Leakage kinetics of the liposomal chemotherapeutic agent Doxil: The role of dissolution, protonation, and passive transport, and implications for mechanism of action

Nanomaterial Delivery Vehicles for the Development of Neoantigen Tumor Vaccines for Personalized Treatment

Tumor vaccines have been considered a promising therapeutic approach for treating cancer in recent years. With the development of sequencing technologies, tumor vaccines based on neoantigens or genomes specifically expressed in tumor cells, mainly in the form of peptides, nucleic acids, and dendritic cells, are beginning to receive widespread attention. Therefore, in this review, we have introduced different forms of neoantigen vaccines and discussed the development of these vaccines in treating cancer. Furthermore, neoantigen vaccines are influenced by factors such as antigen stability, weak immunogenicity, and biosafety in addition to sequencing technology. Hence, the biological nanomaterials, polymeric nanomaterials, inorganic nanomaterials, etc., used as vaccine carriers are principally summarized here, which may contribute to the design of neoantigen vaccines for improved stability and better efficacy.

Phthalocyanine-based glucose-responsive nanocochleates for dynamic prevention of β-cell damage in diabetes

Phthalocyanine is a blue-colored macrocyclic compound with excellent anti-oxidant and lipid-peroxidation abilities due to its intermolecular π-π stacking structure. Antioxidants inhibit intracellular reactive oxygen species formation and decrease oxidation defense ability of the enzymes in diabetes management. The present study aimed to fabricate concanavalin A conjugated phthalocyanine-loaded cochleates (Formulation PhConA) as a glucose-sensitive lipidic system and estimate its efficacy in streptozotocin-induced male Sprague Dawley diabetic rats for 28 days. Thin-film hydration and trapping methods were used in the preparation of liposomes and cochleates, respectively, whereas the surface was modified for concanavalin A conjugation using EDAC: NHS (1:1). Formulation PhConA with rod-shaped structures showed particle size of 415.7 ± 0.46 nm, PdI value of 0.435 ± 0.09, encapsulation efficiency of 85.64 ± 0.34%, and 84.55 ± 0.29% release of phthalocyanine for 56 h. The circular dichroism study displayed a slight deviation after the conjugation effect of concanavalin A to cochleates. The in-vivo studies of the formulation PhConA improved the blood glucose levels along with defensive effect on the liver to overcome the hyperlipidemic effect. The rigid structure of cochleates prolongs the drug elimination from systemic circulation and extends its effect for a longer duration by decreasing the blood glucose level. Thus, the glucose-sensitive formulation PhConA showed significant improvement in diabetic rats within the period of 28 days by improving the oxidative defense and protecting the pancreatic β-cells.

An Automated Electroanalytical Method for the Drug Release Profiling of Liposomal Doxorubicin HCl Formulations

Liposomes have emerged as a drug delivery system for various chemotherapeutics providing enhanced bioavailability and reduced toxicity. In vitro drug release profiling of liposomal formulations is one of the essential tests for the premarket approval and post market quality control. We developed an automated electroanalytical method for drug release profiling of liposomal doxorubicin formulation. In this electroanalytical method, square wave voltammetry mode was selected to determine the released drug, the only redox-active analyte, by measuring the current at the pulsed potential ranges. Therefore, no separation from liposomal encapsulated doxorubicin is needed. This electroanalytical method provided a continuous drug release measurement for 24 h. The drug release increased as the release media pH and temperature increased. At 37 °C, the drug release increased from 7 % to 40 % when the pH increased from 5.5 to 7.4, In addition, at pH 6.5, as the temperature increased from 37 °C to 52 °C, total drug release increased by more than two-fold. Complete drug release (more than 80 %) was obtained at pH 6.5 and 52 °C in less than 3 h. The brand name and the two generic formulations showed similar drug release profile in all experimental conditions. This method is an alternative to traditional methods which require separation steps such as dialysis or solid phase extraction to quantitate released doxorubicin. This method may be further applied in the in vitro release testing of other liposomal formulations containing redox-active drug substances, e.g., liposomes encapsulating daunorubicin.

A Microfluidic Platform for Evaluating the Internalization of Liposome Drug Carriers in Tumor Spheroids

The development of in vitro models recapitulating nanoparticle transport under physiological flow conditions is of great importance for predicting the efficacy of nanoparticle drug carriers. Liposomes are extensively used for drug delivery owing to their biocompatibility and biodegradability and the ability to carry both hydrophilic and hydrophobic compounds. Here, we used a library of liposomes with various dimensions and a microfluidic platform comprising a large array of uniformly sized breast cancer spheroids to explore size-dependent liposome internalization and retention in the spheroids under close-to-physiological interstitial conditions. Such a platform showed promising applications in the preclinical screening of small molecule drugs; however, the capability to deliver nanoparticles in the spheroid interior under close-to-physiological flow conditions was not explored. For the liposomes with diameters in the range of 45-200 nm, we show experimentally and by simulations that in comparison with liposome delivery solely by diffusion, flow significantly enhances liposome internalization in the microgels and mitigates the size-dependent spheroid penetration by the liposomes. The utility of the microfluidic platform was validated by evaluating the efficacy of clinically approved doxorubicin-loaded liposomes (Doxil), which exhibited superior retention in the spheroids under flow conditions, in comparison with free doxorubicin. This MF platform can serve as an in vitro model for screening the efficacy of drugs encapsulated in liposomes and find applications for screening other types of nanoparticle carriers for vaccine delivery, diagnostics, and skincare.

SiRNF8 Delivered by DNA Framework Nucleic Acid Effectively Sensitizes Chemotherapy in Colon Cancer

Background

The evident side effects and decreased drug sensitivity significantly restrict the use of chemotherapy. However, nanoparticles based on biomaterials are anticipated to address this challenge.

Methods

Through bioinformatics analysis and colon cancer samples, we initially investigated the expression level of RNF8 in colon cancer. Next, we constructed nanocarrier for delivering siRNF8 based on DNA tetrahedron (si-Tet), and Doxorubicin (DOX) was further intercalated into the DNA structure (si-DOX-Tet) for combination therapy. Further, the effects and mechanism of RNF8 inhibition on the sensitivity of colon cancer cells to DOX chemotherapy have also been studied.

Results

RNF8 expression was increased in colon cancer. Agarose gel electrophoresis, transmission electron microscopy, and size distribution and potential analysis confirmed the successful preparation of the two nanoparticles, with particle sizes of 10.29 and 37.29 nm, respectively. Fluorescence imaging reveals that the carriers can be internalized into colon cancer cells and escape from lysosomes after 12 hours of treatment, effectively delivering siRNF8 and DOX. Importantly, Western blot analysis verified treatment with 50nM si-Tet silenced RNF8 expression by approximately 50% in colon cancer cells, and combined treatment significantly inhibited cell proliferation. Furthermore, the CCK-8 assay demonstrated that si-Tet treatment enhanced the sensitivity of colon cancer cells to the three chemotherapeutic drugs. Significant more DNA damage was detected after treatment with both si-Tet or si-DOX-Tet. Further flow cytometry analysis revealed that si-DOX-Tet treatment led to significantly more apoptosis, approximately 1.6-fold higher than treatment with DOX alone. Mechanistically, inhibiting RNF8 led to decreased ABCG2 expression and DOX efflux, but increased DNA damage, thereby enhancing the chemotherapeutic effect of DOX.

Conclusion

We have successfully constructed si-DOX-Tet. By inhibiting the expression of RNF8, it enhances the chemotherapy sensitivity of DOX. Therefore, this tetrahedral FNA nanocarrier offers a new approach for the combined treatment of colon cancer.

