Hypericin-loaded nanoparticles for the photodynamic treatment of ovarian cancer

Co-delivery of siRNA and hypericin into cancer cells by hyaluronic acid modified PLGA-PEI nanoparticles

CONTEXT

Malignant tumors cause more death because of the resistance of the hypoxic cancer cell toward radiotherapy. Targeting for hypoxic cancer area and gene silencing to overcome the hypoxia are two kinds of important therapeutic strategies for treating tumors.

OBJECTIVE

In order to explore the combined effects of gene therapy and hypericin (Hy) on tumor cells, hypoxia-inducible factor 1 alpha (HIF-1α) small interfering ribonucleic acid (siRNA) was transfected into the hypoxic human nasopharyngeal carcinoma (CNE2) cells using Hy-encapsulated nanocomplexes (Hy-HPP NPs) as a carrier which would achieve dual targeting to the tumor necrosis area.

MATERIALS AND METHODS

NPs were prepared by emulsion-diffusion-evaporation method. Formulations were evaluated by conducting in vitro physicochemical studies, electrophoresis, in vivo study, and biochemical studies.

RESULTS AND DISCUSSIONS

Hy-loaded nanoparticles with a mean size of around 160 nm was able to enhance the accumulation in the tumors by enhanced permeability and retention effect. The electrophoresis confirmed the good stability of siRNA/Hy-HPP NPs in the presence of phosphate-buffered saline (pH 7.4), competitive heparin, and RNase. The results of transfection showed that the uptake of siRNA was significantly increased up to 50% in CNE2 cells. The level of the HIF-1α with Hy-encapsulated nanocomplexes was significantly reduced to 30% in the transfected CNE2 cells. In vivo studies, the carrier exhibited higher intensity at the tumor tissue cells and higher affinity toward the necrotic tumor tissue.

CONCLUSION

Results demonstrated that Hy-HPP NPs could significantly enhance the tranfection efficiency of siRNA, suggesting Hy-encapsulated nanoparticle as an efficient gene carrier. The co-delivery of HIF-1α siRNA (siHIF-1α) and Hy could efficiently decrease the level of HIF-1α and increase the affinity toward necrotic tissues. Hence, this is a promising strategy for further application in radiotherapy.

Drug Carrier for Photodynamic Cancer Therapy

Photodynamic therapy (PDT) is a non-invasive combinatorial therapeutic modality using light, photosensitizer (PS), and oxygen used for the treatment of cancer and other diseases. When PSs in cells are exposed to specific wavelengths of light, they are transformed from the singlet ground state (S₀) to an excited singlet state (S₁-Sn), followed by intersystem crossing to an excited triplet state (T₁). The energy transferred from T₁ to biological substrates and molecular oxygen, via type I and II reactions, generates reactive oxygen species, (¹O₂, H₂O₂, O₂*, HO*), which causes cellular damage that leads to tumor cell death through necrosis or apoptosis. The solubility, selectivity, and targeting of photosensitizers are important factors that must be considered in PDT. Nano-formulating PSs with organic and inorganic nanoparticles poses as potential strategy to satisfy the requirements of an ideal PDT system. In this review, we summarize several organic and inorganic PS carriers that have been studied to enhance the efficacy of photodynamic therapy against cancer.

Poly(D, L-lactide-co-glycolide) nanoparticles as delivery agents for photodynamic therapy: enhancing singlet oxygen release and photototoxicity by surface PEG coating

Poly(D, L-lactide-co-glycolide) (PLGA) nanoparticles (NPs) are being considered as nanodelivery systems for photodynamic therapy. The physico-chemical and biological aspects of their use remain largely unknown. Herein we report the results of a study of PLGA NPs for the delivery of the model hydrophobic photosensitizer ZnTPP to HeLa cells. ZnTPP was encapsulated in PLGA with high efficiency and the NPs showed negative zeta potentials and diameters close to 110 nm. Poly(ethylene glycol) (PEG) coating, introduced to prevent opsonization and clearance by macrophages, decreased the size and zeta potential of the NPs by roughly a factor of two and improved their stability in the presence of serum proteins. Photophysical studies revealed two and three populations of ZnTPP and singlet oxygen in uncoated and PEGylated NPs, respectively. Singlet oxygen is confined within the NPs in bare PLGA while it is more easily released into the external medium after PEG coating, which contributes to a higher photocytotoxicity towards HeLa cells in vitro. PLGA NPs are internalized by endocytosis, deliver their cargo to lysosomes and induce cell death by apoptosis upon exposure to light. In conclusion, PLGA NPs coated with PEG show high potential as delivery systems for photodynamic applications.

