Solubilization of poorly soluble PDT agent, meso-tetraphenylporphin, in plain or immunotargeted PEG-PE micelles results in dramatically improved cancer cell killing in vitro

Photodynamic therapy using OR141-loaded nanovesicles for eradication of leukemic cells from ovarian tissue

In 2020, the estimated number of new leukemia cases was higher than 30,000 in girls between 0 and 19 years old. Due to cancer treatment, some of these patients may lose both endocrine and reproductive functions. Transplantation of cryopreserved ovarian tissue is not advised after cancer remission because it has a high risk of reintroducing malignant cells in the patient, potentially leading to leukemia recurrence. To safely transplant the ovarian tissue from these patients and restore their fertility, our goal was to develop a photodynamic therapy (PDT) strategy to eliminate leukemia ex vivo. To this end, we designed, optimized, and characterized OR141-loaded niosomes (ORN) to develop the most effective formulation for ex vivo purging ovarian fragments from chronic myelogenous leukemia cells. After establishing the best ORN formulation, the PDT efficiency of optimized ORN was determined for human ovarian stromal cells and acute myeloid leukemia cell line (HL60). Blank niosomes treatment on ovarian stromal cells causes no significant toxicity, showing that the composition of the nanoparticle is not toxic. On the other hand, the in vitro studies showed that while ovarian stromal cells were still viable (82.04 ± 2.79%) after the treatment by 0.5 µM ORN, the same treatment yielded 95.43 ± 3.89% toxicity and cell death in the cancer cells. In conclusion, our results showed that our novel PDT procedure could be a promising strategy to destroy leukemia cells in ovarian tissue fragments allowing safe transplantation in cancer survivors.

Nanoemulsion applications in photodynamic therapy

Nanoemulsion, or nanoscaled-size emulsions, is a thermodynamically stable system formed by blending two immiscible liquids, blended with an emulsifying agent to produce a single phase. Nanoemulsion science has advanced rapidly in recent years, and it has opened up new opportunities in a variety of fields, including pharmaceuticals, biotechnology, food, and cosmetics. Nanoemulsion has been recognized as a potential drug delivery technology for various drugs, such as photosensitizing agents (PS). In photodynamic therapy (PDT), PSs produce cytotoxic reactive oxygen species under specific light irradiation, which oxidize the surrounding tissues. Over the past decades, the idea of PS-loaded nanoemulsions has received researchers' attention due to their ability to overcome several limitations of common PSs, such as limited permeability, non-specific phototoxicity, hydrophobicity, low bioavailability, and self-aggregation tendency. This review aims to provide fundamental knowledge of nanoemulsion formulations and the principles of PDT. It also discusses nanoemulsion-based PDT strategies and examines nanoemulsion advantages for PDT, highlighting future possibilities for nanoemulsion use.

Secure transplantation by tissue purging using photodynamic therapy to eradicate malignant cells

The field of photodynamic therapy (PDT) for treating various malignant neoplasms has been given researchers' attention due to its ability to be a selective and minimally invasive cancer therapy strategy. The possibility of tumor cell infection and hence high recurrence rates in cancer patients tends to restrict autologous transplantation. So, the photodynamic tissue purging process, which consists of selective photoinactivation of the malignant cells in the graft, is defined as a compromising strategy to purify contaminated tissues before transplantation. In this strategy, the direct malignant cells' death results from the reactive oxygen species (ROS) generation through the activation of a photosensitizer (PS) by light exposure in the presence of oxygen. Since new PS generations can effectively penetrate the tissue, PDT could be an ideal ex vivo tissue purging protocol that eradicates cancer cells derived from various malignancies. The challenge is that the applied pharmacologic ex vivo tissue purging should efficiently induce tumor cells with minor influence on normal tissue cells. This review aims to provide an overview of the current status of the most effective PDT strategies and PS development concerning their potential application in ex vivo purging before hematopoietic stem cell or ovarian tissue transplantation.

Photodynamic cancer therapy using liposomes as an advanced vesicular photosensitizer delivery system

The multidisciplinary field of photodynamic therapy (PDT) is a combination of photochemistry and photophysics sciences, which has shown tremendous potential for cancer therapy application. PDT employs a photosensitizing agent (PS) and light to form cytotoxic reactive oxygen species and subsequently oxidize light-exposed tissue. Despite numerous advantages of PDT and enormous progress in this field, common PSs are still far from ideal treatment because of their poor permeability, non-specific phototoxicity, side effects, hydrophobicity, weak bioavailability, and tendency to self-aggregation. To circumvent these limitations, PS can be encapsulated in liposomes, an advanced drug delivery system that has demonstrated the ability to enhance drug permeability into biological membranes and loading both hydrophobic and lipophilic agents. Moreover, liposomes can also be coated by targeting agents to improve delivery efficiency. The present review aims to summarize the principles of PDT, various PS generations, PS-loaded nanoparticles, liposomes, and their impact on PDT, then discuss recent photodynamic cancer therapy strategies using liposomes as PS-loaded vectors, and highlight future possibilities and perspectives.

