Drug Carrier for Photodynamic Cancer Therapy

Development of 5-Fluorouracil/pH-Responsive Adjuvant-Embedded Extracellular Vesicles for Targeting αvβ3 Integrin Receptors in Tumors

To selectively target and treat murine melanoma B16BL6 tumors expressing αvβ3 integrin receptors, we engineered tumor-specific functional extracellular vesicles (EVs) tailored for the targeted delivery of antitumor drugs. This objective was achieved through the incorporation of a pH-responsive adjuvant, cyclic arginine-glycine-aspartic acid peptide (cRGD, serving as a tumor-targeting ligand), and 5-fluorouracil (5-FU, employed as a model antitumor drug). The pH-responsive adjuvant, essential for modulating drug release, was synthesized by chemically conjugating 3-(diethylamino)propylamine (DEAP) to deoxycholic acid (DOCA, a lipophilic substance capable of integrating into EVs' membranes), denoted as DEAP-DOCA. The DOCA, preactivated using N-(2-aminoethyl)maleimide (AEM), was chemically coupled with the thiol group of the cRGD-DOCA through the thiol-maleimide click reaction, resulting in the formation of cRGD-DOCA. Subsequently, DEAP-DOCA, cRGD-DOCA, and 5-FU were efficiently incorporated into EVs using a sonication method. The resulting tumor-targeting EVs, expressing cRGD ligands, demonstrated enhanced in vitro/in vivo cellular uptake specifically for B16BL6 tumors expressing αvβ3 integrin receptors. The ionization characteristics of the DEAP in DEAP-DOCA induced destabilization of the EVs membrane at pH 6.5 through protonation of the DEAP substance, thereby expediting 5-FU release. Consequently, an improvement in the in vivo antitumor efficacy was observed for B16BL6 tumors. Based on these comprehensive in vitro/in vivo findings, we anticipate that this EV system holds substantial promise as an exceptionally effective platform for antitumor therapeutic delivery.

Design of AsLOV2 domain as a carrier of light-induced dissociable FMN photosensitizer

Flavin mononucleotide (FMN) is a highly efficient photosensitizer (PS) yielding singlet oxygen (1 O2 ). However, its 1 O2 production efficiency significantly decreases upon isoalloxazine ring encapsulation into the protein matrix in genetically encoded photosensitizers (GEPS). Reducing isoalloxazine ring interactions with surrounding amino acids by protein engineering may increase 1 O2 production efficiency GEPS, but at the same time weakened native FMN-protein interactions may cause undesirable FMN dissociation. Here, in contrast, we intentionally induce the FMN release by light-triggered sulfur oxidation of strategically placed cysteines (oxidation-prone amino acids) in the isoalloxazine-binding site due to significantly increased volume of the cysteinyl side residue(s). As a proof of concept, in three variants of the LOV2 domain of Avena sativa (AsLOV2), namely V416C, T418C, and V416C/T418C, the effective 1 O2 production strongly correlated with the efficiency of irradiation-induced FMN dissociation (wild type (WT) < V416C < T418C < V416C/T418C). This alternative approach enables us: (i) to overcome the low 1 O2 production efficiency of flavin-based GEPSs without affecting native isoalloxazine ring-protein interactions and (ii) to utilize AsLOV2, due to its inherent binding propensity to FMN, as a PS vehicle, which is released at a target by light irradiation.

Photodynamic therapy of cationic and anionic BSA-curcumin nanoparticles on amastigotes of Leishmania braziliensis and Leishmania major and Leishmania amazonensis

Cutaneous leishmaniasis is a neglected disease prevalent in tropical countries, and conventional treatment can cause several serious side effects. Photodynamic therapy (PDT) can be considered a promising treatment alternative, as it is non-invasive therapy that has no side effects and uses accessible and low-cost substances, such as curcumin. This study evaluated the PDT response with cationic and anionic BSA nanoparticles encapsulated with curcumin in macrophages infected with L. braziliensis, L. major, and L. amazonensis. The nanoparticle system was characterized using a steady-state technique, scanning electron microscopy (SEM) study, and its biological activity was evaluated using macrophage cell lines infected with different Leishmania species. All spectroscopy measurements demonstrated that BSA curcumin (BSACur) has good photophysical properties, and confocal microscopy shows that macrophages and protozoa internalized the nanoparticles. The viability test demonstrated that at low concentrations, such as 0.1, 0.7, and 1.0 µmol. L-1, there was a decrease in cell viability after PDT application. Furthermore, a decrease in the number of parasites recovered was observed in the PDT groups. The results allowed us to conclude that curcumin loaded into BSA nanoparticles may have potential application in drug delivery systems for PDT protocols, demonstrating reduced cell viability at lower concentrations than free curcumin.

Metal-based nanoparticles in cancer therapy: Exploring photodynamic therapy and its interplay with regulated cell death pathways

Photodynamic therapy (PDT) represents a non-invasive treatment strategy currently utilized in the clinical management of selected cancers and infections. This technique is predicated on the administration of a photosensitizer (PS) and subsequent irradiation with light of specific wavelengths, thereby generating reactive oxygen species (ROS) within targeted cells. The cellular effects of PDT are dependent on both the localization of the PS and the severity of ROS challenge, potentially leading to the stimulation of various cell death modalities. For many years, the concept of regulated cell death (RCD) triggered by photodynamic reactions predominantly encompassed apoptosis, necrosis, and autophagy. However, in recent decades, further explorations have unveiled additional cell death modalities, such as necroptosis, ferroptosis, cuproptosis, pyroptosis, parthanatos, and immunogenic cell death (ICD), which helps to achieve tumor cell elimination. Recently, nanoparticles (NPs) have demonstrated substantial advantages over traditional PSs and become important components of PDT, due to their improved physicochemical properties, such as enhanced solubility and superior specificity for targeted cells. This review aims to summarize recent advancements in the applications of different metal-based NPs as PSs or delivery systems for optimized PDT in cancer treatment. Furthermore, it mechanistically highlights the contribution of RCD pathways during PDT with metal NPs and how these forms of cell death can improve specific PDT regimens in cancer therapy.

Carbon Nanotubes for Targeted Therapy: Safety, Efficacy, Feasibility and Regulatory Aspects

It is crucial that novel and efficient drug delivery techniques be created in order to improve the pharmacological profiles of a wide variety of classes of medicinal compounds. Carbon nanotubes (CNTs) have recently come to the forefront as an innovative and very effective technique for transporting and translocating medicinal compounds. CNTs were suggested and aggressively researched as multifunctional novel transporters designed for targeted pharmaceutical distribution and used in diagnosis. CNTs can act as vectors for direct administration of pharmaceuticals, particularly chemotherapeutic medications. Multi-walled CNTs make up the great majority of CNT transporters, and these CNTs were used in techniques to target cancerous cells. It is possible to employ Carbon nanotubes (CNTs) to transport bioactive peptides, proteins, nucleic acids, and medicines by functionalizing them with these substances. Due to their low toxicity and absence of immunogenicity, carbon nanotubes are not immunogenic. Ammonium-functionalized carbon nanotubes are also attractive vectors for gene-encoding nucleic acids. CNTs that have been coupled with antigenic peptides have the potential to be developed into a novel and efficient approach for the use of synthetic vaccines. CNTs bring up an enormous number of new avenues for future medicine development depending on targets within cells, which have until now been difficult to access. This review focuses on the numerous applications of various CNT types used as medicine transport systems and on the utilization of CNTs for therapeutical purposes.

