Multifunctional Liposomes for Image-Guided Intratumoral Chemo-Phototherapy

Advances in localized prostate cancer: A special focus on photothermal therapy

Prostate cancer (PCa) is a high prevalence disease, per 10000 habitants, that tends to increase with age. This pathology is difficult to detect at an early stage due to the absence of symptoms, hence the importance of monitoring signs for early detection. This disease can be detected by various methods, including plasmatic levels of prostate-specific antigen (PSA) and rectal touch, with biopsy being necessary to confirm the diagnosis. Patients affected by prostate cancer can have localized or advanced disease. There are conventional approaches that have been used as a reference in localized cancer, such as active surveillance, surgery, or radiotherapy. However, the adverse effects might vary and, sometimes, they can be permanent. An overview about the innovative therapeutic approaches to improve outcomes in terms of both tumor remission and side effects for localized PCa is presented. In case of emerging light-based treatment strategies, they aimed at ablating tumor tissue by inducing an external light are non-invasive, localized and, considerably, they are able to reduce lesions in peripheral tissues. One is photodynamic therapy (PDT) and it involves the photooxidation of molecules culminating in the formation of reactive oxygen species (ROS), inducing cell death. On the other hand, photothermal therapy (PTT) is based on inducing hyperthermia in cancer cells by irradiating them with beams of light at a specific wavelength. To improve the heat generated, gold nanoparticles (AuNPs) have those desirable characteristics that have drawn attention to PTT. Various studies point to AuNPs as efficient nanomaterials in PTT for the treatment of tumors, including prostate cancer. This review includes the most representative advances in this research field, dated from 1998 to 2023. It is noticed that several advances have been made and the way to find the effective treatment without impacting adverse side effects is shorter.

Advances and perspectives in phototherapy-based combination therapy for cancer treatment

Phototherapy, including photothermal therapy (PTT) and photodynamic therapy (PDT), has the advantages of spatiotemporal selectivity, non-invasiveness, and negligible drug resistance. Phototherapy has been approved for treating superficial epidermal tumors. However, its therapeutic efficacy is limited by the hypoxic tumor microenvironment and the highly expressed heat shock protein. Moreover, poor tissue penetration and focused irradiation laser region in phototherapy make treating deep tissues and metastatic tumors challenging. Combination therapy strategies, which integrate the advantages of each treatment and overcome their disadvantages, can significantly improve the therapeutic efficacy. Recently, many combination therapy strategies have been reported. Our study summarizes the strategies used for combining phototherapy with other cancer treatments such as chemotherapy, immunotherapy, sonodynamic therapy, gas therapy, starvation therapy, and chemodynamic therapy. Some research cases were selected to analyze the combination therapy effect, delivery platform feature, and synergetic anticancer mechanisms. Moreover, additional research cases are summarized in the tables. This review provides strong evidence that phototherapy-based combination strategies can enhance the anticancer effect compared with phototherapy alone. Additionally, the challenges and future perspectives associated with these combinational therapies are discussed.

Advances in liposomes loaded with photoresponse materials for cancer therapy

Cancer treatment is presently a significant challenge in the medical domain, wherein the primary modalities of intervention include chemotherapy, radiation therapy and surgery. However, these therapeutic modalities carry side effects. Photothermal therapy (PTT) and photodynamic therapy (PDT) have emerged as promising modalities for the treatment of tumors in recent years. Phototherapy is a therapeutic approach that involves the exposure of materials to specific wavelengths of light, which can subsequently be converted into either heat or Reactive Oxygen Species (ROS) to effectively eradicate cancer cells. Due to the hydrophobicity and lack of targeting of many photoresponsive materials, the use of nano-carriers for their transportation has been extensively explored. Among these nanocarriers, liposomes have been identified as an effective drug delivery system due to their controllability and availability in the biomedical field. By binding photoresponsive materials to liposomes, it is possible to reduce the cytotoxicity of the material and regulate drug release and accumulation at the tumor site. This article provides a comprehensive review of the progress made in cancer therapy using photoresponsive materials loaded onto liposomes. Additionally, the article discusses the potential synergistic treatment through the combination of phototherapy with chemo/immuno/gene therapy using liposomes.

PNIPAM-stabilized cubosomes as fusogenic delivery nanovectors for anticancer applications

In recent years, lipid cubic nanoparticles have emerged as promising nanocarriers for drug delivery, due to the several advantages they exhibit with respect to other lipid systems. Here, we report on lipid cubic nanoparticles stabilized by PNIPAM-based amphiphilic block copolymers, specifically, poly(N, N-dimethylacrylamide)-block-poly(N-isopropylacrylamide) (PDMA-b-PNIPAM), as a new class of drug delivery systems (DDS). In vitro studies on the internalization efficiency of the DDS towards two types of human cancer cells (colon HCT-116 and bladder T24 cells), carried out employing a set of sensitive techniques (confocal laser scanning microscopy (CLSM), flow cytometry, scanning electron microscopy (SEM), fluorescence spectroscopy), highlight a prominent role of PDMA-b-PNIPAM stabilizer in enhancing the uptake of cubosomes, compared to the standard Pluronic F127-based formulations. The drug delivery potential of cubosomes, tested by encapsulating a chemotherapeutic drug, camptothecin (CPT), and conducting cytotoxicity studies against 2D plated cells and 3D spheroids, confirm that PDMA-b-PNIPAM-stabilized cubosomes improve the efficacy of treatment with CPT. The origin of this effect lies in the higher lipophilicity of the stabilizer, as we confirm by studying the interaction between the cubosomes and biomimetic membranes of lipid vesicles with Small Angle X-Ray Scattering (SAXS) and CLSM experiments. These results corroborate our fundamental understanding of the interaction between cubosomes and cells, and on the role of polymer to formulate lipid cubic nanoparticles as DDS.

Phospholipid Encapsulation of an Anti-Fibrotic Endopeptide to Enhance Cellular Uptake and Myocardial Retention

BACKGROUND

Cardioprotective effects of N-acetyl-ser-asp-lys-pro (Ac-SDKP) have been reported in preclinical models of myocardial remodeling. However, the rapid degradation of this endogenous peptide in vivo limits its clinical use.