Nature vs. Manmade: Comparing Exosomes and Liposomes for Traumatic Brain Injury

Traumatic brain injury (TBI) of all severities is a significant public health burden, causing a range of effects that can lead to death or a diminished quality of life. Liposomes and mesenchymal stem cell-derived exosomes are two drug delivery agents with potential to be leveraged in the treatment of TBI by increasing the efficacy of drug therapies as well as having additional therapeutic effects. They exhibit several physical similarities, but key differences affect their performances as nanocarriers. Liposomes can be produced commercially at scale, and liposomes achieve higher encapsulation efficiency. Meanwhile, the intrinsic cargo and targeting moieties of exosomes, which liposomes lack, give exosomes a greater ability to facilitate neural regeneration, and exosomes do not trigger the infusion reactions that liposomes can. However, there are concerns about both exosomes and liposomes regarding interactions with tumors. The same routes of administration can be used for both exosomes and liposomes, resulting in somewhat different distribution throughout the body. While the effect of the nanocarrier type on accumulation in the brain is not concrete, targeting leads to increased accumulation of both exosomes and liposomes in the brain, upon which on-demand release can be used for both drug deliverers. Although neither have been applied to TBI in humans, preclinical trials have shown their immense potential, as have clinical trials pertaining to other brain injuries and conditions. While questions remain, research thus far shows that the various differences make exosomes a better choice of nanocarrier for TBI.

Combinatorial Polydopamine-Liposome Nanoformulation as an Effective Anti-Breast Cancer Therapy

Introduction

Drug delivery systems (DDSs) based on liposomes are potential tools to minimize the side effects and substantially enhance the therapeutic efficacy of chemotherapy. However, it is challenging to achieve biosafe, accurate, and efficient cancer therapy of liposomes with single function or single mechanism. To solve this problem, we designed a multifunctional and multimechanism nanoplatform based on polydopamine (PDA)-coated liposomes for accurate and efficient combinatorial cancer therapy of chemotherapy and laser-induced PDT/PTT.

Methods

ICG and DOX were co-incorporated in polyethylene glycol modified liposomes, which were further coated with PDA by a facile two-step method to construct PDA-liposome nanoparticles (PDA@Lipo/DOX/ICG). The safety of nanocarriers was investigated on normal HEK-293 cells, and the cellular uptake, intracellular ROS production capacity, and combinatorial treatment effect of the nanoparticles were assessed on human breast cancer cells MDA-MB-231. In vivo biodistribution, thermal imaging, biosafety assessment, and combination therapy effects were estimated based on MDA-MB-231 subcutaneous tumor model.

Results

Compared with DOX·HCl and Lipo/DOX/ICG, PDA@Lipo/DOX/ICG showed higher toxicity on MDA-MB-231 cells. After endocytosis by target cells, PDA@Lipo/DOX/ICG produced a large amount of ROS for PDT by 808 nm laser irradiation, and the cell inhibition rate of combination therapy reached up to 80.4%. After the tail vein injection (DOX equivalent of 2.5 mg/kg) in mice bearing MDA-MB-231 tumors, PDA@Lipo/DOX/ICG significantly accumulated at the tumor site at 24 h post injection. After 808 nm laser irradiation (1.0 W/cm², 2 min) at this timepoint, PDA@Lipo/DOX/ICG efficiently suppressed the proliferation of MDA-MB-231 cell and even thoroughly ablated tumors. Negligible cardiotoxicity and no treatment-induced side effects were observed.

Conclusion

PDA@Lipo/DOX/ICG is a multifunctional nanoplatform based on PDA-coated liposomes for accurate and efficient combinatorial cancer therapy of chemotherapy and laser-induced PDT/PTT.

Neoadjuvant Gold Nanoshell-Based Photothermal Therapy Combined with Liposomal Doxorubicin in a Mouse Model of Colorectal Cancer

Introduction

Traditional cancer treatments, such as chemotherapy, are often incapable of achieving complete responses as standalone therapies. Hence, current treatment strategies typically rely on a combination of several approaches. Nanoparticle-based photothermal therapy (PTT) is a technique used to kill cancer cells through localized, severe hyperthermia that has shown promise as an add-on treatment to multiple cancer therapies. Here, we evaluated whether the combination of gold nanoshell (NS)-based PTT and liposomal doxorubicin could improve outcome in a mouse model of colorectal cancer.

Methods

First, NS-based PTT was performed on tumor-bearing mice. Radiolabeled liposomes were then injected at different timepoints to follow their accumulation in the tumor and determine the ideal injection time after PTT. In addition, fluorescent liposomes were used to observe the liposomal distribution in the tumor after PTT. Finally, we combined PTT and doxorubicin-loaded liposomes and studied the effect of the treatment strategy on the mice by following tumor growth and survival.

Results

PTT significantly improved liposomal accumulation in the tumor, but only when the liposomes were injected immediately after the therapy. The liposomes accumulated mostly in regions adjacent to the ablated areas. When PTT was combined with liposomal doxorubicin, the mice experienced a slowdown in tumor growth and an improvement in survival.

Conclusion

According to our preclinical study, NS-based PTT seems promising as an add-on treatment for liposomal chemotherapy and potentially other systemic therapies, and could be relevant for future application in a clinical setting.

The potential impact of nanomedicine on COVID-19-induced thrombosis

Extensive reports of pulmonary embolisms, ischaemic stroke and myocardial infarctions caused by coronavirus disease 2019 (COVID-19), as well as a significantly increased long-term risk of cardiovascular diseases in COVID-19 survivors, have highlighted severe deficiencies in our understanding of thromboinflammation and the need for new therapeutic options. Due to the complexity of the immunothrombosis pathophysiology, the efficacy of treatment with conventional anti-thrombotic medication is questioned. Thrombolytics do appear efficacious, but are hindered by severe bleeding risks, limiting their use. Nanomedicine can have profound impact in this context, protecting delicate (bio)pharmaceuticals from degradation en route and enabling delivery in a targeted and on demand manner. We provide an overview of the most promising nanocarrier systems and design strategies that may be adapted to develop nanomedicine for COVID-19-induced thromboinflammation, including dual-therapeutic approaches with antiviral and immunosuppressants. Resultant targeted and side-effect-free treatment may aid greatly in the fight against the ongoing COVID-19 pandemic.

Tuning Liposome Stability in Biological Environments and Intracellular Drug Release Kinetics

Ideal drug carriers should be stable in biological environments but eventually release their drug load once inside the targeted cells. These two aspects can be in contrast with each other, thus they need to be carefully tuned in order to achieve the desired properties for specific applications. Quantifying drug release profiles in biological environments or inside cells can be highly challenging, and standard methods to determine drug release kinetics in many cases cannot be applied to complex biological environments or cells. Within this context, the present work combined kinetic studies by flow cytometry with aging experiments in biological fluids and size-exclusion chromatography to determine drug release profiles in biological environments and inside cells. To this purpose, anionic and zwitterionic liposomes were used as model nanomedicines. By changing lipid composition, liposome stability in serum and intracellular release kinetics could be tuned and formulations with very different properties could be obtained. The methods presented can be used to characterize liposome release profiles in complex biological media, as well as inside cells. In this way, liposome composition can be tuned in order to achieve formulations with optimal balance between stability and release kinetics for specific applications.

Long-Circulating and Fusogenic Liposomes Loaded with Paclitaxel and Doxorubicin: Effect of Excipient, Freezing, and Freeze-Drying on Quality Attributes

Liposomes can increase plasma half-life, enhance targeting, and diminish the side-effects of loaded drugs. On the downside, physical and chemical instabilities of dispersions often result in a reduced lifespan, which limits their availability on the market. Solid formulations obtained by freeze-drying can immobilize vesicles and provide extended shelf life. For both processes, the choice of excipients and process parameters are crucial to protect the carrier layers against tension caused by freezing and/or dehydration. The aim of this work is to evaluate the influence of freezing and drying parameters, besides excipient choice, to obtain solid long-circulating and fusogenic liposomes (LCFL-PTX/DXR) co-encapsulating paclitaxel (PTX) and doxorubicin (DXR) at a synergistic ratio (1:10).

METHODS

LCFL-PTX/DXR was evaluated by freeze-drying microscopy (glass transition, Tg'), differential scanning calorimetry (collapse temperature, Tc), freeze-thawing and freeze-drying processes. Freeze-dried samples were evaluated by thermogravimetry (residual moisture) and the resuspended liposomes were characterized in terms of size, polydispersity index (PI), zeta potential (ZP), and drug content. Liposomes morphology was evaluated by cryomicroscopy.