The Potential of Nano-Based Photodynamic Treatment as a Therapy against Oral Leukoplakia: A Narrative Review

Oral leukoplakia is a predominantly white lesion of the oral mucosa that cannot be classified as any other definable lesion with the risk of progressing into malignancy. Despite the advancements in conventional therapy, the rates of malignant transformation remain notably high, affecting 4.11% of adults, due to the difficulty of accurate diagnosis and indistinct treatment. Photodynamic therapy (PDT), being a minimally invasive surgical intervention, employs a variety of factors, including light, nano-photosensitizers (PSs) and oxygen in the management of precancerous lesions. PDT faces limitations in administering photosensitizers (PSs) because of their low water solubility. However, these challenges could be effectively resolved through the incorporation of PSs in nanostructured drug delivery systems, such as gold nanoparticles, micelles, liposomes, metal nanoparticles, dendrimers and quantum dots. This review will give an overview of the different innovative PS approaches in the management of premalignant lesions, highlighting the most recent advancements. From a clinical perspective, it is expected that nanotechnology will overcome barriers faced by traditional therapeutics and will address critical gaps in clinical cancer care.

The use of nanomaterials in advancing photodynamic therapy (PDT) for deep-seated tumors and synergy with radiotherapy

Photodynamic therapy (PDT) has been under development for at least 40 years. Multiple studies have demonstrated significant anti-tumor efficacy with limited toxicity concerns. PDT was expected to become a major new therapeutic option in treating localized cancer. However, despite a shifting focus in oncology to aggressive local therapies, PDT has not to date gained widespread acceptance as a standard-of-care option. A major factor is the technical challenge of treating deep-seated and large tumors, due to the limited penetration and variability of the activating light in tissue. Poor tumor selectivity of PDT sensitizers has been problematic for many applications. Attempts to mitigate these limitations with the use of multiple interstitial fiberoptic catheters to deliver the light, new generations of photosensitizer with longer-wavelength activation, oxygen independence and better tumor specificity, as well as improved dosimetry and treatment planning are starting to show encouraging results. Nanomaterials used either as photosensitizers per se or to improve delivery of molecular photosensitizers is an emerging area of research. PDT can also benefit radiotherapy patients due to its complementary and potentially synergistic mechanisms-of-action, ability to treat radioresistant tumors and upregulation of anti-tumoral immune effects. Furthermore, recent advances may allow ionizing radiation energy, including high-energy X-rays, to replace external light sources, opening a novel therapeutic strategy (radioPDT), which is facilitated by novel nanomaterials. This may provide the best of both worlds by combining the precise targeting and treatment depth/volume capabilities of radiation therapy with the high therapeutic index and biological advantages of PDT, without increasing toxicities. Achieving this, however, will require novel agents, primarily developed with nanomaterials. This is under active investigation by many research groups using different approaches.

Research progress on reactive oxygen species production mechanisms in tumor sonodynamic therapy

In recent years, because of the growing desire to improve the noninvasiveness and safety of tumor treatments, sonodynamic therapy has gradually become a popular research topic. However, due to the complexity of the therapeutic process, the relevant mechanisms have not yet been fully elucidated. One of the widely accepted possibilities involves the effect of reactive oxygen species. In this review, the mechanism of reactive oxygen species production by sonodynamic therapy (SDT) and ways to enhance the sonodynamic production of reactive oxygen species are reviewed. Then, the clinical application and limitations of SDT are discussed. In conclusion, current research on sonodynamic therapy should focus on the development of sonosensitizers that efficiently produce active oxygen, exhibit biological safety, and promote the clinical transformation of sonodynamic therapy.

Research progress on reactive oxygen species production mechanisms in tumor sonodynamic therapy

In recent years, because of the growing desire to improve the noninvasiveness and safety of tumor treatments, sonodynamic therapy has gradually become a popular research topic. However, due to the complexity of the therapeutic process, the relevant mechanisms have not yet been fully elucidated. One of the widely accepted possibilities involves the effect of reactive oxygen species. In this review, the mechanism of reactive oxygen species production by sonodynamic therapy (SDT) and ways to enhance the sonodynamic production of reactive oxygen species are reviewed. Then, the clinical application and limitations of SDT are discussed. In conclusion, current research on sonodynamic therapy should focus on the development of sonosensitizers that efficiently produce active oxygen, exhibit biological safety, and promote the clinical transformation of sonodynamic therapy.

Biopolymer-Based Nanogel Approach in Drug Delivery: Basic Concept and Current Developments

Due to their increased surface area, extent of swelling and active substance-loading capacity and flexibility, nanogels made from natural and synthetic polymers have gained significant interest in scientific and industrial areas. In particular, the customized design and implementation of nontoxic, biocompatible, and biodegradable micro/nano carriers makes their usage very feasible for a range of biomedical applications, including drug delivery, tissue engineering, and bioimaging. The design and application methodologies of nanogels are outlined in this review. Additionally, the most recent advancements in nanogel biomedical applications are discussed, with particular emphasis on applications for the delivery of drugs and biomolecules.

Folic Acid-Functionalized Albumin/Graphene Oxide Nanocomposite to Simultaneously Deliver Curcumin and 5-Fluorouracil into Human Colorectal Cancer Cells: An In Vitro Study

Background

Nowadays, due to various inherent properties, graphene-based nanoparticles are widely used in drug delivery research. On the other hand, folate receptors are highly expressed on the surface of human tumor cells. In this work, to enhance the 5-fluorouracil (5FU) and curcumin (Cur) effects on colon cancer, we constructed a folic acid- (FA-) modified codelivery carrier based on graphene nanoparticles (GO-Alb-Cur-FA-5FU).

Materials and Methods

The HUVEC and HT-29 were selected for evaluating the antitumor effect of the prepared nanocarriers. The structure of nanocarriers was characterized by FTIR spectroscopy, X-ray diffraction analysis, TEM microscopy, and a DLS analyzer. The efficiency of the prepared carrier was evaluated by fluorescence microscopy using Annexin V and the PI kit. The cytotoxicity of the carrier's component individually and the efficacy of the drug carrier GO-Alb-Cur-FA-5FU were assessed by MTT.

Results

The results of the pharmacological tests indicated that the new nanoparticles cause increased apparent toxicity in HT-29 cells. The apoptosis rate of the HT-29 and HUVEC cells treated with IC50 values of GO-Alb-Cur-FA-5FU for 48 h was higher than the cells treated with IC50 values of 5FU and Cur individually, which indicated the greater inhibitory efficacy of GO-Alb-Cur-FA-5FU than free drugs.

Conclusion

The designed GO-Alb-CUR-FA-5FU delivery system can be applied for targeting colon cancer cells and can be severe as a potential candidate for future drug development.

Recent Advances in Applications of Fluorescent Perylenediimide and Perylenemonoimide Dyes in Bioimaging, Photothermal and Photodynamic Therapy

The emblematic perylenediimide (PDI) motif which was initially used as a simple dye has undergone incredible development in recent decades. The increasing power of synthetic organic chemistry has allowed it to decorate PDIs to achieve highly functional dyes. As these PDI derivatives combine thermal, chemical and photostability, with an additional high absorption coefficient and near-unity fluorescence quantum yield, they have been widely studied for applications in materials science, particularly in photovoltaics. Although PDIs have always been in the spotlight, their asymmetric counterparts, perylenemonoimide (PMI) analogues, are now experiencing a resurgence of interest with new efforts to create architectures with equally exciting properties. Namely, their exceptional fluorescence properties have recently been used to develop novel systems for applications in bioimaging, biosensing and photodynamic therapy. This review covers the state of the art in the synthesis, photophysical characterizations and recently reported applications demonstrating the versatility of these two sister PDI and PMI compounds. The objective is to show that after well-known applications in materials science, the emerging trends in the use of PDI- and PMI-based derivatives concern very specific biomedicinal applications including drug delivery, diagnostics and theranostics.