Computer modeling of the complexes of Chlorin e6 with amphiphilic polymers

Recently it has been shown that Chlorin e6 (Ce6) when complexed with Pluronics (hydrophilic ethylene and propylene oxide block copolymers) and poly(N-vinylpyrrolidone) (PVP) exhibits considerably higher phototoxicity towards tumor cells than free Ce6. The present work aimed to model Ce6 interactions with hydrophilic Pluronic F127 and PVP and find out the nature of intermolecular forces stabilizing these complexes. Modeling included 3 steps: (i) application of molecular dynamics to study polymer folding using AMBER 8 program, (ii) evaluation of partial charges in the Ce6 molecule using different quantum mechanical, semi-empirical and topological approaches and (iii) docking analysis of Ce6 interactions with polymer coils using AUTODOCK 4.2. It was found that the folding in regular polymers does not occur stochastically, but involves the formation of "primary" helical structures, which further combined to form hairpin-like "secondary" structures. The latter in turn associated to form coils with minimal solvent accessible hydrophobic area. The Ce6 ring lies flat on the surface of the polymer coil at the interface between hydrophobic and hydrophilic regions. Calculations showed higher affinity of Ce6 for PVP in comparison to Pluronic and revealed marginal contribution of Coulomb forces to the stabilization of both complexes, which are mainly stabilized by van der Waals and hydrogen interactions.

Photoactivation of hypericin decreases the viability of RINm5F insulinoma cells through reduction in JNK/ERK phosphorylation and elevation of caspase-9/caspase-3 cleavage and Bax-to-Bcl-2 ratio

Insulinomas cause neuroglycopenic symptoms, permanent neurological damage and even death. Current available therapies cannot satisfactorily treat malignant insulinomas and some benign insulinomas. The promising phototherapeutic results and harmless side effects of hypericin in some cancer treatments prompted us to explore possible anti-growth activity of photoactivated hypericin against RINm5F insulinoma cells and underlying mechanisms. We now show that detectable and maximal internalization of hypericin in RINm5F insulinoma cells occurred in 20 and 60 min respectively. Hypericin was considerably associated with the plasma membrane, appreciably localized in the sub-plasma membrane region and substantially accumulated in the cytoplasm. Photoactivated hypericin decreased the viability of RINm5F insulinoma cells due to its anti-proliferative and apoptotic actions. Photoactivation of hypericin inhibited cell proliferation reflected by decreased expression of the proliferation marker Ki-67 and cell-cycle arrest in the G₀/G₁-phase. The anti-proliferative effect resulted from down-regulation of phosphorylation of c-Jun N-terminal kinase (JNK) and extracellular-signal-regulated kinase (ERK). Photoactivated hypericin triggered apoptosis through activation of caspase-3 and caspase-9 and elevation of the Bax-to B-cell lymphoma 2 (Bcl-2) ratio. The findings lay a solid foundation for implementation of hypericin-mediated photodynamic therapy in treatment of insulinomas.

Photoexcited hypericin exerts strong antigrowth activity in RINm5F insulinoma cells via inhibition of cell proliferation by reducing JNK/ERK phosphorylation and stimulation of apoptosis by elevating caspase-9/caspase-3 cleavage and Bax-to-Bcl-2 ratio.

Development of nanoscale approaches for ovarian cancer therapeutics and diagnostics

Ovarian cancer is the deadliest of all gynecological cancers and the fifth leading cause of death due to cancer in women. This is largely due to late-stage diagnosis, poor prognosis related to advanced-stage disease, and the high recurrence rate associated with development of chemoresistance. Survival statistics have not improved significantly over the last three decades, highlighting the fact that improved therapeutic strategies and early detection require substantial improvements. Here, we review and highlight nanotechnology-based approaches that seek to address this need. The success of Doxil, a PEGylated liposomal nanoencapsulation of doxorubicin, which was approved by the FDA for use on recurrent ovarian cancer, has paved the way for the current wave of nanoparticle formulations in drug discovery and clinical trials. We discuss and summarize new nanoformulations that are currently moving into clinical trials and highlight novel nanotherapeutic strategies that have shown promising results in preclinical in vivo studies. Further, the potential for nanomaterials in diagnostic imaging techniques and the ability to leverage nanotechnology for early detection of ovarian cancer are also discussed.

Anticancer efficacy of photodynamic therapy with hematoporphyrin-modified, doxorubicin-loaded nanoparticles in liver cancer

Photodynamic therapy (PDT) in combination with chemotherapy has great potential for cancer treatment. However, there have been very few attempts to developing cancer-targeted co-delivered systems of photosensitizers and anticancer drugs. We developed hematoporphyrin (HP)-modified doxorubicin (DOX)-loaded nanoparticles (HP-NPs) to improve the therapeutic effect of PDT in treating liver cancer. HP is not only a ligand for low density lipoprotein (LDL) receptors on the hepatoma cells but also a well-known photosensitizer for PDT. In vitro phototoxicity in HepG2 (human hepatocellular carcinoma) cells and in vivo anticancer efficacy in HepG2 tumor-bearing mice of free HP and HP-NPs were evaluated. The in vitro phototoxicity in HepG2 cells determined by MTT assay, annexin V-FITC staining and FACS analysis was enhanced in HP-NPs compared with free HP. Furthermore, compared with free HP-based PDT, in vivo anticancer efficacy in HepG2 tumor-bearing mice was markedly improved by HP-NPs-based PDT. Moreover, in both cases, the therapeutic effect was increased according to the irradiation time and number of PDT sessions. In conclusion, the HP-NPs prepared in this study represent a potentially effective co-delivery system of photosensitizer (HP) and anticancer drug (DOX) which improved the effects of PDT in liver cancer.

