Preparation and properties evaluation of a novel pH-sensitive liposomes based on imidazole-modified cholesterol derivatives

Efficient delivery of curcumin by functional solid lipid nanoparticles with promoting endosomal escape and liver targeting properties

In the realm of intracellular drug delivery, overcoming the barrier of endosomal entrapment stands as a critical factor influencing the effectiveness of nanodrug delivery systems. This study focuses on the synthesis of an acid-sensitive fatty acid derivative called imidazole-stearic acid (IM-SA). Leveraging the proton sponge effect attributed to imidazole groups, IM-SA was anticipated to play a pivotal role in facilitating endosomal escape. Integrated into the lipid core of solid lipid nanoparticles (SLNs), IM-SA was paired with hyaluronic acid (HA) coating on the surface of SLNs loading with curcumin (CUR). The presence of IM-SA and HA endowed HA-IM-SLNs@CUR with dual functionalities, enabling the promotion of endosomal escape, and specifical targeting of liver cancer. HA-IM-SLNs@CUR exhibited a particle size of ∼228 nm, with impressive encapsulation efficiencies (EE) of 87.5 % ± 2.3 % for CUR. Drugs exhibit significant pH sensitive release behavior. Cellular experiments showed that HA-IM-SLN@CUR exhibits enhanced drug delivery capability. The incorporation of IM-SA significantly improved the endosomal escape of HA-IM-SLN@CUR, facilitating accelerated intracellular drug release and increasing intracellular drug concentration, exhibiting excellent growth inhibitory effects on HepG2 cells. Animal experiments revealed a 3.4-fold increase in CUR uptake at the tumor site with HA-IM-SLNs@CUR over the free CUR, demonstrating remarkable tumor homing potential with the tumor growth inhibition rate of 97.2 %. These findings indicated the significant promise of HA-IM-SLNs@CUR in the realm of cancer drug delivery.

Novel targeting liposomes with enhanced endosomal escape for co-delivery of doxorubicin and curcumin

Effective endosomal escape is crucial for enhancing the efficiency of nanodrug delivery systems. In this study, we developed a novel liposomal system utilizing acid-sensitive N-(3-amino-propyl) imidazole cholesterol (IM-Chol), specifically designed for the targeted co-delivery of doxorubicin (DOX) and curcumin (CUR) to hepatocellular carcinoma (HCC). Designated as GA-IM-LIP@DOX/CUR, this liposomal system incorporates glycyrrhetinic acid (GA) to improve target specificity toward HCC cells. Notably, both drugs exhibited pH-sensitive release profiles, facilitating precise drug release within acidic environments. Our investigation into cellular uptake demonstrated that modified liposomes, GA-IM-LIP@FITC and IM-LIP@FITC, achieved progressively enhanced intracellular accumulation of FITC compared to unmodified liposomes. Competitive inhibition assays utilizing free GA further validated the targeting efficacy of GA. Moreover, the GA-IM-LIP@FITC and IM-LIP@FITC groups exhibited rapid endosomal escape of FITC within the first two hours, in contrast to delayed escape observed in the LIP@FITC group, confirming that the protonation of IM-Chol promotes drug release into the cytosol. In vivo studies substantiated that GA-IM-LIP@DOX/CUR effectively inhibited tumor growth. This research provides significant insights into the design and functionality of the GA-IM-LIP@DOX/CUR liposomal system, underscoring its potential to enhance drug delivery strategies in the treatment of HCC.

Therapeutic Response of Multifunctional Lipid and Micelle Formulation in Hepatocellular Carcinoma

