programmatically interact with histone deacetylase (HDAC) as the triggering stimulus for disassembly. These nanomaterials consist of co-polypeptides comprising poly(acetyl L-lysine) and poly(ethylene glycol) blocks. Under neutral pH conditions, they self-assemble into particles. The hydrodynamic diameters of particles were typically withing the range of 108-190 nm, depending on degree of acetylation of the hydrophobic block. However, their stability is compromised upon exposure to HDACs, depending on enzyme concentration and exposure time. Our investigation, utilizing HDAC8 as the model enzyme, revealed that the primary mechanism behind disassembly involves a decrease in amphiphilicity within the block copolymer due to the deacetylation of lysine residues within the particles' hydrophobic domains. To elucidate the response mechanism, we encapsulated a fluorescent dye within these nanoparticles. Upon incubation with HDAC, the nanoparticle structure collapsed, leading to controlled release of the dye over time. Notably, this release was not triggered by denatured HDAC8, other proteolytic enzymes like trypsin, or the co-presence of HDAC8 and its inhibitor. We also demonstrated the biocompatibility and cellular effects of these materials in the context of drug delivery in different types of anticancer cell lines, such as MIA PaCa-2, PANC-1, cancer like stem cells (CSCs), and non-cancerous HPNE cells. We observed that the release of a model drug (such as a STAT3 pathway inhibitor, Napabucasin) can be loaded into these nanoparticles, with >90% of the dosage can be released over 3 h under the influence of HDAC8 enzyme in a controlled fashion. Further, we conducted a comprehensive computational study to unveil the possible interaction mechanism between enzymes and particles. By drawing parallels to the mechanism of naturally occurring histone proteins, this research represents a pioneering step toward developing functional materials capable of harnessing the activity of epigenetic enzymes such as HDACs.

Polymeric Nanoparticles for Drug Delivery

The recent emergence of nanomedicine has revolutionized the therapeutic landscape and necessitated the creation of more sophisticated drug delivery systems. Polymeric nanoparticles sit at the forefront of numerous promising drug delivery designs, due to their unmatched control over physiochemical properties such as size, shape, architecture, charge, and surface functionality. Furthermore, polymeric nanoparticles have the ability to navigate various biological barriers to precisely target specific sites within the body, encapsulate a diverse range of therapeutic cargo and efficiently release this cargo in response to internal and external stimuli. However, despite these remarkable advantages, the presence of polymeric nanoparticles in wider clinical application is minimal. This review will provide a comprehensive understanding of polymeric nanoparticles as drug delivery vehicles. The biological barriers affecting drug delivery will be outlined first, followed by a comprehensive description of the various nanoparticle designs and preparation methods, beginning with the polymers on which they are based. The review will meticulously explore the current performance of polymeric nanoparticles against a myriad of diseases including cancer, viral and bacterial infections, before finally evaluating the advantages and crucial challenges that will determine their wider clinical potential in the decades to come.

Development of Multivalent Conjugates with a Single Non-Canonical Amino Acid

Proteins represent powerful biomacromolecules due to their unique functionality and broad utility both in the cell and in non-biological applications. The genetic encoding of non-canonical amino acids (ncAAs) facilitates functional diversification of these already powerful proteins. Specifically, ncAAs have been demonstrated to provide unique functional handles to bioorthogonally introduce novel functionality via conjugation reactions. Herein we examine the ability of a single ncAA to serve as a handle to generate multivalent bioconjugates to introduce two or more additional components to a protein, yielding a multivalent conjugate. To accomplish this aim, p-bromopropargyloxyphenyalanine (pBrPrF) was genetically encoded into both superfolder green fluorescent protein (sfGFP) and ubiquitin model proteins to serve as a conjugation handle. A sequential bioconjugation sequence involving a copper-assisted cycloaddition reaction coupled with a subsequent Sonogashira cross-coupling was then optimized. The linkage of two additional molecules to the model protein via these reactions yielded the desired multivalent bioconjugate. This domino approach using a single ncAA has a plethora of applications in both therapeutics and diagnostics as multiple unique moieties can be introduced into proteins in a highly controlled fashion.

pH-triggered "PEG" sheddable and folic acid-targeted nanoparticles for docetaxel delivery in breast cancer treatment