METHOD

To prolong its bioavailability, Ac-SDKP was encapsulated by phosphocholine lipid bilayers (liposomes) similar to mammalian cell membranes. The physical properties of the liposome structures were assessed by dynamic light scattering and scanning electron microscopy. The uptake of Ac-SDKP by RAW 264.7 macrophages and human and murine primary cardiac fibroblasts was confirmed by fluorescence microscopy and flow cytometry. Spectrum computerized tomography and competitive enzyme-linked immunoassays were performed to measure the ex vivo cardiac biodistribution of Ac-SDKP. The biological effects of this novel synthetic compound were examined in cultured macrophages and cardiac fibroblasts and in a murine model of acute myocardial infarction induced by permanent coronary artery ligation.

RESULTS

A liposome formulation resulted in the greater uptake of Ac-SDKP than the naked peptide by cultured RAW 264.7 macrophages and cardiac fibroblasts. Liposome-delivered Ac-SDKP decreased fibroinflammatory genes in cultured cardiac fibroblasts co-treated with TGF-β1 and macrophages stimulated with LPS. Serial tissue and serum immunoassays showed the high bioavailability of Ac-SDKP in mouse myocardium and in circulation. Liposome-delivered Ac-SDKP improved cardiac function and reduced myocardial fibroinflammatory responses in mice with acute myocardial infarction.

CONCLUSION

Encapsulation of Ac-SDKP in a cell membrane-like phospholipid bilayer enhances its plasma and tissue bioavailability and offers cardioprotection against ischemic myocardial injury. Future clinical trials can use this novel approach to test small protective endogenous peptides in myocardial remodeling.

Image-guided drug delivery in nanosystem-based cancer therapies

The past decades have shown significant advancements in the development of solid tumor treatment. For instance, implementation of nanosystems for drug delivery has led to a reduction in side effects and improved delivery to the tumor region. However, clinical translation has faced challenges, as tumor drug levels are still considered to be inadequate. Interdisciplinary research has resulted in the development of more advanced drug delivery systems. These are coined "smart" due to the ability to be followed and actively manipulated in order to have better control over local drug release. Therefore, image-guided drug delivery can be a powerful strategy to improve drug activity at the target site. Being able to visualize the inflow of the administered smart nanosystem within the tumor gives the potential to determine the right moment to apply the facilitator to initiate drug release. Here we provide an overview of available nanosystems, imaging moieties, and imaging techniques. We discuss preclinical application of these smart drug delivery systems, the strength of image-guided drug delivery, and the future of personalized treatment.

Immune checkpoint blockade enhances chemophototherapy in a syngeneic pancreatic tumor model

Pancreatic cancer (PaCa) suffers from poor treatment options for locally advanced cases. Chemophototherapy (CPT) is an emerging anti-tumor modality, and porphyrin–phospholipid liposomes have been shown to be versatile drug carriers for CPT in preclinical rodent models. Here we show that in the syngeneic subcutaneous KPC PaCa tumor model, exhausted CD8⁺ T cells are localized in the tumor, and that CPT is enhanced in combination with immune checkpoint blockade (ICB). Addition of ICB using anti-programmed cell death 1 (PD-1) and cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) antibodies resulted in ablation of medium-sized, established KPC tumors (∼200 mm³) without recurrence for over 100 days. Mice rejected subsequent tumor re-challenge. Flow cytometry and tumor slice analysis following injection of a fluorescently labeled anti-PD-1 antibody showed that CPT improved antibody delivery to the tumor microenvironment. Treatment of large established tumors (∼400 mm³) using with CPT and ICB induced appreciable tumor regression and delay in regrowth. Taken together, these data demonstrate the utility of combining CPT with immunotherapies.

Stimuli-responsive liposomal nanoformulations in cancer therapy: Pre-clinical & clinical approaches

The site-specific delivery of antitumor agents is of importance for providing effective cancer suppression. Poor bioavailability of anticancer compounds and the presence of biological barriers prevent their accumulation in tumor sites. These obstacles can be overcome using liposomal nanostructures. The challenges in cancer chemotherapy and stimuli-responsive nanocarriers are first described in the current review. Then, stimuli-responsive liposomes including pH-, redox-, enzyme-, light-, thermo- and magneto-sensitive nanoparticles are discussed and their potential for delivery of anticancer drugs is emphasized. The pH- or redox-sensitive liposomes are based on internal stimulus and release drug in response to a mildly acidic pH and GSH, respectively. The pH-sensitive liposomes can mediate endosomal escape via proton sponge. The multifunctional liposomes responsive to both redox and pH have more capacity in drug release at tumor site compared to pH- or redox-sensitive alone. The magnetic field and NIR irradiation can be exploited for external stimulation of liposomes. The light-responsive liposomes release drugs when they are exposed to irradiation; thermosensitive-liposomes release drugs at a temperature of >40 °C when there is hyperthermia; magneto-responsive liposomes release drugs in presence of magnetic field. These smart nanoliposomes also mediate co-delivery of drugs and genes in synergistic cancer therapy. Due to lack of long-term toxicity of liposomes, they can be utilized in near future for treatment of cancer patients.

Metal complex-based liposomes: Applications and prospects in cancer diagnostics and therapeutics

Metal complexes are of increasing interest as pharmaceutical agents in cancer diagnostics and therapeutics, while some of them suffer from issues such as limited water solubility and severe systemic toxicity. These drawbacks severely hampered their efficacy and clinical applications. Liposomes hold promise as delivery vehicles for constructing metal complex-based liposomes to maximize the therapeutic efficacy and minimize the side effects of metal complexes. This review provides an overview on the latest advances of metal complex-based liposomal delivery systems. First, the development of metal complex-mediated liposomal encapsulation is briefly introduced. Next, applications of metal complex-based liposomes in a variety of fields are overviewed, where drug delivery, cancer imaging (single photon emission computed tomography (SPECT), positron emission tomography (PET), and magnetic resonance imaging (MRI)), and cancer therapy (chemotherapy, phototherapy, and radiotherapy) were involved. Moreover, the potential toxicity, action of toxic mechanisms, immunological effects of metal complexes as well as the advantages of metal complex-liposomes in this content are also discussed. In the end, the future expectations and challenges of metal complex-based liposomes in clinical cancer therapy are tentatively proposed.