Rational design of block copolymer self-assemblies in photodynamic therapy

Photodynamic therapy is a technique already used in ophthalmology or oncology. It is based on the local production of reactive oxygen species through an energy transfer from an excited photosensitizer to oxygen present in the biological tissue. This review first presents an update, mainly covering the last five years, regarding the block copolymers used as nanovectors for the delivery of the photosensitizer. In particular, we describe the chemical nature and structure of the block copolymers showing a very large range of existing systems, spanning from natural polymers such as proteins or polysaccharides to synthetic ones such as polyesters or polyacrylates. A second part focuses on important parameters for their design and the improvement of their efficiency. Finally, particular attention has been paid to the question of nanocarrier internalization and interaction with membranes (both biomimetic and cellular), and the importance of intracellular targeting has been addressed.

Micelles Loaded With Puerarin And Modified With Triphenylphosphonium Cation Possess Mitochondrial Targeting And Demonstrate Enhanced Protective Effect Against Isoprenaline-Induced H9c2 Cells Apoptosis

Background

The protective role of puerarin (PUE) against myocardial infarction is closely related to its regulation on mitochondria. However, free PUE can hardly reach the mitochondria of ischemic cardiomyocytes due to the lack of mitochondrial targeting of PUE. Here PUE was loaded into mitochondria-targeted micelles (PUE@TPP/PEG-PE) for precisely delivering PUE into mitochondria with the aim of enhancing the anti-apoptosis effect.

Methods

The mitochondriotropic polymer TPP-PEG-PE was synthesized for the preparation of PUE@TPP/PEG-PE micelles modified with triphenylphosphonium (TPP) cation. The physicochemical properties and anti-apoptosis effect of PUE@TPP/PEG-PE micelles were investigated. The coumarin 6 (C6)-labeled TPP/PEG-PE (C6@TPP/PEG-PE) micelles were used to observe the enhanced cellular uptake, mitochondrial targeting and lysosomes escape. Moreover, in vivo and ex vivo biodistribution of lipophilic near-infrared dye 1,1ʹ-dioctadecyl-3,3,3′,3ʹ-tetramethylindotricarbocyanine iodide (DiR)-labeled PUE@TPP/PEG-PE (DiR@TPP/PEG-PE) micelles were detected through fluorescence imaging.

Results

The successful synthesis of TPP-PEG-PE conjugate was confirmed. PUE@TPP/PEG-PE micelles had a particle size of 17.1 nm, a zeta potential of −6.2 mV, and a sustained-release behavior. The in vitro results showed that the intracellular uptake of C6@TPP/PEG-PE micelles was significantly enhanced in H9c2 cells. C6@TPP/PEG-PE micelles could deliver C6 to mitochondria and reduce the capture of lysosomes. In addition, compared with the PUE@PEG-PE micelles and free PUE, the PUE@TPP/PEG-PE micelles exerted an enhanced protective effect against isoprenaline-induced H9c2 cell apoptosis, as evident by the decreased percentage of apoptotic cells, Caspase-3 activity, ROS level, Bax expression, and increased Bcl-2 expression. The in vivo detecting results of the targeting effect using DiR probe also indicated that TPP/PEG-PE micelles could accumulate and retain in the ischemic myocardium.

Conclusion

The results of this study demonstrate the promising potential of applying PUE@TPP/PEG-PE micelles in mitochondria-targeted drug delivery to achieve maximum therapeutic effects of PUE.

Receptor-mediated Uptake of Folic Acid-functionalized Dextran Nanoparticles for Applications in Photodynamic Therapy

In photodynamic therapy (PDT), photosensitizers and light are used to cause photochemically induced cell death. The selectivity and the effectiveness of the phototoxicity in cancer can be increased by a specific uptake of the photosensitizer into tumor cells. A promising target for this goal is the folic acid receptor α (FRα), which is overexpressed on the surface of many tumor cells and mediates an endocytotic uptake. Here, we describe a polysaccharide-based nanoparticle system suitable for targeted uptake and its photochemical and photobiological characterization. The photosensitizer 5, 10, 15, 20-tetraphenyl-21H, 23H-porphyrine (TPP) was encapsulated in spermine- and acetal-modified dextran (SpAcDex) nanoparticles and conjugated with folic acid (FA) on the surface [SpAcDex(TPP)-FA]. The particles are successfully taken up by human HeLa-KB cells, and a light-induced cytotoxicity is observable. An excess of free folate as the competitor for the FRα-mediated uptake inhibits the phototoxicity. In conclusion, folate-modified SpAcDex particles are a promising drug delivery system for a tumor cell targeted photodynamic therapy.

