Formation strategies,mechanism of intracellular delivery and potential clinical applications of pH-sensitive liposomes

pH-sensitive liposomes are designed to specifically triggered release the loaded drugs in response to the change of pH in the surrounding serum.So pH-sensitive liposomes can effectively deliver drug or gene fragments into the cytoplasm via the endocytotic pathway.Furthermore,pH-sensitive liposomes can be successfully used in clinical if they enable the encapsulated drugs to be targeted to pathological tissues(such as primary tumors,metastases,local ischemia,inflammation and infection)of the body in which pH is less than the normal physiological value.That’s the reason why a growing amount of literatures described the development and applications of pH-sensitive liposomes to improve the therapeutic index of the encapsulated active ingredients.In this review,the commonly used pH-sensitive molecules for pH-sensitive liposome and the mechanisms of intracellular delivery of pH-sensitive liposomes were addressed.Besides,the potential clinical applications were fully discussed in detail with an expectation to contribute to the clinical research of pH-sensitive liposomes.

Delivery of docetaxel using pH-sensitive liposomes based on D-α-tocopheryl poly(2-ethyl-2-oxazoline) succinate:Comparison with PEGylated liposomes

This study aimed to investigate the ability of the novel materials D-α-tocopheryl poly(2-ethyl-2-oxazoline) succinate(TPOS) to construct pH-sensitive liposomes. TPOS was initially synthesized and characterized by TLC, FTIR, and ~1H-NMR. The buffering capacity of polyethylene glycol-distearoyl phosphatidylethanolamine(PEG-DSPE) and TPOS was determined by acid-base titration, and TPOS displayed a slower downtrend and gentler slope of titration curve than PEG-DSPE within pH 7.4–5.0. Studies on the in vitro drug release demonstrated that TPOS modified docetaxel(DOC) liposomes(TPOS-DOC-L) had a slower drugrelease rate at pH 7.4 similar to PEGylated-DOC liposomes(PEG-DOC-L), whereas the release rate reached approximately 86.92% ± 1.69% at pH 6.4. In vitro cellular uptake assays by microplate reader, and flow cytometry revealed that TPOS modified coumarin 6 liposomes(TPOS-C6-L) had stronger cellular uptake at pH 6.4 than that at pH 7.4( P < 0.01). Conversely, for PEGylated C6 liposomes(PEG-C6-L) and conventional C6 liposomes(C6-L), very similar cellular uptakes were exhibited at different pH values. Confocal laser scanning microscopy images showed that PEG-C6-L and C6-L were mainly located in lysosomes. By contrast, TPOS-C6-L showed broader cytoplasmic release and distribution at 4 h. MTT assay showed that the cytotoxicity of TPOS-DOC-L was similar to that of PEG-DOC-L and conventional DOC liposomes(DOC-L) at the same DOC concentration and at pH 7.4, but was much lower than those at pH 6.4 after 48 h of incubation. The apoptosis of PEG-DOC-L and DOC-L had no remarkable improvement with decreased pH from 7.4 to 6.4. Meanwhile, TPOS-DOC-Lsignificantly induced the apoptosis of HeLa cells with decreased pH. Therefore, TPOS can be a biomaterial for the construction of a pH-sensitive drug delivery system.

Chitosan/Sodium Alginate Multilayer pH-Sensitive Films Based on Layer-by-Layer Self-Assembly for Intelligent Packaging

The abuse of plastic food packaging has brought about severe white pollution issues around the world.Developing green and sustainable biomass packaging is an effective way to solve this problem.Hence,a chitosan/sodium alginate-based multilayer film is fabricated via a layer-by-layer(LBL)self-assembly method.With the help of superior interaction between the layers,the multilayer film possesses excellent mechanical properties(with a tensile strength of 50 MPa).Besides,the film displays outstanding water retention property(blocking moisture of 97.56%)and ultraviolet blocking property.Anthocyanin is introduced into the film to detect the food quality since it is one natural plant polyphenol that is sensitive to the pH changes ranging from 1 to 13 in food when spoilage occurs.It is noted that the film is also bacteriostatic which is desired for food packaging.This study describes a simple technique for the development of advanced multifunctional and fully biodegradable food packaging film and it is a sustainable alternative to plastic packaging.

