Efficient Intracellular Drug Delivery Research Articles

Fluffy hybrid nanoadjuvants for reversing the imbalance of osteoclastic and osteogenic niches in osteoporosis

Osteoporosis is majorly caused by an imbalance between osteoclastic and osteogenic niches. Despite the development of nationally recognized first-line anti-osteoporosis drugs, including alendronate (AL), their low bioavailability, poor uptake rate, and dose-related side effects present significant challenges in treatment. This calls for an urgent need for more effective bone-affinity drug delivery systems. In this study, we produced hybrid structures with bioactive components and stable fluffy topological morphology by cross-linking calcium and phosphorus precursors based on mesoporous silica to fabricate nanoadjuvants for AL delivery. The subsequent grafting of -PEG-DAsp8 ensured superior biocompatibility and bone targeting capacity. RNA sequencing revealed that these fluffy nanoadjuvants effectively activated adhesion pathways through CARD11 and CD34 molecular mechanisms, hence promoting cellular uptake and intracellular delivery of AL. Experiments showed that small-dose AL nanoadjuvants effectively suppress osteoclast formation and potentially promote osteogenesis. In vivo results restored the balance between osteogenic and osteoclastic niches against osteoporosis as well as the consequent significant recovery of bone mass. Therefore, this study constructed a drug nanoadjuvant with peculiar topological structures and high bone targeting capacities, efficient intracellular drug delivery as well as bone bioactivity. This provides a novel perspective on drug delivery for osteoporosis and treatment strategies for other bone diseases.

Oxygen Self-Supplied Perfluorocarbon-Modified Micelles for Enhanced Cancer Photodynamic Therapy and Ferroptosis.

Photodynamic therapy (PDT) and ferroptosis show significant potential in tumor treatment. However, their therapeutic efficacy is often hindered by the oxygen-deficient tumor microenvironment and the challenges associated with efficient intracellular drug delivery into tumor cells. Toward this end, this work synthesized perfluorocarbon (PFC)-modified Pluronic F127 (PFC-F127), and then exploits it as a carrier for codelivery of photosensitizer Chlorin e6 (Ce6) and the ferroptosis promoter sorafenib (Sor), yielding an oxygen self-supplying nanoplatform denoted as Ce6-Sor@PFC-F127. The PFCs on the surface of the micelle play a crucial role in efficiently solubilizing and delivering oxygen as well as increasing the hydrophobicity of the micelle surface, giving rise to enhanced endocytosis by cancer cells. The incorporation of an oxygen-carrying moiety into the micelles enhances the therapeutic impact of PDT and ferroptosis, leading to amplified endocytosis and cytotoxicity of tumor cells. Hypotonic saline technology was developed to enhance the cargo encapsulation efficiency. Notably, in a murine tumor model, Ce6-Sor@PFC-F127 effectively inhibited tumor growth through the combined use of oxygen-enhanced PDT and ferroptosis. Taken together, this work underscores the promising potential of Ce6-Sor@PFC-F127 as a multifunctional therapeutic nanoplatform for the codelivery of multiple cargos such as oxygen, photosensitizers, and ferroptosis inducers.

Mn-phenolic networks as synergistic carrier for STING agonists in tumor immunotherapy

The cGAS-STING pathway holds tremendous potential as a regulator of immune responses, offering a means to reshape the tumor microenvironment and enhance tumor immunotherapy. Despite the emergence of STING agonists, their clinical viability is hampered by stability and delivery challenges, as well as variations in STING expression within tumors. In this study, we present Mn-phenolic networks as a novel carrier for ADU-S100, a hydrophilic STING agonist, aimed at bolstering immunotherapy. These nanoparticles, termed TMA NMs, are synthesized through the coordination of tannic acid and manganese ions, with surface modification involving bovine serum albumin to enhance their colloidal stability. TMA NMs exhibit pH/GSH-responsive disintegration properties, enabling precise drug release. This effectively addresses drug stability issues and facilitates efficient intracellular drug delivery. Importantly, TMA NMs synergistically enhance the effects of ADU-S100 through the concurrent release of Mn2+, which serves as a sensitizer of the STING pathway, resulting in significant STING pathway activation. Upon systemic administration, these nanoparticles efficiently accumulate within tumors. The activation of STING pathways not only induces immunogenic cell death (ICD) in tumor cells but also orchestrates systemic remodeling of the immunosuppressive microenvironment. This includes the promotion of cytokine release, dendritic cell maturation, and T cell infiltration, leading to pronounced suppression of tumor growth. Combining with the excellent biocompatibility and biodegradability, this Mn-based nanocarrier represents a promising strategy for enhancing tumor immunotherapy through the cGAS-STING pathway.