Nanoparticle-Mediated Combination Therapy: Two-in-One Approach for Cancer

Cancer represents a group of heterogeneous diseases characterized by uncontrolledgrowth and spread of abnormal cells, ultimately leading to death. Nanomedicine plays a significantrole in the development of nanodrugs, nanodevices, drug delivery systems and nanocarriers. Someof the major issues in the treatment of cancer are multidrug resistance (MDR), narrow therapeuticwindow and undesired side effects of available anticancer drugs and the limitations of anticancerdrugs. Several nanosystems being utilized for detection, diagnosis and treatment such as theranosticcarriers, liposomes, carbon nanotubes, quantum dots, polymeric micelles, dendrimers and metallicnanoparticles. However, nonbiodegradable nanoparticles causes high tissue accumulation andleads to toxicity. MDR is considered a major impediment to cancer treatment due to metastatictumors that develop resistance to chemotherapy. MDR contributes to the failure of chemotherapiesin various cancers, including breast, ovarian, lung, gastrointestinal and hematological malignancies.Moreover, the therapeutic efficiency of anticancer drugs or nanoparticles (NPs) used alone is lessthan that of the combination of NPs and anticancer drugs. Combination therapy has long beenadopted as the standard first-line treatment of several malignancies to improve the clinical outcome.Combination therapy with anticancer drugs has been shown to generally induce synergistic drugactions and deter the onset of drug resistance. Therefore, this review is designed to report andanalyze the recent progress made to address combination therapy using NPs and anticancer drugs.We first provide a comprehensive overview of the angiogenesis and of the different types of NPscurrently used in treatments of cancer; those emphasized in this review are liposomes, polymericNPs, polymeric micelles (PMs), dendrimers, carbon NPs, nanodiamond (ND), fullerenes, carbonnanotubes (CNTs), graphene oxide (GO), GO nanocomposites and metallic NPs used forcombination therapy with various anticancer agents. Nanotechnology has provided the convenienttools for combination therapy. However, for clinical translation, we need continued improvementsin the field of nanotechnology.

Puerarin-loaded PEG-PE micelles with enhanced anti-apoptotic effect and better pharmacokinetic profile

Puerarin (PUE) is the most abundant isoflavonoid in kudzu root. It is widely used as a therapeutic agent for the treatment of cardiovascular diseases. However, the short elimination half-life, poor-bioavailability, and acute intravascular hemolysis of PUE are the main obstacles to its widespread clinical applications. Whereas PEG-PE micelles possess the ability to release medicine slowly, enhance the cellular uptake of drugs and improve their biocompatibility. Therefore, it was aim to fabricate puerarin-loaded PEG-PE (PUE@PEG-PE) micelles to improve the pharmaceutical properties of drugs. It can be observed from the TEM images that PUE@PEG-PE micelles appeared obvious core-shell structure and remained well-dispersed without aggregation and adhesion. PUE was successfully embedded in the core of PEG-PE micelles, which was confirmed by FT-IR and ¹H NMR spectra. In vitro studies showed that PUE@PEG-PE micelles exhibited a sustained release behavior in pH 7.4 PBS buffer and decreased hemolysis rate of PUE. Compared with PUE, PUE@PEG-PE micelles showed a 3.2-fold increase in the half-life of PUE and a 1.58-fold increase in bioavailability. In addition, the PUE@PEG-PE micelles exerted enhanced protective effect against isoprenaline-induced H9c2 cells apoptosis compared with PUE, as evident by decreased percentage of Hoechst-positive cells, Caspase 3 activity, Bax expression, and increased Bcl-2 expression. Notably, the PEG-PE micelles exhibited favorable cellular uptake efficiency on H9c2 cells, and this may account for their enhanced anti-apoptotic effect of the incorporated drug. Altogether, the PUE@PEG-PE micelles were not only able to control the drug release but also offered promise to enhance the pharmacokinetic and pharmacodynamic potential of PUE.

Optimization of Photosensitized Tryptophan Oxidation in the Presence of Dimegin-Polyvinylpyrrolidone-Chitosan Systems

By the example of a model process of tryptophan photooxidation in the aqueous medium in the presence of a three-component photosensitizing complex (porphyrin photosensitizer-polyvinylpyrrolidone- chitosan, PPS-PVP-CT) in the temperature range of 20-40 °С, we have demonstrated a possibility of modification of such a process by selecting different molar ratios of the components in the reaction mixture. The actual objective of this selection is the formation of a certain PPS-PVP-CT composition in which PVP macromolecules would coordinate with PPS molecules and at the same time practically block the complex binding of PPS molecules with chitosan macromolecules. Such blocking allows utilization of the bactericidal properties of chitosan to a greater extent, since chitosan is known to depress the PPS photosensitizing activity in PPS-PVP-CT complexes when using those in photodynamic therapy (PDT). The optimal composition of photosensitizing complexes appears to be dependent on the temperature at which the PDT sessions are performed. We have analyzed the correlations of the effective rate constants of tryptophan photooxidation with the photophysical characteristics of the formed complexes.

Polymeric Micelles of Biodegradable Diblock Copolymers: Enhanced Encapsulation of Hydrophobic Drugs

Polymeric micelles are potentially efficient in encapsulating and performing the controlled release of various hydrophobic drug molecules. Understanding the fundamental physicochemical properties behind drug⁻polymer systems in terms of interaction strength and compatibility, drug partition coefficient (preferential solubilization), micelle size, morphology, etc., encourages the formulation of polymeric nanocarriers with enhanced drug encapsulating capacity, prolonged circulation time, and stability in the human body. In this review, we systematically address some open issues which are considered to be obstacles inhibiting the commercial availability of polymer-based therapeutics, such as the enhancement of encapsulation capacity by finding better drug⁻polymer compatibility, the drug-release kinetics and mechanisms under chemical and mechanical conditions simulating to physiological conditions, and the role of preparation methods and solvents on the overall performance of micelles.