Overcoming neutrophil-induced immunosuppression in postoperative cancer therapy: Combined sialic acid-modified liposomes with scaffold-based vaccines

Immunotherapy is a promising approach for preventing postoperative tumor recurrence and metastasis. However, inflammatory neutrophils, recruited to the postoperative tumor site, have been shown to exacerbate tumor regeneration and limit the efficacy of cancer vaccines. Consequently, addressing postoperative immunosuppression caused by neutrophils is crucial for improving treatment outcomes. This study presents a combined chemoimmunotherapeutic strategy that employs a biocompatible macroporous scaffold-based cancer vaccine (S-CV) and a sialic acid (SA)-modified, doxorubicin (DOX)-loaded liposomal platform (DOX@SAL). The S-CV contains whole tumor lysates as antigens and imiquimod (R837, Toll-like receptor 7 activator)-loaded PLGA nanoparticles as immune adjuvants for cancer, which enhance dendritic cell activation and cytotoxic T cell proliferation upon localized implantation. When administered intravenously, DOX@SAL specifically targets and delivers drugs to activated neutrophils in vivo, mitigating neutrophil infiltration and suppressing postoperative inflammatory responses. In vivo and vitro experiments have demonstrated that S-CV plus DOX@SAL, a combined chemo-immunotherapeutic strategy, has a remarkable potential to inhibit postoperative local tumor recurrence and distant tumor progression, with minimal systemic toxicity, providing a new concept for postoperative treatment of tumors.

Selective ischemic-hemisphere targeting Ginkgolide B liposomes with improved solubility and therapeutic efficacy for cerebral ischemia-reperfusion injury

Cerebral ischemia-reperfusion injury(CI/RI)remains the main cause of disability and death in stroke patients due to lack of effective therapeutic strategies.One of the main issues related to CI/RI treatment is the presence of the blood-brain barrier(BBB),which affects the intracerebral delivery of drugs.Ginkgolide B(GB),a major bioactive component in commercially available products of Ginkgo biloba,has been shown significance in CI/RI treatment by regulating inflammatory pathways,oxidative damage,and metabolic disturbance,and seems to be a candidate for stroke recovery.However,limited by its poor hydrophilicity and lipophilicity,the development of GB preparations with good solubility,stability,and the ability to cross the BBB remains a challenge.Herein,we propose a combinatorial strategy by conjugating GB with highly lipophilic docosahexaenoic acid(DHA)to obtain a covalent complex GB-DHA,which can not only enhance the pharmacological effect of GB,but can also be encapsulated in liposomes stably.The amount of finally constructed Lipo@GB-DHA targeting to ischemic hemisphere was validated 2.2 times that of free solution in middle cerebral artery occlusion(MCAO)rats.Compared to the marketed ginkgolide injection,Lipo@GB-DHA significantly reduced infarct volume with better neurobehavioral recovery in MCAO rats after being intravenously administered both at 2 h and 6 h post-reperfusion.Low levels of reactive oxygen species(ROS)and high neuron survival in vitro was maintained via Lipo@GB-DHA treatment,while microglia in the ischemic brain were polarized from the pro-inflammatory M1 phenotype to the tissue-repairing M2 phenotype,which modulate neuroinflammatory and angiogenesis.In addition,Lipo@GB-DHA inhibited neuronal apoptosis via regulating the apoptotic pathway and maintained homeostasis by activating the autophagy pathway.Thus,transforming GB into a lipophilic complex and loading it into liposomes provides a promising nanomedicine strategy with excellent CI/RI therapeutic efficacy and industrialization prospects.