Preparation of Functional Nanoparticles-Loaded Magnetic Carbon Nanohorn Nanocomposites towards Composite Treatment

Combination therapy for cancer is expected for the synergetic effect of different treatments, and the development of promising carrier materials is demanded for new therapeutics. In this study, nanocomposites including functional nanoparticles (NPs) such as samarium oxide NP for radiotherapy and gadolinium oxide NP as a magnetic resonance imaging agent were synthesized and chemically combined with iron oxide NP-embedded or carbon dot-coating iron oxide NP-embedded carbon nanohorn carriers, where iron oxide NP is a hyperthermia reagent and carbon dot exerts effects on photodynamic/photothermal treatments. These nanocomposites exerted potential for delivery of anticancer drugs (doxorubicin, gemcitabine, and camptothecin) even after being coated with poly(ethylene glycol). The co-delivery of these anticancer drugs played better drug-release efficacy than the independent drug delivery, and the thermal and photothermal procedures enlarged the drug release. Thus, the prepared nanocomposites can be expected as materials to develop advanced medication for combination treatment.

Multifunctional Photoactive Nanomaterials for Photodynamic Therapy against Tumor: Recent Advancements and Perspectives

Numerous treatments are available for cancer, including chemotherapy, immunotherapy, radiation therapy, hormone therapy, biomarker testing, surgery, photodynamic therapy, etc. Photodynamic therapy (PDT) is an effective, non-invasive, novel, and clinically approved strategy to treat cancer. In PDT, three main agents are utilized, i.e., photosensitizer (PS) drug, oxygen, and light. At first, the photosensitizer is injected into blood circulation or applied topically, where it quickly becomes absorbed or accumulated at the tumor site passively or actively. Afterward, the tumor is irradiated with light which leads to the activation of the photosensitizing molecule. PS produces the reactive oxygen species (ROS), resulting in the death of the tumor cell. However, the effectiveness of PDT for tumor destruction is mainly dependent on the cellular uptake and water solubility of photosensitizer molecules. Therefore, the delivery of photosensitizer molecules to the tumor cell is essential in PDT against cancer. The non-specific distribution of photosensitizer results in unwanted side effects and unsuccessful therapeutic outcomes. Therefore, to improve PDT clinical outcomes, the current research is mostly focused on developing actively targeted photosensitizer molecules, which provide a high cellular uptake and high absorption capacity to the tumor site by overcoming the problem associated with conventional PDT. Therefore, this review aims to provide current knowledge on various types of actively and passively targeted organic and inorganic nanocarriers for different cancers.

Application of Nanoparticles: Diagnosis, Therapeutics, and Delivery of Insulin/Anti-Diabetic Drugs to Enhance the Therapeutic Efficacy of Diabetes Mellitus

Diabetes mellitus (DM) is a chronic metabolic disorder of carbohydrates, lipids, and proteins due to a deficiency of insulin secretion or failure to respond to insulin secreted from pancreatic cells, which leads to high blood glucose levels. DM is one of the top four noncommunicable diseases and causes of death worldwide. Even though great achievements were made in the management and treatment of DM, there are still certain limitations, mainly related to the early diagnosis, and lack of appropriate delivery of insulin and other anti-diabetic agents. Nanotechnology is an emerging field in the area of nanomedicine and NP based anti-diabetic agent delivery is reported to enhance efficacy by increasing bioavailability and target site accumulation. Moreover, theranostic NPs can be used as diagnostic tools for the early detection and prevention of diseases owing to their unique biological, physiochemical, and magnetic properties. NPs have been synthesized from a variety of organic and inorganic materials including polysaccharides, dendrimers, proteins, lipids, DNA, carbon nanotubes, quantum dots, and mesoporous materials within the nanoscale size. This review focuses on the role of NPs, derived from organic and inorganic materials, in the diagnosis and treatment of DM.

Folate receptor-targeted near-infrared photodynamic therapy for folate receptor-overexpressing tumors

BACKGROUND

Photodynamic therapy (PDT) is a minimally invasive form of cancer therapy, and the development of a novel photosensitizer (PS) with optimal properties is important for enhancing PDT efficacy. Folate receptor (FR) membrane protein is frequently overexpressed in 40% of human cancer and a good candidate for tumor-specific targeting. Specific active targeting of PS to FR can be achieved by conjugation with the folate moiety. A folate-linked, near-infrared (NIR)-sensitive probe, folate-Si-rhodamine-1 (FolateSiR-1), was previously developed and is expected to be applicable to NIR-PDT.

AIM

To investigate the therapeutic efficacy of NIR-PDT induced by FolateSiR-1, a FR-targeted PS, in preclinical cancer models.

METHODS

FolateSiR-1 was developed by conjugating a folate moiety to the Si-rhodamine derivative through a negatively charged tripeptide linker. FR expression in the designated cell lines was examined by western blotting (WB). The selective binding of FolateSiR-1 to FR was confirmed in FR overexpressing KB cells (FR+) and tumors by fluorescence microscopy and in vivo fluorescence imaging. Low FR expressing OVCAR-3 and A4 cell lines were used as negative controls (FR-). The NIR light (635 ± 3 nm)-induced phototoxic effect of FolateSiR-1 was evaluated by cell viability imaging assays. The time-dependent distribution of FolateSiR-1 and its specific accumulation in KB tumors was determined using in vivo longitudinal fluorescence imaging. The PDT effect of FolateSiR-1 was evaluated in KB tumor-bearing mice divided into four experimental groups: (1) FolateSiR-1 (100 μmol/L) alone; (2) FolateSiR-1 (100 μmol/L) followed by NIR irradiation (50 J/cm²); (3) NIR irradiation (50 J/cm²) alone; and (4) no treatment. Tumor volume measurement and immunohistochemical (IHC) and histological examinations of the tumors were performed to analyze the effect of PDT.

RESULTS

High FR expression was observed in the KB cells by WB, but not in the OVCAR-3 and A4 cells. Substantial FR-specific binding of FolateSiR-1 was observed by in vitro and in vivo fluorescence imaging. Cell viability imaging assays showed that NIR-PDT induced cell death in KB cells. In vivo longitudinal fluorescence imaging showed rapid peak accumulation of FolateSiR-1 in the KB tumors 2 h after injection. In vivo PDT conducted at this time point caused tumor growth delay. The relative tumor volumes in the PDT group were significantly reduced compared to those in the other groups [5.81 ± 1.74 (NIR-PDT) vs 12.24 ± 2.48 (Folate-SiR-1), vs 11.84 ± 3.67 (IR), vs 12.98 ± 2.78 (Untreated), at Day 16, P < 0.05]. IHC analysis revealed reduced proliferation marker Ki-67-positive cells in the PDT treated tumors, and hematoxylin-eosin staining revealed features of necrotic- and apoptotic cell death.

CONCLUSION

FolateSiR-1 has potential for use in PDT, and FR-targeted NIR-PDT may open a new effective strategy for the treatment of FR-overexpressing tumors.