Deep-penetrating photodynamic therapy with KillerRed mediated by upconversion nanoparticles

The fluorescent protein KillerRed, a new type of biological photosensitizer, is considered as a promising substitute for current synthetic photosensitizes used in photodynamic therapy (PDT). However, broad application of this photosensitiser in treating deep-seated lesions is challenging due to the limited tissue penetration of the excitation light with the wavelength falling in the visible spectral range. To overcome this challenge, we employ upconversion nanoparticles (UCNPs) that are able to convert deep-penetrating near infrared (NIR) light to green light to excite KillerRed locally, followed by the generation of reactive oxygen species (ROS) to kill tumour cells under centimetre-thick tissue. The photosensitizing bio-nanohybrids, KillerRed-UCNPs, are fabricated through covalent conjugation of KillerRed and UCNPs. The resulting KillerRed-UCNPs exhibit excellent colloidal stability in biological buffers and low cytotoxicity in the dark. Cross-comparison between the conventional KillerRed and UCNP-mediated KillerRed PDT demonstrated superiority of KillerRed-UCNPs photosensitizing by NIR irradiation, manifested by the fact that ∼70% PDT efficacy was achieved at 1-cm tissue depth, whereas that of the conventional KillerRed dropped to ∼7%.

STATEMENT OF SIGNIFICANCE

KillerRed is a protein photosensitizer that holds promise as an alternative for the existing hydrophobic photosensitizers that are widely used in clinical photodynamic therapy (PDT). However, applications of KillerRed to deep-seated tumours are limited by the insufficient penetration depth of the excitation light in highly scattering and absorbing biological tissues. Herein, we reported the deployment of upconversion nanoparticles (UCNPs) to enhance the treatment depth of KillerRed by converting the deep-penetrating near-infrared (NIR) light to upconversion photoluminescence and activating the PDT effect of KillerRed under deep tissues. This work demonstrated clear potential of UCNPs as the NIR-to-visible light converter to overcome the light penetration limit that has plagued PDT application for many years.

Folate chitosan conjugated doxorubicin and pyropheophorbide acid nanoparticles (FCDP–NPs) for enhance photodynamic therapy

Newly prepared folate chitosan conjugated doxorubicin and pyropheophorbide acid nanoparticles (FCDP–NPs) showed remarkable PDT activity against HepG2 cells.

In vivo studies of nanostructure-based photosensitizers for photodynamic cancer therapy

Animal models, particularly rodents, are major translational models for evaluating novel anticancer therapeutics. In this review, different types of nanostructure-based photosensitizers that have advanced into the in vivo evaluation stage for the photodynamic therapy (PDT) of cancer are described. This article focuses on the in vivo efficacies of the nanostructures as delivery agents and as energy transducers for photosensitizers in animal models. These materials are useful in overcoming solubility issues, lack of tumor specificity, and access to tumors deep in healthy tissue. At the end of this article, the opportunities made possible by these multiplexed nanostructure-based systems are summarized, as well as the considerable challenges associated with obtaining regulatory approval for such materials. The following questions are also addressed: (1) Is there a pressing demand for more nanoparticle materials? (2) What is the prognosis for regulatory approval of nanoparticles to be used in the clinic?

NIR excitation of upconversion nanohybrids containing a surface grafted Bodipy induces oxygen-mediated cancer cell death

We report the preparation of water-dispersible, ca. 30 nm-sized nanohybrids containing NaYF₄:Er³⁺, Yb³⁺ up-conversion nanoparticles (UCNPs), capped with a polyethylene glycol (PEG) derivative and highly loaded with a singlet oxygen photosensitizer, specifically a diiodo-substituted Bodipy (IBDP). The photosensitizer, bearing a carboxylic group, was anchored to the UCNP surface and, at the same time, embedded in the PEG capping; the combined action of the UCNP surface and PEG facilitated the loading for an effective energy transfer and, additionally, avoided photosensitizer leaching from the nanohybrid (UCNP-IBDP@PEG). The effectiveness of the nanohybrids in generating singlet oxygen after near-infrared (NIR) excitation (975 nm) with a continuous wavelength (CW) laser was evidenced by using a probe molecule. In vitro assays demonstrated that the UCNP-IBDP@PEG nanohybrid was taken up by the SH-SY5Y human neuroblastoma-derived cells showing low cytotoxicity. Moreover, ca. 50% cancer cell death was observed after NIR irradiation (45 min, 239 mW).

Targeted in vitro photodynamic therapy via aptamer-labeled, porphyrin-loaded virus capsids

Virus capsids have emerged as multifunctional platform systems for development of bio-derived nanomaterials. In this work we investigate the use of aptamer decorated MS2 bacteriophage capsids, loaded with photosensitizer for targeted photodynamic therapy in vitro. MS2 capsids were loaded with approximately 250 cationic porphyrins through a novel assembly packaging mechanism, followed by exterior decoration of the capsid with a cancer-targeting nucleic acid aptamer via chemical conjugation. The ability of these aptamer-virus-porphyrin constructs to specifically target and eradicate MCF-7 human breast cancer cells upon photoactivation was assessed. Photoinduced cytotoxicity was evaluated via live/dead staining and a metabolic activity assay with MCF-10A cells as a control. Results show that MCF-7 cells incubated with targeted, porphyrin-loaded virus capsids exhibited cell death whereas the MCF-10A cells did not. Furthermore, MCF-7 cells incubated with porphyrin-loaded viruses decorated with a non-targeting aptamer exhibited no observable phototoxicity. Combined, the results presented in this work demonstrate our unique virus-based loading strategy offers a viable approach for efficient targeted delivery of photoactive compounds for site-specific photodynamic cancer therapy using bio-derived nanomaterials.