Hepatic stellate cells (HSCs), as an important part of the tumor microenvironment (TME), could be activated by tumor cells as cancer-associated fibroblasts (CAFs), thereby promoting the production of extracellular matrix (ECM) and favoring the development of tumors. Therefore, blocking the "CAFs-ECM" axis is a promising pathway to improve antitumor efficacy. Based on this, we developed a multifunctional nanosized delivery system composed of hyaluronic acid-modified pH-sensitive liposomes (CTHLs) and glycyrrheic acid-modified nanomicelles (DGNs), which combines the advantages of targeted delivery, pH-sensitivity, and deep drug penetration. To mimic actual TME, a novel HSCs+BEL-7402 cocultured cell model and a m-HSCs+H22 coimplanted mice model were established. As expected, CTHLs and DGNs could target CAFs and tumor cells, respectively, and promote the drug penetration and retention in tumor regions. Notably, CTHLs+DGNs not only exhibited a superior antitumor effect in three-level tumor-bearing mice but also presented excellent antimetastasis efficiency in lung-metastatic mice. The antitumor mechanism revealed that the lipid&micelle mixed formulations effectively inhibited the activation of CAFs, reduced the deposition of ECM, and reversed the epithelial-mesenchymal transition (EMT) of tumor cells. In brief, the nanosized delivery system composed of CTHLs and DGNs could effectively improve the therapeutic effect of liver cancer by blocking the "CAFs-ECM" axis, which has a good clinical application prospect.

A novel pH-responsive nanoniosomal emulsion for sustained release of curcumin from a chitosan-based nanocarrier: emphasis on the concurrent improvement of loading, sustained release, and apoptosis induction

Curcumin application as an anti-cancer drug is faced with several impediments. This study has developed a platform that facilitates the sustained release of curcumin, improves loading efficiency, and anti-cancer activity. Montmorillonite (MMT) nanoparticles were added to chitosan (CS)-agarose (Aga) hydrogel and then loaded with curcumin (Cur) to prepare a curcumin-loaded nanocomposite hydrogel. The loading capacity increased from 63% to 76% by adding MMT nanoparticles to a chitosan-agarose hydrogel. Loading the fabricated nanocomposite in the nanoniosomal emulsion resulted in sustained release of curcumin under acidic conditions. Release kinetics analysis showed diffusion and erosion are the dominant release mechanisms, indicating non-fickian (or anomalous) transport based on the Korsmeyer-Peppas model. FTIR spectra confirmed that all nanocomposite components were present in the fabricated nanocomposite. Besides, XRD results corroborated the amorphous structure of the prepared nanocomposite. Zeta potential results corroborated the stability of the fabricated nanocarrier. Cytotoxicity of the prepared CS-Aga-MMT-Cur on MCF-7 cells was comparable to that of curcumin-treated cells (p <0.001). Moreover, the percentage of apoptotic cells increased due to the enhanced release profile resulting from the addition of MMT to the hydrogel and the incorporation of the fabricated nanocomposite into the nanoniosomal emulsion. To recapitulate, the current delivery platform improved loading, sustained release, and curcumin anti-cancer effect. Hence, this platform could be a potential candidate to mitigate cancer therapy restrictions with curcumin. This article is protected by copyright. All rights reserved.

Imidazole-Based pH-Sensitive Convertible Liposomes for Anticancer Drug Delivery

In efforts to enhance the activity of liposomal drugs against solid tumors, three novel lipids that carry imidazole-based headgroups of incremental basicity were prepared and incorporated into the membrane of PEGylated liposomes containing doxorubicin (DOX) to render pH-sensitive convertible liposomes (ICL). The imidazole lipids were designed to protonate and cluster with negatively charged phosphatidylethanolamine-polyethylene glycol when pH drops from 7.4 to 6.0, thereby triggering ICL in acidic tumor interstitium. Upon the drop of pH, ICL gained more positive surface charges, displayed lipid phase separation in TEM and DSC, and aggregated with cell membrane-mimetic model liposomes. The drop of pH also enhanced DOX release from ICL consisting of one of the imidazole lipids, sn-2-((2,3-dihexadecyloxypropyl)thio)-5-methyl-1H-imidazole. ICL demonstrated superior activities against monolayer cells and several 3D MCS than the analogous PEGylated, pH-insensitive liposomes containing DOX, which serves as a control and clinical benchmark. The presence of cholesterol in ICL enhanced their colloidal stability but diminished their pH-sensitivity. ICL with the most basic imidazole lipid showed the highest activity in monolayer Hela cells; ICL with the imidazole lipid of medium basicity showed the highest anticancer activity in 3D MCS. ICL that balances the needs of tissue penetration, cell-binding, and drug release would yield optimal activity against solid tumors.

Endogenous Oleoylethanolamide Crystals Loaded Lipid Nanoparticles with Enhanced Hydrophobic Drug Loading Capacity for Efficient Stroke Therapy

Introduction

Although the preparation of lipid nanoparticles (LNPs) achieves great success, their retention of highly hydrophobic drugs is still problematic.