Multifunctional nanoparticles have attracted significant attentions for oncology and cancer treatment. In fact, they could address critical point for tumour treatment by creating a stimuli-responsive targeted drug delivery system that can exist stably in the systemic circulation, efficiently penetrate the tumour tissue, and then accumulate in tumour cells in large quantities. A novel stepwise pH-responsive multifunctional nanoparticles (FPDPCNPs/DTX) for targeted delivery of the antitumour drug docetaxel (DTX) is prepared by coating a tumour acidity-sensitive "sheddable" FA modified β-carboxylic amide functionalized PEG layer (folic acid-polyethylene glycol-2,3-dimethylmaleic anhydride, FA-PEG-DA) on the cationic drug-loaded core (poly(β-amino ester-cholesterol, PAE-Chol) through electrostatic interaction in this study. The charge shielding behaviour of the FPDPCNPs/DTX was confirmed by zeta potential assay. The surface charges of the nanoparticles can change from positive to negative after PEG coating. The IC50 values of FPDPCNPs/DTX was 3.04 times higher than that of PEG "unsheddable" nanoparticles in cytotoxicity experiments. The results of in vivo experiment further showed that FPDPCNPs/DTX had enhanced tumour targeting effect, the tumour inhibition rate of FPDPCNPs/DTX was as high as 81.99%, which was 1.51 times that of free DTX. Under a micro acidic environment and folate receptor (FR)-mediated targeting, FPDPCNPs/DTX contributed to more uptake of DTX by MCF-7 cells. In summary, FPDPCNPs/DTX as a multifunctional nano-drug delivery system provides a promising strategy for efficiently delivering antitumour drugs.

The synthesis and development of poly(ε-caprolactone) conjugated polyoxyethylene sorbitan oleate-based micelles for curcumin drug release: an in vitro study on breast cancer cells

BACKGROUND

it is now known that curcumin (Cur) has a broad range of biological properties; however, photosensitivity, as well as low bioavailability and short half-life, have limited its clinical application. To overcome these problems the synthesis of poly(ε-caprolactone)-Tween 80 (PCL-T) copolymers was performed.

METHODS

the copolymers of PCL-T were created using the solvent evaporation/extraction technique. Then Cur was loaded in PCL-T micelles (PCL-T-M) by a self-assembly method. The characterization of copolymer and micelles was assessed by gel permeation chromatography (GPC), Fourier transform infrared spectroscopy (FT-IR), proton nuclear magnetic resonance spectroscopy (1HNMR), differential scanning calorimetry (DSC), transmission electron microscopy (TEM), and dynamic light scattering (DLS) methods. The MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] assay was used to indicate the cytotoxicity of the free Cur, PCL-T-M, and Cur-loaded PCL-T-M.

RESULTS

TEM analysis showed monodispersed and spherical shapes with a size of about 90 nm. Cur was released from PCL-T-M at pH 7.4 (45%) and 5.5 (90%) during 6 days. After 24 and 48 h, the IC50 of the free Cur, PCL-T-M, and Cur-loaded PCL-T-M on MCF-7 cells were 80.86 and 54.45 μg mL-1, 278.30 and 236.19 μg mL-1, 45.47 and 19.05 μg mL-1, respectively.

CONCLUSION

this study showed that, in the same concentration, the effectiveness of the Cur-loaded PCL-T-M is more than the free Cur, and the nano-system has been able to overcome delivery obstacles of Cur drug. Thus, PCL-T-M can be a candidate as a drug carrier for the delivery of Cur and future therapeutic investigations on breast cancer.

Micellar Form of a Ferrocene-Containing Camphor Sulfonamide with Improved Aqueous Solubility and Tumor Curing Potential

The discovery of new anticancer drugs with а higher, more specific activity and diminished side effects than the conventional chemotherapeutic agents is a tremendous challenge to contemporary medical research and development. To achieve a pronounced efficacy, the design of antitumor agents can combine various biologically active subunits in one molecule, which can affect different regulatory pathways in cancer cells. We recently demonstrated that a newly synthesized organometallic compound, a ferrocene-containing camphor sulfonamide (DK164), possesses promising antiproliferative activity against breast and lung cancer cells. However, it still encounters the problem of solubility in biological fluids. In this work, we describe a novel micellar form of DK164 with significantly improved solubility in aqueous medium. DK164 was embedded in biodegradable micelles based on a poly(ethylene oxide)-b-poly(α-cinnamyl-ε-caprolactone-co-ε-caprolactone)-b-poly(ethylene oxide) triblock copolymer (PEO113-b-P(CyCL3-co-CL46)-b-PEO113), and the physicochemical parameters (size, size distribution, zeta potential, encapsulation efficiency) and biological activity of the obtained system were studied. We used cytotoxicity assays and flow cytometry to determine the type of cell death, as well as immunocytochemistry to assess the influence of the encapsulated drug on the dynamics of cellular key proteins (p53 and NFkB) and the process of autophagy. According to our results, the micellar form of the organometallic ferrocene derivate (DK164-NP) exhibited several advantages compared to the free substance, such as higher metabolic stability, better cellular uptake, improved bioavailability, and long-term activity, maintaining nearly the same biological activity and anticancer properties of the drug.