RESULTS

Trehalose protected PTX cargo upon freeze-thawing and more than 80% of the original DXR retention. The formulations with trehalose resulted in a cake with 5-7% of moisture content (200-240 nm); 44-60% of PTX retention, and 25-35% of DXR retention, with the variations caused by cryoprotector concentration and process changes.

CONCLUSIONS

Trehalose protected liposome integrity, maintaining PTX retention and most of DXR upon freeze-thawing. Freeze-drying reduced the retention of both drugs inside all liposomes, whereas formulation with trehalose presented minor losses. Therefore, this frozen formulation is an alternative product option, with no need for manipulation before use.

Novel Tumor-Targeted Self-Nanostructured and Compartmentalized Water-in-Oil-in-Water Polyurethane-Polyurea Nanocapsules for Cancer Theragnosis

Encapsulation of water-soluble bioactive compounds for enabling specific accumulation in tumor locations, while avoiding premature clearance and/or degradation in the bloodstream, is one of the main hallmarks in nanomedicine, especially that of NIR fluorescent probes for cancer theragnosis. The herein reported technology furnishes water-dispersible double-walled polyurethane-polyurea hybrid nanocapsules (NCs) loaded with indocyanine green (ICG-NCs), using a versatile and highly efficient one-pot and industrially scalable synthetic process based on the use of two different prepolymers to set up the NCs walls. Flow cytometry and confocal microscopy confirmed that both ICG-loaded NCs internalized in monocyte-derived dendritic cells (moDCs). The in vivo analysis of xenograft A375 mouse melanoma model revealed that amphoteric functionalization of NCs' surface promotes the selective accumulation of ICG-NCs in tumor tissues, making them promising agents for a less-invasive theragnosis of cancer.

Ligand-mediated nanomedicines against breast cancer: a review

Ligand-mediated targeting represents the cutting edge in precision-guided therapy for several diseases. Surface engineering of nanomedicines with ligands exhibiting selective or tailored affinity for overexpressed biomolecules of a specific disease may increase therapeutic efficiency and reduce side effects and recurrence. This review focuses on newly developed approaches and strategies to improve treatment and overcome the mechanisms associated with breast cancer resistance.

How Various Drug Delivery Methods Could Aid in the Translation of Genome Prime Editing Technologies

Drug delivery systems can be engineered to enhance the localization of therapeutics in specific tissues in response to externally applied stimuli and/or local environmental changes. In recent decades, efforts to improve drug delivery techniques at both nano- and macroscale have led to a new era of therapeutic efficacy. Such technological advancements resulted in improved drug delivery systems regularly entering the clinical setting. However, these delivery innovations are unfortunately not always readily applied to newly developed technologies. One of these new and exciting technologies that has been overlooked by drug delivery scientists is prime editing. Prime editing is a novel genome editing technology that exhibits the plug-and-play capability of CRISPR/Cas9 editors while avoiding double-strand DNA breaks throughout the entire process. This article focuses on describing the potential advantages and disadvantages of selecting nanomedicine technologies along with prime editing capabilities for the delivery of cargo.

Research on the synthesis of nanoparticles of betulinic acid and their targeting antitumor activity

Betulinic acid (BA), a natural pentacyclic lupine-type triterpene, has shown its prominent efficiency on the selective antitumor activity. However, its poor water solubility and bioavailability have limited its application. Herein, targeting nanoparticles were prepared to improve BA-based liposome (BL)'s restricted chemotherapeutic efficacy. Multi-layers membranes from the cancer cells were added as highly penetrative targeting ligands to functionalize the BA-based liposomes. In vitro experiments including the MTT assay and the fluorescence imaging of live/dead staining were adopted to prove its great inhibition in the growth of tumor cells. And it manifests that the antitumor efficacy of BL coated with cell membranes (BLCM) achieves nearly 4.3 times as that of BL under the same conditions in the MTT experiments. In addition, the fluorescence imaging stained with DAPI-FITC was applied to prove the targeting positioning effects on the BLCM. In a nutshell, the nanomedicine has good targeting antitumor efficacy and has great potential in being applied for the personalized cancer clinical treatment.

From blood to brain: blood cell-based biomimetic drug delivery systems

Brain drug delivery remains a major difficulty for several challenges including the blood-brain barrier, lesion spot targeting, and stability during circulation. Blood cells including erythrocytes, platelets, and various subpopulations of leukocytes have distinct features such as long-circulation, natural targeting, and chemotaxis. The development of biomimetic drug delivery systems based on blood cells for brain drug delivery is growing fast by using living cells, membrane coating nanotechnology, or cell membrane-derived nanovesicles. Blood cell-based vehicles are superior delivery systems for their engineering feasibility and versatile delivery ability of chemicals, proteins, and all kinds of nanoparticles. Here, we focus on advances of blood cell-based biomimetic carriers for from blood to brain drug delivery and discuss their translational challenges in the future.

A Screening Study for the Development of Simvastatin-Doxorubicin Liposomes, a Co-Formulation with Future Perspectives in Colon Cancer Therapy

An increasing number of studies published so far have evidenced the benefits of Simvastatin (SIM) and Doxorubicin (DOX) co-treatment in colorectal cancer. In view of this, the current study aimed to investigate the pharmaceutical development of liposomes co-encapsulating SIM and DOX, by implementing the Quality by Design (QbD) concept, as a means to enhance the antiproliferative effect of the co-formulation on C26 murine colon cancer cells co-cultured with macrophages. It is known that the quality profile of liposomes is dependent on the critical quality attributes (CQAs) of liposomes (drug entrapped concentration, encapsulation efficiency, size, zeta potential, and drug release profile), which are, in turn, directly influenced by various formulation factors and processing parameters. By using the design of experiments, it was possible to outline the increased variability of CQAs in relation to formulation factors and identify by means of statistical analysis the material attributes that are critical (phospholipids, DOX and SIM concentration) for the quality of the co-formulation. The in vitro studies performed on a murine colon cancer cell line highlighted the importance of delivering the optimal drug ratio at the target site, since the balance antiproliferative vs. pro-proliferative effects can easily be shifted when the molar ratio between DOX and SIM changes.

Polymeric Composite Matrix with High Biobased Content as Pharmaceutically Relevant Molecular Encapsulation and Release Platform

Drug delivery systems (DDS) that can temporally control the rate and extent of release of therapeutically active molecules find applications in many clinical settings, ranging from infection control to cancer therapy. With an aim to design a locally implantable, controlled-release DDS, we demonstrated the feasibility of using cellulose nanocrystal (CNC)-reinforced poly (l-lactic acid) (PLA) composite beads. The performance of the platform was evaluated using doxorubicin (DOX) as a model drug for applications in triple-negative breast cancer. A facile, nonsolvent-induced phase separation (NIPS) method was adopted to form composite beads. We observed that CNC loading within these beads played a critical role in the mechanical stability, porosity, water uptake, diffusion, release, and pharmacological activity of the drug from the delivery system. When loaded with DOX, composite beads significantly controlled the release of the drug in a pH-dependent pattern. For example, PLA/CNC beads containing 37.5 wt % of CNCs showed a biphasic release of DOX, where 41 and 82% of the loaded drug were released at pH 7.4 and pH 5.5, respectively, over 7 days. Drug release followed Korsmeyer's kinetics, indicating that the release mechanism was mostly diffusion and swelling-controlled. We showed that DOX released from drug-loaded PLA/CNC composite beads locally suppressed the growth and proliferation of triple-negative breast cancer cells, MBA-MB-231, via the apoptotic pathway. The efficacy of the DDS was evaluated in human tissue explants. We envision that such systems will find applications for designing biobased platforms with programmed stability and drug delivery functions.