Enzyme‐Inspired Nanoreactor Containing Light‐Controlled “Trojan Horse” for Redox‐Hypersensitive Drug Delivery

AbstractThe applications of bioresponsive materials are limited by the low levels of physiological triggers and spatiotemporal barriers in vivo. To address these issues, a light‐controlled “Trojan horse” strategy is proposed by encapsulating a photo‐caged reducing agent within reduction‐responsive polymer vesicles. The polymersomes act as an enzyme‐inspired nanoreactor for efficient photo‐synthesis of dithiothreitol in situ, which attacks the disulfide bonds in polymer backbones and disintegrates the vehicles from the inside in a nanoconfined space. The assembly‐catalyzed photoreduction reaction overcomes the temporal and spatial barriers for hyper‐responsivity and enables ultrafast drug release even at 0.014 mm of dithiothreitol residues, a concentration 715 times lower than that required to cleave disulfide bonds. In addition, in both vitro and vivo, the equipment of upconverting nanoparticles and photothermal agents creates a near‐infrared light‐activated and self‐heating nanoreactor, which allows for efficient intracellular drug delivery and excellent photo‐chemo‐immunotherapy of tumors. This work presents a new approach to designing smart materials and a promising platform for on‐demand drug delivery applications.

Synthesis of Photo, Oxidative, and Reductive Triple-Stimuli-Responsive Block Copolymer Micelles as Nanocarriers for Controlled Release.

With the rapid development of nanotechnology, stimuli-responsive nanomaterials have provided an alternative for designing controllable drug delivery systems due to their spatiotemporally controllable properties. The environment of the human body is complex and cancer cells proliferate rapidly; the traditional nanocarriers could not release the loaded drugs sufficiently, and the release level of the drug is not sufficient for the requirement of treatment. Herein, a photoresponsive, glutathione, and reactive oxygen species block copolymer mPEG2k-ONB-SS-PO-mPEG2k is prepared by Cu(I)-catalyzed azide-alkyne cycloaddition click polymerization. The ο-nitrobenzyl groups, peroxalate ester bonds, disulfide bonds, and triazole units are regularly and repeatedly arranged in hydrophobic blocks. The photo, oxidative, and reductive responsive characteristics of the copolymers in different conditions were investigated by ultraviolet and visible spectrophotometry, dynamic light scattering, and transmission electron microscopy. Nile Red is encapsulated into the core of micelles as a model drug and exhibits the drug release behaviors in various environments. This research provides a way to design potential drug carriers and a promising platform for efficient intracellular drug delivery in cancer therapy.

Drug-induced hierarchical self-assembly of poly(amino acid) for efficient intracellular drug delivery

As a potent anticancer drug, gambogic acid (GA) suffers from its poor water solubility and low chemical stability and shows a limited clinical outcome. To address this problem, we report here a simple and effective strategy to immobilize and deliver GA using a reducible diblock poly(amino acid) as a model. The electrostatic interaction between GA and polymer enables a high drug loading content up to 53.6 %. Moreover, the drug complexation induces a micelle-to-vesicle transformation, combined with a conformation transition from random coil to α-helix. The hierarchically assembled drug nanocomplexes can serve as a smart carrier for efficient cell internalization and triggered release of multiple drugs under intracellular acidic and reductive conditions, resulting in a synergistic antitumor efficacy in vitro. This work provides a new insight into the drug-carrier interaction and a facile nanoplatform for drug delivery applications.