HER2-Specific Peptide (LTVSPWY) and Antibody (Herceptin) Targeted Core Cross-Linked Micelles for Breast Cancer: A Comparative Study

This study aims to prepare a novel breast cancer-targeted micelle-based nanocarrier, which is stable in circulation, allowing intracellular drug release, and to investigate its cytotoxicity, apoptosis, and cytostatic effects, in vitro. The shell part of the micelle is composed of zwitterionic sulfobetaine ((N-3-sulfopropyl-N,N-dimethylamonium)ethyl methacrylate), while the core part is formed by another block, consisting of AEMA (2-aminoethyl methacrylamide), DEGMA (di(ethylene glycol) methyl ether methacrylate), and a vinyl-functionalized, acid-sensitive cross-linker. Following this, a targeting agent (peptide (LTVSPWY) and antibody (Herceptin®)), in varying amounts, were coupled to the micelles, and they were characterized by 1H NMR, FTIR (Fourier-transform infrared spectroscopy), Zetasizer, BCA protein assay, and fluorescence spectrophotometer. The cytotoxic, cytostatic, apoptotic, and genotoxic effects of doxorubicin-loaded micelles were investigated on SKBR-3 (human epidermal growth factor receptor 2 (HER2)-positive) and MCF10-A (HER2-negative). According to the results, peptide-carrying micelles showed a higher targeting efficiency and better cytostatic, apoptotic, and genotoxic activities than antibody-carrying and non-targeted micelles. Also, micelles masked the toxicity of naked DOX on healthy cells. In conclusion, this nanocarrier system has great potential to be used in different drug-targeting strategies, by changing targeting agents and drugs.

Dendritic-Linear Copolymer and Dendron Lipid Nanoparticles for Drug and Gene Delivery

Polymers constitute a diverse class of macromolecules that have demonstrated their unique advantages to be utilized for drug or gene delivery applications. In particular, polymers with a highly ordered, hyperbranched structure─"dendrons"─offer significant benefits to the design of such nanomedicines. The incorporation of dendrons into block copolymer micelles can endow various unique properties that are not typically observed from linear polymer counterparts. Specifically, the dendritic structure induces the conical shape of unimers that form micelles, thereby improving the thermodynamic stability and achieving a low critical micelle concentration (CMC). Furthermore, through a high density of highly ordered functional groups, dendrons can enhance gene complexation, drug loading, and stimuli-responsive behavior. In addition, outward-branching dendrons can support a high density of nonfouling polymers, such as poly(ethylene glycol), for serum stability and variable densities of multifunctional groups for multivalent cellular targeting and interactions. In this paper, we review the design considerations for dendron-lipid nanoparticles and dendron micelles formed from amphiphilic block copolymers intended for gene transfection and cancer drug delivery applications. These technologies are early in preclinical development and, as with other nanomedicines, face many obstacles on the way to clinical adoption. Nevertheless, the utility of dendron micelles for drug delivery remains relatively underexplored, and we believe there are significant and dramatic advancements to be made in tumor targeting with these platforms.

Combinations of chemo-, immuno-, and gene therapies using nanocarriers as a multifunctional drug platform

INTRODUCTION

Cancer immunotherapies have created a new generation of therapeutics to employ the immune system to attack cancer cells. However, these therapies are typically based on biologics that are nonspecific and often exhibit poor tumor penetration and dose-limiting toxicities. Nanocarriers allow the opportunity to overcome these barriers as they have the capabilities to direct immunomodulating drugs to tumor sites via passive and active targeting, decreasing potential adverse effects from nonspecific targeting. In addition, nanocarriers can be multifunctionalized to deliver multiple cancer therapeutics in a single drug platform, offering synergistic potential from co-delivery approaches.

AREAS COVERED

This review focuses on the delivery of cancer therapeutics using emerging nanocarriers to achieve synergistic results via co-delivery of immune-modulating components (i.e. chemotherapeutics, monoclonal antibodies, and genes).