Nanoscale metal–organic frameworks as photosensitizers and nanocarriers in photodynamic therapy

Photodynamic therapy (PDT) is a new therapeutic system for cancer treatment that is less invasive and offers greater selectivity than chemotherapy, surgery, and radiation therapy. PDT employs irradiation light of known wavelength to excite a photosensitizer (PS) agent that undergoes photochemical reactions to release cytotoxic reactive oxygen species (ROS) that could trigger apoptosis or necrosis-induced cell death in tumor tissue. Nanoscale metal–organic frameworks (NMOFs) have unique structural advantages such as high porosity, large surface area, and tunable compositions that have attracted attention toward their use as photosensitizers or nanocarriers in PDT. They can be tailored for specific drug loading, targeting and release, hypoxia resistance, and with photoactive properties for efficient response to optical stimuli that enhance the efficacy of PDT. In this review, an overview of the basic chemistry of NMOFs, their design and use as photosensitizers in PDT, and as nanocarriers in synergistic therapies is presented. The review also discusses the morphology and size of NMOFs and their ability to improve photosensitizing properties and localize within a targeted tissue for effective and selective cancer cell death over healthy cells. Furthermore, targeting strategies that improve the overall PDT efficacy through stimulus-activated release and sub-cellular internalization are outlined with relevance to in vitro and in vivo studies from recent years.

Dual-responsive nano-prodrug micelles for MRI-guided tumor PDT and immune synergistic therapy

Micelles as nanocarriers not only offer new opportunities for early diagnosis and treatment of malignant cancers but also encounter numerous barriers in the path of efficient delivery of drugs to diseased areas in the body. To address these issues, we developed a pH/GSH responsive nano-prodrug micelle (NLG919/PGA-Cys-PPA@Gd) with a high drug-loading ratio and controlled drug release performance for MRI-guided tumor photodynamic therapy (PDT) and immune synergistic therapy. Under normal conditions, theranostic nanomicelles remained stable and in a photo-quenched state. Upon accumulation in the tumor site, however, the micelles demonstrated tumor microenvironment (TME) triggered photoactive formed-PPA (a photosensitizer) and NLG919 (an indoleamine 2,3-dioxygenase (IDO) inhibitor) release because the amide bonds of PGA-Cys-PPA and the disulfide linkage of Cys were sensitive to pH and GSH, respectively. More importantly, these micelles could avoid the undesired PPA leakage in blood circulation due to the conjugation between PPA and polymers. Furthermore, the obtained micelles could also enhance the contrast of T₁-weighted MRI of tumors by virtue of their high relaxivity (r₁ = 29.85 mM^-1 s^-1). In vitro and in vivo results illustrated that the micelles had good biocompatibility and biosafety. On the basis of the efficient drug delivery strategies in PDT and IDO pathway inhibition, this intelligent dual-drug delivery system could serve as an effective approach for MRI guided combination therapy of cancer.

New Generation of Photosensitizers Based on Inorganic Nanomaterials

Advance of nanomaterials and nanotechnology has offered new possibilities for photodynamic therapy (PDT). Large amount of different kinds of sensitizers and targeting moieties can now be loaded in nanometer's volume, which not only results in the improvement of the efficacy of PDT, but also enables the control of image-guided PDT with unprecedented precision and variation. This chapter shall overview the recently most studied inorganic nanomaterials for PDT.

Recent advances in nanoparticle-based targeting tactics for antibacterial photodynamic therapy

Abstract

The rise of antibacterial drug resistance means treatment options are becoming increasingly limited. We must find ways to tackle these hard-to-treat drug-resistant and biofilm infections. With the lack of new antibacterial drugs (such as antibiotics) reaching the clinics, research has switched focus to exploring alternative strategies. One such strategy is antibacterial photodynamic therapy (aPDT), a system that relies on light, oxygen, and a non-toxic dye (photosensitiser) to generate cytotoxic reactive oxygen species. This technique has already been shown capable of handling both drug-resistant and biofilm infections but has limited clinical approval to date, which is in part due to the low bioavailability and selectivity of hydrophobic photosensitisers. Nanotechnology-based techniques have the potential to address the limitations of current aPDT, as already well-documented in anti-cancer PDT. Here, we review recent advances in nanoparticle-based targeting tactics for aPDT.

Graphical Abstract

Biological Evaluation of Photodynamic Effect Mediated by Nanoparticles with Embedded Porphyrin Photosensitizer

Clinically approved photodynamic therapy (PDT) is a minimally invasive treatment procedure that uses three key components: photosensitization, a light source, and tissue oxygen. However, the photodynamic effect is limited by both the photophysical properties of photosensitizers as well as their low selectivity, leading to damage to adjacent normal tissue and/or inadequate biodistribution. Nanoparticles (NPs) represent a new option for PDT that can overcome most of the limitations of conventional photosensitizers and can also promote photosensitizer accumulation in target cells through enhanced permeation and retention effects. In this in vitro study, the photodynamic effect of TPP photosensitizers embedded in polystyrene nanoparticles was observed on the non-tumor NIH3T3 cell line and HeLa and G361 tumor cell lines. The efficacy was evaluated by viability assay, while reactive oxygen species production, changes in membrane mitochondrial potential, and morphological changes before and after treatment were imaged by atomic force microscopy. The tested nanoparticles with embedded TPP were found to become cytotoxic only after activation by blue light (414 nm) due to the production of reactive oxygen species. The photodynamic effect observed in this evaluation was significantly higher in both tumor lines than the effect observed in the non-tumor line, and the resulting phototoxicity depended on the concentration of photosensitizer and irradiation time.

Theranostic nanoplatforms of emodin-chitosan with blue laser light on enhancing the anti-biofilm activity of photodynamic therapy against Streptococcus mutans biofilms on the enamel surface

Background

Combining photosensitizer and light irradiation, named antimicrobial photodynamic therapy (aPDT) is an adjuvant therapy for eliminating microbial biofilms. This ex vivo study evaluates the effect of anti-biofilm activity of aPDT based on emodin-chitosan nanoparticles (Emo-CS-NPs) plus blue laser light against Streptococcus mutans biofilm on the enamel surface.

Materials

After determination of the fractional inhibitory concentration index of Emo and CS by checkerboard array assay, Emo-CS-NPs were synthesized and characterized. Following treatment of pre-formed S. mutans biofilms on the enamel slabs, cellular uptake of Emo-CS-NPs and intracellular reactive oxygen species (ROS) production were determined. The anti-biofilm and anti-metabolic activities of aPDT were investigated. Eventually, lactic acid production capacity, concentrations of S. mutans extracellular DNA (eDNA) levels, and expression of the gene involved in the biofilm formation (gtfB) were evaluated.

Results

The maximum uptake of Emo-CS-NPs occurs in an incubation time of 5 min. When irradiated, Emo-CS-NPs were photoactivated, generating ROS, and led to a decrease in the cell viability and metabolic activity of S. mutans significantly (P < 0.05). S. mutans eDNA and lactic acid production outcomes indicated that Emo-CS-NPs-mediated aPDT led to a significant reduction of eDNA levels (48%) and lactic acid production (72.4%) compared to the control group (P < 0.05). In addition, gtfB mRNA expression in S. mutans was downregulated (7.8-fold) after aPDT in comparison with the control group (P < 0.05).

Conclusions

Our data support that, aPDT using Emo-CS-NPs revealed the highest cellular uptake and ROS generation. Emo-CS-NPs based aPDT could inhibit significantly biofilm formation and reduce effectively virulence potency of S. mutans; thus, it could be an adjuvant therapy against dental caries.