Nanococktail Based on Supramolecular Glyco-Assembly for Eradicating Tumors In Vivo

The development of robust phototherapeutic strategies for eradicating tumors remains a significant challenge in the transfer of cancer phototherapy to clinical practice. Here, a phototherapeutic nanococktail atovaquone/17-dimethylaminoethylamino-17-demethoxygeldanamycin/glyco-BODIPY (ADB) was developed to enhance photodynamic therapy (PDT) and photothermal therapy (PTT) via alleviation of hypoxia and thermal resistance that was constructed using supramolecular self-assembly of glyco-BODIPY (BODIPY-SS-LAC, BSL-1), hypoxia reliever atovaquone (ATO), and heat shock protein inhibitor 17-dimethylaminoethylamino-17-demethoxygeldanamycin (17-DMAG). Benefiting from a glyco-targeting and glutathione (GSH) responsive units BSL-1, ADB can be rapidly taken up by hepatoma cells, furthermore the loaded ATO and 17-DMAG can be released in original form into the cytoplasm. Using in vitro and in vivo results, it was confirmed that ADB enhanced the synergetic PDT and PTT upon irradiation using 685 nm near-infrared light (NIR) under a hypoxic tumor microenvironment where ATO can reduce O₂ consumption and 17-DMAG can down-regulate HSP90. Moreover, ADB exhibited good biosafety, and tumor eradication in vivo. Hence, this as-developed phototherapeutic nanococktail overcomes the substantial obstacles encountered by phototherapy in tumor treatment and offers a promising approach for the eradication of tumors.

Advantageous Reactivity of Unstable Metal Complexes: Potential Applications of Metal-Based Anticancer Drugs for Intratumoral Injections

Injections of highly cytotoxic or immunomodulating drugs directly into the inoperable tumor is a procedure that is increasingly applied in the clinic and uses established Pt-based drugs. It is advantageous for less stable anticancer metal complexes that fail administration by the standard intravenous route. Such hydrophobic metal-containing complexes are rapidly taken up into cancer cells and cause cell death, while the release of their relatively non-toxic decomposition products into the blood has low systemic toxicity and, in some cases, may even be beneficial. This concept was recently proposed for V(V) complexes with hydrophobic organic ligands, but it can potentially be applied to other metal complexes, such as Ti(IV), Ga(III) and Ru(III) complexes, some of which were previously unsuccessful in human clinical trials when administered via intravenous injections. The potential beneficial effects include antidiabetic, neuroprotective and tissue-regenerating activities for V(V/IV); antimicrobial activities for Ga(III); and antimetastatic and potentially immunogenic activities for Ru(III). Utilizing organic ligands with limited stability under biological conditions, such as Schiff bases, further enhances the tuning of the reactivities of the metal complexes under the conditions of intratumoral injections. However, nanocarrier formulations are likely to be required for the delivery of unstable metal complexes into the tumor.

Cholesterol Microdomain Enhances the Biofilm Eradication of Antibiotic Liposomes

Resistance and tolerance of biofilms to antibiotics is the greatest challenge in the treatment of bacterial infections. Therefore, developing an effective strategy against biofilms is a top priority. Liposomes are widely used as antibiotic drug carriers; however, common liposomes lack affinity for biofilms. Herein, biofilm-targeted antibiotic liposomes are created by simply adjusting their cholesterol content. The tailored liposomes exhibit significantly enhanced bacterial inhibition and biofilm eradication effects that are positively correlated with the cholesterol content of liposomes. The experiments further demonstrate that this enhanced effect can be ascribed to the effective drug release through the pores, which are formed by the combination of cholesterol microdomains in liposomal lipid bilayers with membrane-damaged toxins in biofilms. Consequently, liposome encapsulation with a high cholesterol concentration improves noticeably the pharmacodynamics and biocompatibility of antibiotics after pulmonary administration. This work may provide a new direction for the development of antibiofilm formulations that can be widely used for the treatment of infections caused by bacterial biofilms.

Two Laser Treatments Can Improve Tumor Ablation Efficiency of Chemophototherapy

Chemophototherapy is an emerging tumor ablation modality that can improve local delivery of chemotherapeutic agents. Long circulating doxorubicin (Dox) in porphyrin-phospholipid (PoP) liposomes (LC-Dox-PoP) has previously been developed as an effective chemophototherapy agent. In the present study, we observed that in mice, LC-Dox-PoP showed enhanced accumulation in human pancreatic tumor xenografts even with suboptimal light doses, as assessed by fluorometric analysis of tissue homogenates and microscopic imaging of Dox and PoP in tumor slices. A second laser treatment, at a time point in which tumors had greater drug accumulation as a result of the first laser treatment, induced potent tumor ablation. Efficacy studies were carried out in two human pancreatic cancer subcutaneous mouse tumor models; MIA PaCa-2 or low-passage patient derived pancreatic cancer xenografts. A single treatment of 3 mg/kg LC-Dox-PoP and an initial 150 J/cm² laser treatment 1 h after drug administration, followed by second laser treatment of 50 J/cm² 8 h after drug administration, was more effective than a single laser treatment of 200 J/cm² at either of those time points. Thus, this study presents proof-of-principle and rationale for using two discrete laser treatments to enhance the efficacy of chemophototherapy.

Nanoscale Coordination Polymers for Combined Chemotherapy and Photodynamic Therapy of Metastatic Cancer

Combination therapy enhances anticancer efficacy through synergistic effects of different drugs/modalities and can potentially address the challenges in the treatment of metastatic diseases. Here we report the design of carb/pyro nanoscale coordination polymer nanoparticles that carry carboplatin (carb) in the core and the photosensitizer pyrolipid (pyro) on the shell for the treatment of metastatic triple negative breast cancer. Upon light irradiation, carb/pyro generated reactive oxygen species to cause severe cell apoptosis and early calreticulin exposure. Upon intravenous injection and local light irradiation, carb/pyro significantly regressed tumor growth in the 4T1 murine metastatic breast cancer model. When combined with an anti-CD47 antibody, carb/pyro with light irradiation completely eradicated primary and metastatic 4T1 tumors in 50% mice. The anticancer efficacy of carb/pyro was also demonstrated in the CT26 murine colorectal cancer model.