Methods

Herein, we report a novel strategy for efficiently loading hydrophobic drugs to LNPs for stroke therapy. Oleoylethanolamide (OEA), an endogenous highly hydrophobic molecule with outstanding neuroprotective effect, was successfully loaded to OEA-SPC&DSPE-PEG lipid nanoparticles (OSDP LNPs) with a drug loading of 15.9 ± 1.2 wt%. Efficient retention in OSDP LNPs greatly improved the pharmaceutical property and enhanced the neuroprotective effect of OEA.

Results

Through the data of positron emission tomography (PET) and TTC-stained brain slices, it could be clearly visualized that the acute ischemic brain tissues were preserved as penumbral tissues and bounced back with reperfusion. The in vivo experiments stated that OSDP LNPs could significantly improve the survival rate, the behavioral score, the cerebral infarct volume, the edema degree, the spatial learning and memory ability of the MCAO (middle cerebral artery occlusion) rats.

Discussion

These results suggest that the OSDP LNPs have a great chance to develop hydrophobic OEA into a potential anti-stroke formulation.

Coiled coil exposure and histidine tags drive function of an intracellular protein drug carrier

In recent years, protein engineering efforts have yielded a diverse set of binding proteins that hold promise for various therapeutic applications. Despite this, their inability to reach intracellular targets limits their applications to cell surface or soluble targets. To address this challenge, we previously reported a protein carrier that binds antibodies and delivers them to therapeutic targets inside cancer cells. This carrier, known as the Hex carrier, is comprised of a self-assembling coiled coil hexamer at the core, with each alpha helix fused to a linker, an antibody binding domain, and a six Histidine-tag (His-tag). In this work, we designed different versions of the carrier to determine the role of each building block in cytosolic protein delivery. We found that increasing exposure of the Hex coiled coil on the carriers, through molecular design or removing antibodies, increased internalization, pointing to a role of the coiled coil in promoting endocytosis. We observed a clear increase in endosomal disruption events when His-tags were present on the carrier relative to when they were removed, due to an endosomal buffering effect. Finally, we found that the antibody binding domains of the Hex carrier could be replaced with monomeric ultra-stable GFP for intracellular delivery and endosomal escape. Our results demonstrate that the Hex coiled coil, in conjunction with His-tags, could be a generalizable vehicle for delivering small and large proteins to intracellular targets. This work also highlights new biological applications for oligomeric coiled coils and shows the direct and quantifiable impact of histidine residues on endosomal disruption. These findings could inform the design of future drug delivery vehicles in applications beyond intracellular protein delivery.

Transferrin receptors/magnetic resonance dual-targeted nanoplatform for precise chemo-photodynamic synergistic cancer therapy

Various drug delivery strategies to improve cancer therapeutic efficacy have been actively investigated. One major challenge is to improve the targeting ability. Here elaborately designed nanocarriers (NCs) named as Tf-5-ALA-PTX-NCs are demonstrated to address this problem. In this nanostructure, paclitaxel (PTX) and 5-aminolevulinic acid (5-ALA) were co-encapsulated within magnetic nanocarriers to achieve synergistic chemotherapy and photodynamic therapy, while transferrin (Tf) was conjugated with modified copolymer Pluronic P123 and embedded in the surface of the nanocarriers, which endows nanocarriers with Tf targeting and magnetic targeting to enhance the anti-tumor outcome. Results demonstrated that Tf-5-ALA-PTX-NCs significantly enhanced the targeting drug delivery to MCF-7 cells and synergistically induced apoptosis and death of MCF-7 cells in vitro and highly efficient tumor ablation in vivo. Intriguingly, Tf-5-ALA-PTX-NCs have a controllable "on/off" switch to enhance the drug release. The dual-targeted nanocarriers would be a promising versatile anti-tumor drug delivery and imaging-guided cancer chemo-photodynamic synchronization therapy strategy.