Applicability of new degradable hypericin–polymer-conjugates as photosensitizers: principal mode of action demonstrated by in vitro models

Novel degradable polymers are shown to be promising carriers for the delivery of hypericin for PDT, significantly enhancing solubility of the free drug without compromising the photoactivity.

Preparation and evaluation of hypocrellin A loaded poly(lactic-co-glycolic acid) nanoparticles for photodynamic therapy

The PLGA/HA NPs showed improved dispersibility and enhanced photostability, while maintaining high phototoxicity and ROS production ability.

Hypericin-loaded lipid nanocapsules for photodynamic cancer therapy in vitro

Hypericin (Hy), a naturally occurring photosensitizer (PS), is extracted from Hypericum perforatum plants, commonly known as St. John's wort. The discovery of the in vitro and in vivo photodynamic activities of hypericin as a photosensitizer generated great interest, mainly to induce a very potent antitumoral effect. However, this compound belongs to the family of naphthodianthrones which are known to be poorly soluble in physiological solutions and produce non-fluorescent aggregates (A. Wirz et al., Pharmazie, 2002, 57, 543; A. Kubin et al., Pharmazie, 2008, 63, 263). These phenomena can reduce its efficiency as a photosensitizer for the clinical application. In the present contribution, we have prepared, characterized, and studied the photochemical properties of Hy-loaded lipid nanocapsule (LNC) formulations. The amount of singlet oxygen ((1)O2) generated was measured by the use of p-nitroso-dimethylaniline (RNO) as a selective scavenger under visible light irradiation. Our results showed that Hy-loaded LNCs suppressed aggregation of Hy in aqueous media, increased its apparent solubility, and enhanced the production of singlet oxygen in comparison with free drug. Indeed, encapsulation of Hy in LNCs led to an increase of (1)O2 quantum yield to 0.29-0.44, as compared to 0.02 reported for free Hy in water. Additionally, we studied the photodynamic activity of Hy-loaded LNCs on human cervical carcinoma (HeLa) and Human Embryonic Kidney (HEK) cells. The cell viability decreased radically to 10-20% at 1 μM, reflecting Hy-loaded LNC25 phototoxicity.

Hypericin encapsulated in solid lipid nanoparticles: phototoxicity and photodynamic efficiency

The hydrophobicity of some photosensitizers can induce aggregation in biological systems, which consequently reduces photodynamic activity. The conjugation of photosensitizers with nanocarrier systems can potentially be used to overcome this problem. The objective of this study was to prepare and characterise hypericin-loaded solid lipid nanoparticles (Hy-SLN) for use in photodynamic therapy (PDT). SLN were prepared using the ultrasonication technique, and their physicochemical properties were characterised. The mean particle size was found to be 153 nm, with a low polydispersity index of 0.28. One of the major advantages of the SLN formulation is its high entrapment efficiency (EE%). Hy-SLN showed greater than 80% EE and a drug loading capacity of 5.22% (w/w). To determine the photodynamic efficiency of Hy before and after encapsulation in SLN, the rate constants for the photodecomposition of two (1)O2 trapping reagents, DPBF and AU, were determined. These rate constants exhibited an increase of 60% and 50% for each method, respectively, which is most likely due to an increase in the lifetime of the triplet state caused by the increase in solubility. Hy-SLN presented a 30% increase in cell uptake and a correlated improvement of 26% in cytotoxicity. Thus, all these advantages suggest that Hy-loaded SLN has potential for use in PDT.

Photosan-II loaded hollow silica nanoparticles: preparation and its effect in killing for QBC939 cells

BACKGROUND

Nanoparticles have been explored recently as an efficient means to deliver photosensitizers for photodynamic therapy. However, it is largely unknown if polyhematoporphyrin (C34H38N4NaO5, Photosan-II, PS) or other photosensitizers can be efficiently delivered by hollow silica nanoparticles (HSNP).

METHODS

Polyhematoporphyrin (C34H38N4NaO5, Photosan-II, PS) was loaded into hollow silica nanoparticles (HSNP) by one-step wet chemical-based synthetic route. Dynamic light scattering (DLS) and polydispersive index (PDI) were used for measurement of the particles size and size distribution. Transmission electron microscope and scanning electron microscopy were used for the microstructure, morphological and chemical composition analysis. Fourier transform infrared spectrometry spectra and fluorescence emission spectrum were obtained. The photobiological activity of the PS-loaded HSNP was evaluated on human cholangiocarcinoma QBC939 cells. The cellular viability was determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay. Apoptotic and necrotic cells were measured by flow cytometry.

RESULTS

DLS measurements showed that the size of the particles is in the range of 25-90 nm. PDI of the PS-loaded HSNP is 0.121 ± 0.01, indicating that samples have excellent quality with narrow size distribution to monomodal systems. In MTT assay, PS-loaded HSNP and free PS of the same concentration killed about 95.3% ± 2.0% and 55.7% ± 1.9% of QBC939 cells, respectively. The flow cytometry demonstrated that the laser induced cell death with PS-loaded HSNP was much more severe than that of free PS (P<0.05).