Light-Triggered Release of Large Biomacromolecules from Porphyrin-Phospholipid Liposomes

Liposomes containing small amounts of porphyrin-phospholipid (PoP) have been shown to encapsulate small molecular weight cargos and then release them upon exposure to red light. A putative mechanism involves transient pore formation in the bilayer induced by PoP-mediated photo-oxidation of unsaturated lipids. However, little is known about the properties of such pores. This study assesses whether large carbohydrate and protein molecules could be released from PoP liposomes upon red light exposure. A small fluorophore with ∼0.5 kDa in molecular weight, fluorescently labeled dextrans of ∼5 and ∼500 kDa, and a ∼240 kDa fluorescent protein were passively entrapped in PoP liposomes. When exposed to 665 nm irradiation, liposomes containing PoP, but not liposomes lacking it, released all these cargos in a size-dependent manner that occurred with oxidation of unsaturated lipids included in the bilayer. Thus, this study demonstrates the feasibility of light-triggered release of large biomacromolecules from liposomes.

Membrane-destabilizing ionizable lipid empowered imaging-guided siRNA delivery and cancer treatment

One of the imperative medical requirements for cancer treatment is how to establish an imaging-guided nanocarrier that combines therapeutic and imaging agents into one system. siRNA therapeutics have shown promising prospects in controlling life-threatening diseases. However, it is still challenging to develop siRNA formulations with excellent cellular entry capability, efficient endosomal escape, and simultaneous visualization. Herein, we fabricated multifunctional ionizable lipid nanoparticles (iLNPs) for targeted delivery of siRNA and MRI contrast agent. The iLNPs comprises DSPC, cholesterol, PEGylated lipid, contrast agent DTPA-BSA (Gd), and ionizable lipid termed iBL0104. siRNA-loaded iLNPs (iLNPs/siRNA) could be decorated with a tumor targeting cyclic peptide (c(GRGDSPKC)) (termed GARP), or without targeting modification (termed GAP). Data revealed that GARP/siRNA iLNPs exhibited significantly higher cellular entry efficiency than GAP/siRNA iLNPs. GARP/siRNA iLNPs rapidly and effectively escaped from endosome and lysosome after internalization. Compared with GAP/siPLK1, GARP/siPLK1 exhibited better tumor inhibition efficacy in both cell-line derived xenograft and liver cancer patient derived xenograft murine models. In addition, GARP formulation displayed ideal MRI effect in tumor-bearing mice, and was well tolerated by testing animals. Therefore, this study provides an excellent example for achieving imaging-guided and tumor-targeted siRNA delivery and cancer treatment, highlighting its promising potential for translational medicine application.

Liposome technologies towards colorectal cancer therapeutics

Colorectal cancer (CRC) is the third most common cancer and the fourth most common deadly cancer worldwide. After treatment with curative intent recurrence rates vary with staging 0-13% in Stage 1, 11-61% in S2 and 28-73% in Stage 3. The toxicity to healthy tissues from chemotherapy and radiotherapy and drug resistance severely affect the quality of life and cancer specific outcomes of CRC patients. To overcome some of these limitations, many efforts have been made to develop nanomaterial-based drug delivery systems. Among these nanocarriers, liposomes represented one of the most successful candidates in delivering targeted oncological treatment, improving safety profile and therapeutic efficacy of encapsulated drugs. In this review we will discuss liposome design with a particular focus on the targeting feature and triggering functions. We will also summarise the recent advances in liposomal delivery system for CRC treatment in both the preclinical and clinical studies. We will finally provide our perspectives on the liposome technology development for the future clinical translation. STATEMENT OF SIGNIFICANCE: Conventional treatments for colorectal cancer (CRC) severely affect the therapeutic effects for advanced patients. With the development of nanomedicines, liposomal delivery system appears to be one of the most promising nanocarriers for CRC treatment. In last three years several reviews in this area have been published focusing on the preclinical research and drug delivery function, which is a fairly narrow focus in the field of liposome technology for CRC therapy. Our review presented the most recent advances of the liposome technology (both clinical and preclinical applications) for CRC with strong potential for further clinical translation. We believe it will attract lots of attention from various audiences, including researchers, clinicians and the industry.

Visible-to-NIR-Light Activated Release: From Small Molecules to Nanomaterials

Photoactivatable (alternatively, photoremovable, photoreleasable, or photocleavable) protecting groups (PPGs), also known as caged or photocaged compounds, are used to enable non-invasive spatiotemporal photochemical control over the release of species of interest. Recent years have seen the development of PPGs activatable by biologically and chemically benign visible and near-infrared (NIR) light. These long-wavelength-absorbing moieties expand the applicability of this powerful method and its accessibility to non-specialist users. This review comprehensively covers organic and transition metal-containing photoactivatable compounds (complexes) that absorb in the visible- and NIR-range to release various leaving groups and gasotransmitters (carbon monoxide, nitric oxide, and hydrogen sulfide). The text also covers visible- and NIR-light-induced photosensitized release using molecular sensitizers, quantum dots, and upconversion and second-harmonic nanoparticles, as well as release via photodynamic (photooxygenation by singlet oxygen) and photothermal effects. Release from photoactivatable polymers, micelles, vesicles, and photoswitches, along with the related emerging field of photopharmacology, is discussed at the end of the review.