PEGylated phospholipid micelles containing D-α-tocopheryl succinate as multifunctional nanocarriers for enhancing the antitumor efficacy of doxorubicin

The aim of this investigation is to clarify the effect of D-α-tocopheryl succinate (vitamin E succinate, VES) and distearoylphosphatidyl ethanolamine-poly(ethylene glycol) (DSPE-PEG) on the encapsulation and controlled release of doxorubicin (DOX) in nano-assemblies and their consequences on the anti-tumor efficacy of DOX. DOX molecules were successfully loaded into the hybrid micelles with VES and DSPE-PEG (VDPM) via thin-film hydration method, exhibiting a small hydrodynamic particle size (~30 nm) and a weak negative zeta potential of around -5 mv. The obtained DOX-loaded VDPM2 displayed retarded DOX release at pH of 7.4, while substantially accelerated drug release at acidic pH of 5.0. Furthermore, the DOX-loaded VDPM2 exhibited substantially slower drug release rate at pH 7.4 compared with the drug-loaded VDPM1 or DPM preparation, benefiting for decreasing the premature DOX release during blood circulation. In vitro cell experiment indicated that DOX-loaded micelles (DPM, VDPM1 and VDPM2) improved the cellular uptake of DOX in 4T1 and MDA-MB-231 cells. The existence of VES component in the structure of DOX-loaded micelles had no obvious influence on the subcellular distribution of the encapsulated DOX molecules. Furthermore, the DOX-loaded VDPM2 exhibited more pronounced cytotoxicity to 4T1 and MDA-MB-231 cancerous cells compared with DOX-loaded DPM and free DOX solution. The hybrid nanocarriers including VES and DSPE-PEG selectively induced intracellular ROS accumulation and increased level of cytoplasmic calcium ion in cancerous cells by interacting with mitochondria and endoplasmic reticulum, bringing about the improved cytotoxicity of DOX. In vivo antitumor efficacy investigation of DOX-loaded VDPM2 against 4T1 xenograft-bearing mice displayed satisfied therapeutic activity with negligible systemic toxicity, as evidenced by the histological analysis and change of body weight. The proposed DOX-loaded VDPM preparation, as a mulifunctional chemotherapeutic nanomedicine system, holds great potential and bright prospect for clinical tumor therapy.

Current Trends on Repurposing and Pharmacological Enhancement of Andrographolide

Andrographolide, the main bioactive component separated from Andrographis paniculata in 1951, has been scrutinized with a modern drug discovery approach for anti-inflammatory properties since 1984. Identification of new uses of existing drugs can be facilitated by searching for evidence linking them to known or yet undiscovered drug targets and human disease states to develop new therapeutic indications.Furthermore, a wide spectrum of biological properties of andrographolide such as anticancer, antibacterial, antiviral, hepatoprotective, antioxidant, anti-malarial, anti-atherosclerosis are also reported. However, poor water solubility and instability limit its clinical application. It becomes crucial to enhance its pharmacological function and find a new treatment option for more diseases. Therefore, this article reviews the major recent developments in andrographolide, including repurposing applications in different diseases and underlying mechanisms, particularly focusing on pharmacological enhancement of andrographolide such as derivatives, chemical modifications with potent biological activity and drug delivery. The repurposing and pharmacological enhancement of andrographolide would not only have exciting therapeutic potential to different diseases to facilitate drug marketing, but also decrease the economic burden on healthcare worldwide.

The efficiency and mechanism of a new absorption enhancer, malic acid, for enhancing the oral bioavailability of docetaxel

This study investigated the efficiency and the related mechanisms of a new absorption enhancer, DL-malic acid (MA), on the oral bioavailability of docetaxel (DTX). Polyethylene glycol polycarbonate (PEG-PCL) modified liposomes (PLip) were prepared for DTX, and incorporated into the pH-sensitive microspheres (MS) with sustained release. MA decreased the transepithelial electrical resistance (TEER) across a Caco-2 cell monolayer by 20% and 57% after 2 and 3 h of co-incubation with DTX-PLip and the cells, respectively, indicating that MA could open tight junctions but not instantaneously. After long enough exposure (4 h) of MA to the small intestine of rats, only the absorption rate constant (k_a) of DTX-PLip, but not Duopafei^®, was increased, which could be related to the intestinal mucosal permeability of DTX. After co-administration in rats, MA significantly enhanced the oral bioavailability of DTX in DTX-PLip-MS from 44.67% to 81.27%, rather than DTX-PLip and Duopafei^®, which could be related to the prolonged intestinal retention time of DTX-PLip via the MS and the promoted drug intercellular transport by MA. The absorption-enhancing effects of MA on DTX-PLip-MS were further confirmed by in vivo imaging. The above findings suggest that MA served as a new and efficient absorption enhancer for DTX-PLip-MS.HIGHlIGHTSIn this study, malic acid as a new absorption enhancer for DTX in polymer-liposome (PLip) embedded in pH-sensitive microspheres (MS) was found for the first time.The malic acid could significantly enhance oral bioavailability of DTX in DTX-PLip-MS (from 44.67 % to 81.27%) rather than Duopafei^® and DTX-PLip after co-administration.The absorption enhancement may be closely related to the intestinal retention time and mucosal permeability.These findings will provide an important reference for the study of absorption enhancers for promoting intercellular insoluble drug transport.