Polymers as enhancers of photodynamic activity of chlorin photosensitizers for photodynamic therapy

The impact of water-soluble and amphiphilic polymers with different structures, namely carboxymethyl cellulose (CMC), polyvinyl alcohol (PVA) and polyvinylpyrrolidone (PVP), was studied on the photoactivity of chlorin photosensitizers (PSs) in photodynamic therapy (PDT). It was shown that such polymers can cause a considerable increase in the PS activity, both in the process of singlet oxygen photogeneration in cell experiments, and in the model reaction of a substrate photooxidation in water. Amongst the studied polymers, CMC and PVP appeared to have the most significant influence on the photoactivity of PSs. The observed effect of the polymers on the photosensitizing activity of PSs can be attributed to the presence of chlorin-polymer interactions resulting in the porphyrin disaggregation in aqueous phase. The effect of the polymers on the photocytotoxicity of PSs is attributed to the absence of interactions between chlorin and polypeptide or lipoproteins which results in a decrease of the photoactivity of chlorins in cell culture. The PS/polymer systems appear to be a new effective dosage form of PDT drugs.

Immunoconjugates and long circulating systems: origins, current state of the art and future directions

Significant progress has been made recently in the area of immunoconjugated drugs and drug delivery systems (DDS). The immuno-modification of either the drug or DDS has proven to be a very promising approach that has significantly improved the targeted accumulation in pathological sites while decreasing its undesirable side effects in healthy tissues. The arrangement for both prolonged life in the circulation and specific target recognition represents another potent strategy in the development of immuno-targeted systems. The longevity of immuno-targeted DDS such as immunoliposomes and immunomicelles improves their targetability even in the presence of the additional passive accumulation in areas with a compromised vasculature. The added use of the immuno-targeted systems takes advantage of the specific microenvironment of pathological sites including lowered pH, increased temperature, and variation in the enzymatic activity. "Smart" stimulus-responsive systems combine different valuable functionalities including PEG-protection, targeting antibody, cell-penetration, and stimulus-sensitive functions. In this review we examined the evolution, current status and future directions in the area of therapeutical immunoconjugates and long-circulating immuno-targeted DDS.

Smart nanocarriers for pH-triggered targeting and release of hydrophobic drugs

The use of hybrid pH-sensitive micelles based mainly on the (PEO)(129)(P2VP)(43)(PCL)(17) ABC miktoarm star copolymer as potential triggered drug delivery systems was investigated. Co-micellization of this star copolymer with a second copolymer labeled by a targeting ligand, i.e. biotin, on the pH sensitive block (poly-2-vinylpyridine) is considered here in order to impart possible active targeting of the tumor cells. Two architectures were studied for these labeled copolymers, i.e. a miktoarm star or a linear ABC terpolymer, and the respective hybrid micelles are compared in terms of cytotoxicity (cells viability) and cellular uptake (using fluorescent dye loaded micelles). Finally, the triggered drug release in the cytosol of tumor cells was investigated by studying, on the one hand, the lysosomal integrity after internalization and, on the other hand, the release profile in function of the pH.

pH-sensitive poly(histidine)-PEG/DSPE-PEG co-polymer micelles for cytosolic drug delivery

To introduce pH sensitivity into the DSPE-PEG-based micellar system and achieve the quick intracellular drug release in response to the acidity in endosomes, a mixed polymeric micelle was developed based on three grafted copolymers, including 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-polyethylene glycol-2000(DSPE-PEG(2000)), antinucleosome antibody (mAb 2C5)-modified DSPE-PEG(3400) (DSPE-PEG(3400)-2C5), and poly(ethylene glycol)-coupled poly(L-histidine) (PHIS-PEG(2000)). The structure of PHIS-PEG(2000) was confirmed by (1)H NMR spectroscopy. The mixed micelles with the diameter ranging from 110 to 135 nm were prepared using a dialysis method against pH 7.6 PBS. Paclitaxel (PCT) was used as a model drug, the encapsulation efficiency and loading content of PCT were 88% and 5%, respectively. The mixed micelles composed with 50 wt% of PHIS-PEG(2000) showed the desired pH-dependent drug release property with much faster drug release than micelles without PHIS-PEG(2000). At pH around 5.5, about 75-95% of the loaded drug was released within 2 h. The MTT assay showed PCT-loaded mixed micelles had higher cytotoxicity at pH 5.8 than that at pH 7.4. Further modification of the mixed micelles with anti-cancer nucleosome-specific monoclonal antibody 2C5 significantly increased their cellular uptake efficiency and cytotoxicity. Thus, the low pH in endosomes could trigger the PCT release from the pH-sensitive mixed micelles after 2C5-mediated endocytosis. The results of this study suggest that the mixed micelles (DSPE-PEG(2000)/DSPE-PEG(3400)-2C5/PHIS-PEG(2000)) could enhance the tumor cell-specific internalization and trigger the quick drug release, resulting in the improved anti-cancer efficacy.