A Nucleus-Targeted Nanosystem Integrated with Photodynamic Therapy and Chemotherapy

Minimally invasive photodynamic therapy, destroying lesions with a light-activated photosensitizer, has been increasingly performed since it is highly efficiency, safe, synergistically compatible, repeatable, and minimally-invasive, with few adverse reactions. However, the most present photosensitizer or nanodrug delivery system containing a photosensitizer can target tumor cells but rarely cell nuclei. In this regard, the nucleus-targeting drug delivery system has been developed aiming impair tumor cells in an efficient and direct manner. In this study, the cationic liposome (Clip) drug delivery system integrated with low dose nucleus-targeting chemotherapeutic drug Doxorubicin (DOX) and photosensitizer AlPcS4 (Clip-AlPcS4@DOX) was synthesized. Among them, Clip was used to efficiently load drugs into cells almost at the same time, low dose DOX was used to open the channel for the materials to enter the nucleus on the premise of ensuring low cytotoxicity and then introduced photosensitizer into the nucleus, AlPcS4 photosensitizer was used to damage directly and efficiently through the photodynamic therapy (PDT) effect after entering the nucleus. In summary, a nucleus-targeting nanodrug delivery system (Clip-AlPcS4@DOX) was designed and synthesized and could be induced cell apoptosis more quickly and efficiently. Therefore, it could be a promising nucleus-targeting nanosized reagent integrating the PDT and chemotherapy for gastric therapy.

Photodynamic therapy mediated by nanoparticles Aluminum Chloro Phthalocyanine in oral squamous carcinoma cells

The aim of this study is to investigate the antineoplastic potential of photodynamic therapy (PDT) mediated by an aluminum-phthalocyanine chloride nanoemulsion (AlPc-NE), against an oral squamous cell carcinoma (OSCC) cell line in vitro. Both OSCC (SCC9) and A431 cell lines were studied in vitro. Four study groups were used: Group 1 (phosphate-buffered saline [PBS]), Group 2 (PBS + 28.3 J/cm² irradiation), Group 3 (AlPc-NE alone), and Group 4 (AlPc-NE + 28.3 J/cm² irradiation). To test the effect of PDT with AlPc-NE, cell viability, migration, and cell death assays were performed. Moreover, the expressions of Ki-67 and TP53 were evaluated using immunoassays. The results showed that PDT mediated by all AlPc-NE concentrations evaluated (i.e., 0.7, 0.35, and 0.17 nM AlPc) significantly reduced the viability of SCC9 cells. Migration and cell death assays also revealed that PDT with AlPc-NE significantly reduced the rate of migration and increased cell death compared to the control groups. In addition, it was found that PDT with AlPc-NE reduced Ki-67 and mutated TP53 immunoexpression. PDT with AlPc-NE is effective in reducing the viability and migration of SCC9. Moreover, PDT with AlPc-NE nanoemulsions reduces the cell proliferation and expression of mutant TP53.

Enhanced photothermal heating and combination therapy of NIR dye via conversion to self-assembled ionic nanomaterials

Combination nanodrugs are promising therapeutic agents for cancer treatment. However, they often require the use of complex nanovehicles for transportation into the tumor site. Herein, a new class of carrier-free ionic nanomaterials (INMs) is presented, which are self-assembled by the drug molecules themselves. In this regard, a photothermal therapy (PTT) mechanism is combined with a chemotherapy (chemo) mechanism using ionic liquid chemistry to develop a combination drug to deliver multiple cytotoxic mechanisms simultaneously. Nanodrugs were developed from an ionic material-based chemo-PTT combination drug by using a simple reprecipitation method. Detailed examination of the photophysical properties (absorption, fluorescence emission, quantum yield, radiative and non-radiative rate) of the INMs revealed significant spectral changes which are directly related to their therapeutic effect. The reactive oxygen species quantum yield and the light to heat conversion efficiency of the photothermal agents were shown to be enhanced in combination nanomedicines as compared to their respective parent compounds. The ionic nanodrugs exhibited an improved dark and light cytotoxicity in vitro as compared to either the chemotherapeutic or photothermal parent compounds individually, due to a synergistic effect of the combined therapies, improved photophysical properties and their nanoparticles' morphology that enhanced the cellular uptake of the drugs. This study presents a general framework for the development of carrier-free dual-mechanism nanotherapeutics.

Preparation, characterization and releasing property of antibacterial nano-capsules composed of ε-PL-EGCG and sodium alginate-chitosan

Aquatic products with high moisture and protein content are susceptible to bacterial growth and spoilage. Searching for efficient and safe natural antibacterial agents to preserve aquatic products has been concerned widely. In this study, ε-poly-lysine-epigallocatechin gallate/sodium alginate-chitosan nanoparticles (ε-PL-EGCG/SA-CS NPs) were prepared using sodium alginate and chitosan as wall materials and ε-PL-EGCG as core material. The size of nanoparticles was about 200 nm and the encapsulation efficiency was 78.2%. Transmission electron microscopy (TEM) images confirmed the prepared spherical nanoparticles. Fourier transform infrared spectroscopy (FTIR) and multifunctional polycrystalline X-ray diffraction (XRD) spectra indicated that ε-PL-EGCG was encapsulated in the nanoparticles. Thermo-gravimetric analysis (TGA) illustrated that the thermal stability of encapsulated ε-PL-EGCG was improved more than that of bare ε-PL-EGCG. In addition, in vitro release assays showed that the ε-PL-EGCG was released continuously over 36 h. Bacteria inhibition results showed that the ε-PL-EGCG/SA-CS NPs significantly inhibited specific spoilage bacteria E3 that screened out of aquatic products, Escherichia coli and Staphylococcus aureus. In conclusion, ε-PL-EGCG/SA-CS NPs are an effective antibacterial means with wide application prospects in the field of aquatic products preservation.

Cancer-Targeted Azo Dye for Two-Photon Photodynamic Therapy in Human Colon Tissue

Inappropriate cancer management can be prevented by simultaneous cancer diagnosis, treatment, and real-time assessment of therapeutic processes. Here, we describe the design of a two-photon (TP) photosensitizer (PS), ACC-B, for high temporal and spatioselective near-infrared cancer therapy. ACC-B consisting of a biotin unit significantly enhanced the cancer sensitivity of the PS. Upon TP irradiation, ACC-B generated reactive oxygen species (ROS) through the type I photodynamic therapy (PDT) process and triggered highly selective cancer ablation. In addition, fluorescence microscopy images revealed that ACC-B-loaded live human colon tissues showed a marked difference in ACC-B uptake between normal and cancer tissues, and this property was used for real-time imaging. Upon 770 nm TP treatment, ACC-B generated ROS efficiently in live colon cancer tissues with high spatial selectivity. During PDT, ACC-B can provide in situ spatioselective visualization of cellular behavior and molecular information for therapeutic assessment in specific regions.

Enzyme-Responsive Materials as Carriers for Improving Photodynamic Therapy

Photodynamic therapy (PDT) is a mini-invasive therapy on malignancies via reactive oxygen species (ROS) induced by photosenitizer (PS) upon light irradiation. However, poor target of PS to tumor limits the clinical application of PDT. Compared with normal tissues, tumor tissues have a unique enzymatic environment. The unique enzymatic environment in tumor tissues has been widely used as a target for developing smart materials to improve the targetability of drugs to tumor. Enzyme-responsive materials (ERM) as a smart material can respond to the enzymes in tumor tissues to specifically deliver drugs. In PDT, ERM was designed to react with the enzymes highly expressed in tumor tissues to deliver PS in the target site to prevent therapeutic effects and avoid its side-effects. In the present paper, we will review the application of ERM in PDT and discuss the challenges of ERM as carriers to deliver PS for further boosting the development of PDT in the management of malignancies.