Review of Curcumin Physicochemical Targeting Delivery System

Curcumin (CUR), as a traditional Chinese medicine monomer extracted from the rhizomes of some plants in Ginkgo and Araceae, has shown a wide range of therapeutic and pharmacological activities such as anti-tumor, anti-inflammatory, anti-oxidation, anti-virus, anti-liver fibrosis, anti-atherosclerosis, and anti-Alzheimer’s disease. However, some issues significantly affect its biological activity, such as low aqueous solubility, physico-chemical instability, poor bioavailability, and low targeting efficacy. In order to further improve its curative effect, numerous efficient drug delivery systems have been carried out. Among them, physicochemical targeting preparations could improve the properties, targeting ability, and biological activity of CUR. Therefore, in this review, CUR carrier systems are discussed that are driven by physicochemical characteristics of the microenvironment (eg, pH variation of tumorous tissues), affected by external influences like magnetic fields and vehicles formulated with thermo-sensitive materials.

The Multifaceted Histidine-Based Carriers for Nucleic Acid Delivery: Advances and Challenges

Histidines incorporated into carriers of nucleic acids may enhance the extracellular stability of the nanoparticle, yet aid in the intracellular disruption of the nanoparticle, enabling the release of the nucleic acid. Moreover, protonation of histidines in the endosomes may result in endosomal swelling with subsequent lysis. These properties of histidine are based on its five-member imidazole ring in which the two nitrogen atoms may form hydrogen bonds or act as a base in acidic environments. A wide variety of carriers have integrated histidines or histidine-rich domains, which include peptides, polyethylenimine, polysaccharides, platform delivery systems, viral phages, mesoporous silica particles, and liposomes. Histidine-rich carriers have played key roles in our understanding of the stability of nanocarriers and the escape of the nucleic acids from endosomes. These carriers show great promise and offer marked potential in delivering plasmids, siRNA, and mRNA to their intracellular targets.

Nano Encapsulated Curcumin: And Its Potential for Biomedical Applications

Curcumin, a yellow-colored polyphenol extracted from the rhizome of turmeric root, is commonly used as a spice and nutritional supplement. It exhibits many pharmacological activities such as anti-inflammatory, anti-bacterial, anti-cancer, anti-Alzheimer, and anti-fungal. However, the therapeutic application of curcumin is limited by its extremely low solubility in aqueous buffer, instability in body fluids, and rapid metabolism. Nano delivery system has shown excellent potential to improve the solubility, biocompatibility and therapeutic effect of curcumin. In this review, we focus on the recent development of nano encapsulated curcumin and its potential for biomedical applications.

Comparative study of intratracheal and oral gefitinib for the treatment of primary lung cancer

Oral gefitinib tablets are widely applied for the treatment of non-small cell lung cancer (NSCLC) though its broad distribution in the body may result in weak therapeutic efficiency and undesired side effects. Here, liposomal gefitinib dry powder inhalers (LGDs) were prepared using the injection-lyophilization method. LGDs were rough porous particles under a scanning electron microscope, which can be rapidly rehydrated to liposomes. LGDs and gefitinib powders were separately intratracheally (i.t.) administered into the lungs of primary lung cancer rats, while powdered gefitinib tablets were orally administered. Gefitinib was rapidly absorbed from the lung after i.t. administration of LGDs. The maximal gefitinib concentration in the circulation and the area under curve (AUC) of i.t. LGDs were higher than those of i.t. gefitinib powders and oral gefitinib. More importantly, much higher concentration and longer retention of gefitinib in the lung were shown after i.t. administration of LGDs and gefitinib powders but remarkably less drug distribution in the liver compared to oral gefitinib. LGDs showed higher therapeutic effect on rat primary lung cancer than i.t. gefitinib powders and oral gefitinib with reduction of inflammation, weak lung injury, and high apoptosis. Combination of inhalation and liposomes of anticancer drugs is a promising strategy for treatment of primary lung cancer.