Thinking outside the macrocycle: Potential biomedical roles for nanostructured porphyrins and phthalocyanines — a SPP/JPP Young Investigator Award paper

Porphyrins and phthalocyanines feature strong light absorption, capacity for metal chelation, and a track record of use in human therapeutic applications. Various conjugates and formulations of these macrocycles have shown potential to forge new applications in the biomedical sciences. Our lab has explored several such approaches including porphyrin polymer hydrogels, porphyrin-lipid nanovesicles, and surfactant-stripped micelles. These all feature in common a high density of tetrapyrroles, as well as unique functional properties. Porphyrin polymer hydrogels with high porphyrin density and bright fluorescence emission were demonstrated for use as a new class of implantable biosensors. Porphyrin-lipid nanovesicles hold potential for phototherapy, imaging, and also drug and vaccine delivery. Surfactant-stripped micelles have been developed for high-contrast photoacoustic imaging. In this ICPP Young Investigator Award brief perspective, we discuss our own efforts on these fronts. Taken together, the results show that tetrapyrroles enable new approaches for tackling biomedical problems and also confirm what was already well-known to members of the Society of Porphyrins and Phthalocyanines: that these molecules are remarkably versatile and enable research to flow in unexpected directions.

Labeling of Erythrocytes by Porphyrin-Phospholipid

A method is developed for membrane labeling of erythrocytes with porphyrin-phospholipid (PoP). To generate a concentrated PoP solution for labeling human red blood cells (RBCs), various surfactants and solvents are screened to identify conditions that avoid hemolysis, while minimizing non-specific PoP co-precipitation with RBCs in the pellet during centrifugation washes. Cholate, Tween 80 and Tween 40 are identified as useful surfactants for this purpose. When labeled RBCs are mixed with unlabeled ones, substantial non-specific PoP exchange is observed. Egg-yolk lecithin is included in a washing buffer to remove loosely bound PoP and reduce PoP exchange with unlabeled erythrocytes, based on flow cytometry and photodynamic hemolysis assays. Murine RBCs that are labeled with ⁶⁴Cu-chelated PoP displayed altered biodistribution with longer blood circulation relative to directly administered ⁶⁴Cu-chelated PoP.

Nanobowl-Supported Liposomes Improve Drug Loading and Delivery

Liposomal drug delivery for cancer therapy can be limited due to drug leakage in circulation. Here, we develop a new method to enhance the stability of actively loaded liposomal doxorubicin (DOX) through embedding a stiff nanobowl in the liposomal water cavity. Nanobowl-supported liposomal DOX (DOX@NbLipo) resists the influence of plasma protein and blood flow shear force to prevent drug leakage. This approach yields improved drug delivery to tumor sites and enhanced antitumor efficacy. Compared to alternative methods of modifying liposome surface and composition for stability, this approach designs a physical support for an all-aqueous nanoliposomal cavity. Nanobowl stabilization of liposomes is a simple and effective method to improve carrier stability and drug delivery.

Octahedral Molybdenum Cluster Complexes with Optimized Properties for Photodynamic Applications

Two new octahedral molybdenum cluster complexes act as an efficient singlet oxygen supplier in the context of the photodynamic therapy of cancer cells under blue-light irradiation. These complexes integrate the {Mo₆I₈}⁴⁺ core with 4'-carboxybenzo-15-crown-5 or cholate apical ligands and were characterized by ¹H NMR, HR ESI-MS, and CHN elemental analysis. Both complexes display high quantum yields of luminescence and singlet oxygen formation in aqueous media associated with a suitable stability against hydrolysis. They are internalized into lysosomes of HeLa cells with no dark toxicity at pharmacologically relevant concentrations and have a strong phototoxic effect under blue-light irradiation, even in the presence of fetal bovine serum. The last feature is essential for further translation to in vivo experiments. Overall, these complexes are attractive molecular photosensitizers toward photodynamic applications.

Tetramodal Imaging and Synergistic Cancer Radio-Chemotherapy Enabled by Multiple Component-Encapsulated Zeolitic Imidazolate Frameworks

The abundant species of functional nanomaterials have attracted tremendous interests as components to construct multifunctional composites for cancer theranostics. However, their distinct chemical properties substantially require a specific strategy to integrate them in harmony. Here, we report the preparation of a distinctive multifunctional composite by encapsulating small-sized semiconducting copper bismuth sulfide (CBS) nanoparticles and rare-earth down-conversion (DC) nanoparticles in larger-sized zeolitic imidazolate framework-8 (ZIF8) nanoparticles, followed by loading an anticancer drug, doxorubicin (DOX). Such composites can be used for tetramodal imaging, including traditional computed tomography and magnetic resonance imaging and, recently, for photoacoustic imaging and fluorescence imaging. With a pH-responsive release of the encapsulated components, synergistic radio-chemotherapy with a high (87.6%) tumor inhibition efficiency is achieved at moderate doses of the CBS&DC-ZIF8@DOX composite with X-ray irradiation. This promising strategy highlights the extending capacity of zeolitic imidazolate frameworks to encapsulate multiple distinct components for enhanced cancer imaging and therapy.

Soy Lecithin-Derived Liposomal Delivery Systems: Surface Modification and Current Applications

The development of natural phospholipids for nanostructured drug delivery systems has attracted much attention in the past decades. Lecithin that was derived from naturally occurring in soybeans (SL) has introduced some auspicious accomplishments to the drug carrying aspect, like effectual encapsulation, controlled release, and successful delivery of the curative factors to intracellular regions in which they procure these properties from their flexible physicochemical and biophysical properties, such as large aqueous center and biocompatible lipid, self-assembly, tunable properties, and high loading capacity. Despite the almost perfect properties as a drug carrier, liposome is known to be quite quickly eliminated from the body systems. The surface modification of liposomes has been investigated in many studies to overcome this drawback. In this review, we intensively discussed the surface-modified liposomes that enhancing the targeting, cellular uptake, and therapeutic response. Moreover, the recent applications of soy lecithin-derived liposome, focusing on cancer treatment, brain targeting, and vaccinology, are also summarized.