CONCLUSIONS

Photosan-II-loaded hollow silica nanoparticles not only can quickly deliver Photosan-II into cells but also can reach a more high concentration than free Photosan-II. HSNP is a desirable vehicle and the release system that shows promises for photodynamic therapy use, which not only improve the aqueous solubility, stability and transport efficiency of PS, but also increase its photodynamic efficacy compared to free PS.

Photodynamic nanomedicine in the treatment of solid tumors: perspectives and challenges

Photodynamic therapy (PDT) is a promising treatment strategy where activation of photosensitizer drugs with specific wavelengths of light results in energy transfer cascades that ultimately yield cytotoxic reactive oxygen species which can render apoptotic and necrotic cell death. Without light the photosensitizer drugs are minimally toxic and the photoactivating light itself is non-ionizing. Therefore, harnessing this mechanism in tumors provides a safe and novel way to selectively eradicate tumor with reduced systemic toxicity and side effects on healthy tissues. For successful PDT of solid tumors, it is necessary to ensure tumor-selective delivery of the photosensitizers, as well as, the photoactivating light and to establish dosimetric correlation of light and drug parameters to PDT-induced tumor response. To this end, the nanomedicine approach provides a promising way towards enhanced control of photosensitizer biodistribution and tumor-selective delivery. In addition, refinement of nanoparticle designs can also allow incorporation of imaging agents, light delivery components and dosimetric components. This review aims at describing the current state-of-the-art regarding nanomedicine strategies in PDT, with a comprehensive narrative of the research that has been carried out in vitro and in vivo, with a discussion of the nanoformulation design aspects and a perspective on the promise and challenges of PDT regarding successful translation into clinical application.

Sonodynamic and sonocatalytic damage of BSA molecules by Cresol Red, Cresol Red-DA and Cresol Red-DA-Fe under ultrasonic irradiation

The interaction of Cresol Red derivatives (Cresol Red (o-Cresolsulfonphthalein), Cresol Red-DA (3,3'-Bis [N,N-di (carboxymethyl) aminomethyl]-o-cresolsulfonphthalein) and Cresol Red-DA-Fe(III) (3,3'-Bis [N,N-di (carboxymethyl) aminomethyl]-o-cresolsulfonphthalein-Ferrous(III)) with bovine serum albumin (BSA) were studied by the combination of ultraviolet spectroscopy, circular dichroism (CD) spectroscopy, fluorescence spectroscopy and synchronous fluorescence spectroscopy. On that basis, the sonodynamic and sonocatalytic damages of Cresol Red derivatives to BSA under ultrasonic irradiation were also investigated by means of corresponding spectrum technology. Meanwhile, some influenced factors such as ultrasonic irradiation time, Cresol Red derivatives concentration and ionic strength on the damage degree of BSA molecules were also reviewed. In addition, the binding site and damage site of BSA molecules were estimated by synchronous fluorescence spectra. Finally, the results of oxidation-extraction photometry (OEP) using several reactive oxygen species (ROS) scavengers indicated that the damage of BSA molecules is mainly due to the generation of ROS. Perhaps, this paper may offer some important subjects for broadening the application of Cresol Red derivatives in sonodynamic therapy (SDT) and sonocatalytic therapy (SCT) technologies for tumor treatment.

Shining light on nanotechnology to help repair and regeneration

Phototherapy can be used in two completely different but complementary therapeutic applications. While low level laser (or light) therapy (LLLT) uses red or near-infrared light alone to reduce inflammation, pain and stimulate tissue repair and regeneration, photodynamic therapy (PDT) uses the combination of light plus non-toxic dyes (called photosensitizers) to produce reactive oxygen species that can kill infectious microorganisms and cancer cells or destroy unwanted tissue (neo-vascularization in the choroid, atherosclerotic plaques in the arteries). The recent development of nanotechnology applied to medicine (nanomedicine) has opened a new front of advancement in the field of phototherapy and has provided hope for the development of nanoscale drug delivery platforms for effective killing of pathological cells and to promote repair and regeneration. Despite the well-known beneficial effects of phototherapy and nanomaterials in producing the killing of unwanted cells and promoting repair and regeneration, there are few reports that combine all three elements i.e. phototherapy, nanotechnology and, tissue repair and regeneration. However, these areas in all possible binary combinations have been addressed by many workers. The present review aims at highlighting the combined multi-model applications of phototherapy, nanotechnology and, reparative and regeneration medicine and outlines current strategies, future applications and limitations of nanoscale-assisted phototherapy for the management of cancers, microbial infections and other diseases, and to promote tissue repair and regeneration.

Matrix mediated fluorescence enhancement — why nanoparticles and PPIX make a friendly couple

The hexyl ester of 5-aminolevulinic acid (HAL) is an efficient inducer of the endogenous photosensitizer protoporphyrin IX (PPIX) in neoplastic tissue and approved for the fluorescence photodetection of bladder cancer. It is, however, limited to topical application due to unsuitable pharmacokinetic and pharmacodynamic properties following systemic administration. In this study we sought to prepare HAL laden polymeric nanoparticles made from polylactic acid (PLA) as possible means to improve the systemic bioavailability of HAL. Nanoparticles were prepared by nanoprecipitation. Particle size and morphology of freshly prepared and dehydrated nanoparticles were assessed and the ability to generate PPIX fluorescence was tested on a T24 human bladder carcinoma cell line. Fluorescence intensities of cells incubated with nanoencapsulated HAL were significantly higher than in presence of free HAL. Interestingly, the effect was — at least partly — provoked by the direct interaction of exogenously induced PPIX with the nanoparticles.