Linear-like polypeptide-based micelle with pH-sensitive detachable PEG to deliver dimeric camptothecin for cancer therapy

Nano drug delivery systems have made significant progress in delivering anticancer drugs camptothecin(CPT).However,many challenges for CPT delivery remain,including low drug loading efficiency,premature drug leakage,and poor cellular internalization.Herein,we report a novel dual-sensitive polypeptide-based micelle with remarkably high drug loading of CPT for cancer therapy.This self-assembled micelle possesses the following essential components for CPT:(1)pH-sensitive PEG(OHC-PEG-CHO)for prolonging blood circulation and allowing biocompatibility by shielding the cationic micelles,which can be detached under the tumor acidic microenvironment and facilitates the cellular uptake;(2)polypeptide polylysine-polyphenylalanine(PKF)synthesized via ring-opening polymerization for micelle formation and CPT analogue loading;(3)dimeric CPT(DCPT)with redox-sensitive linker for increasing CPT loading and ensuring drug release at tumor sites.Interestingly,the linear-like morphology of PEG-PKF/DCPT micelles was able to enhance their cellular internalization when compared with the spherical blank PKF micelles.Also,the anticancer efficacy of DCPT against lung cancer cells was significantly improved by the micelle formation.In conclusion,this work provides a promising strategy facilitating the safety and effective application of CPT in cancer therapy.

Mechanistic engineering of celastrol liposomes induces ferroptosis and apoptosis by directly targeting VDAC2 in hepatocellular carcinoma

Hepatocellular carcinoma(HCC)is one of most common and deadliest malignancies.Celastrol(Cel),a natural product derived from the Tripterygium wilfordii plant,has been extensively researched for its potential effectiveness in fighting cancer.However,its clinical application has been hindered by the unclear mechanism of action.Here,we used chemical proteomics to identify the direct targets of Cel and enhanced its targetability and antitumor capacity by developing a Cel-based liposomes in HCC.We demonstrated that Cel selectively targets the voltage-dependent anion channel 2(VDAC2).Cel directly binds to the cysteine residues of VDAC2,and induces cytochrome C release via dysregulating VDAC2-mediated mitochondrial permeability transition pore(mPTP)function.We further found that Cel induces ROS-mediated ferroptosis and apoptosis in HCC cells.Moreover,coencapsulation of Cel into alkyl glucoside-modified liposomes(AGCL)improved its antitumor efficacy and minimized its side effects.AGCL has been shown to effectively suppress the proliferation of tumor cells.In a xenograft nude mice experiment,AGCL significantly inhibited tumor growth and promoted apoptosis.Our findings reveal that Cel directly targets VDAC2 to induce mitochondria-dependent cell death,while the Cel liposomes enhance its targetability and reduces side effects.Overall,Cel shows promise as a therapeutic agent for HCC.

Leveraging immunoliposomes as nanocarriers against SARS-CoV-2 and its emerging variants

The global COVID-19 pandemic arising from SARS-CoV-2 has impacted many lives,gaining interest worldwide ever since it was first identified in December 2019.Till 2023,752 million cumulative cases and 6.8 million deaths were documented globally.COVID-19 has been rapidly evolving,affecting virus transmissibility and properties and contributing to increased disease severity.The Omicron is themost circulating variant of concern.Although success in its treatment has indicated progress in tackling the virus,limitations in delivering the current antiviral agents in battling emerging variants remain remarkable.With the latest advancements in nanotechnology for controlling infectious diseases,liposomes have the potential to counteract SARS-CoV-2 because of their ability to employ different targeting strategies,incorporating monoclonal antibodies for the active and passive targeting of infected patients.This review will present a concise summary of the possible strategies for utilizing immunoliposomes to improve current treatment against the occurrence of SARSCoV-2 and its variants.