Indocyanine green binds to DOTAP liposomes for enhanced optical properties and tumor photoablation

Indocyanine green (ICG) is a clinically-approved near infrared (NIR) dye used for optical imaging. The dye is only slightly soluble in water and is prone to aggregation in saline solutions, so that alternative formulations can improve photophysical performance. Numerous nanoscale formulations of ICG have been described in the literature, but we sought to develop an approach that does not require additional purification steps. Pre-formed liposomes incorporating 45 mol% of the cationic lipid 1,2-dioleoyl-3-trimethylammonium-propane (DOTAP) rapidly bind ICG, resulting in enhanced NIR optical properties. ICG binding is dependent on the amount of DOTAP incorporated in the liposomes. A dye-to-lipid mass ratio of [0.5 : 25] is sufficient for full complexation, without additional purification steps following mixing. NIR absorption, fluorescence intensity, and photoacoustic signals are increased for the liposome-bound dye. Not only is the optical character enhanced by simple mixing of ICG with liposomes, but retention in 4T1 mammary tumors is observed following intratumor injection, as assessed by fluorescence and photoacoustic imaging. Subsequent photothermal therapy with 808 nm laser irradiation is effective and results in tumor ablation without regrowth for at least 30 days. Thus, ICG optical properties and photothermal ablation outcomes can be improved by mixing the dye with pre-formed DOTAP liposomes in conditions that result in full dye-binding to the liposomes.

Pharmacokinetics and pharmacodynamics of liposomal chemophototherapy with short drug-light intervals

Chemophototherapy (CPT) merges photodynamic therapy with chemotherapy and can substantially enhance drug delivery. Using a singular liposomal formulation for CPT, we describe a semi-mechanistic pharmacokinetic-pharmacodynamic (PK/PD) model to investigate observed antitumor effects. Long-circulating, sterically-stabilized liposomes loaded with doxorubicin (Dox) stably incorporate small amounts of a porphyrin-phospholipid (PoP) photosensitizer in the bilayer. These were administered intravenously to mice bearing low-passage, patient-derived pancreatic cancer xenografts (PDX). Dox PK was described with a two-compartment model and tumor drug disposition kinetics were modeled with first-order influx and efflux rates. Tumor irradiation with 665 nm laser light (200 J/cm2) 1 h after liposome administration increased tumor vascular permeabilization and drug accumulation, which was accounted for in the PK/PD model with increased tumor influx and efflux rates by approximately 12- and 4- fold, respectively. This modeling approach provided an overall 7-fold increase in Dox area under the curve in the tumor, matching experimental data (7.4-fold). A signal transduction model based on nonlinear direct cell killing accounted for observed tumor growth patterns. This PK/PD model adequately describes the CPT anti-PDX tumor response based on enhanced drug delivery at the short drug-light interval used.

Current Trends in Cancer Nanotheranostics: Metallic, Polymeric, and Lipid-Based Systems

Theranostics has emerged in recent years to provide an efficient and safer alternative in cancer management. This review presents an updated description of nanotheranostic formulations under development for skin cancer (including melanoma), head and neck, thyroid, breast, gynecologic, prostate, and colon cancers, brain-related cancer, and hepatocellular carcinoma. With this focus, we appraised the clinical advantages and drawbacks of metallic, polymeric, and lipid-based nanosystems, such as low invasiveness, low toxicity to the surrounding healthy tissues, high precision, deeper tissue penetration, and dosage adjustment in a real-time setting. Particularly recognizing the increased complexity and multimodality in this area, multifunctional hybrid nanoparticles, comprising different nanomaterials and functionalized with targeting moieties and/or anticancer drugs, present the best characteristics for theranostics. Several examples, focusing on their design, composition, imaging and treatment modalities, and in vitro and in vivo characterization, are detailed herein. Briefly, all studies followed a common trend in the design of these theranostics modalities, such as the use of materials and/or drugs that share both inherent imaging (e.g., contrast agents) and therapeutic properties (e.g., heating or production reactive oxygen species). This rationale allows one to apparently overcome the heterogeneity, complexity, and harsh conditions of tumor microenvironments, leading to the development of successful targeted therapies.

Highly-Soluble Cyanine J-aggregates Entrapped by Liposomes for In Vivo Optical Imaging around 930 nm

Near infrared (NIR) dyes are useful for in vivo optical imaging. Liposomes have been used extensively for delivery of diverse cargos, including hydrophilic cargos which are passively loaded in the aqueous core. However, most currently available NIR dyes are only slightly soluble in water, making passive entrapment in liposomes challenging for achieving high optical contrast.

Methods: We modified a commercially-available NIR dye (IR-820) via one-step Suzuki coupling with dicarboxyphenylboronic acid, generating a disulfonated heptamethine; dicarboxyphenyl cyanine (DCP-Cy). DCP-Cy was loaded in liposomes and used for optical imaging.

Results: Owing to increased charge in mildly basic aqueous solution, DCP-Cy had substantially higher water solubility than indocyanine green (by an order of magnitude), resulting in higher NIR absorption. Unexpectedly, DCP-Cy tended to form J-aggregates with pronounced spectral red-shifting to 934 nm (from 789 nm in monomeric form). J-aggregate formation was dependent on salt and DCP-Cy concentration. Dissolved at 20 mg/mL, DCP-Cy J-aggregates could be entrapped in liposomes. Full width at half maximum absorption of the liposome-entrapped dye was just 25 nm. The entrapped DCP-Cy was readily detectable by fluorescence and photoacoustic NIR imaging. Upon intravenous administration to mice, liposomal DCP-Cy circulated substantially longer than the free dye. Accumulation was largely in the spleen, which was visualized with fluorescence and photoacoustic imaging.

Conclusions: DCP-Cy is simple to synthesize and exhibits high aqueous solubility and red-shifted absorption from J-aggregate formation. Liposomal dye entrapment is possible, which facilitates in vivo photoacoustic and fluorescence imaging around 930 nm.

Photo-triggerable liposomal drug delivery systems: from simple porphyrin insertion in the lipid bilayer towards supramolecular assemblies of lipid–porphyrin conjugates

Light-responsive liposomes are considered nowadays as one of the most promising nanoparticulate systems for the delivery and release of an active pharmaceutical ingredient (API) in a spatio-temporal manner.