Functional metal–organic framework-based nanocarriers for accurate magnetic resonance imaging and effective eradication of breast tumor and lung metastasis

The use of nanoscale metal–organic frameworks (MOFs) as drug delivery vehicles has attracted considerable attention in tumor therapy. In this study, novel biocompatible MOF-based nanocarriers were used as part of a facile and reproducible strategy for precision cancer theranostics. Both diagnostic (Mn2+) and therapeutic compounds (doxorubicin, DOX) were incorporated into the multifunctional MOF-based nanocarriers, which exhibited high colloidal stability and promoted T1-weighted proton relaxivity and low-pH-activated drug release. The obtained MOF-based nanocarriers exhibited significantly high cellular uptake and efficient intracellular drug delivery into cancer cells, which resulted in high apoptosis and cytotoxicity, in addition to effectively inhibiting the migration of 4T1 breast cancer cells. Moreover, the MOF-based nanocarriers could intensively deliver diagnostic and therapeutic agents to tumors to enable precise visualization of the nanocarrier accumulation and accurate tumor positioning, diagnosis, and imaging-guided therapy using magnetic resonance imaging (MRI). In addition, the functional MOF-based nanocarriers exhibited effective ablation of the primary breast cancer, as well as significant inhibition of lung metastasis with a high survival rate. Therefore, the developed nanocarriers represent a viable platform for cancer theranostics.

When liposomes met antibodies: Drug delivery and beyond.

Drug encapsulated liposomes and monoclonal antibodies (Mabs) are two distinctively different classes of therapeutics, but both aim to become the ultimate "magic bullet". While PEGylated liposomes rely on the enhanced permeability and retention (EPR) effect for accumulation in solid tumor tissues, Mabs are designed to bind tightly to specific surface antigens on target cells to exert effector functions. Immunoliposome (IL) refers to the structural combination of liposomes and antibodies, whereas the antibodies are usually decorated on the liposome surface. ILs can therefore take advantage of interactions between antibodies and cancer cells for more efficient endocytosis and intracellular drug delivery. The antibody structure, affinity, density, as well as the liposome surface properties and drug to lipid ratios all contribute to the IL pharmacokinetic(PK) and pharmacodynamic(PD) behaviors. The optimal formulation parameters may vary for different target cells and tissues. Furthermore, besides the delivery of cytotoxic drugs to cancer cells, new ILs are being developed to interact with multiple target receptors, multiple target cells and trigger multiple therapeutic effects. We envision that the IL format can be a great platform for the molecular engineering of multi-valent, multi-specific interactions to achieve complex biological functions for therapeutic benefits, especially in the area of cancer immunotherapy.

Actively Targeted and Redox Responsive Delivery of Anticancer Drug by Chitosan Nanoparticles.

The clinical efficacy of methotrexate (MTX) is limited by its poor water solubility, its low bioavailability, and the development of resistance in cancer cells. Herein, we developed novel folate redox-responsive chitosan (FTC) nanoparticles for intracellular MTX delivery. l-Cysteine and folic acid molecules were selected to be covalently linked to chitosan in order to confer it redox responsiveness and active targeting of folate receptors (FRs). NPs based on these novel polymers could possess tumor specificity and a controlled drug release due to the overexpression of FRs and high concentration of reductive agents in the microenvironment of cancer cells. Nanoparticles (NPs) were prepared using an ionotropic gelation technique and characterized in terms of size, morphology, and loading capacity. In vitro drug release profiles exhibited a glutathione (GSH) dependence. In the normal physiological environment, NPs maintained good stability, whereas, in a reducing environment similar to tumor cells, the encapsulated MTX was promptly released. The anticancer activity of MTX-loaded FTC-NPs was also studied by incubating HeLa cells with formulations for various time and concentration intervals. A significant reduction in viability was observed in a dose- and time-dependent manner. In particular, FTC-NPs showed a better inhibition effect on HeLa cancer cell proliferation compared to non-target chitosan-based NPs used as control. The selective cellular uptake of FTC-NPs via FRs was evaluated and confirmed by fluorescence microscopy. Overall, the designed NPs provide an attractive strategy and potential platform for efficient intracellular anticancer drug delivery.