Combined Magnetoliposome Formation and Drug Loading in One Step for Efficient Alternating Current-Magnetic Field Remote-Controlled Drug Release

We have developed a reproducible and facile one step strategy for the synthesis of doxorubicin loaded magnetoliposomes by using a thin-layer evaporation method. Liposomes of around 200 nm were made of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) and iron oxide nanoparticles (NPs) with negative, positive, and hydrophobic surfaces that were incorporated outside, inside, or between the lipid bilayers, respectively. To characterize how NPs are incorporated in liposomes, advanced cryoTEM and atomic force microscope (AFM) techniques have been used. It was observed that only when the NPs are attached outside the liposomes, the membrane integrity is preserved (lipid melt transition shifts to 38.7 °C with high enthalpy 34.8 J/g) avoiding the leakage of the encapsulated drug while having good colloidal properties and the best heating efficiency under an alternating magnetic field (AMF). These magnetoliposomes were tested with two cancer cell lines, MDA-MB-231 and HeLa cells. First, 100% of cellular uptake was achieved with a high cell survival (above 80%), which is preserved (83%) for doxorubicin-loaded magnetoliposomes. Then, we demonstrate that doxorubicin release can be triggered by remote control, using a noninvasive external AMF for 1 h, leading to a cell survival reduction of 20%. Magnetic field conditions of 202 kHz and 30 mT seem to be enough to produce an effective heating to avoid drug degradation. In conclusion, these drug-loaded magnetoliposomes prepared in one step could be used for drug release on demand at a specific time and place, efficiently using an external AMF to reduce or even eliminate side effects.

Liver-targeted liposomes for codelivery of curcumin and combretastatin A4 phosphate: preparation, characterization, and antitumor effects

Background

Recent efforts have been focused on combining two or more therapeutic approaches with different mechanisms to enhance antitumor therapy. Moreover, nanosize drug-delivery systems for codelivering two drugs with proapoptotic and antiangiogenic activities have exhibited great potential in efficient treatment of cancers.

Methods

Glycyrrhetinic acid (GA)–modified liposomes (GA LPs) for liver-targeted codelivery of curcumin (Cur) and combretastatin A4 phosphate (CA4P) were prepared and characterized. In vitro cellular uptake, cytotoxicity, cell migration, in vivo biodistribution, antitumor activity, and histopathological studies were performed.

Results

Compared with unmodified LPs (Cur-CA4P LPs), Cur-CA4P/GA LPs were taken up effectively by human hepatocellular carcinoma cells (BEL-7402) and showed higher cytotoxicity than free drugs. In vivo real-time near-infrared fluorescence–imaging results indicated that GA-targeted LPs increased accumulation in the tumor region. Moreover, Cur-CA4P/GA LPs showed stronger inhibition of tumor proliferation than Cur, Cur + CA4P, and Cur-CA4P LPs in vivo antitumor studies, which was also verified by H&E staining.

Conclusion

GA-modified LPs can serve as a promising nanocarrier for liver-targeted co-delivery of antitumor drugs against hepatocellular carcinoma.

Preparation, Characterization, and In Vitro pH-sensitivity Evaluation of Superparamagnetic Iron Oxide Nanoparticle- Misonidazole pH-sensitive Liposomes

Background:

The use of Misonidazole (MISO), the first and a potential hypoxic tumor cell radiosensitizer, has been limited by peripheral neurotoxicity, thus discouraging phase III clinical trials.

Objective:

To develop a targeted drug delivery and tracing System with pH-sensitive liposomes (SpHLs) and Superparamagnetic Iron Oxide Nanoparticles (SPIONs) to counter MISO-related adverse effects and to enable tracing under magnetic resonance.

Methods:

SPION-MISO-SpHLs were prepared by a reverse evaporation and freeze-thawing method. HPLC and phenanthroline spectrophotometry were established for MISO and Fe determination. The characterization and in vitro pH-sensitivity of SPION-MISO-SpHLs were evaluated.