Binding of an amphiphilic phthalocyanine to pre-formed liposomes confers light-triggered cargo release

Liposomes are able to load a range of cargos and have been used for drug delivery applications, including for stimuli-triggered drug release. Here, we describe an approach for imparting near infrared (NIR) light-triggered release to pre-formed liposomes, using a newly-synthesized cationic, amphiphilic phthalocyanine. When simply mixed in aqueous solution with cargo-loaded liposomes, the cationic amphiphilic phthalocyanine, but not a cationic hydrophilic azaphthalocyanine, spontaneously incorporates into the liposome bilayer. This enables subsequent release of loaded cargo (doxorubcin or basic orange) upon irradiation with NIR light. The rate of release could be altered by varying the amount of photosensitizer added to the liposomes. In the absence of NIR light exposure, stable cargo loading of the liposomes was maintained. Introduction.

Loading and Releasing Ciprofloxacin in Photoactivatable Liposomes

We demonstrate that ciprofloxacin can be actively loaded into liposomes that contain small amounts of porphyrin-phospholipid (PoP). PoP renders the liposomes photoactivatable, so that the antibiotic is released from the carrier under red light irradiation (665 nm). The use of 2 molar % PoP in the liposomes accommodated active loading of ciprofloxacin. Further inclusion of 2 molar % of an unsaturated phospholipid accelerated light-triggered drug release, with more than 90 % antibiotic release from the liposomes occurring in less than 30 seconds. With or without laser treatment, ciprofloxacin PoP liposomes inhibited the growth of Bacillus subtilis in liquid media, apparently due to uptake of the liposomes by the bacteria. However, when liposomes were first separated from smaller molecules with centrifugal filtration, only the filtrate from laser-treated liposomes was bactericidal, confirming effective release of active antibiotic. These results establish the feasibility of remote loading antibiotics into photoactivatable liposomes, which could lead to opportunities for enhanced localized antibiotic therapy.

Liposomes Loaded with Cisplatin and Magnetic Nanoparticles: Physicochemical Characterization, Pharmacokinetics, and In-Vitro Efficacy

With the aim improving drug delivery, liposomes have been employed as carriers for chemotherapeutics achieving promising results; their co-encapsulation with magnetic nanoparticles is evaluated in this work. The objective of this study was to examine the physicochemical characteristics, the pharmacokinetic behaviour, and the efficacy of pegylated liposomes loaded with cisplatin and magnetic nanoparticles (magnetite) (Cis-MLs). Cis-MLs were prepared by a modified reverse-phase evaporation method. To characterize their physicochemical properties, an evaluation was made of particle size, ζ-potential, phospholipid and cholesterol concentration, phase transition temperature (T_m), the encapsulation efficiency of cisplatin and magnetite, and drug release profiles. Additionally, pharmacokinetic studies were conducted on normal Wistar rats, while apoptosis and the cytotoxic effect were assessed with HeLa cells. We present a method for simultaneously encapsulating cisplatin at the core and also embedding magnetite nanoparticles on the membrane of liposomes with a mean vesicular size of 104.4 ± 11.5 nm and a ζ-potential of −40.5 ± 0.8 mV, affording a stable formulation with a safe pharmacokinetic profile. These liposomes elicited a significant effect on cell viability and triggered apoptosis in HeLa cells.

Organic Dye Based Nanoparticles for Cancer Phototheranostics

Phototheranostics, which simultaneously combines photodynamic and/or photothermal therapy with deep-tissue diagnostic imaging, is a promising strategy for the diagnosis and treatment of cancers. Organic dyes with the merits of strong near-infrared absorbance, high photo-to-radical and/or photothermal conversion efficiency, great biocompatibility, ready chemical structure fine-tuning capability, and easy metabolism, have been demonstrated as attractive candidates for clinical phototheranostics. These organic dyes can be further designed and fabricated into nanoparticles (NPs) using various strategies. Compared to free molecules, these NPs can be equipped with multiple synergistic functions and show longer lifetime in blood circulation and passive tumor-targeting property via the enhanced permeability and retention effect. In this article, the recent progress of organic dye-based NPs for cancer phototheranostic applications is summarized, which extends the anticancer arsenal and holds promise for clinical uses in the near future.

Short Drug-Light Intervals Improve Liposomal Chemophototherapy in Mice Bearing MIA PaCa-2 Xenografts

Chemophototherapy (CPT) is an emerging tumor treatment that combines phototherapy and chemotherapy. Long-circulating (LC) liposomes can stably incorporate 2 mol % porphyrin-phospholipid (PoP) in the bilayer and load doxorubicin (Dox) to generate LC-Dox-PoP liposomes, for single-agent CPT. Following intravenous administration to mice, LC-Dox-PoP liposomes (2 mg/kg Dox) circulated with similar blood concentration ranges produced by a typical human clinical dose of DOXIL (50 mg/m² Dox). This dosing approach aims to achieve physiologically relevant Dox and PoP concentrations as well as CPT vascular responses in mice bearing subcutaneous human pancreatic MIA PaCa-2 xenografts. Phototreatment with 2 mg/kg LC-Dox-PoP induced vascular permeabilization, leading to a 12.5-fold increase in Dox tumor influx estimated by a pharmacokinetic model, based on experimental data. Shorter drug-light intervals (0.5-3 h) led to greater tumoral drug deposition and improved treatment outcomes, compared to longer drug-light intervals. At 2 mg/kg Dox, CPT with LC-Dox-PoP liposomes induced tumor regression and growth inhibition, whereas chemotherapy using several other formulations of Dox did not. LC-Dox-PoP liposomes were well tolerated at the 2 mg/kg dose.

Multicolor Liposome Mixtures for Selective and Selectable Cargo Release

Many approaches exist for stimuli-triggered cargo release from nanocarriers, but few can provide for on-demand release of multiple payloads, selectively. Here, we report the synthesis of purpurin-phospholipid (Pur-P), a lipid chromophore that has near-infrared absorbance red-shifted by 30 nm compared to a structurally similar pyropheophorbide-phospholipid (Pyr-P). Liposomes containing small amounts of either Pur-P or Pyr-P exhibited similar physical properties and fluorescence self-quenching. Loaded with distinct cargos, Pur-P and Pyr-P liposomes were mixed into a single colloidal suspension and selectively released cargo depending on irradiation wavelength. Spatiotemporal control of distinct cargo release was achieved by controlling multicolor laser placement. Using basic orange and doxorubicin anthraquinones, multidimensional cytotoxicity gradients were established to gauge efficacy against cancer cells using light-released drug. Wavelength selectivity of cargo release was maintained following intramuscular administration to mice.