Synthesis and photodynamic properties of maltohexaose-conjugated porphyrins

A series of porphyrin derivatives with one to four maltohexaose moieties in their meso positions have been synthesized. Zinc or free-base m-THPP (5,10,15,20-tetrakis(m-hydroxyphenyl)-porphyrin) was used as the porphyrin platform. The reaction of m-THPP with 3-iodopropyl nonadecaacetylmaltohexaoside afforded a mixture of all possible combinations of glycoconjugated porphyrins having one to four maltohexaose moieties; monoglycosylated (Ac-1), bisglycosylated (Ac-cis-2 and Ac-trans-2), triglycosylated (Ac-3), and tetraglycosylated (Ac-4) porphyrins were obtained in 11–26% yield. Removal of acetyl groups at maltohexaose moiety afforded highly water-soluble glycoconjugated porphyrins 1–4. Zinc derivatives were synthesized in a similar manner. These maltohexaose-linked porphyrins exhibit remarkable water-solublity (530 mg/mL for 4). The singlet oxygen production ability upon visible light irradiation is not affected by the maltohexaose substitution. Photo- and dark cytotoxicities of the maltohexaose-conjugated porphyrins 1–4 and Zn-1–4 were examined against a HeLa cell line, which showed that the mono-maltohexaosylated derivative (1 and Zn-1) was the most effective photosensitizer for PDT.

Immunomicelles for advancing personalized therapy

Personalized medicine, which ultimately seeks to afford tailored therapeutic regimens for individual patients, is quickly emerging as a new paradigm in the diagnosis and treatment of diseases. The idea of casting aside generic treatments in favor of patient-centric therapies has become feasible owing to advances in nanotechnology and drug delivery coupled with an enhanced knowledge of genomics and an understanding of disease at the molecular level. This review highlights polymeric immunomicelles as a class of nanocarriers that have the potential to combine diagnosis, targeted drug therapy, as well as imaging and monitoring of therapeutic response, to render a personalized approach to the management of disease. Smart multi-functional immunomicelles, as the next generation of nanocarriers, are poised for facilitating personalized cancer treatment. This review provides an assessment of immunomicelles as tools for advancing personalized therapy of diseases, with cancer being the major focus.

Antinuclear antibodies with nucleosome-restricted specificity for targeted delivery of chemotherapeutic agents

Circulating antinuclear autoantibodies (ANAs) are well known to accompany various pathological conditions and can be artificially induced by immunization. Research and clinical data permit us to hypothesize a definite connection between cancer and ANAs. Based on the available data, my group's research suggested that exogenous ANAs may be used as anticancer therapeutics. Among these ANAs, nucleosome-specific ANAs may be particularly useful. Advances in cancer immunotherapy with monoclonal antibodies re-emphasized the role of humoral immunity in neoplasia control. The development of a universal antibody targeting diverse cancers is of clear importance. We showed that certain natural ANAs recognize the surface of numerous tumor cells but not normal cells via cell surface-bound nucleosomes originating from the apoptotically dying neighboring tumor cells, mediate antibody-dependent cellular cytotoxicity of tumor cells in vitro and inhibit the development of murine tumor in syngeneic mice. A single monoclonal antinuclear nucleosome-specific autoantibody, mAb 2C5, specifically recognizes multiple unrelated human tumor cell lines and accumulates at a high tumor-to-normal cell ratio in various human tumors in nude mice. Immunotherapy with mAb 2C5 resulted in significant suppression of the growth of several human tumors. In addition, mAb 2C5, when used in subtherapeutic quantities, can serve as a highly efficient specific ligand to target various drug- or diagnostic agent-loaded pharmaceutical nanocarriers, such as liposomes and polymeric micelles, to various tumors. Here, the data (accumulated predominantly in our laboratory over several years) on mAb 2C5-mediated tumor targeting of chemotherapeutic agents is reviewed.

Can nanotechnology potentiate photodynamic therapy?

Photodynamic therapy (PDT) uses the combination of non-toxic dyes and harmless visible light to produce reactive oxygen species that can kill cancer cells and infectious microorganisms. Due to the tendency of most photosensitizers (PS) to be poorly soluble and to form nonphotoactive aggregates, drug-delivery vehicles have become of high importance. The nanotechnology revolution has provided many examples of nanoscale drug-delivery platforms that have been applied to PDT. These include liposomes, lipoplexes, nanoemulsions, micelles, polymer nanoparticles (degradable and nondegradable), and silica nanoparticles. In some cases (fullerenes and quantum dots), the actual nanoparticle itself is the PS. Targeting ligands such as antibodies and peptides can be used to increase specificity. Gold and silver nanoparticles can provide plasmonic enhancement of PDT. Two-photon excitation or optical upconversion can be used instead of one-photon excitation to increase tissue penetration at longer wavelengths. Finally, after sections on in vivo studies and nanotoxicology, we attempt to answer the title question, "can nano-technology potentiate PDT?"