EXPERT OPINION

Nanocarrier-mediated delivery of combinatorial immunotherapy creates the opportunity to fine-tune drug release while achieving superior tumor targeting and tumor cell death, compared to free drug counterparts. As these nanoplatforms are constantly improved upon, combinatorial immunotherapy will afford the greatest benefit to treat an array of tumor types while inhibiting cancer evasion pathways.

Specifically Targeted Transport of Plasma Membrane Transporters: From Potential Mechanisms for Regulating Cell Health or Disease to Applications

Normal substrate transport and signal transmission are the premise to ensure the health of biological somatic cells. Therefore, a comprehensive understanding of the molecular mechanism of intercellular substrate transport is of great significance for clinical treatment. In order to better understand the membrane protein through its interaction with receptors, to help maintain a healthy cell and the molecular mechanisms of disease, in this paper, we seek to clarify, first of all, the recognition mechanism for different types of membrane protein receptors; pathogen invasion using the transport pathway involved in the membrane; and the latest specific target sites of various kinds of membrane transport carriers; to provide an explanation and summary of the system. Secondly, the downstream receptor proteins and specific substrates of different membrane transporters were classified systematically; the functional differences of different subclasses and their relationship with intracellular transport disorders were analyzed to further explore the potential relationship between cell transport disorders and diseases. Finally, the paper summarizes the use of membrane transporter-specific targets for drug design and development from the latest research results; it points out the transporter-related results in disease treatment; the application prospects and the direction for drug development and disease treatment providing a new train of thought; also for disease-specific targeted therapy, it provides a certain reference value.

Advances in antibody nanoconjugates for diagnosis and therapy: A review of recent studies and trends

Nowadays, the targeted imaging probe and drug delivery systems are the novel breakthrough area in the nanomedicine and treatment of various diseases. Conjugation of monoclonal antibodies and their fragments on nanoparticles (NPs) have a remarkable impact on personalized medicine, such that it provides specific internalization and accumulation in the tumor microenvironment. Targeted imaging and early detection of cancer is presumably the strong participant to a diminution in mortality and recurrence of cancer disease that will be the next generation of the imaging device in clinical application. These intelligent delivery systems can deliver therapeutic agents that target cancerous tissue with minimal side effects and a wide therapeutic window. Overall, the linkage between the antibody and NPs is a critical subject and requires precise design and development. The attachment of antibody nanoconjugates (Ab-NCs) on the antigen surface shouldn't affect the function of the antibody-antigen binding. Also, the stability of the antibody nanoconjugates in blood circulation is concerned to avoid the release of drug in non-targeted regions and the possible for specific toxicity while disposal to the desired site. Here, we update the recent progress of Ab-NCs to improve early detection and cancer therapy.

Imidazole-Mediated Dual Location Disassembly of Acid-Degradable Intracellular Drug Delivery Block Copolymer Nanoassemblies

Acid-degradable (or acid-cleavable) polymeric nanoassemblies have witnessed significant progress in anti-cancer drug delivery. However, conventional nanoassemblies designed with acid-cleavable linkages at a single location have several challenges, such as, sluggish degradation, undesired aggregation of degraded products, and difficulty in controlled and on-demand drug release. Herein, a strategy that enables the synthesis of acid-cleavable nanoassemblies labeled with acetaldehyde acetal groups in both hydrophobic cores and at core/corona interfaces, exhibiting synergistic response to acidic pH at dual locations and thus inducing rapid drug release is reported. The systematic analyses suggest that the acid-catalyzed degradation and disassembly are further enhanced by decreasing copolymer concentration (i.e., increasing proton/acetal mole ratio). Moreover, incorporation of acid-ionizable imidazole pendants in the hydrophobic cores improve the encapsulation of doxorubicin, the anticancer drug, through π-π interactions and enhance the acid-catalyzed hydrolysis of acetal linkages situated in the dual locations. Furthermore, the presence of the imidazole pendants induce the occurrence of core-crosslinking that compensates the kinetics of acetal hydrolysis and drug release. These results, combined with in vitro cell toxicity and cellular uptake, suggest the versatility of the dual location acid-degradation strategy in the design and development of effective intracellular drug delivery nanocarriers.

In Vitro and In Vivo Evaluation of Novel DTX-Loaded Multifunctional Heparin-Based Polymeric Micelles Targeting Folate Receptors and Endosomes

BACKGROUND

The development of biocompatible tumor-targeting delivery systems for anticancer agents is essential for efficacious cancer chemotherapy. Nanoparticles, as drug delivery cargoes for cancer therapy, are rapidly improving to overcome the limitations of conventional chemotherapeutic agents. Heparin-modified nanoparticles are currently being considered as one of the favorable carriers for the delivery of chemotherapeutics to cancer tissues.