Bioinspired Multifunctional Melanin-Based Nanoliposome for Photoacoustic/Magnetic Resonance Imaging-Guided Efficient Photothermal Ablation of Cancer

Background: The construction of theranostic nanosystems with concurrently high biosafety and therapeutic performance is a challenge but has great significance for the clinical translation of nanomedicine for combating cancer. Methods: Bio-inspired melanin-based nanoliposomes (Lip-Mel) as theranostic agents were constructed for simultaneous photoacoustic (PA) imaging- and T1-weighted magnetic resonance (MR) imaging-guided photothermal ablation of tumors, which was demonstrated both in vitro and in vivo. The high biosafety of Lip-Mel was also systematically evaluated. Results: The achieved Lip-Mel nanoliposomes demonstrated their imaging capability for both PA and T1-weighted MR imaging (r1 = 0.25 mM-1·s-1) both in vitro and in vivo, providing the potential for therapeutic guidance and monitoring. Importantly, the desirable photothermal-conversion efficiency of the as-prepared Lip-Mel achieved complete eradication of tumors in breast cancer-bearing mice, exhibiting remarkable photothermal-based therapeutic performance. In particular, the efficient encapsulation of melanin into the PEGylated liposome mitigated the potential toxicity of melanin and improved the photothermal performance of the loaded melanin. Systematic in vivo biosafety evaluations demonstrated the high biocompatibility of Lip-Mel at a high dose of 100 mg/kg. Conclusion: In this work, we reported a bioinspired strategy where melanin, a natural product in the human body, is encapsulated into PEGylated nanoliposomes for efficient theranostics with high biocompatibility. This work provides a new strategy for creating desirable theranostic agents with concurrent high biocompatibility and satisfactory theranostic performance through the use of materials that totally originate from biosystems.

Effective light-triggered contents release from helper lipid-incorporated liposomes co-encapsulating gemcitabine and a water-soluble photosensitizer

Triggered drug release is a promising strategy for delivering anticancer drugs to cancer cells and tissues. We found that liposomes co-encapsulating calcein (a water-soluble model drug and fluorescence marker) and talaporfin sodium (TPS, a water-soluble photosensitizer) released the drug upon irradiation with a near-infrared (NIR)-laser. The liposomes were composed of phospholipid (DSPC)/helper lipid (DOPE)/cholesterol/PEG-lipid (PEG₂₀₀₀-DSPE) at a molar ratio of 85/10/5/5 and released a large amount of drug (70%<, within 10 min) upon irradiation, but no drug in the absence of NIR-laser irradiation and/or TPS. NIR-laser-triggered drug release was facilitated by the incorporation of DOPE into the liposomes, and the amount of DOPE incorporated affected drug leakage in the absence of NIR-laser-irradiation at 37 °C (body temperature). Drug leakage was tuned by incorporating cholesterol into the liposomes. NIR-laser-triggered drug release from the liposomes was confirmed using the anticancer drug gemcitabine. NIR-laser treatment of liposomes co-encapsulating gemcitabine and TPS provided the maximum cytotoxic effect towards EMT6/P cells. These results suggest that these novel light sensitive liposomes may be useful for drug delivery to cancer cells.

Intrabilayer 64Cu Labeling of Photoactivatable, Doxorubicin-Loaded Stealth Liposomes

Doxorubicin (Dox)-loaded stealth liposomes (similar to those in clinical use) can incorporate small amounts of porphyrin-phospholipid (PoP) to enable chemophototherapy (CPT). PoP is also an intrinsic and intrabilayer ⁶⁴Cu chelator, although how radiolabeling impacts drug delivery has not yet been assessed. Here, we show that ⁶⁴Cu can radiolabel the stable bilayer of preformed Dox-loaded PoP liposomes with inclusion of 1% ethanol without inducing drug leakage. Dox-PoP liposomes labeled with intrabilayer copper behaved nearly identically to unlabeled ones in vitro and in vivo with respect to physical parameters, pharmacokinetics, and CPT efficacy. Positron emission tomography and near-infrared fluorescence imaging visualized orthotopic mammary tumors in mice with passive liposome accumulation following administration. A single CPT treatment with 665 nm light (200 J/cm²) strongly inhibited primary tumor growth. Liposomes accumulated in lung metastases, based on NIR imaging. These results establish the feasibility of CPT interventions guided by intrinsic multimodal imaging of Dox-loaded stealth PoP liposomes.

Amphiphilic semiconducting polymer as multifunctional nanocarrier for fluorescence/photoacoustic imaging guided chemo-photothermal therapy

Chemo-photothermal nanotheranostics has the advantage of synergistic therapeutic effect, providing opportunities for optimized cancer therapy. However, current chemo-photothermal nanotheranostic systems generally comprise more than three components, encountering the potential issues of unstable nanostructures and unexpected conflicts in optical and biophysical properties among different components. We herein synthesize an amphiphilic semiconducting polymer (PEG-PCB) and utilize it as a multifunctional nanocarrier to simplify chemo-photothermal nanotheranostics. PEG-PCB has a semiconducting backbone that not only serves as the diagnostic component for near-infrared (NIR) fluorescence and photoacoustic (PA) imaging, but also acts as the therapeutic agent for photothermal therapy. In addition, the hydrophobic backbone of PEG-PCB provides strong hydrophobic and π-π interactions with the aromatic anticancer drug such as doxorubicin for drug encapsulation and delivery. Such a trifunctionality of PEG-PCB eventually results in a greatly simplified nanotheranostic system with only two components but multimodal imaging and therapeutic capacities, permitting effective NIR fluorescence/PA imaging guided chemo-photothermal therapy of cancer in living mice. Our study thus provides a molecular engineering approach to integrate essential properties into one polymer for multimodal nanotheranostics.