Cholesterol Levels Affect the Performance of AuNPs-Decorated Thermo-Sensitive Liposomes as Nanocarriers for Controlled Doxorubicin Delivery

Stimulus-responsive liposomes (L) for triggering drug release to the target site are particularly useful in cancer therapy. This research was focused on the evaluation of the effects of cholesterol levels in the performance of gold nanoparticles (AuNPs)-functionalized L for controlled doxorubicin (D) delivery. Their interfacial and morphological properties, drug release behavior against temperature changes and cytotoxic activity against breast and ovarian cancer cells were studied. Langmuir isotherms were performed to identify the most stable combination of lipid components. Two mole fractions of cholesterol (3.35 mol% and 40 mol%, L1 and L2 series, respectively) were evaluated. Thin-film hydration and transmembrane pH-gradient methods were used for preparing the L and for D loading, respectively. The cationic surface of L allowed the anchoring of negatively charged AuNPs by electrostatic interactions, even inducing a shift in the zeta potential of the L2 series. L exhibited nanometric sizes and spherical shape. The higher the proportion of cholesterol, the higher the drug loading. D was released in a controlled manner by diffusion-controlled mechanisms, and the proportions of cholesterol and temperature of release media influenced its release profiles. D-encapsulated L preserved its antiproliferative activity against cancer cells. The developed liposomal formulations exhibit promising properties for cancer treatment and potential for hyperthermia therapy.

Recent progress on nanomedicine-induced ferroptosis for cancer therapy

The current treatment strategies for cancer therapy have posed many problems in achieving high efficacy. Therefore, an urgent step is needed to develop innovative therapies that can win beyond satisfactory results against tumor. Ferroptosis that is a kind of non-apoptotic based programmed cell death has played a crucial role in eradicating tumors by reactive oxygen species and iron-dependent pathways. Research shows a remarkable potential of ferroptosis in eliminating aggressive malignancies resistant to traditional therapies. The combination of nanomedicine and ferroptosis has revealed a close relationship for the treatment of various cancer types with high efficacy. This review introduces the basics of nanomedicine-based ferroptosis first to emphasize the feasibility and properties of ferroptosis in cancer therapy. Then, the current research on the applications of nanomedicine for the ferroptosis-based anticancer therapy is highlighted. Finally, conclusions and future research directions in perspective of various challenges in developing nanomedicine-based ferroptosis into clinical therapeutics are discussed.

Surfactant Assisted Rapid-Release Liposomal Strategies Enhance the Antitumor Efficiency of Bufalin Derivative and Reduce Cardiotoxicity

Background

BF211, a derivative of bufalin (BF), shows significantly improved solubility and potent antitumor efficiency compared to BF. Unfortunately, the unwanted toxicity such as cardiotoxicity caused by unspecific distribution has hindered its clinical use.

Methods

PEGylated BF211 liposomes (BF211@Lipo) were designed and optimizely prepared based on the pre-prescription research. In vitro and in vivo cardiotoxicity was evaluated. In vivo pharmacokinetics and biodistribution of BF211@Lipo were investigated. In vivo antitumor activity and toxicity were evaluated in HepG2 cell xenograft models. The rapid-release triggered by Poloxamer 188 (P188) was assessed in vitro and in vivo.

Results

The optimized BF211@Lipo displayed a spherical morphology with a size of (164.6 ± 10.3) nm and a high encapsulation efficiency of (93.24 ± 2.15) %. The in vivo concentration–time curves of BF211 loaded in liposomes showed a prolonged half-life in plasma and increased tumor accumulation. No obvious abnormality in electrocardiograms was observed in guinea pigs even at 9 mg/kg. Moreover, to improve the efficient release of BF211@Lipo, a surfactant-assisted rapid-release strategy was developed, and the release-promoting mechanism was revealed by the fluorescence resonance energy transfer (FRET) and fluorescence nanoparticle tracking analysis (fl-NTA) technology. Sequential injection of BF211@Lipo and P188 could ignite the “cold” liposomes locally in tumor regions, facilitating the burst release of BF211 and enhancing the therapeutic index.

Conclusion

Our progressive efforts that begin with preparation technology and dosage regimen enable BF211 to like a drug, providing a promising nano platform to deliver the cardiac glycosides and alleviate the side effects by decreasing unspecific biodistribution.

Microfluidic-assisted fabrication of phosphatidylcholine-based liposomes for controlled drug delivery of chemotherapeutics

Microfluidic enables precise control over the continuous mixing of fluid phases at the micrometre scale, aiming to optimize the processing parameters and to facilitate scale-up feasibility. The optimization of parameters to obtain monodispersed drug-loaded liposomes however is challenging. In this work, two phosphatidylcholines (PC) differing in acyl chain length were selected, and used to control the release of the chemotherapeutic agent doxorubicin hydrochloride, an effective drug used to treat breast cancer. Microfluidics was used to rapidly screen manufacturing parameters and PC formulations to obtain monodispersed unilamellar liposomal formulations with a reproducible size (i.e. < 200 nm). Cholesterol was included in all liposomal formulations; some formulations also contained DMPC(1,2-dimyristoyl-sn-glycero-3-phosphocholine) and/or DSPC(1,2-distearoyl-sn-glycero-3-phosphocholine). Systematic variations in microfluidics total flow rate (TFR) settings were performed, while keeping a constant flow rate ratio (FRR). A total of six PC-based liposomes were fabricated using the optimal manufacturing parameters (TFR 500 μL/min, FRR 0.1) for the production of reproducible, stable liposome formulations with a narrow size distribution. Liposomes actively encapsulating doxorubicin exhibited high encapsulation efficiencies (>80%) for most of the six formulations, and sustained drug release profiles in vitro over 48 h. Drug release profiles varied as a function of the DMPC/DSPC mol content in the lipid bilayer, with DMPC-based liposomes exhibiting a sustained release of doxorubicin when compared to DSPC liposomes. The PC-based liposomes, with a slower release of doxorubicin, were tested in vitro, as to investigate their cytotoxic activity against three human breast cancer cell lines: the non-metastatic ER+/PR + MCF7 cells, the triple-negative aggressive MDA-MB 231 cells, and the metastatic HER2-overexpressing/PR + BT474 cells. Similar cytotoxicity levels to that of free doxorubicin were reported for DMPC₅ and DMPC₃ binary liposomes (IC₅₀ ~ 1 μM), whereas liposomes composed of a single PC were less cytotoxic (IC₅₀ ~ 3-4 μM). These results highlight that microfluidics is suitable for the manufacture of monodispersed and size-specific PC-based liposomes in a controlled single-step; furthermore, selected PC-based liposome represent promising nanomedicines for the prolonged release of chemotherapeutics, with the aim of improving outcomes for patients.

Membrane fusion and drug delivery with carbon nanotube porins

The plasma membrane protects cell content from the outer environment. Overcoming this obstacle and delivering drugs efficiently into cells still remain a major hurdle for modern pharmacology and medicine. We developed and demonstrated a simple nanomaterial platform—a dimer of small-diameter carbon nanotube porins (CNTPs)—which functions as a potent membrane fusogen. Molecular simulations revealed a distinct fusion mechanism. CNTP-studded vesicles loaded with a chemotherapeutic agent, doxorubicin, delivered the drug to cancer cells, killing a majority of them. Our work provides new opportunities for understanding membrane fusion mechanisms, designing synthetic fusogens, and developing simple and efficient drug carriers for delivery of therapeutics and vaccines.

Drug delivery mitigates toxic side effects and poor pharmacokinetics of life-saving therapeutics and enhances treatment efficacy. However, direct cytoplasmic delivery of drugs and vaccines into cells has remained out of reach. We find that liposomes studded with 0.8-nm-wide carbon nanotube porins (CNTPs) function as efficient vehicles for direct cytoplasmic drug delivery by facilitating fusion of lipid membranes and complete mixing of the membrane material and vesicle interior content. Fusion kinetics data and coarse-grained molecular dynamics simulations reveal an unusual mechanism where CNTP dimers tether the vesicles, pull the membranes into proximity, and then fuse their outer and inner leaflets. Liposomes containing CNTPs in their membranes and loaded with an anticancer drug, doxorubicin, were effective in delivering the drug to cancer cells, killing up to 90% of them. Our results open an avenue for designing efficient drug delivery carriers compatible with a wide range of therapeutics.