Pure photosensitizer-driven nanoassembly with core-matched PEGylation for imaging-guided photodynamic therapy

Pure drug-assembled nanomedicines (PDANs) are currently under intensive investigation as promising nanoplatforms for cancer therapy. However, poor colloidal stability and less tumor-homing ability remain critical unresolved problems that impede their clinical translation. Herein, we report a core-matched nanoassembly of pyropheophorbide a (PPa) for photodynamic therapy (PDT). Pure PPa molecules are found to self-assemble into nanoparticles (NPs), and an amphiphilic PEG polymer (PPa-PEG_2K) is utilized to achieve core-matched PEGylating modification via the π‒π stacking effect and hydrophobic interaction between the PPa core and the PPa-PEG_2K shell. Compared to PCL-PEG_2K with similar molecular weight, PPa-PEG_2K significantly increases the stability, prolongs the systemic circulation and improves the tumor-homing ability and ROS generation efficiency of PPa-nanoassembly. As a result, PPa/PPa-PEG_2K NPs exert potent antitumor activity in a 4T1 breast tumor-bearing BALB/c mouse xenograft model. Together, such a core-matched nanoassembly of pure photosensitizer provides a new strategy for the development of imaging-guided theragnostic nanomedicines.

Metal Nanoparticles for Photodynamic Therapy: A Potential Treatment for Breast Cancer

Breast cancer (BC) is the most common malignant tumor in women worldwide, which seriously threatens women’s physical and mental health. In recent years, photodynamic therapy (PDT) has shown significant advantages in cancer treatment. PDT involves activating photosensitizers with appropriate wavelengths of light, producing transient levels of reactive oxygen species (ROS). Compared with free photosensitizers, the use of nanoparticles in PDT shows great advantages in terms of solubility, early degradation, and biodistribution, as well as more effective intercellular penetration and targeted cancer cell uptake. Under the current circumstances, researchers have made promising efforts to develop nanocarrier photosensitizers. Reasonably designed photosensitizer (PS) nanoparticles can be achieved through non-covalent (self-aggregation, interfacial deposition, interfacial polymerization or core-shell embedding and physical adsorption) or covalent (chemical immobilization or coupling) processes and accumulate in certain tumors through passive and/or active targeting. These PS loading methods provide chemical and physical stability to the PS payload. Among nanoparticles, metal nanoparticles have the advantages of high stability, adjustable size, optical properties, and easy surface functionalization, making them more biocompatible in biological applications. In this review, we summarize the current development and application status of photodynamic therapy for breast cancer, especially the latest developments in the application of metal nanocarriers in breast cancer PDT, and highlight some of the recent synergistic therapies, hopefully providing an accessible overview of the current knowledge that may act as a basis for new ideas or systematic evaluations of already promising results.

Hybrid Inorganic-Organic Core-Shell Nanodrug Systems in Targeted Photodynamic Therapy of Cancer

Hybrid inorganic-organic core-shell nanoparticles (CSNPs) are an emerging paradigm of nanodrug carriers in the targeted photodynamic therapy (TPDT) of cancer. Typically, metallic cores and organic polymer shells are used due to their submicron sizes and high surface to volume ratio of the metallic nanoparticles (NPs), combined with enhances solubility, stability, and absorption sites of the organic polymer shell. As such, the high loading capacity of therapeutic agents such as cancer specific ligands and photosensitizer (PS) agents is achieved with desired colloidal stability, drug circulation, and subcellular localization of the PS agents at the cancer site. This review highlights the synthesis methods, characterization techniques, and applications of hybrid inorganic-organic CSNPs as loading platforms of therapeutic agents for use in TPDT. In addition, cell death pathways and the mechanisms of action that hybrid inorganic-organic core-shell nanodrug systems follow in TPDT are also reviewed. Nanodrug systems with cancer specific properties are able to localize within the solid tumor through the enhanced permeability effect (EPR) and bind with affinity to receptors on the cancer cell surfaces, thus improving the efficacy of short-lived cytotoxic singlet oxygen. This ability by nanodrug systems together with their mechanism of action during cell death forms the core basis of this review and will be discussed with an overview of successful strategies that have been reported in the literature.

Progress of Phototherapy Applications in the Treatment of Bone Cancer

Bone cancer including primary bone cancer and metastatic bone cancer, remains a challenge claiming millions of lives and affecting the life quality of survivors. Conventional treatments of bone cancer include wide surgical resection, radiotherapy, and chemotherapy. However, some bone cancer cells may remain or recur in the local area after resection, some are highly resistant to chemotherapy, and some are insensitive to radiotherapy. Phototherapy (PT) including photodynamic therapy (PDT) and photothermal therapy (PTT), is a clinically approved, minimally invasive, and highly selective treatment, and has been widely reported for cancer therapy. Under the irradiation of light of a specific wavelength, the photosensitizer (PS) in PDT can cause the increase of intracellular ROS and the photothermal agent (PTA) in PTT can induce photothermal conversion, leading to the tumoricidal effects. In this review, the progress of PT applications in the treatment of bone cancer has been outlined and summarized, and some envisioned challenges and future perspectives have been mentioned. This review provides the current state of the art regarding PDT and PTT in bone cancer and inspiration for future studies on PT.

Improved Photophysical Properties of Ionic Material-Based Combination Chemo/PDT Nanomedicine

Herein, a cost-effective and prompt approach to develop ionic material-based combination nanodrugs for cancer therapy is presented. A chemotherapeutic (phosphonium) cation and photodynamic therapeutic (porphyrin) anion are combined using a single step ion exchange reaction. Afterward, a nanomedicine is prepared from this ionic materials-based combination drug using a simplistic strategy of reprecipitation. Improved photophysical characteristics such as a slower nonradiative rate constant, an enhanced phosphorescence emission, a longer lifetime, and a bathochromic shift in absorbance spectra of porphyrin are observed in the presence of a chemotherapeutic countercation. The photodynamic therapeutic activity of nanomedicines is investigated by measuring the singlet oxygen quantum yield using two probes. As compared to the parent porphyrin compound, the synthesized combination material showed a 2-fold increase in the reactive oxygen species quantum yield, due to inhibition of face-to-face aggregation of porphyrin units in the presence of bulky chemotherapeutic ions. The dark cytotoxicity of combination therapy nanomedicines in the MCF-7 (cancerous breast) cell line is also increased as compared to their corresponding parent compounds in vitro. This is due to the high cellular uptake of the combination nanomedicines as compared to that of the free drug. Further, selective toxicity toward cancer cells was acquired by functionalizing nanomedicine with folic acid followed by incubation with MCF-7 and MCF-10A (noncancerous breast). Light toxicity experiments indicate that the synthesized ionic nanomedicine shows a greater cell death than either parent drug due to the improved photophysical properties and effective combination effect. This facile and economical strategy can easily be utilized in the future to develop many other combination ionic nanomedicines with improved photodynamics.