Predicting liposome formulations by the integrated machine learning and molecular modeling approaches

Liposome is one of the most widely used carriers for drug delivery because of the great biocompatibility and biodegradability.Due to the complex formulation components and preparation process,formulation screening mostly relies on trial-and-error process with low efficiency.Here liposome formulation prediction models have been built by machine learning(ML)approaches.The important parameters of liposomes,including size,polydispersity index(PDI),zeta potential and encapsulation,are predicted individually by optimal ML algorithm,while the formulation features are also ranked to provide important guidance for formulation design.The analysis of key parameter reveals that drug molecules with logS[-3,-6],molecular complexity[500,1000]and XLogP3(≥2)are priority for preparing liposome with higher encapsulation.In addition,naproxen(NAP)and palmatine HCl(PAL)represented the insoluble and water-soluble molecules are prepared as liposome formulations to validate prediction ability.The consistency between predicted and experimental value verifies the satisfied accuracy of ML models.As the drug properties are critical for liposome particles,the molecular interactions and dynamics of NAP and PAL liposome are further investigated by coarse-grained molecular dynamics simulations.The modeling structure reveals that NAP molecules could distribute into lipid layer,while most PAL molecules aggregate in the inner aqueous phase of liposome.The completely different physical state of NAP and PAL confirms the importance of drug properties for liposome formulations.In summary,the general prediction models are built to predict liposome formulations,and the impacts of key factors are analyzed by combing ML with molecular modeling.The availability and rationality of these intelligent prediction systems have been proved in this study,which could be applied for liposome formulation development in the future.

The Applications of Mitoxantrone and Its Liposome in Adult Acute Myeloid Leukemia

Acute myeloid leukemia (AML), a rapidly progressing hematopoietic malignancy, can only be cured hopefully by hematopoietic stem cells transplantation (HSCT). Before HSCT, we usually exert effects by attempting certain regimens to induce these tumor cells to death. Administered in AML patients, the classic “3 + 7” intensive induction regimen including anthracyclines and cytarabine is recommended by guidelines worldwide. However, conventional regimens consist of anthracyclines, a category of drug limited by cumulative, dose-related, progressive myocardial damage and congestive heart failure occurs when its total doses break through the cut-off. Based on this background, mitoxantrone (MIT), an anthraquinone, was developed to a new form to reduce cardiotoxicity. Meanwhile, the nanomedicine, mitoxantrone liposome (Lipo-MIT), was characterized by improved bioavailability and limited toxicity. This drug has great therapeutic potential, but different side effects. We conclude the overall history and development of MIT and Lipo-MIT, which show controversial efficacy of MIT compared to doxorubicin and therapeutic potential of Lipo-MIT. This article reviewed the application of MIT and liposome forms in adult AML patients. .

Nonclinical Study of the Active Components of Doxorubicin Hydrochloride Liposome Injection in Vivo

Objectives: A non-clinical study was performed to establish a LC-MS/MS method to determine the in vivo active components of doxorubicin hydrochloride liposome injection in the plasma of Sprague-Dawley rats. Methods: Ten male SD rats were administered tail vein with a single dose of 10 mg/kg, and the concentrations of doxorubicin hydrochloride in plasma, heart, liver, spleen, lung, and kidney were determined by liquid chromatography-tandem mass spectrometry, and the pharmacokinetic parameters were calculated. Results: The final concentration of doxorubicin hydrochloride ranged from 500 ng/mL to 250,000 ng/mL, and the lower limit of quantification was 500 ng/mL;the main pharmacokinetic parameters: T1/2 was (19.282 ± 10.305) h, Cmax was (118514.828 ± 26155.134) ng/mL, AUC0-24 and AUC0-∞ were (1216659.205 ± 192706.268) ng/mL⋅h and (2082244.523 ± 860139.487) ng/mL⋅h, MRT0-24 and MRT0-∞ were (9.237 ± 0.423) h and (26.52 ± 14.015) h, respectively, and clearance (CL) was (0.005 ± 0.002) mL/h⋅ng. Conclusions: The method is simple, rapid, and sensitive, which can be used for the determination of doxorubicin hydrochloride concentration in the plasma of SD rats and pharmacokinetic non-clinical studies.