Dynamic methotrexate nano-prodrugs with detachable PEGylation for highly selective synergistic chemotherapy

To promote the highly selective synergistic chemotherapy, the pH-ultra-sensitive dynamic methotrexate nano-prodrugs with detachable PEGylation were successfully prepared via facile method, and the synergistic nanodrugs could be further constructed through encapsulating Doxorubicin (DOX) following the self-assembly process. The nano-prodrugs exhibited the low critical micelle concentration (CMC), negative zeta potential and stability for 5 days in PBS and FBS at physiological pH (7.4) for stable blood circulation, DePEGylation and dynamic size change at tumoral extracellular pH (6.8) for improved tumor accumulation and cellular internalization, and efficiently synergistic drug release at tumoral intracellular pH (5.0) for enhanced tumor apoptosis and cytotoxicity. Moreover, in vivo experiment suggested that the synergistic nanodrugs could significantly improve tumor accumulation and restrain tumor growth while decreasing adverse effects. Therefore, the dynamic methotrexate nano-prodrugs with detachable PEGylation are easy to clinically transform for highly selective synergistic chemotherapy.

Doxorubicin Hydrochloride-Loaded Nonionic Surfactant Vesicles to Treat Metastatic and Non-Metastatic Breast Cancer

Doxorubicin hydrochloride (DOX) is currently used to treat orthotropic and metastatic breast cancer. Because of its side effects, the use of DOX in cancer patients is sometimes limited; for this reason, several scientists tried designing drug delivery systems which can improve drug therapeutic efficacy and decrease its side effects. In this study, we designed, prepared, and physiochemically characterized nonionic surfactant vesicles (NSVs) which are obtained by self-assembling different combinations of hydrophilic (Tween 20) and hydrophobic (Span 20) surfactants, with cholesterol. DOX was loaded in NSVs using a passive and pH gradient remote loading procedure, which increased drug loading from ∼1 to ∼45%. NSVs were analyzed in terms of size, shape, size distribution, zeta potential, long-term stability, entrapment efficiency, and release kinetics, and nanocarriers having the best physiochemical parameters were selected for further in vitro tests. NSVs with and without DOX were stable and showed a sustained drug release up to 72 h. In vitro studies, with MCF-7 and MDA MB 468 cells, demonstrated that NSVs, containing Span 20, were better internalized in MCF-7 and MDA MB 468 cells than NSVs with Tween 20. NSVs increased the anticancer effect of DOX in MCF-7 and MDA MB 468 cells, and this effect is time and dose dependent. In vitro studies using metastatic and nonmetastatic breast cancer cells also demonstrated that NSVs, containing Span 20, had higher cytotoxicity than NSVs with Tween 20. The resulting data suggested that DOX-loaded NSVs could be a promising nanocarrier for the potential treatment of metastatic breast cancer.

Epigenetic Regulation and Nonepigenetic Mechanisms of Ferroptosis Drive Emerging Nanotherapeutics in Tumor

Currently, traditional cancer therapy still falls far short of expectations. However, a variety of invasive cancers that are resistant to chemotherapy (such as platinum drugs, one of the most applied antineoplastics in clinic) and targeted agents are susceptible to ferroptosis. Ferroptosis is a form of cell death that is driven by cell metabolism and iron-dependent lipid peroxidation. Ferroptosis inducers can eliminate the drug resistance of tumor cells in the mesenchymal state, effectively inhibit the drug resistance of acquired tumor cells, and optimize cancer efficacy. Research based on the epigenetic mechanism of ferroptosis is still in the stage of screening and verifying the regulatory effect, and there is no complete regulatory mechanism network. In this review, we expound on the epigenetic regulation and nonepigenetic mechanisms of ferroptosis and review the epigenetic-based mechanisms of tumor therapy potential and emerging nonepigenetic-based therapies (nanotherapeutics).

Anti-Cancer Nanomedicines: A Revolution of Tumor Immunotherapy

Immunotherapies have been accelerating the development of anti-cancer clinical treatment, but its low objective responses and severe off-target immune-related adverse events (irAEs) limit the range of application. Strategies to remove these obstacles primarily focus on the combination of different therapies and the exploitation of new immunotherapeutic agents. Nanomedicine potentiates the effects of activating immune cells selectively and reversing tumor induced immune deficiency microenvironment through multiple mechanisms. In the last decade, a variety of nano-enabled tumor immunotherapies was under clinical investigation. As time goes by, the advantages of nanomedicine are increasingly prominent. With the continuous development of nanotechnology, nanomedicine will offer more distinctive perspectives in imaging diagnosis and treatment of tumors. In this Review, we wish to provide an overview of tumor immunotherapy and the mechanisms of nanomaterials that aim to enhance the efficacy of tumor immunotherapy under development or in clinic treatment.

Manufacturing drug co-loaded liposomal formulations targeting breast cancer: Influence of preparative method on liposomes characteristics and in vitro toxicity

Developing more efficient manufacturing methods for nano therapeutic systems is becoming important, not only to better control their physico-chemical characteristics and therapeutic efficacy but also to ensure scale-up is cost-effective. The principle of cross-flow chemistry allows precise control over manufacturing parameters for the fabrication of uniform liposomal formulations, as well as providing reproducible manufacturing scale-up compared to conventional methods. We have herein investigated the use of microfluidics to produce PEGylated DSPC liposomes loaded with doxorubicin and compared their performance against identical formulations prepared by the thin-film method. The isoprenylated coumarin umbelliprenin was selected as a co-therapeutic. Umbelliprenin-loaded and doxorubicin:umbelliprenin co-loaded liposomes were fabricated using the optimised microfluidic set-up. The role of umbelliprenin as lipid bilayer fluidity modulation was characterized, and we investigated its role on liposomes size, size distribution, shape and stability compared to doxorubicin-loaded liposomes. Finally, the toxicity of all liposomal formulations was tested on a panel of human breast cancer cells (MCF-7, MDA-MB 231, BT-474) to identify the most potent formulation by liposomal fabrication method and loaded compound(s). We herein show that the microfluidic system is an alternative method to produce doxorubicin:umbelliprenin co-loaded liposomes, allowing fine control over liposome size (100-250 nm), shape, uniformity and doxorubicin drug loading (>80%). Umbelliprenin was shown to confer fluidity to model lipid biomembranes, which helps to explain the more homogeneous size and shape of co-loaded liposomes compared to liposomes without umbelliprenin. The toxicity of doxorubicin:umbelliprenin co-loaded liposomes was lower than that of free doxorubicin, due to the delayed release of doxorubicin from liposomes. An alternative, rapid and easy manufacturing method for the production of liposomes has been established using microfluidics to effectively produce uniform doxorubicin:umbelliprenin co-loaded liposomal formulations with proven cytotoxicity in human breast cancer cell lines in vitro.

Contrastive Studies of Cytarabine/Daunorubicin Dual-Loaded Liposomes Prepared by pH Gradient and Cu2+ Gradient Method

Conventional combination chemotherapy often leads to unsatisfactory clinical outcomes due to the different distribution characteristics in vivo and the superimposed systemic toxicity of the drug cocktail. Co-encapsulated nano preparations have been gradually developed in recent years. In this work, cytarabine (Ara-C)/daunorubicin (DNR) liposomes were prepared by the pH gradient (ADL-pH) and Cu²⁺ gradient (ADL-Cu) methods. Ara-C did not show significant release from either ADL-Cu or ADL-pH in vitro during 168 h, which related to its logP_oct. Different drug-loading patterns showed different release characteristics of DNR due to the different existence forms, ADL-pH contains the citrate form, while in ADL-Cu, there is the Cu²⁺ complex. To evaluate the release behavior, daunorubicin liposome (DL) and daunorubicin-Cu²⁺ complex (DNR-Cu) were prepared. The addition of EDTA in the release medium significantly increased the release rate of DNR from DL-Cu, while lower pH accelerated DNR release from both DL-pH and DL-Cu. The PK confirmed that ADL-Cu and ADL-pH could prolong the drug circulation time, and ADL-Cu had a mean retention time 1.5 times that of ADL-pH. Furthermore, both liposomes allowed the two drugs to maintain a relatively constant plasma concentration ratio for a prolonged time. Cytotoxicity assays showed that Ara-C/DNR with a molar ratio of 5:1 and 3:1 exhibited an excellent synergistic effect, which was more obvious at 5:1. In vitro antitumor results revealed that ADL-Cu exhibited more cytotoxicity than ADL-pH. All factors tested in this work suggest the considerable potential of ADL-Cu and ADL-pH for anticancer treatment.