Hypericin for visualization of high grade gliomas: first clinical experience

AIMS

We aimed to demonstrate that Hypericin, a component of St. Johns Wort, selectively visualizes malignant gliomas. Hypericin is known as one of the most powerful photosensitizers in nature with excellent fluorescent properties.

METHODS

In five patients with a recurrence of a malignant glioma a newly developed water soluble formulation of hypericin was given intravenously (0.1 mg/kg body weight) 6 h before the surgical procedure. Tumor resection was performed under white light and fluorescence mode. The intensity grade of the tissue fluorescence was categorisized by the surgeon in three grades, highly fluorescent, weakly fluorescent and not fluorescent. In these areas tissue samples were taken and investigated by two blinded independent neuropathologists. Tissue samples were histologically classified differentiating between tumor tissue, tumor necrosis, tissue with scattered tumor cells and normal brain tissue.

RESULTS

In all patients tumor tissue was clearly distinguishable by its typically red fluorescence color from normal brain tissue which was colored blue under a special fluorescent filter. Histological evaluation of the 110 tissue samples showed a specificity of 100% and sensitivity of 91% for one of the two neuropathologists, whereas specificity for second pathologist was 90% and sensitivity 94%. The i.v. application of Hypericin proofed to be safe in all cases and there were no side effects observed.

CONCLUSION

Hypericin in its water soluble form is a well tolerated drug. In addition to its high photosensitizing properties hypericin will open up interesting new therapeutic possibilities especially when used in combination with fluorescence detection and simultaneously photodynamic therapy.

Design of photosensitizer/cyclodextrin nanoassemblies: spectroscopy, intracellular delivery and photodamage

The engineering of multifunctional nanoparticles carrying photosensitizer drugs (PS) and exposing binding groups for cellular receptors is of increasing interest in therapeutics and diagnostics applications. Natural and modified cyclodextrins (CDs) offer useful scaffolds to bind PS guests by supramolecular interactions. In particular, amphiphilic β-CDs, which form nanoaggregates of diverse shape and size according to the polarity of substituent groups on the rims, include in their different compartments as CD cavity, hydrophilic and hydrophobic portion, PS with different physicochemical properties. PS embedded in cationic amphiphilic CD nanoassemblies are effective in inducing photodynamic damage in cancer cells. For a carrier/PS system to be used in photodynamic therapy (PDT) or photodynamic diagnosis (PDD), the appropriate combination of the delivery characteristics with the preservation of the photodynamic activity of the PS is strictly required. Homogeneous multilayer films based on cationic amphiphilic β-CD entrapping anionic porphyrins can be constructed to exploit interfacial electrostatic interactions between the two components. The capability of CDs to generate restricted microenvironments for PS which can facilitate photoinduced energy transfer with suitable donor molecules was investigated for potential application in fluorescence diagnosis. Besides, recent findings suggest that PDT could represent a useful tool for properly addressing an alternative approach for killing pathogens and combating infections at a clinical level. Finally, modified CDs can bind gold nanoparticles, yielding hybrid organic/inorganic nanoparticles which were studied in water solution and after casting on solid substrates. These binary assemblies could further encapsulate PS or other conventional drugs, opening new intriguing routes on multimodal therapy.

New frontier in hypericin-mediated diagnosis of cancer with current optical technologies

Photosensitizers (PSs) have shown great potentials as molecular contrast agents in photodynamic diagnosis (PDD) of cancer. While the diagnostic values of PSs have been proven previously, little efforts have been put into developing optical imaging and diagnostic algorithms. In this article, we review the recent development of optical probes that have been used in conjunction with a potent PS, hypericin (HY). Various fluorescence techniques such as laser confocal microscopy, fluorescence urine cytology, endoscopy and endomicroscopy are covered. We will also discuss about image processing and classification approaches employed for accurate PDD. We anticipate that continual efforts in these developments could lead to an objective PDD and complete surgical clearance of tumors. Recent advancements in nanotechnology have also opened new horizons for PSs. The use of biocompatible gold nanoparticles as carrier for enhanced targeted delivery of HY has been attained. In addition, plasmonic properties of nanoparticles were harnessed to induce localized hyperthermia and to manage the release of PS molecules, enabling a better therapeutic outcome of a combined photodynamic and photothermal therapy. Finally, we discuss how nanoparticles can be used as contrast agents for other optical techniques such as optical coherence tomography and surface-enhanced Raman scattering imaging.

Photodynamic therapy with hyperbranched poly(ether-ester) chlorin(e6) nanoparticles on human tongue carcinoma CAL-27 cells

BACKGROUND

Hyperbranched polymers represent a new class of drug-delivery vehicle that can be used to prepare nanoparticles with uniform size distribution.