Lytic peptide-grafted beta-cyclodextrin polymer based nano-scaled drug delivery system with enhanced camptothecin anti-cancer efficacy

The aqueous solubility of drug molecules is closely related to its bioactivity like bioavailability and subsequent therapeutic index, especially in the case of hydrophobic drugs like camptothecin (CPT), a potential broad-spectrum anti-cancer agent. Enhanced anti-cancer activity and selectivity of CPT are equally important. Inspired by host-guest effect and drug combination regimen, we developed a novel tumor lytic peptide incorporated drug delivery system by forming beta-cyclodextrin polymer (BCDp) based inclusion complex in nano-scaled size. In this study, BCDp formed inclusion complex with CPT and then a lytic-type peptide (ZH) was grafted. The resulting combinational formulation of BCDp, CPT and ZH, named as ZH-BCDp-CPT inclusion complex, demonstrated greater solubility resulting from its nano-scaled size, amorphous solid state and inclusion structure. Moreover, ZH facilitated quick internalization of conjugated drug via cell membrane lysis, leading to efficient intracellular drug delivery. This novel drug formulation was featured with prolonged circulation, enhanced anti-cancer efficacy, selectivity, anti-cell migration activity and better biocompatibility in comparison with crude CPT and binary BCDp-CPT inclusion complex, all of which were attributed to a cooperative action between ZH and BCDp-CPT inclusion complex. Our results suggested ZH-BCDp-CPT inclusion complex induced cell apoptosis by up-regulation of Bax and P53 and down-regulation of Bcl-2, primarily involved in the mitochondrial pathways.

Cyclic Cell-Penetrating Peptides as Efficient Intracellular Drug Delivery Tools.

Cyclic cell-penetrating peptides are relatively a newer class of peptides that have a huge potential for the intracellular delivery of therapeutic agents aimed at treating challenging ailments like multidrug-resistant bacterial diseases, cancer, and HIV infection. Cell-penetrating peptides (CPPs) have been extensively explored as intracellular delivery vehicles; however, they have some inherent limitations like poor stability, endosomal entrapment, toxicity, and suboptimal cell penetration. Owing to their favorable properties that avoid these limitations, cyclic CPPs can provide a good alternative to linear CPPs. Several Reviews have been published in the past decade that cover CPPs and cyclic peptides independently. To the best of our knowledge, this is one of the first Reviews that covers cyclic CPPs comprehensively in the light of studies published so far. In this Review, we have detailed examples of cyclic CPPs, their structures, and cyclization strategies followed by a detailed account of their advantages over their linear counterparts. A hot area in cyclic CPPs is the exploration of cell-penetration mechanisms; this Review highlights this topic in detail. Finally, we will review the applications of cyclic CPPs, followed by conclusions and future prospects.

Glutathione-Induced Structural Transform of Double-Cross-Linked PEGylated Nanogel for Efficient Intracellular Anticancer Drug Delivery.

A glutathione-sensitive poly[methacrylic acid- co-poly(ethylene glycol) methyl ether methacrylate] (PMAABACy- co-PEGMA) nanogel with tunable stability has been fabricated through covalent and metal double-cross-linking strategies in response to the differential change of GSH concentration between the inside and outside of tumor cells. Herein, the size-controlled PMAA- co-PEGMA that possessed unique core-shell structure was first obtained via adjusting the length of PEGMA. Furthermore, N, N-bis(acryloyl)cystamine was introduced to endow PMAA- co-PEGMA with glutathione-sensitive property. The PMAABACy- co-PEGMA950 nanogel exhibited reasonable particle size and desired hydrodynamic diameter that was further cross-linked by Fe(III) ions to obtain a double-cross-linked PMAABACy/Fe(III)- co-PEGMA950 vehicle. In this double-cross-linked vehicle, the existence of metal cross-linked structure made this vehicle possess favorable structural stability to restrict the premature leakage of therapeutic drug. The introduction of covalent cross-linked structure synchronously imparted the vehicle with glutathione-sensitive property in response to the high intracellular glutathione concentrations in tumor cells to induce its structural transform for realizing the release of drug. Additionally, a series of in vitro evaluations demonstrated that PMAABACy/Fe(III)- co-PEGMA950 displayed remarkable biocompatibility and glutathione-sensitive release toward anticancer drug in the simulated intracellular environment of tumor tissues. Notably, the drug-loaded PMAABACy/Fe(III)- co-PEGMA950 exhibited excellent anticancer activity against tumor cells. The double-cross-linked PMAABACy/Fe(III)- co-PEGMA950 nanogel therefore is expected to be a promising tumor microenvironment-sensitive platform for delivering chemotherapeutic drugs.