A HET-CAM based vascularized intestine tumor model as a screening platform for nano-formulated photosensitizers

The development of new tumor models for anticancer drug screening is a challenge for preclinical research. Conventional cell-based in vitro models such as 2D monolayer cell cultures or 3D spheroids allow an initial assessment of the efficacy of drugs but they have a limited prediction to the in vivo effectiveness. In contrast, in vivo animal models capture the complexity of systemic distribution, accumulation, and degradation of drugs, but visualization of the individual steps is challenging and extracting quantitative data is usually very difficult. Furthermore, there are a variety of ethical concerns related to animal tests. In accordance with the 3Rs principles of Replacement, Reduction and Refinement, alternative test systems should therefore be developed and applied in preclinical research. The Hen's egg test on chorioallantoic membrane (HET-CAM) model provides the generation of vascularized tumor spheroids and therefore, is an ideal test platform which can be used as an intermediate step between in vitro analysis and preclinical evaluation in vivo. We developed a HET-CAM based intestine tumor model to investigate the accumulation and efficacy of nano-formulated photosensitizers. Irradiation is necessary to activate the phototoxic effect. Due to the good accessibility of the vascularized tumor on the CAM, we have developed a laser irradiation setup to simulate an in vivo endoscopic irradiation. The study presents quantitative as well as qualitative data on the accumulation and efficacy of the nano-formulated photosensitizers in a vascularized intestine tumor model.

Photodynamic Therapy: A Compendium of Latest Reviews

Photodynamic therapy (PDT) is a promising therapy against cancer. Even though it has been investigated for more than 100 years, scientific publications have grown exponentially in the last two decades. For this reason, we present a brief compendium of reviews of the last two decades classified under different topics, namely, overviews, reviews about specific cancers, and meta-analyses of photosensitisers, PDT mechanisms, dosimetry, and light sources. The key issues and main conclusions are summarized, including ways and means to improve therapy and outcomes. Due to the broad scope of this work and it being the first time that a compendium of the latest reviews has been performed for PDT, it may be of interest to a wide audience.

Biosupramolecular complexes of amphiphilic photosensitizers with human serum albumin and cucurbit[7]uril as carriers for photodynamic therapy

In the present work, we evaluated the supramolecular interactions between three photosensitizers, namely toluidine blue O (TBO, positively charged) and two fatty acid conjugates of 6 and 14 carbon atoms chain lengths (TBOC6 and TBOC14), with human serum albumin (HSA) and the macrocycle cucurbit[7]uril (CB[7]), alone or in combination within a biosupramolecular system as potential carriers of photosensitizers for Photodynamic therapy (PDT). Binding studies were carried out using photophysical and calorimetric techniques and accompanied with molecular docking simulations. Amphiphilic photosensitizers, particularly TBOC14, showed stronger binding to HSA and (CB[7]). Comparing the different delivery systems, (CB[7]) had a marginal effect on cell uptake and phototoxicity in HeLa cells, while HSA showed enhanced cell uptake with phototoxicities that depended on the photosensitizer. Despite low cell uptake, the combination of both (CB[7]) and HSA was the most phototoxic, which illustrates the potential of combining these systems for PDT applications.

Liposome Photosensitizer Formulations for Effective Cancer Photodynamic Therapy

Photodynamic therapy (PDT) is a promising non-invasive strategy in the fight against that which circumvents the systemic toxic effects of chemotherapeutics. It relies on photosensitizers (PSs), which are photoactivated by light irradiation and interaction with molecular oxygen. This generates highly reactive oxygen species (such as ¹O₂, H₂O₂, O₂, ·OH), which kill cancer cells by necrosis or apoptosis. Despite the promising effects of PDT in cancer treatment, it still suffers from several shortcomings, such as poor biodistribution of hydrophobic PSs, low cellular uptake, and low efficacy in treating bulky or deep tumors. Hence, various nanoplatforms have been developed to increase PDT treatment effectiveness and minimize off-target adverse effects. Liposomes showed great potential in accommodating different PSs, chemotherapeutic drugs, and other therapeutically active molecules. Here, we review the state-of-the-art in encapsulating PSs alone or combined with other chemotherapeutic drugs into liposomes for effective tumor PDT.

Hyaluronan-fullerene/AIEgen nanogel as CD44-targeted delivery of tirapazamine for synergistic photodynamic-hypoxia activated therapy

The therapeutic effect of oxygen-concentration-dependent photodynamic therapy (PDT) can be diminished in the hypoxic environment of solid tumours, the effective solution to this problem is utilising hypoxic-activated bioreduction therapy (BRT). In this research, a biocompatible HA-C60/TPENH₂nanogel which can specifically bind to CD44 receptor was developed for highly efficient PDT-BRT synergistic therapy. The nanogel was degradable in acidic microenvironments of tumours and facilitated the release of biological reduction prodrug tirapazamine (TPZ). Importantly, HA-C60/TPENH₂nanogel produced reactive oxygen species and consumed oxygen content in the cell to activate TPZ, leading to higher cytotoxicity than the free TPZ did. The intracellular observation of nanogel indicated that the HA-C60/TPENH₂nanogel was self-fluorescence for cell imaging. This study applied PDT-BRT to design smart HA-based nanogel with targeted delivery, pH response, and AIEgen feature for efficient cancer therapy.

Keratin-Based Nanoparticles with Tumor-Targeting and Cascade Catalytic Capabilities for the Combinational Oxidation Phototherapy of Breast Cancer

Photodynamic therapy (PDT) holds tantalizing prospects of a prominent cancer treatment strategy. However, its efficacy remains limited by virtue of the hypoxic tumor microenvironment and the inadequate tumor-targeted delivery of photosensitizers, and these can be further exacerbated by the lack of development of a well-controlled nitric oxide (NO) release system at the target site. Inspired by Chinese medicine, we propose a revealing new keratin application. Keratin has garnered attention as an NO generator; however, its oncological use has rarely been investigated. We hypothesized that the incorporation of a phenylboronic acid (PBA) targeting ligand/methylene blue (MB) photosensitizer with a keratin NO donor would facilitate precise tumor delivery, enhancing PDT. Herein, we demonstrated that MB@keratin/PBA/d-α-tocopherol polyethylene glycol 1000 succinate (TPGS) nanoparticles (MB@KPTNPs) specifically targeted breast cancer cells and effectively suppressed their growth. Through MB-mediated biometabolism, the endocytic MB@KPTNPs produced a sufficient amount of intracellular NO that reduced the glutathione level while boosting the efficiency of PDT. A therapeutic combination of NO/PDT was therefore achieved, resulting in significant inhibition of both in vivo tumor growth and lung metastasis. These findings underscore the importance of utilizing keratin-based nanoparticles that simultaneously combine targeting of the tumor and self-generating NO with a cascading catalytic ability as a novel oxidation therapeutic strategy for enhancing PDT.

Poly(methacrylic Acid)-Cellulose Brushes as Anticancer Porphyrazine Carrier

The prospective strategy for treatment of cancer is based on the application of nano-sized macromolecular carriers, which are able penetrate inside and can be accumulated within tumor tissue. In this work graft copolymers of cellulose and poly(methacrylic acid) has been prepared and tested as a nanocontainers for the delivery of drug to tumor. For this purpose, two derivatives of porphyrazine suitable for photodynamic cancer therapy were loaded into prepared polymer brush. Fluorescence imaging was applied for monitoring of accumulation of porphyrazine in the CT26 murine colon carcinoma. The selective accumulation of cellulose brush loaded with porphyrazine in tumor was demonstrated by fluorescence intensity contrast between the tumor area and normal tissues. The tumor growth rate after photodynamic therapy were assessed and inhibition of its growth was revealed.