METHODS

In this study we prepared covalent conjugates between the photosensitizer chlorin(e6) and hyperbranched poly(ether-ester), HPEE. HPEE-ce6 nanoparticles were synthesized by carbodiimide-mediated reaction between HPEE and ce6, and characterized by ultraviolet-visible absorption spectroscopy (UV-Vis), and transmission electron microscopy (TEM). The uptake and phototoxicity of HPEE-ce6 nanoparticles towards human oral tongue cancer CAL-27 cells was detected by confocal laser scanning microscopy (CLSM) and MTT assay, respectively.

RESULTS

The absorption peak of HPEE-ce6 nanoparticles was red-shifted 12-nm compared with ce6, and TEM showed uniform nanoparticles with a diameter of 50-nm. HPEE-ce6 nanoparticles were taken up by CAL-27 cells after 4h incubation and localized in the cytoplasm. The MTT assay showed a significantly (P<0.05) higher phototoxicity compared to free ce6 after 12 J/cm² of 660-nm laser illumination.

CONCLUSIONS

This is the first time to our knowledge that hyperbranched polymers have been used in PDT drug delivery.

Enhanced photodynamic efficacy and efficient delivery of Rose Bengal using nanostructured poly(amidoamine) dendrimers: potential application in photodynamic therapy of cancer

Photodynamic therapy (PDT) is a promising treatment methodology whereby diseased cells and tissues are destroyed by reactive oxygen species (ROS) by using a combination of light and photosensitizers (PS). The medical application of Rose Bengal (RB), photosensitizer with very good ROS generation capability, is limited due to its intrinsic toxicity and insufficient lipophilicity. In this report, we evaluate the potential of polyamidoamine (PAMAM) dendrimers in delivering RB and its phototoxic efficiency towards a model cancer cell line. The spherical, nanoscaled dendrimers could efficiently encapsulate RB and showed characteristic spectral responses. The controlled release property of dendrimer-RB formulation was clearly evident from the in vitro drug release study. ROS generation was confirmed in dendrimer-RB system upon white light illumination. Photosensitization of Dalton's Lymphoma Ascite (DLA) cells incubated with dendrimer-RB formulation caused remarkable photocytotoxicity. Importantly, the use of dendrimer-based delivery system reduced the dark toxicity of RB.

Characterization and optimization of mTHPP nanoparticles for photodynamic therapy of head and neck cancer

OBJECTIVES

To characterize the properties of polymeric micelles containing different loading percentages of mTHPP, a photosensitizer for photodynamic therapy (PDT), with respect to fluorescence, singlet oxygen ((1)O(2)) yield, and in vitro cytotoxicity in head and neck cancer cells.

STUDY DESIGN

Laboratory study.

SETTING

Polymer chemistry laboratory.

SUBJECTS AND METHODS

Absorption and emission spectroscopy was used to characterize the mTHPP-loaded micelles. The (1)O(2) yield was measured to determine the efficiency of reactive oxygen species (ROS) generation. In vitro studies were conducted using the HN5 cells and confirmed with H2009 cells to determine the photodynamic efficacy. DNA assay and confocal microscopy was used to measure intracellular fluorescence.

RESULTS

The mTHPP micelles demonstrated the highest fluorescence intensity at 0.5% loading. The (1)O(2) generation of the micelles in solution peaked at 2% loading. Phototoxicity and dark toxicity experiments in HN5 and H2009 cells demonstrated that the best therapeutic index was achieved with the 2% loaded micelles with 100% cell cytotoxicity at a micelle concentration of 10 µg/mL and less than 10% dark cytotoxicity. In comparison, 10% loaded micelles demonstrated 100% cell cytotoxicity at a concentration of 20 µg/mL under both light and dark conditions. Confocal microscopy demonstrated increasing intracellular fluorescence with higher loading.

CONCLUSIONS

The 2% mTHPP-loaded micelles generated greater (1)O(2), and 0.5% loading led to the most efficient generation of fluorescence in solution. Higher mTHPP loading density led to increased cellular fluorescence and dark cytotoxicity. Overall, 2% mTHPP-loaded micelles provided the optimal composition for photodynamic therapy with the largest therapeutic window.

Polylactide-co-glycolide nanoparticles for controlled delivery of anticancer agents

The effectiveness of anticancer agents may be hindered by low solubility in water, poor permeability, and high efflux from cells. Nanomaterials have been used to enable drug delivery with lower toxicity to healthy cells and enhanced drug delivery to tumor cells. Different nanoparticles have been developed using different polymers with or without surface modification to target tumor cells both passively and/or actively. Polylactide-co-glycolide (PLGA), a biodegradable polyester approved for human use, has been used extensively. Here we report on recent developments concerning PLGA nanoparticles prepared for cancer treatment. We review the methods used for the preparation and characterization of PLGA nanoparticles and their applications in the delivery of a number of active agents. Increasing experience in the field of preparation, characterization, and in vivo application of PLGA nanoparticles has provided the necessary momentum for promising future use of these agents in cancer treatment, with higher efficacy and fewer side effects.