Preparation Process of Hydroxypropyl Tetrahydropyrantriol Liposomes

[Objectives] To explore the optimal process for preparing hydroxypropyl tetrahydropyrantriol liposomes. [Methods] A refractive index method was used to determine the content of hydroxypropyl tetrahydropyrantriol. Using particle size distribution and encapsulation rate as evaluation indicators, the effects of hydration time, ratio of organic phase to aqueous phase, granulation method, as well as thin film dispersion and reverse evaporation methods on liposomes preparation were investigated, and the optimal preparation method was selected. Single factor experiments were used to screen the drug phospholipid ratio, ultrasound time, and phospholipid cholesterol ratio, and the preparation process was optimized through orthogonal experiments. [Results] The optimal process of preparing hydroxypropyl tetrahydropyrantriol liposomes was as below: 1 : 10 of drug phospholipid ratio, 6 min of ultrasound time, 4 : 1 of phospholipid cholesterol ratio, (60.94%±7.24%) of entrapment efficiency, (86.44±6.08) nm of particle size, (0.195±0.077) of PDI. [Conclusions] The optimal preparation process of hydroxypropyl tetrahydropyrantriol liposomes selected by orthogonal experiment could effectively improve the encapsulation efficiency of hydroxypropyl tetrahydropyranotriol and reduce particle size. Moreover, the method was stable and reliable.

Microwave ablation combined with transarterial chemoembolization containing doxorubicin hydrochloride liposome for treating primary and metastatic liver cancers

Aims:To determine the safety and efficacy of microwave ablation(MWA)and transarterial chemoembolization(TACE)with doxorubicin hydrochloride liposome(DHL)in patients with primary liver cancer(PLC)and metastatic liver cancer(MLC).Materials and methods:The medical records of patients with primary or metastatic liver cancer who underwent MWA combined with TACE containing DHL from March 2019 to March 2022 were collected and analyzed.Treatment-related adverse events(AEs)were recorded.Local tumor response was evaluated according to the modified RECIST criteria.Local tumor progression-free survival(LTPFS)and overall survival(OS)were calculated using the Kaplan-Meier method.Results:Altogether,96 patients with liver cancer were included(PLC,n=45;MLC,n=51).Forty(41.7%)patients experienced AEs during treatment,and eight(8.3%)patients developed grade 3 AEs.Compared to before treatment,the serum total bilirubin level and neutrophil to lymphocyte ratio significantly increased after treatment.The median LTPFS was 14.5 months in patients with PLC and 10.7 months in patients with MLC.The median OS was not reached in patients with PLC or MLC.The 1-month and 3-month disease control rates reached more than 80%in both groups.Conclusion:MWA combined with TACE with DHL may be a safe and effective method for the treatment of liver cancer.

Liposomal dual delivery systems in visceral leishmaniasis enhance the synergistic effects of combination therapy:A promise for the future

Visceral leishmaniasis(VL)is a neglected tropical disease,and this review has summarized the current treatment scenario and its prospects.It also highlights alternative approaches used by research groups in India and around the world to develop cutting-edge and potent anti-leishmanial treatments.Even though numerous medications could be utilized to treat VL,the limitations of current treatments including their toxicity,cost,route of administration,and duration of doses,have contributed to the emergence of resistance.Combination therapy might be a better option due to its shorter duration,easier route of administration,and ability to extend the lifespan of individual drugs.However,there is a risk of not delivering both the drugs to the target site together,which can be overcome by the liposomal entrapment of those drugs and at a time knock an opportunity to reduce the dosage of amphotericin B if the combination drug provides a synergistic effect with it.Therefore,this review presents a novel strategy to fight against VL by introducing dual drug-loaded liposomes.

Immune checkpoint inhibition mediated with liposomal nanomedicine for cancer therapy

Immune checkpoint blockade(ICB)therapy for cancer has achieved great success both in clinical results and on the market.At the same time,success drives more attention from scientists to improve it.However,only a small portion of patients are responsive to this therapy,and it comes with a unique spectrum of side effects termed immunerelated adverse events(irAEs).The use of nanotechnology could improve ICBs’delivery to the tumor,assist them in penetrating deeper into tumor tissues and alleviate their irAEs.Liposomal nanomedicine has been investigated and used for decades,and is well-recognized as the most successful nano-drug delivery system.The successful combination of ICB with liposomal nanomedicine could help improve the efficacy of ICB therapy.In this review,we highlighted recent studies using liposomal nanomedicine(including new emerging exosomes and their inspired nanovesicles)in associating ICB therapy.