Human Serum Albumin-Oligothiophene Bioconjugate: A Phototheranostic Platform for Localized Killing of Cancer Cells by Precise Light Activation

The electronic, optical, and redox properties of thiophene-based materials have made them pivotal in nanoscience and nanotechnology. However, the exploitation of oligothiophenes in photodynamic therapy is hindered by their intrinsic hydrophobicity that lowers their biocompatibility and availability in water environments. Here, we developed human serum albumin (HSA)-oligothiophene bioconjugates that afford the use of insoluble oligothiophenes in physiological environments. UV-vis and electrophoresis proved the conjugation of the oligothiophene sensitizers to the protein. The bioconjugate is water-soluble and biocompatible, does not have any "dark toxicity", and preserves HSA in the physiological monomeric form, as confirmed by dynamic light scattering and circular dichroism measurements. In contrast, upon irradiation with ultralow light doses, the bioconjugate efficiently produces reactive oxygen species (ROS) and leads to the complete eradication of cancer cells. Real-time monitoring of the photokilling activity of the HSA-oligothiophene bioconjugate shows that living cells "explode" upon irradiation. Photodependent and dose-dependent apoptosis is one of the primary mechanisms of cell death activated by bioconjugate irradiation. The bioconjugate is a novel theranostic platform able to generate ROS intracellularly and provide imaging through the fluorescence of the oligothiophene. It is also a real-time self-reporting system able to monitor the apoptotic process. The induced phototoxicity is strongly confined to the irradiated region, showing localized killing of cancer cells by precise light activation of the bioconjugate.

Overcoming barriers in photodynamic therapy harnessing nano-formulation strategies

Photodynamic therapy (PDT) has been extensively investigated for decades for tumor treatment because of its non-invasiveness, spatiotemporal selectivity, lower side-effects, and immune activation ability. It can be a promising treatment modality in several medical fields, including oncology, immunology, urology, dermatology, ophthalmology, cardiology, pneumology, and dentistry. Nevertheless, the clinical application of PDT is largely restricted by the drawbacks of traditional photosensitizers, limited tissue penetrability of light, inefficient induction of tumor cell death, tumor resistance to the therapy, and the severe pain induced by the therapy. Recently, various photosensitizer formulations and therapy strategies have been developed to overcome these barriers. Significantly, the introduction of nanomaterials in PDT, as carriers or photosensitizers, may overcome the drawbacks of traditional photosensitizers. Based on this, nanocomposites excited by various light sources are applied in the PDT of deep-seated tumors. Modulation of cell death pathways with co-delivered reagents promotes PDT induced tumor cell death. Relief of tumor resistance to PDT with combined therapy strategies further promotes tumor inhibition. Also, the optimization of photosensitizer formulations and therapy procedures reduces pain in PDT. Here, a systematic summary of recent advances in the fabrication of photosensitizers and the design of therapy strategies to overcome barriers in PDT is presented. Several aspects important for the clinical application of PDT in cancer treatment are also discussed.

Photoinduced Photosensitizer-Antibody Conjugates Kill HIV Env-Expressing Cells, Also Inactivating HIV

HIV-infected cells persist for decades in patients administered with antiretroviral therapy (ART). Meanwhile, an alarming surge in drug-resistant HIV viruses has been occurring. Addressing these issues, we propose the application of photoimmunotherapy (PIT) against not only HIV Env-expressing cells but also HIV. Previously, we showed that a human anti-gp41 antibody (7B2) conjugated to cationic or anionic photosensitizers (PSs) could specifically target and kill the HIV Env-expressing cells. Here, our photolysis studies revealed that the binding of photoimmunoconjugates (PICs) on the membrane of HIV Env-expressing cells is sufficient to induce necrotic cell death due to physical damage to the membrane by singlet oxygen, which is independent of the type of PSs. This finding persuaded us to study the virus photoinactivation of PICs using two HIV-1 strains, X4 HIV-1 NL4-3 and JR-CSF virus. We observed that the PICs could destroy the viral strains, probably via physical damage on the HIV envelope. In conclusion, we report the application of PIT as a possible dual-tool for HIV immunotherapy and ART by killing HIV-expressing cells and cell-free HIV, respectively.

Aptamer-Targeted Photodynamic Platforms for Tumor Therapy

Achieving controlled and accurate delivery of photosensitizers (PSs) into tumor sites is a major challenge in conventional photodynamic therapy (PDT). Aptamer is a short oligonucleotide sequence (DNA or RNA) with a folded three-dimensional structure, which can selectively bind to specific small molecules, proteins, or the whole cells. Aptamers could act as ligands and be modified onto PSs or nanocarriers, enabling specific recognition and binding to tumor cells or their membrane proteins. The resultant aptamer-modified PSs or PSs-containing nanocarriers generate amounts of reactive oxygen species with light irradiation and obtain superior photodynamic therapeutic efficiency in tumors. Herein, we overview the recent progress in the designs and applications of aptamer-targeted photodynamic platforms for tumor therapy. First, we focus on the progress on the rational selection of aptamers and summarize the applications of aptamers which have been applied for targeted tumor diagnosis and therapy. Then, aptamer-targeted photodynamic therapies including various aptamer-PSs, aptamer-nanocarriers containing PSs, and aptamer-nano-photosensitizers are highlighted. The aptamer-targeted synergistically therapeutic platforms including PDT, photothermal therapy, and chemotherapy, as well as the imaging-guided theranostics, are also discussed. Finally, we offer an insight into the development trends and future perspectives of aptamer-targeted photodynamic platforms for tumor therapy.

Transferrin Modified GSH Sensitive Hyaluronic Acid Derivative Micelle to Deliver HSP90 Inhibitors to Enhance the Therapeutic Efficacy of Brain Cancers

Simple Summary

Heat shock protein 90 (HSP90) is a key element of a multi-chaperone complex involved in the stabilizing of many client proteins, oncoproteins, which play essential roles in tumorigenesis. As the result, HSP90 has been taken as a promising target for anticancer therapies. AUY922 has good antitumor activity by inhibiting the ATPase activity of HSP90, while it has certain limitations, including poor water solubility and lack of selectivity, which have incited the development of a novel targeted nanoformulation. In this study, we have successfully synthesized and characterized a GSH-sensitive micelle that can encapsulate hydrophobic AUY922 in its core region to enhance its therapeutic efficacy against brain cancers. All in vitro and in vivo experimental results showed nanoformulated AUY922 has a better therapeutic efficacy against brain cancer in comparison to the free AUY922.

Abstract

Herein, GSH-sensitive hyaluronic acid-poly(lactic-co-glycolic acid) (HA-SS-PLGA) was synthesized. Surface modification of PLGA with hyaluronic acid produced a highly stable micelle at physiological pH while a micelle was destabilized at a higher GSH level. Fluorescence microscopy results showed that rhodamine-encapsulated micelle was taken up by brain cancer cells, while competitive inhibition was observed in the presence of free HA and free transferrin. In vitro cytotoxicity results revealed that transferrin-targeted nanoformulated AUY922 (TF-NP-AUY922) shows higher cytotoxicity than either free AUY922 or non-targeted AUY922-loaded micelles (NP-AUY922). In comparison to the control groups, free AUY922, TF-NP-AUY922 or NP-AUY922 treatment revealed the upregulation of HSP70, while the expression of HSP90 client proteins was simultaneously depleted. In addition, the treatment group induced caspase-dependent PARP cleavage and the upregulation of p53 expression, which plays a key role in apoptosis of brain cancer cells. In vivo and ex vivo biodistribution studies showed that cypate-loaded micelle was taken up and accumulated in the tumor regions. Furthermore, in vivo therapeutic efficacy studies revealed that the AUY922-loaded micelle significantly suppressed tumor growth in comparison to the free AUY922, or control groups using tumor-bearing NOD-SCID mice. Moreover, biochemical index and histological analysis revealed synthesized micelle does not show any significant cytotoxicity to the selected major organs. Overall, a synthesized micelle is the best carrier for AUY922 to enhance the therapeutic efficiency of brain cancer.