Nanostructured delivery system for zinc phthalocyanine: preparation, characterization, and phototoxicity study against human lung adenocarcinoma A549 cells

In this study, zinc phthalocyanine (ZnPc) was loaded onto poly-ɛ-caprolactone (PCL) nanoparticles (NPs) using a solvent emulsification–evaporation method. The process yield and encapsulation efficiency were 74.2% ± 1.2% and 67.1% ± 0.9%, respectively. The NPs had a mean diameter of 187.4 ± 2.1 nm, narrow distribution size with a polydispersity index of 0.096 ± 0.004, zeta potential of −4.85 ± 0.21 mV, and spherical shape. ZnPc has sustained release, following Higuchi’s kinetics. The photobiological activity of the ZnPc-loaded NPs was evaluated on human lung adenocarcinoma A549 cells. Cells were incubated with free ZnPc or ZnPc-loaded NPs for 4 h and then washed with phosphate-buffered saline. Culture medium was added to the wells containing the cells. Finally, the cells were exposed to red light (660 nm) with a light dose of 100 J/cm². The cellular viability was determined after 24 h of incubation. ZnPc-loaded NPs and free photosensitizer eliminated about 95.9% ± 1.8% and 28.7% ± 2.2% of A549 cells, respectively. The phototoxicity was time dependent up to 4 h and concentration dependent at 0–5 μg ZnPc. The cells viability decreased with the increase of the light dose in the range of 10–100 J/cm². Intense lysis was observed in the cells incubated with the ZnPcloaded NPs and irradiated with red light. ZnPc-loaded PCL NPs are the release systems that promise photodynamic therapy use.

Polymeric nanoparticles for photodynamic therapy

Photodynamic therapy is a relatively new clinical therapeutic modality that is based on three key components: photosensitizer, light, and molecular oxygen. Nanoparticles, especially targeted ones, have recently emerged as an efficient carrier of drugs or contrast agents, or multiple kinds of them, with many advantages over molecular drugs or contrast agents, especially for cancer detection and treatment. This paper describes the current status of PDT, including basic mechanisms, applications, and challenging issues in the optimization and adoption of PDT; as well as recent developments of nanoparticle-based PDT agents, their advantages, designs and examples of in vitro and in vivo applications, and demonstrations of their capability of enhancing PDT efficacy over existing molecular drug-based PDT.

Tumor ablation and nanotechnology

Next to surgical resection, tumor ablation is a commonly used intervention in the treatment of solid tumors. Tumor ablation methods include thermal therapies, photodynamic therapy, and reactive oxygen species (ROS) producing agents. Thermal therapies induce tumor cell death via thermal energy and include radiofrequency, microwave, high intensity focused ultrasound, and cryoablation. Photodynamic therapy and ROS producing agents cause increased oxidative stress in tumor cells leading to apoptosis. While these therapies are safe and viable alternatives when resection of malignancies is not feasible, they do have associated limitations that prevent their widespread use in clinical applications. To improve the efficacy of these treatments, nanoparticles are being studied in combination with nonsurgical ablation regimens. In addition to better thermal effect on tumor ablation, nanoparticles can deliver anticancer therapeutics that show a synergistic antitumor effect in the presence of heat and can also be imaged to achieve precision in therapy. Understanding the molecular mechanism of nanoparticle-mediated tumor ablation could further help engineer nanoparticles of appropriate composition and properties to synergize the ablation effect. This review aims to explore the various types of nonsurgical tumor ablation methods currently used in cancer treatment and potential improvements by nanotechnology applications.

Optimizing photodynamic therapy by liposomal formulation of the photosensitizer pyropheophorbide-a methyl ester: in vitro and ex vivo comparative biophysical investigations in a colon carcinoma cell line

Photodynamic therapy (PDT), induced by a photosensitizer (PS) encapsulated in a nanostructure, has emerged as an appropriate treatment to cure a multitude of oncological and non-oncological diseases. Pyropheophorbide-a methyl ester (PPME) is a second-generation PS tested in PDT, and is a potential candidate for future clinical applications. The present study, carried out in a human colon carcinoma cell line (HCT-116), evaluates the improvement resulting from a liposomal formulation of PPME versus free-PPME. Absorption and fluorescence spectroscopies, fluorescence lifetime measurements, subcellular imaging and co-localization analysis have been performed in order to analyze the properties of PPME for each delivery mode. The benefit of drug encapsulation in DMPC-liposomes is clear from our experiments, with a 5-fold higher intracellular drug delivery than that observed with free-PPME at similar concentrations. The reactive oxygen species (ROSs) produced after PPME-mediated photosensitization have been identified and quantified by using electron spin resonance spectroscopy. Our results demonstrate that PPME-PDT-mediated ROSs are composed of singlet oxygen and a hydroxyl radical. The small amounts of PPME inside mitochondria, as revealed by fluorescence co-localization analysis, could maybe explain the very low apoptotic cell death measured in HCT-116 cells.

Electrostatic surface modifications to improve gene delivery

IMPORTANCE OF THE FIELD

Gene therapy has the potential to treat a wide variety of diseases, including genetic diseases and cancer.

AREAS COVERED IN THIS REVIEW

This review introduces biomaterials used for gene delivery and then focuses on the use of electrostatic surface modifications to improve gene delivery materials. These modifications have been used to stabilize therapeutics in vivo, add cell-specific targeting ligands, and promote controlled release. Coatings of nanoparticles and microparticles as well as non-particulate surface coatings are covered in this review. Electrostatic principles are crucial for the development of multilayer delivery structures fabricated by the layer-by-layer method.