Dual acid-responsive bola-type supramolecular vesicles for efficient intracellular anticancer drug delivery

Dual acid-responsive bola-type supramolecular vesicles have been successfully constructed for efficient intracellular anticancer drug delivery and controlled release.

Facile preparation of biodegradable dual stimuli-responsive micelles from waterborne polyurethane for efficient intracellular drug delivery

A novel waterborne polyurethane based on main chain degradation under acidic and reductive conditions of tumors was synthesized.

PH-triggered intracellular release of doxorubicin from polyaspartamide-encapsulated mesoporous silica nanoparticles

Mesoporous silica nanoparticles (MSNs) conjugating doxorubicin (DOX) via a pH-sensitive cleavable linkage, hydrazine (HYD) were synthesized. MSN-HYD-DOX were encapsulated with the polyaspartamide (PASPAM) grafted with the hydrophilic o-(2-aminoethyl)-o′-methylpoly(ethylene glycol) (PEG) and the cell permeating ligand, biotin (Biotin). The chemical structure of the synthesized MSN-HYD-DOX and PASPAM-g-PEG/Biotin was confirmed using FT-IR and 1H-NMR spectroscopy. The mean diameter of the MSN-HYD-DOX@PASPAM-g-PEG/Biotin nanoparticle was 142 nm and 121 nm, respectively, examined by dynamic light scattering (DLS) and transmission electron microscope (TEM). The HYD bond was effectively cleaved in acidic condition, and thus DOX was released much faster at pH 5.0 than at pH 7.4. The cell viability in MSN-HYD-DOX@PASPAM-g-PEG/Biotin system was much lower than that of the free DOX drug because of efficient intracellular drug delivery associated with the biotin ligand.

DOC-LS, a new liposome for dermal delivery, and its endocytosis by HaCaT and CCC-ESF-1 cells.

The main objective of this work was to investigate the uptake channels of skin cells through which coumarin 6, transported by deoxycholate-mediated liposomes (DOC-LS), was internalised; this was also compared against the action of conventional LS. Coumarin 6-loaded DOC-LS and LS were characterised for size distribution, zeta potential, and shape, and analysed in vitro in human epidermal immortal keratinocyte (HaCaT) (epidermal) and human embryonic skin fibroblast (CCC-ESF-1) (dermal) cell lines. Various endocytosis inhibitors were incubated with cells treated with the nanocarriers. Flow cytometry results indicated that HaCaT and CCC-ESF-1 cells internalise the tested preparations through pinocytotic vesicles, macropinocytosis, clathrin-mediated endocytic pathways, and via lysosomes, which consume a considerable amount of energy. The endocytosis pathways of DOC-LS and LS showed no difference. This study provides a basis for the application of LS being combined with a microneedle system for efficient intracellular drug delivery, targeting cutaneous histocyte disorders.