AT101-Loaded Cubosomes as an Alternative for Improved Glioblastoma Therapy

Introduction

AT101, the R-(-)-enantiomer of the cottonseed-derived polyphenol gossypol, is a promising drug in glioblastoma multiforme (GBM) therapy due to its ability to trigger autophagic cell death but also to facilitate apoptosis in tumor cells. It does have some limitations such as poor solubility in water-based media and consequent low bioavailability, which affect its response rate during treatment. To overcome this drawback and to improve the anti-cancer potential of AT101, the use of cubosome-based formulation for AT101 drug delivery has been proposed. This is the first report on the use of cubosomes as AT101 drug carriers in GBM cells.

Materials and Methods

Cubosomes loaded with AT101 were prepared from glyceryl monooleate (GMO) and the surfactant Pluronic F-127 using the top-down approach. The drug was introduced into the lipid prior to dispersion. Prepared formulations were then subjected to complex physicochemical and biological characterization.

Results

Formulations of AT101-loaded cubosomes were highly stable colloids with a high drug entrapment efficiency (97.7%) and a continuous, sustained drug release approaching 35% over 72 h. Using selective and sensitive NMR diffusometry, the drug was shown to be efficiently bound to the lipid-based cubosomes. In vitro imaging studies showed the high efficiency of cubosomal nanoparticles uptake into GBM cells, as well as their marked ability to penetrate into tumor spheroids. Treatment of GBM cells with the AT101-loaded cubosomes, but not with the free drug, induced cytoskeletal rearrangement and shortening of actin fibers. The prepared nanoparticles revealed stronger in vitro cytotoxic effects against GBM cells (A172 and LN229 cell lines), than against normal brain cells (SVGA and HMC3 cell lines).

Conclusion

The results indicate that GMO-AT101 cubosome formulations are a promising basic tool for alternative approaches to GBM treatment.

High-throughput microfluidics for evaluating microbubble enhanced delivery of cancer therapeutics in spheroid cultures

Drug penetration into solid tumours remains a major challenge in the effective treatment of cancer. Microbubble (MB) mediated sonoporation offers a potential solution to this by enhancing the uptake of drugs into cells. Additionally, in using an ultrasound (US) trigger, drug delivery can be localised to the tumour, thus reducing the off-site toxicity associated with systemic delivery. The majority of in vitro studies involving the observation of MB-enhanced drug efficacy have been conducted on 2D monolayer cell cultures, which are known to be poor models for in vivo tumours. 3D spheroid cultures allow for the production of multicellular cultures complete with extracellular matrix (ECM) components. These cultures effectively recreate many of the physiological features of the tumour microenvironment and have been shown to be far superior to previous 2D monolayer models. However, spheroids are typically handled in well-plates in which the fluid environment is static, limiting the physiological relevance of the model. The combination of 3D cultures and microfluidics would allow for the production of a dynamic system in which spheroids are subjected to in vivo like fluid flow and shear stresses. This study presents a microfluidic device containing an array of spheroid traps, into which multiple pre-grown colorectal cancer (CRC) spheroids were loaded. Reservoirs interfaced with the chip use hydrostatic pressure to passively drive flow through the system and subject spheroids to capillary like flow velocities. The use of reservoirs also enabled multiple chips to be run in parallel, allowing for the screening of multiple therapeutic treatments (n = 690 total spheroids analysed). This microfluidic platform was used to investigate MB enhanced drug delivery and showed that co-delivery of 3 μM doxorubicin (DOX) + MB + US reduced spheroid viability to 48 ± 2%, compared to 75 ± 5% observed with 3 μM DOX alone. Delivery of drug loaded MBs (DLMBs), in which DOX-loaded liposomes (DOX-LS) were conjugated to MBs, reduced spheroid viability to 62 ± 3%, a decrease compared to the 75 ± 3% viability observed with DOX-LS in the absence of MBs + US.

Cell-penetrating corosolic acid liposome as a functional carrier for delivering chemotherapeutic drugs

Corosolic acid (CA), a natural pentacyclic triterpenoid, exhibits antitumor and synergistic therapy effect with chemotherapeutic drugs mainly through inhibiting STAT3 activation. In this study, it is found that CA possesses cholesterol-like properties in liposome by regulating membrane phase behavior to form stable cholesterol-free CA liposomes (CALP). Compared with traditional cholesterol liposomes (CHOLP), CALP exhibit stronger membrane fusion and higher cellular uptake, and other functions including inhibition of STAT3 activation and suppression of the recruitment of macrophages to tumor microenvironment. Therefore, CALP is used as a functional carrier, and doxorubicin-loaded CALP (DOX/CALP) based on PEGylated liposomal doxorubicin (DOXIL^Ⓡ) are prepared by replacing its cholesterol with CA. The physicochemical properties and biological activities are compared with those of doxorubicin-loaded cholesterol liposomes (DOX/LP). Both DOX/CALP and DOX/LP possess approximately similar physical properties and exhibit high stability and low drug leakage as shown by the published data of DOXIL^Ⓡ. Nevertheless, it is noteworthy that DOX/CALP displays higher in vitro cellular uptake and tumor spheroid permeation along with stronger cytotoxicity against tumor cells than DOX/LP. Despite DOX/CALP has the same PK parameters, normal tissue biodistribution, and safety profile as DOX/LP, the results of an in vivo study in 4T1-bearing mice indicate that the DOX/CALP treatment group exhibit higher tumor accumulation, more significant tumor growth inhibition, and longer life span than the DOX/LP group. Overall, DOX/CALP is a representative example of CA-doped liposomes, suggesting that CALP as a functional drug carrier for solving low efficacy of present liposomal drugs might have promising application potential. STATEMENT OF SIGNIFICANCE: An original drug delivery nanocarrier, corosolic acid liposome (CALP), was developed in this study. It was found that CA possesses cholesterol-like function to regulate phospholipid membrane phase behavior. By replacing the cholesterol with CA, the liposomes were converted into high cellular uptake carriers, possessing anti-inflammatory activity and synergism with chemotherapeutic drugs. The variability of CALP formulations enabled to deliver therapeutic agents. The use of CALP to deliver doxorubicin not only significantly enhanced the therapeutic efficacy compared with the classic PEGylated liposomal doxorubicin, but also maintained the improved safety. Because CALP can be obtained by conventional liposome preparation methods, its use as functional drug carriers for solving low efficacy of present liposomal drugs would have promising application potential.

Parallel evolution of polymer chemistry and immunology: Integrating mechanistic biology with materials design

To develop new therapeutics involves the interaction of multiple disciplines to yield safe, functional devices and formulations. Regardless of drug function and potency, administration with controlled timing, dosing, and targeting is required to properly treat or regulate health and disease. Delivery approaches can be optimized through advances in materials science, clinical testing, and basic biology and immunology. Presently, laboratories focused on developing these technologies are composed of, or collaborate with, chemists, biologists, materials scientists, engineers, and physicians to understand the way our body interacts with drug delivery devices, and how to synthesize new, rationally designed materials to improve targeted and controlled drug delivery. In this review, we discuss both device-based and micro/nanoparticle-based materials in the clinic, our biologic understanding of how our immune system interacts with these materials, how this diverse set of immune cells has become a target and variable in drug delivery design, and new directions in polymer chemistry to address these interactions and further our advances in medical therapeutics.