OBJECTIVE

This study was aimed at evaluating the in vitro and in vivo antitumor activity of a novel targeted, pH-sensitive, heparin-based polymeric micelle loaded with the poorly water-soluble anticancer drug, docetaxel (DTX). The micelles could overcome the limited water solubility, non-specific distribution, and insufficient drug concentration in tumor tissues.

METHODS

DTX-loaded folate targeted micelles were prepared and evaluated for physicochemical properties, drug release, in vitro cellular uptake and cytotoxicity in folate receptor-positive and folate receptor-negative cells. Furthermore, the antitumor activity of DTX-loaded micelles was evaluated in the tumor-bearing mice. Some related patents were also studied in this research.

RESULTS

The heparin-based targeted micelles exhibited higher in vitro cellular uptake and cytotoxicity against folate receptor over-expressed cells due to the specific receptor-mediated endocytosis. DTX-loaded micelles displayed greater antitumor activity, higher anti-angiogenesis effects, and lower systemic toxicity compared with free DTX in a tumor-induced mice model as confirmed by tumor growth monitoring, immunohistochemical evaluation, and body weight shift. DTX-loaded targeting micelles demonstrated no considerable toxicity on major organs of tumor-bearing mice compared with free DTX.

CONCLUSION

Our results indicated that DTX-loaded multifunctional heparin-based micelles with desirable antitumor activity and low toxicity possess great potential as a targeted drug delivery system in the treatment of cancer.

Recent advances in HER2-targeted delivery for cancer therapy

Human epidermal growth factor receptor 2 (HER2), a tyrosine kinase receptor with a molecular mass of 185kDa, is overexpressed in several cancers, such as breast, gastric, ovary, prostate, and lung. HER2 is a promising target in cancer therapy because of its crucial role in cell migration, proliferation, survival, angiogenesis, and metastasis through various intracellular signaling cascades. This receptor is an ideal target for the delivery of chemotherapeutic agents because of its accessibility to the extracellular domain. In this review, we highlight different HER2-targeting strategies and various approaches for HER2-targeted delivery systems to improve outcomes for cancer therapy.

The evolution of polymer conjugation and drug targeting for the delivery of proteins and bioactive molecules

Polymer conjugation can be considered one of the leading approaches within the vast field of nanotechnology-based drug delivery systems. In fact, such technology can be exploited for delivering an active molecule, such as a small drug, a protein, or genetic material, or it can be applied to other drug delivery systems as a strategy to improve their in vivo behavior or pharmacokinetic activities such as prolonging the half-life of a drug, conferring stealth properties, providing external stimuli responsiveness, and so on. If on the one hand, polymer conjugation with biotech drug is considered the linchpin of the protein delivery field boasting several products in clinical use, on the other, despite dedicated research, conjugation with low molecular weight drugs has not yet achieved the milestone of the first clinical approval. Some of the primary reasons for this debacle are the difficulties connected to achieving selective targeting to diseased tissue, organs, or cells, which is the main goal not only of polymer conjugation but of all delivery systems of small drugs. In light of the need to achieve better drug targeting, researchers are striving to identify more sophisticated, biocompatible delivery approaches and to open new horizons for drug targeting methodologies leading to successful clinical applications. This article is categorized under: Therapeutic Approaches and Drug Discovery > Emerging Technologies Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease Toxicology and Regulatory Issues in Nanomedicine > Regulatory and Policy Issues in Nanomedicine.

Nanocomposites for the delivery of bioactive molecules in tissue repair: vital structural features, application mechanisms, updated progress and future perspectives

In recent years, nanocomposites have attracted great attention in tissue repair as carriers for bioactive molecule delivery due to their biochemical and nanostructural similarity to that of physiological tissues, and controlled delivery of bioactive molecules. In this review, we aim to comprehensively clarify how the applications of nanocomposites for bioactive molecule delivery in tissue repair are achieved by focusing on the following aspects: (1) vital structural features (size, shape, pore, etc.) of nanocomposites that have crucial effects on the biological properties and function of bioactive molecule-delivery systems, (2) delivery performance of bioactive molecules possessing high entrapment efficiency of bioactive molecules and good controlled- and sustained-release of bioactive molecules, (3) application mechanisms of nanocomposites to deliver and release bioactive molecules in tissue repair, (4) updated research progress of nanocomposites for bioactive molecule delivery in hard and soft tissue repair, and (5) future perspectives in the development of bioactive molecule-delivery systems based on nanocomposites.