Results:

The maximal entrapment efficiencies of MISO and SPIONs in SPION-MISO-SpHLs were 30.2% and 23.7%, respectively. The cumulative release rates of MISO and SPIONs were respectively 2.49 and 2.47 times higher in pH 5.5 than in pH 7.4 buffer. The mean particle size of SPION-MISOSpHLs was 950 nm. The zeta potential was -58.9 mV in pH 7.4 buffer and 36.3 mV in pH 5.5 buffer. SEM imaging showed that SPION-MISO-SpHLs had similar spherical morphologies. SPIONs were packed in the center of liposomes and were well dispersed in a TEM graph. Magnetization curve showed that SPION-MISO-SpHLs retained superparamagnetic properties. SPION-MISO-SpHLs were compared with MISO+SPION+blank liposome in hypoxia and control groups of A549 cells. MISO and SPION concentrations in culture medium showed significant differences between the same concentration groups (P < 0.0001) and at different times (P < 0.0001).

Conclusion:

SPION-MISO-SpHLs possess pH-dependent release ability and superparamagnetism, and thus provides a system for targeted delivery and tracing under magnetic resonance.

Physicochemical Analysis of DPPC and Photopolymerizable Liposomal Binary Mixture for Spatiotemporal Drug Release

The development of a spatiotemporal drug delivery system with a long release profile, high loading efficiency, and robust therapeutic effects is still a challenge. Liposomal nanocarriers have secured a fortified position in the biomedical field over decades. Herein, liposomal binary mixtures of 1,2-dipalmitoyl- sn-glycero-3-phosphocholine (DPPC) and photopolymerizable 1,2-bis(10,12-tricosadiynoyl)- sn-glycero-3-phosphocholine (DC_8,9PC) phospholipids were prepared for drug delivery applications. The diacetylenic groups of DC_8,9PC produce intermolecular cross-linking following UV irradiation. Exposure of the liposomal mixture to 254 nm radiation induces a pore within the lipid bilayer, expediting the release of its entrapped 5,6-carboxyfluorescein dye. The dosage and rate of the released content are highly dependent on the number and size of the induced pore. Photochemical cross-linking studies at different exposure times were reported through the analysis of UV-visible spectrophotometry, nano differential scanning calorimetry, Fourier transform infrared spectroscopy, and Raman spectroscopy. The optimal irradiation time was established after 8 min of exposure, inducing lipid cross-linking with minimal oxidative degradation, which plays an essential role in the pathogenesis of numerous diseases due to the formation of primary and secondary oxidation products, accordingly reducing the encapsulated drug therapeutic level.

Targeting Strategies for the Combination Treatment of Cancer Using Drug Delivery Systems

Cancer cells have characteristics of acquired and intrinsic resistances to chemotherapy treatment-due to the hostile tumor microenvironment-that create a significant challenge for effective therapeutic regimens. Multidrug resistance, collateral toxicity to normal cells, and detrimental systemic side effects present significant obstacles, necessitating alternative and safer treatment strategies. Traditional administration of chemotherapeutics has demonstrated minimal success due to the non-specificity of action, uptake and rapid clearance by the immune system, and subsequent metabolic alteration and poor tumor penetration. Nanomedicine can provide a more effective approach to targeting cancer by focusing on the vascular, tissue, and cellular characteristics that are unique to solid tumors. Targeted methods of treatment using nanoparticles can decrease the likelihood of resistant clonal populations of cancerous cells. Dual encapsulation of chemotherapeutic drug allows simultaneous targeting of more than one characteristic of the tumor. Several first-generation, non-targeted nanomedicines have received clinical approval starting with Doxil® in 1995. However, more than two decades later, second-generation or targeted nanomedicines have yet to be approved for treatment despite promising results in pre-clinical studies. This review highlights recent studies using targeted nanoparticles for cancer treatment focusing on approaches that target either the tumor vasculature (referred to as 'vascular targeting'), the tumor microenvironment ('tissue targeting') or the individual cancer cells ('cellular targeting'). Recent studies combining these different targeting methods are also discussed in this review. Finally, this review summarizes some of the reasons for the lack of clinical success in the field of targeted nanomedicines.