Polymeric nanohybrids and functionalized carbon nanotubes as drug delivery carriers for cancer therapy

The scope of nanotechnology to develop target specific carriers to achieve higher therapeutic efficacy is gaining importance in the pharmaceutical and other industries. Specifically, the emergence of nanohybrid materials is posed to edge over chemotherapy and radiation therapy as cancer therapeutics. This is primarily because nanohybrid materials engage controlled production parameters in the making of engineered particles with specific size, shape, and other essential properties. It is widely expressed that these materials will significantly contribute to the next generation of medical care technology and pharmaceuticals in areas of disease diagnosis, disease prevention and many other treatment procedures. This review focuses on the currently used nanohybrid materials, polymeric nanoparticles and nanotubes, which show great potential as effective drug delivery systems for cancer therapy, as they can be grafted with cell-specific receptors and intracellular targeting molecules for the targeted delivery of therapeutics. Specifically, this article focuses on the current status, recent advancements, potentials and limitations of polymeric nanohybrids and functionalized carbon nanotubes as drug delivery carriers.

Utilization of monoclonal antibody-targeted nanomaterials in the treatment of cancer

Due to their excellent specificity for a single epitope, monoclonal antibodies (mAbs) present a means of influencing the function of cells at the molecular level. In particular they show great promise in the treatment of cancer because they can inhibit cancer cell proliferation, tumor angiogenesis, invasiveness and malignant spread of cancerous cells. Many mAbs are in various stages of testing and 11 are currently marketed in the US or Europe for the treatment of cancers that express particular antigens such as human epidermal growth factor receptor-2, CD20, epidermal growth factor receptor and vascular endothelial growth factor. Strategies to conjugate mAbs to toxins, radioactive isotopes and chemotherapeutic drugs to improve efficacy are under intense investigation and numerous immunoconjugates have been studied in the clinical setting. However, the molecules have limitations, and so nanomaterials (NMs), which potentially offer more flexibility of design and functionality in providing platforms for binding of multiple therapeutic agents in a single structure, are being examined as an alternative. Studies utilizing mAb-targeted NMs have shown that they exhibit focused targeting, improved pharmacokinetics and improved "passive" drug delivery via leaky vasculature. Nevertheless, before they can be utilized to treat cancer, potential NM toxicity must be thoroughly investigated. Thus, rigorous testing of NM-mAb conjugates in both in vitro and in vivo systems is underway to determine how NM-mAb conjugates will interact with cells and tissues of the body. In this review, we discuss the broad range of nanomaterials that are under investigation as potential platforms for the presentation of mAbs either as single therapeutics or in combination with other drugs and their advantages and limitations in specifically targeting cancer.

Chemiluminescent nanomicelles for imaging hydrogen peroxide and self-therapy in photodynamic therapy

Hydrogen peroxide is a signal molecule of the tumor, and its overproduction makes a higher concentration in tumor tissue compared to normal tissue. Based on the fact that peroxalates can make chemiluminescence with a high efficiency in the presence of hydrogen peroxide, we developed nanomicelles composed of peroxalate ester oligomers and fluorescent dyes, called peroxalate nanomicelles (POMs), which could image hydrogen peroxide with high sensitivity and stability. The potential application of the POMs in photodynamic therapy (PDT) for cancer was also investigated. It was found that the PDT-drug-loaded POMs were sensitive to hydrogen peroxide, and the PDT drug could be stimulated by the chemiluminescence from the reaction between POMs and hydrogen peroxide, which carried on a self-therapy of the tumor without the additional laser light resource.

Design and synthesis of novel functional lipid-based bioconjugates for drug delivery and other applications

The modification of biologicals such as proteins/peptides, small molecules, and other polymers with lipids provides an efficient method for mediating their insertion into liposomes and lipid-core micellar nanocarriers. In this chapter, we describe several representative protocols developed in our laboratory for the bioconjugation of liposomes and lipid-core micelles for drug/gene delivery and diagnostic imaging applications.

Palmitoyl ascorbate-loaded polymeric micelles: cancer cell targeting and cytotoxicity

PURPOSE

To evaluate the potential of palmitoyl ascorbate (PA)-loaded micelles for ascorbate-mediated cancer cell targeting and cytotoxicity.

METHODS

PA was incorporated in polyethylene glycol-phosphatidyl ethanolamine micelles at varying concentrations. The formulations were evaluated for PA content by RP-HPLC. A stable formulation was selected based on size and zeta potential measurements. A co-culture of cancer cells and GFP-expressing non-cancer cells was used to determine the specificity of PA micelle binding. In vitro cytotoxicity of the micellar formulations towards various cancer cell lines was investigated using a cell viability assay. To elucidate the mechanism of action of cell death in vitro, the effect of various H(2)O(2) scavengers and metal chelators on PA-mediated cytotoxicity was studied. The in vivo anti-cancer activity of PA micelles was studied in female Balb/c mice bearing a murine mammary carcinoma (4T1 cells).

RESULTS

PA micelles associated preferentially with various cancer cells compared to non-cancer cells in co-culture. PA micelles exhibited anti-cancer activity in cancer cell lines both in vitro and in vivo. The mechanism of cell death was due primarily to generation of reactive oxygen species (ROS).

CONCLUSIONS

The anti-cancer activity of PA micelles associated with its enhanced cancer cell binding and subsequent generation of ROS.