Synergistic chemotherapy/PTT/oxygen enrichment by multifunctional liposomal polydopamine nanoparticles for rheumatoid arthritis treatment

Amultifunctional liposomal polydopamine nanoparticle(MPM@Lipo)was designed in this study,to combine chemotherapy,photothermal therapy(PTT)and oxygen enrichment to clear hyperproliferating inflammatory cells and improve the hypoxic microenvironment for rheumatoid arthritis(RA)treatment.MPM@Lipo significantly scavenged intracellular reactive oxygen species and relieved joint hypoxia,thus contributing to the repolarization of M1 macrophages into M2 phenotype.Furthermore,MPM@Lipo could accumulate at inflammatory joints,inhibit the production of inflammatory factors,and protect cartilage in vivo,effectively alleviating RA progression in a rat adjuvant-induced arthritis model.Moreover,upon laser irradiation,MPM@Lipo can elevate the temperature to not only significantly obliterate excessively proliferating inflammatory cells but also accelerate the production of methotrexate and oxygen,resulting in excellent RA treatment effects.Overall,the use of synergistic chemotherapy/PTT/oxygen enrichment therapy to treat RA is a powerful potential strategy.

Current developments in drug delivery with thermosensitive liposomes

Thermosensitive liposomes(TSLs) have been an important research area in the field of tumor targeted chemotherapy. Since the first TSLs appeared that using 1,2-dipalmitoyl-snglyce-ro-3-phosphocholine(DPPC) as the primary liposomal lipid, many studies have been done using this type of liposome from basic and practical aspects. While TSLs composed of DPPC enhance the cargo release near the phase transition temperature, it has been shown that many factors affect their temperature sensitivity. Thus numerous attempts have been undertaken to develop new TSLs for improving their thermal response performance. The main objective of this review is to introduce the development and recent update of innovative TSLs formulations, including combination of radiofrequency ablation(RFA), highintensity focused ultrasound(HIFU), magnetic resonance imaging(MRI) and alternating magnetic field(AMF). In addition, various factors affecting the design of TSLs, such as lipid composition, surfactant, size and serum components are also discussed.

Analytical methods for investigating in vivo fate of nanoliposomes:A review

Nanoliposomes are considered to be the most successful nanoparticle drug delivery system, but their fate in vivo has not been fully understood due to lack of reliable bioanalytical methods, which seriously limits the development of liposomal drugs. Hence, an overview of currently used bioanalytical methods is imperative to lay the groundwork for the need of developing a bioanalytical method for liposome measurements in vivo. Currently, major analytical methods for nanoliposomes measurement in vivo include fluorescence labeling, radiolabeling, magnetic resonance imaging（MRI）, mass spectrometry and computed tomography. In this review, these bioanalytical methods are summarized, and the advantages and disadvantages of each are discussed. We provide insights into the applicability and limitations of these analytical methods in the application of nanoliposomes measurement in vivo, and highlight the recent development of instrumental analysis techniques. The review is devoted to providing a comprehensive overview of the investigation of nanoliposomes design and associated fate in vivo, promoting the development of bioanalytical techniques for nanoliposomes measurement, and understanding the pharmacokinetic behavior, effectiveness and potential toxicity of nanoliposomes in vivo.

A Concise Review of Gold Nanoparticles-Based Photo-Responsive Liposomes for Controlled Drug Delivery

The focus of drug delivery is shifting toward smart drug carriers that release the cargo in response to a change in the microenvironment due to an internal or external trigger. As the most clinically successful nanosystem, liposomes naturally come under the spotlight of this trend. This review summarizes the latest development about the design and construction of photo-responsive liposomes with gold nanoparticles for the controlled drug release. Alongside, we overview the mechanism involved in this process and the representative applications.