Sonoprinting liposomes on tumor spheroids by microbubbles and ultrasound

Ultrasound-triggered drug-loaded microbubbles have great potential for drug delivery due to their ability to locally release drugs and simultaneously enhance their delivery into the target tissue. We have recently shown that upon applying ultrasound, nanoparticle-loaded microbubbles can deposit nanoparticles onto cells grown in 2D monolayers, through a process that we termed "sonoprinting". However, the rigid surfaces on which cell monolayers are typically growing might be a source of acoustic reflections and aspherical microbubble oscillations, which can influence microbubble-cell interactions. In the present study, we aim to reveal whether sonoprinting can also occur in more complex and physiologically relevant tissues, by using free-floating 3D tumor spheroids as a tissue model. We show that both monospheroids (consisting of tumor cells alone) and cospheroids (consisting of tumor cells and fibroblasts, which produce an extracellular matrix) can be sonoprinted. Using doxorubicin-liposome-loaded microbubbles, we show that sonoprinting allows to deposit large amounts of doxorubicin-containing liposomes to the outer cell layers of the spheroids, followed by doxorubicin release into the deeper layers of the spheroids, resulting in a significant reduction in cell viability. Sonoprinting may become an attractive approach to deposit drug patches at the surface of tissues, thereby promoting the delivery of drugs into target tissues.

On-demand PEGylation and dePEGylation of PLA-based nanocarriers via amphiphilic mPEG-TK-Ce6 for nanoenabled cancer chemotherapy

Rationale: PEGylation of nanocarriers could extend blood circulation time and enhance tumor accumulation via the enhanced permeability and retention (EPR) effect. Unfortunately, the PEG moiety suppresses tumor cell internalization of nanocarriers, resulting in limited therapeutic efficiency (known as the PEG dilemma). Designing stimuli-responsive shell-detachable nanocarriers, which could detach the PEG corona from the nanocarriers in desired tumor tissues in response to the local environment, is an appealing approach to overcome the PEG dilemma, but nanocarrier applications are also limited by a lack of universal stimuli for PEG detachment. Methods: In this study, we synthesized red light-responsive, amphiphilic mPEG bridged to the photosensitizer Ce6 via a thioketal (TK) bond (mPEG-TK-Ce6), which was then used to achieve the PEGylation of polylactide (PLA)-based nanoparticles encapsulating the Pt(IV) prodrug. The therapeutic efficacy of the prepared nanoparticles was evaluated in vitro and in vivo. Results: We demonstrated that the amphiphilic mPEG-TK-Ce6 can realize the PEGylation of Pt(IV) prodrug-loaded PLA nanoparticles and consequently enhanced nanoparticle accumulation in tumor tissues. When the tumor tissues were subjected to 660 nm irradiation, reactive oxygen species (ROS) generated by Ce6 induced the rapid degradation of the adjacent TK bond, resulting in PEG detachment and enhanced tumor cell internalization. Therefore, mPEG-TK-Ce6 facilely achieved PEGylation and light-responsive dePEGylation of the nanocarrier for enhanced antitumor efficacy in nanomedicine. Conclusion: Such red light-responsive amphiphilic mPEG-TK-Ce6 facilely achieved PEGylation and dePEGylation of the nanocarrier, providing a facile strategy to overcome PEG dilemma.

Thioether Phosphatidylcholine Liposomes: A Novel ROS-Responsive Platform for Drug Delivery

Liposomes are the most valuable nanocarriers in clinical use because of their biocompatibility, biodegradation, and effective encapsulation of hydrophilic or hydrophobic drugs. However, their applications are limited by the structure and functions of the most common phospholipids used as the main component of the liposomes. In this work, novel series of thioether phosphatidylcholines (S-PCs) and S-PC-based liposomes (S-LPs) were developed for reactive oxygen species (ROS)-responsive drug release. First of all, S-PCs with different chain lengths were synthesized by a combination of click reaction and heterogeneous esterification. Differential scanning calorimetry studies indicated that S-PCs had different phase transition temperatures depending on their chain lengths. Their critical aggregation concentrations were measured by the fluorescence probe technique indicating the self-assembly ability. After that, S-PC-based stealth liposomes (S-LPs) containing DSPE-PEG₂₀₀₀ and cholesterol were prepared via a classic thin-film method. Doxorubicin (DOX) as a model drug was loaded in the stealth liposomes (DOX/S-LPs) by using the ammonium sulfate gradient method with high encapsulation efficiency. DOX/S-LPs were characterized by dynamic light scattering (DLS), transmission electron microscope (TEM), and cryogenic TEM, confirming their spherical structure with the bilayer thickness of about 4 nm. The ROS sensitivity of S-PCs and S-LPs was carefully evaluated in the presence of H₂O₂ by means of mass spectrometry, DLS, TEM, and ultraviolet spectroscopy and release study. The results indicated the significant structural change of S-LPs after H₂O₂ treatment, which demonstrated that S-LPs possessed an efficient ROS-triggered disintegration because of thioether oxidation of S-PCs. Finally, in vitro and in vivo anticancer efficiency assays revealed the improved drug potency of DOX/S-LPs, which can be attributed to ROS-triggered destruction of S-LPs after the uptake by tumor cells followed by rapid release of DOX. All together, as alternatives of traditional phosphatidylcholines, S-PC-based stealth liposomes are promising ROS-responsive carriers for the controlled delivery of drugs.

Modeling the Distribution of Diprotic Basic Drugs in Liposomal Systems: Perspectives on Malaria Nanotherapy

Understanding how polyprotic compounds distribute within liposome (LP) suspensions is of major importance to design effective drug delivery strategies. Advances in this research field led to the definition of LP-based active drug encapsulation methods driven by transmembrane pH gradients with evidenced efficacy in the management of cancer and infectious diseases. An accurate modeling of membrane-solution drug partitioning is also fundamental when designing drug delivery systems for poorly endocytic cells, such as red blood cells (RBCs), in which the delivered payloads rely mostly on the passive diffusion of drug molecules across the cell membrane. Several experimental models have been proposed so far to predict the partitioning of polyprotic basic/acid drugs in artificial membranes. Nevertheless, the definition of a model in which the membrane-solution partitioning of each individual drug microspecies is studied relative to each other is still a topic of ongoing research. We present here a novel experimental approach based on mathematical modeling of drug encapsulation efficiency (EE) data in liposomal systems by which microspecies-specific partition coefficients are reported as a function of pH and phospholipid compositions replicating the RBC membrane in a simple and highly translatable manner. This approach has been applied to the study of several diprotic basic antimalarials of major clinical importance (quinine, primaquine, tafenoquine, quinacrine, and chloroquine) describing their respective microspecies distribution in phosphatidylcholine-LP suspensions. Estimated EE data according to the model described here closely fitted experimental values with no significant differences obtained in 75% of all pH/lipid composition-dependent conditions assayed. Additional applications studied include modeling drug EE in LPs in response to transmembrane pH gradients and lipid bilayer asymmetric charge, conditions of potential interest reflected in our previously reported RBC-targeted antimalarial nanotherapeutics.

Securing the Payload, Finding the Cell, and Avoiding the Endosome: Peptide-Targeted, Fusogenic Porous Silicon Nanoparticles for Delivery of siRNA

Despite the promise of ribonucleic acid interference therapeutics, the delivery of oligonucleotides selectively to diseased tissues in the body, and specifically to the cellular location in the tissues needed to provide optimal therapeutic outcome, remains a significant challenge. Here, key material properties and biological mechanisms for delivery of short interfering RNAs (siRNAs) to effectively silence target-specific cells in vivo are identified. Using porous silicon nanoparticles as the siRNA host, tumor-targeting peptides for selective tissue homing, and fusogenic lipid coatings to induce fusion with the plasma membrane, it is shown that the uptake mechanism can be engineered to be independent of common receptor-mediated endocytosis pathways. Two examples of the potential broad clinical applicability of this concept in a mouse xenograft model of ovarian cancer peritoneal carcinomatosis are provided: silencing the Rev3l subunit of polymerase Pol ζ to impair DNA repair in combination with cisplatin; and reprogramming tumor-associated macrophages into a proinflammatory state.