Acid/light dual-responsive biodegradable polymeric nanocarriers for efficient intracellular drug delivery

A novel amphiphilic acid/light dual-cleavable diblock copolymer poly(e-caprolactone)-acetal-nitrobenzyl ester-poly(ethylene glycol) (PCL-PEG) was prepared via the ring-opening polymerization of e-caprolactone using 5-propargylether-2-nitrobenzyl alcohol as the initiator and subsequent “click” coupling reaction with azide-terminated poly(ethylene glycol) containing acetal group. Both light-cleavable o-nitrobenzyl methyl ester (ONB) and acid-labile acetal were used as the linkages in between the hydrophilic and hydrophobic polymer blocks. In aqueous solution, the copolymer self-assembled into the spherical polymeric nanoparticles, which were stable under physiological conditions and retained the anticancer drug doxorubicin (DOX) inside. Triggered by acid or UV irradiation, the DOX release rate was significantly enhanced, due to the correspondent degradation of acetal or ONB linkages under the stimulus. In addition, confocal laser scanning microscopy studies further demonstrated the DOX-loaded nanodrug could be efficiently taken up by HeLa cells and exhibited the enhanced DOX release into the cytoplasm upon UV irradiation. Furthermore, in vitro cytotoxicity study verified UV irradiation could improve the antitumor efficacy of the nanodrug against HeLa cells. Thus, this work provides a new method of the design of dual-responsive biodegradable polymers for drug delivery.

Glutathione-responsive self-delivery nanoparticles assembled by curcumin dimer for enhanced intracellular drug delivery

Poor water solubility, short half-life, and low drug efficacy posed a challenge for clinical application of curcumin (CUR). In this work, a kind of CUR prodrug was synthesized by coupling two CUR molecules with a mono-thioether linker for glutathione (GSH)-responsive drug delivery. The synthesized CUR prodrug (CUR-S-CUR dimer) could self-assemble into the homogeneous spherical nanoparticles (NPs) in aqueous solution followed by surface functionalization of trace amounts of DSPE-PEG. These CUR-S-CUR@PEG NPs exhibited a small particle size of ∼100 nm, high CUR-loading content of ∼78 wt%, and good colloid stability. Moreover, the CUR-S-CUR@PEG NPs demonstrated much more efficient cellular uptake and intracellular/nuclear drug delivery compared with free CUR, indicating the advantages of small molecular prodrug assembly. In addition, the GSH with high concentration in tumor cells could trigger the disassembly of CUR-S-CUR@PEG NPs. Furthermore, the cytotoxicity assays indicated that the CUR-S-CUR@PEG NPs exhibited the comparable inhibition effect of tumor cell proliferation with free CUR due to sustained drug release. Therefore, these stimuli-responsive CUR-S-CUR@PEG NPs might have promising potential for highly efficient intracellular drug delivery and controlled drug release in cancer therapy.

A bio-inspired, virus mimicking liposomal delivery system for efficient intracellular drug delivery

A bio-inspired, virus mimicking liposomal delivery system for efficient intracellular drug delivery

IRGD-decorated reduction-responsive nanoclusters for targeted drug delivery.

Herein, reduction-responsive disintegratable nanoclusters (NCs) were prepared as a novel nanovehicle for targeted drug delivery. The NCs, with a diameter of ∼170 nm, were self-assembled from hydrophobically modified and iRGD decorated hydroxyethyl starch (iRGD-HES-SS-C18). DOX was loaded into the NCs as a model drug. DOX@iRGD-HES-SS-C18 NCs can disintegrate into smaller ones and release DOX under reduction stimuli. Due to the ligand-receptor binding interactions between iRGD and integrin αV, DOX@iRGD-HES-SS-C18 NCs can specifically bind to the cell membranes of HepG-2 and 4T1 cells (integrin αV positive), resulting in enhanced cellular uptake as compared to DOX@HES-SS-C18 NCs. After cellular internalization, the NCs were transported to endosomes/lysosomes in which the reductive environment triggered the disintegration and DOX release. As a consequence, DOX@iRGD-HES-SS-C18 NCs exhibited an enhanced antitumor effect as compared to DOX@HES-SS-C18 NCs and free DOX, in an in vitro antitumor activity study. The reduction-responsive disintegratable NCs reported here were proved to be a safe and efficient nanoplatform, holding significant translation potential for tumor-targeted drug delivery.