WHAT THE READER WILL GAIN

The reader will gain knowledge about the composition of biomaterials used for surface modifications and how these coatings and multilayers can be utilized to improve spatial control and efficiency of delivery. Examples are shown for the delivery of nucleic acids, including DNA and siRNA, to in vitro and in vivo systems.

TAKE HOME MESSAGE

The versatile and powerful approach of electrostatic coatings and multilayers will lead to the development of enhanced gene therapies.

Photosensitizer loaded HSA nanoparticles. I: Preparation and photophysical properties

Photodynamic therapy (PDT) is a promising option in the treatment of cancer. Efficient photosensitizers are available but many of them have insufficient physico-chemical properties for parenteral application. We have established nanoparticles consisting of human serum albumin (HSA) as a drug carrier system for 5,10,15,20-tetrakis(m-hydroxyphenyl)porphyrine (mTHPP) and 5,10,15,20-tertrakis(m-hydroxyphenyl)chlorin (mTHPC), two well-known photosensitizers. Nanoparticle loading was performed in water/ethanol mixtures in the presence of dissolved HSA acting as solubilizer for photosensitizers. The HSA concentration was optimized to exclude precipitation in the nanoparticle suspension and to increase binding to nanoparticles. Additionally, the influence of pH and incubation time on drug adsorption was investigated. A freeze drying method was established for mTHPC loaded nanoparticles and the storage stability of the freeze dried formulation was tested. PDT related photophysical parameters of drug loaded HSA nanoparticles, especially singlet oxygen generation, are presented. Both preparations were able to generate singlet oxygen with low quantum yield. In contrast, efficient singlet oxygen generation was obtained when Jurkat cells were incubated with mTHPP and mTHPC loaded HSA nanoparticles. This indicates that the photosensitizer molecules were successfully released from the nanoparticles that were taken up by the cells. Therefore, the efficiency of HSA nanoparticles as drug carriers for photosensitizers was proven under in vitro conditions.

High celecoxib-loaded nanoparticles prepared by a vibrating nozzle device

Drug delivery research has resulted in the availability of several enabling technologies for formulating poorly water-soluble compounds. In this study the vibrating nozzle device, originally used for encapsulation of drugs, cells and microorganisms, has been used to formulate nanoparticles (NP) with high loading capacity. Celecoxib was incorporated in NP of polylactic acid (PLA) and poly(lactic-co-glycolic acid) (PLGA) and the influence of polymers, initial drug : polymer ratio and stabilizer concentration on NP size and surface properties, entrapment efficiency, drug loading and in vitro release profile were investigated. NP were in the size range of 230-270 nm, with a polydispersity index less than 0.25 and a spherical shape. The highest celecoxib loading (13% w/w) was obtained at initial ratio celecoxib : Resomer RG 502 (PLA/PGA = 50/50) of 1 : 5 and 0.1% w/w polyvinyl alcohol concentration. Thermal analysis and X-ray diffraction suggested that celecoxib was amorphous or molecularly dispersed in the polymeric matrix. The release profile exhibited an initial burst followed by sustained release. The freeze-dried NP could be completely dispersed on addition of lyoprotectants. The production of NP by the vibrating nozzle device is highly reproducible, time saving, can be performed under aseptic conditions and offers the possibility of scale-up.

Fabrication and functional characterization of goldnanoconjugates for potential application in ovarian cancer

In this paper we report the surface modification and functional characterization of a gold nanoparticle-based drug delivery system for potential therapeutic application in ovarian cancer. It is currently recognized that nanotechnology may play a pivotal role in drug delivery by increasing efficacy and reducing toxicity of anti-cancer drugs. Here, we report the fabrication of a gold nanoparticles (AuNP) based drug delivery system consisting of folic acid (FA), mercapto-polyethylene glycol (PEG-SH) with a molecular weight of 2000 (designated as PSH2-2K or PSH) and cis-platin (CP) [Au-PSH-CP-FA] for potential therapeutic application in ovarian cancer. Fabrication is done in a three steps incubation process at room temperature (RT). The gold nanoconjugates are characterized with several physico-chemical techniques such as UV-Vis (UV-Visible spectroscopy), TEM (Transmission electron microscopy), ICP (Inductively coupled plasma) and radioactivity measurement with a scintillation counter. Attachment and release profiles of FA from the gold nanoconjugates are performed using (3)H-labelled FA ((3)H-FA). The expressions of folate receptor (FR) for ovarian cancer cell lines (OV-167, OVCAR-5), human umbilical vein endothelial cells (HUVEC) and ovarian surface epithelial (OSE) cells are determined by FACS analysis. Quantitation of platinum content in the nanoconjugates and its release profile is determined by platinum (Pt) analysis using ICP-MS. Biological functional characterization using in vitro proliferation assay demonstrates that Au-PSH-CP-FA not only retains the cytotoxic effect of CP, but it protects the normal cells from the cytotoxic insult, while enhancing the cytotoxic effect on the tumor cells. In future, this strategy may be utilized as a strategy for the treatment of ovarian cancers and may overcome the core side effect issues in anticancer therapy.