Disulfide phosphatidylcholines: alternative phospholipids for the preparation of functional liposomes

Disulfide phosphatidylcholine-based liposomes can be triggered and completely destroyed in a reductive tumor microenvironment resulting in a fast release of encapsulated drugs.

Targeted chemotherapy for subcutaneous and orthotopic non-small cell lung tumors with cyclic RGD-functionalized and disulfide-crosslinked polymersomal doxorubicin

Lung cancer, with its high mortality and increasing morbidity, has become one of the most lethal malignancies worldwide. Here, we developed cyclic RGD peptide-directed and disulfide-crosslinked polymersomal doxorubicin (cRGD-PS-Dox) as a targeted chemotherapy for human non-small cell lung cancer (NSCLC). Notably, cRGD-PS-Dox exhibited a high Dox loading (15.2 wt.%), small hydrodynamic diameter (96 nm), superb stability, prominent targetability to α_vβ₃ integrin overexpressing A549 human lung cancer cells, and rapid release of the drug into nuclei, leading to a significantly improved antitumor activity compared with the control groups, i.e., PS-Dox and Lipo-Dox (a liposome injection employed in clinical settings). The pharmacokinetic and biodistribution results for cRGD-PS-Dox revealed similar elimination half-lives but two-fold enhanced tumor accumulation compared with PS-Dox and Lipo-Dox. Intriguingly, cRGD-PS-Dox effectively suppressed the growth of A549 lung tumors in both subcutaneous and orthotopic models with minimal adverse effects at a Dox dose of 12 mg/kg, leading to significant survival benefits compared with PS-Dox and Lipo-Dox. This α_vβ₃ integrin-targeting multifunctional polymersomal doxorubicin is highly promising for targeted chemotherapy of human NSCLC.

When wrapped in an engineered vesicle and augmented with cancer-targeting peptides, chemotherapy drug doxorubicin shows increased efficacy in a preclinical study. Zhiyuan Zhong, from China’s Soochow University, and his team developed the therapeutic (cRGD-PS-Dox) that targets cancer cells that overexpress a specific protein (α_vβ₃ integrin), such as those of non-small cell lung cancer. In vitro assays showed that cRGD-PS-Dox specifically targeted and inhibited cancer cells, and inhibited the growth and metastasis of human tumor grafts in mice. In vivo imaging confirmed a desirable drug stability profile and accumulation within tumors. These results showed clear advantages over non-targeted doxorubicin treatment controls. Mice treated with cRGD-PS-Dox also survived significantly longer than control-treated mice. The preferential attributes of the therapy make it a promising agent for further study into tumors that overexpress α_vβ₃ integrin.

A rapid and efficient technique for liposomal and nonliposomal drug pharmacokinetics studies using magnetic nanoprobes and its application to leakage kinetics of liposomes

Currently, the pharmacokinetics of liposomes was researched in vivo by measuring the total amount of drug in plasma. This method of using the total drug amount instead of the free drug amount virtually increase the apparent exposure and apparent biological distribution. To solve this problem, we developed a rapid and efficient method by using well-established streptavidin-functional Fe₃O₄@PDA as the separation nanoprobes to efficiently isolate biotin-labeled DTX-liposomes over 75% from plasma in the presence of magnetic field. The isolation procedure takes only 20 min and the concentration of DTX in liposomes from plasma was determined by LC-MS/MS. The method for the determination of DTX in plasma was linear in the range of 5-5000 ng/mL, and the correlation coefficient was 0.9989. Results obtained in this study clearly demonstrated that the pharmacokinetic parameters of non-liposomal drug and total drug are different in vivo. Therefore, traditional method for studying the pharmacokinetics of liposomes in vivo is unreasonable, and the new method mentioned here provided a strategy for studying the pharmacokinetics of liposomes.

Remote loading of liposomes with a 124I-radioiodinated compound and their in vivo evaluation by PET/CT in a murine tumor model

Long circulating liposomes entrapping iodinated and radioiodinated compounds offer a highly versatile theranostic platform. Here we report a new methodology for efficient and high-yield loading of such compounds into liposomes, enabling CT/SPECT/PET imaging and ¹³¹I-radiotherapy.

Methods: The CT contrast agent diatrizoate was synthetically functionalized with a primary amine, which enabled its remote loading into PEGylated liposomes by either an ammonium sulfate- or a citrate-based pH transmembrane gradient. Further, the amino-diatrizoate was radiolabeled with either ¹²⁴I (t_1/2 = 4.18 days) for PET or ¹²⁵I (t_1/2 = 59.5 days) for SPECT, through an aromatic Finkelstein reaction.

Results: Quantitative loading efficiencies (>99%) were achieved at optimized conditions. The ¹²⁴I-labeled compound was remote-loaded into liposomes, with an overall radiolabeling efficiency of 77 ± 1%, and imaged in vivo in a CT26 murine colon cancer tumor model by PET/CT. A prolonged blood circulation half-life of 19.5 h was observed for the radiolabeled liposomes, whereas injections of the free compound were rapidly cleared. Lower accumulation was observed in the spleen, liver, kidney and tumor than what is usually seen for long-circulating liposomes.

Conclusion: The lower accumulation was interpreted as release of the tracer from the liposomes within these organs after accumulation. These results may guide the design of systems for controlled release of remote loadable drugs from liposomes.

Predicting drug delivery efficiency into tumor tissues through molecular simulation of transport in complex vascular networks

Efficient delivery of anticancer drugs into tumor tissues at maximally effective and minimally toxic concentrations is vital for therapeutic success. At present, no method exists that can predict the spatial and temporal distribution of drugs into a target tissue after administration of a specific dose. This prevents accurate estimation of optimal dosage regimens for cancer therapy. Here we present a new method that predicts quantitatively the time-dependent spatial distribution of drugs in tumor tissues at sub-micrometer resolution. This is achieved by modeling the diffusive flow of individual drug molecules through the three-dimensional network of blood-vessels that vascularize the tumor, and into surrounding tissues, using molecular mechanics techniques. By evaluating delivery into tumors supplied by a series of blood-vessel networks with varying degrees of complexity, we show that the optimal dose depends critically on the precise vascular structure. Finally, we apply our method to calculate the optimal dosage of the cancer drug doxil into a section of a mouse ovarian tumor, and demonstrate the enhanced delivery of liposomally administered doxorubicin when compared to free doxorubicin. Comparison with experimental data and a multiple-compartment model show that the model accurately recapitulates known pharmacokinetics and drug-load predictions. In addition, it provides, for the first time, a detailed picture of the spatial dependence of drug uptake into tissues surrounding tumor vasculatures. This approach is fundamentally different to current continuum models, and reveals that the target tumor vascular topology is as important for therapeutic success as the transport properties of the drug delivery platform itself. This sets the stage for revisiting drug dosage calculations.

Designed inorganic porous nanovector with controlled release and MRI features for safe administration of doxorubicin

The inability of traditional chemotherapeutics to reach cancer tissue reduces the treatment efficacy and leads to adverse effects. A multifunctional nanovector was developed consisting of porous silicon, superparamagnetic iron oxide, calcium carbonate, doxorubicin and polyethylene glycol. The particles integrate magnetic properties with the capacity to retain drug molecules inside the pore matrix at neutral pH to facilitate drug delivery to tumor tissues. The MRI applicability and pH controlled drug release were examined in vitro together with in-depth material characterization. The in vivo biodistribution and compound safety were verified using A549 lung cancer bearing mice before proceeding to therapeutic experiments using CT26 cancer implanted mice. Loading doxorubicin into the porous nanoparticle negated the adverse side effects encountered after intravenous administration highlighting the particles' excellent biocompatibility. Furthermore, the multifunctional nanovector induced 77% tumor reduction after intratumoral injection. The anti-tumor effect was comparable with that of free doxorubicin but with significantly alleviated unwanted effects. These results demonstrate that the developed porous silicon-based nanoparticles represent promising multifunctional drug delivery vectors for cancer monitoring and therapy.