Advances in polymeric micelles for drug delivery and tumor targeting

A plethora of formulation techniques have been reported in the literature for targeting drugs to specific sites. Polymeric micelles (PMs) can be targeted to tumor sites by passive as well as active mechanisms. Some inherent properties of PMs, including size in the nanorange, stability in plasma, longevity in vivo, and pathological characteristics of tumor allow PMs to be targeted to the tumor site by a passive mechanism called the enhanced permeability and retention effect. PMs formed from an amphiphilic block copolymer are suitable for encapsulation of poorly water-soluble, hydrophobic anticancer drugs. Other characteristics of PMs such as separate functionality at the outer shell are useful for targeting the anticancer drug to tumor by active mechanisms. PMs can be conjugated with many ligands such as antibody fragments, epidermal growth factors, α(2)-glycoprotein, transferrin, and folate to target micelles to cancer cells. Application of heat or ultrasound are the alternative methods to enhance drug accumulation in tumoral cells. Targeting using micelles can also be directed toward tumor angiogenesis, which is a potentially promising target for anticancer drugs. PMs have been used for the delivery of many anticancer agents in preclinical and clinical studies. This review summarizes recently available information regarding targeting of anticancer drugs to the tumor site using PMs.

Polymeric micelles: polyethylene glycol-phosphatidylethanolamine (PEG-PE)-based micelles as an example

One of the renowned nanosized pharmaceutical carriers for delivery of poorly soluble drugs, especially, in cancer, is micelles, which are self-assembled colloidal particles with a hydrophobic core and hydrophilic shell. Among the micelle-forming compounds, micelles made of polyethylene glycol-phosphatidylethanolamine (PEG-PE) have gained more attention due to some attractive properties such as good stability, longevity, and ability to accumulate in the areas with an abnormal vasculature via the enhanced permeability and retention effect (into the areas with leaky vasculature, such as tumors). Additionally these micelles can be made "targeted" by attaching specific targeting ligand molecules to the micelle surface or can be comprised of stimuli-responsive amphiphilic block copolymers. Addition of second component such as surfactant or another hydrophobic material to the main micelle forming material further improves the solubilizing capacity of micelles without compromising their stability. Micelles carrying various contrast agents may become the imaging agents of choice in different imaging modalities. Here, we have discussed various protocols for preparation and evaluation of PEG-PE-based micelles.

Methylene blue-encapsulated phosphonate-terminated silica nanoparticles for simultaneous in vivo imaging and photodynamic therapy

A bifunctional nanoparticles-based carrier for simultaneous in vivo imaging and photodynamic therapy by encapsulating methylene blue (MB) alone in the phosphonate-terminated silica matrix has been developed. The phosphonate-terminated silica nanoparticles, entrapping water-soluble photosensitizer MB (MB-encapsulated PSiNPs), are synthesized by the controlled synchronous hydrolysis of tetraethoxysilane and trihydroxyl silyl propyl methyl phosphonate in the water-in-oil microemulsion. The resulting MB-encapsulated PSiNPs effectively prevent the leakage of entrapped MB from the particles and provide protection for against reduction by diaphorase. Enough dose of irradiation to the MB-encapsulated PSiNPs under the light of 635 nm results in efficient generation of singlet oxygen and induces photodynamic damage to Hela cells. Furthermore, the non-invasive visualization of MB-encapsulated PSiNPs in mice under the in vivo imaging system confirmed the MB-encapsulated PSiNPs also presents near-infrared luminescence for in vivo imaging. And the effect of the PDT toward the xenograft tumor in vivo is exciting after imaging the MB-encapsulated PSiNPs injected tumor using in vivo optical imaging system. Thus, the single particle platform is effective for simultaneous in vivo imaging and photodynamic therapy without using extra agent, which can provide image-guidance for site-specific photodynamic therapy.

In vitro cytotoxicity of novel pro-apoptotic agent DM-PIT-1 in PEG-PE-based micelles alone and in combination with TRAIL

The purpose of this study was to develope and characterize a micellar formulations of N-{[(2-hydroxy-5- nitrophenyl)amino]carbonothioyl}-3,5-dimethylbenzamide (DM-PIT-1)-a new small molecule non-lipid antagonist of phopshotidylinositol-3.4.5-triphopshate and inhibitor of the PI3-kinase pathway. Micelle-forming PEG(2000)-PE was used to solubilize DM-PIT-1. To improve the specificity of the micellar DM-PIT-1, cancer-targeting anti-nucleosomal mAb2C5 antibodies as well as Tumor necrosis factor- Related Apoptosis-Inducing Ligand (TRAIL) were attached to the surface of polymeric micelles. DM-PIT-1 was effectively incorporated (> 70%) into 14-16 nm micelles, which had a negative surface zeta potential of 4-5 mV. Micellar DM-PIT-1 demonstrated high in vitro cytotoxicity against various cancer cells. An improved potency of the dual-activity DM-PIT-1/TRAIL combination nanoparticles in inducing death of TRAIL-resistant cancer cells was shown. Efficacy of the TRAIL therapy was enhanced by combining it with the 2C5 antibody cancer-targeted micellar form of DM-PIT-1. In conclusion, DM-PIT-1 micellar preparations can be used for targeted combination therapy against TRAIL-resistant cancers.