Light-assisted anticancer photodynamic therapy using porphyrin-doped nanoencapsulates

Photodynamic therapy for cancer: mechanisms, photosensitizers, nanocarriers, and clinical studies

Photodynamic therapy (PDT) is a temporally and spatially precisely controllable, noninvasive, and potentially highly efficient method of phototherapy. The three components of PDT primarily include photosensitizers, oxygen, and light. PDT employs specific wavelengths of light to active photosensitizers at the tumor site, generating reactive oxygen species that are fatal to tumor cells. Nevertheless, traditional photosensitizers have disadvantages such as poor water solubility, severe oxygen-dependency, and low targetability, and the light is difficult to penetrate the deep tumor tissue, which remains the toughest task in the application of PDT in the clinic. Here, we systematically summarize the development and the molecular mechanisms of photosensitizers, and the challenges of PDT in tumor management, highlighting the advantages of nanocarriers-based PDT against cancer. The development of third generation photosensitizers has opened up new horizons in PDT, and the cooperation between nanocarriers and PDT has attained satisfactory achievements. Finally, the clinical studies of PDT are discussed. Overall, we present an overview and our perspective of PDT in the field of tumor management, and we believe this work will provide a new insight into tumor-based PDT.

Design and Synthesis of Metalloporphyrin Nanoconjugates for Dual Light-Responsive Antimicrobial Photodynamic Therapy

Antimicrobial photodynamic therapy (APDT) utilizes photosensitizers (PSs) that eradicate a broad spectrum of bacteria in the presence of light and molecular oxygen. On the other hand, some light sources such as ultraviolet (UVB and UVC) have poor penetration and high cytotoxicity, leading to undesired PDT of the PSs. Herein, we have synthesized conjugatable mesosubstituted porphyrins and extensively characterized them. Time-dependent density functional theory (TD-DFT) calculations revealed that metalloporphyrin EP (5) is a suitable candidate for further applications. Subsequently, the metalloporphyrin was conjugated with lignin-based zinc oxide nanocomposites (ZnOAL and ZnOKL) to develop hydrophilic nanoconjugates (ZnOAL@EP and ZnOKL@EP). Upon dual light (UV + green light) exposure, nanoconjugates showed enhanced singlet oxygen generation ability and also demonstrated pH responsiveness. These nanoconjugates displayed significantly improved APDT efficiency (4-7 fold increase) to treat bacterial infection under dual light irradiation.

Glycosylated Porphyrin Derivatives for Sonodynamic Therapy: ROS Generation and Cytotoxicity Studies in Breast Cancer Cells

Sonodynamic therapy (SDT) is a promising alternative to photodynamic therapy for achieving site-specific cytotoxic therapy. Porphyrin derivative molecules have been reported extensively in photodynamic therapy. We have previously shown that the glycosylation of porphyrin-based sonosensitizers can enhance their cellular uptake. However, the sonodynamic potential of these water-soluble glycosylated porphyrins has not been investigated. In this study, we characterized the sonodynamic response of two water-soluble glycosylated porphyrin derivatives. Ultrasound (US) exposure was performed (1 MHz frequency, intensities of 0.05-1.1 W/cm2) for 0-3 min in continuous mode. Reactive oxygen species (ROS) generation was quantified via ultraviolet-visible (UV-vis) spectrophotometry. MTT assay was used to quantify cytotoxicity caused by sonodynamic effects from these derivatives in the human mammary carcinoma (SUM-159) cell line in vitro. ROS generation from the porphyrin derivatives was demonstrated at a concentration of 15 μM. No significant cytotoxic effects were observed with the sonosensitizer alone or US exposure alone over the tested range of intensities and duration. The free base porphyrin derivative caused 60-70% cell death, whereas the zinc-porphyrin derivative with Zn metal conjugation caused nearly 50% cytotoxicity when exposed at 0.6 W/cm2 intensity for 3 min. These studies demonstrate the potential of anticancer SDT with soluble glycosylated porphyrins.

Applications of supramolecular assemblies in drug delivery and photodynamic therapy

One of the world's serious health challenges is cancer. Anti-cancer agents delivered to normal cells and tissues pose several problems and challenges. In this connection, photodynamic therapy (PDT) is a minimally invasive therapeutic technique used for selectively destroying malignant cells while sparing the normal tissues. Development in photosensitisers (PSs) and light sources have to be made for PDT as a first option treatment for patients. In the pursuit of developing new attractive molecules and their formulations for PDT, researchers are working on developing such type of PSs that perform better than those being currently used. For the widespread clinical utilization of PDT, effective PSs are of particular importance. Host-guest interactions based on nanographene assemblies such as functionalized hexa-cata-hexabenzocoronenes, hexa-peri-hexabenzocoronenes and coronene have attracted increasing attention owing to less complicated synthetic steps and purification processes (gel permeation chromatography) during fabrication. Noncovalent interactions provide easy and facile approaches for building supramolecular PSs and enable them to have sensitive and controllable photoactivities, which are important for maximizing photodynamic effects and minimizing side effects. Various versatile supramolecular assemblies based on cyclodextrins, cucurbiturils, calixarenes, porphyrins and pillararenes have been designed in order to make PDT an effective therapeutic technique for curing cancer and tumours. The supramolecular assemblies of porphyrins display efficient electron transfer and fluorescence for use in bioimaging and PDT. The multifunctionalization of supramolecular assemblies is used for designing biomedically active PSs, which are helpful in PDT. It is anticipated that the development of these functionalized supramolecular assemblies will provide more fascinating advances in PDT and will dramatically expand the potential and possibilities in cancer treatments.

Synthesis of Metallo-Chromone Porphyrin Nano-Starch Sensitizers as Photodynamic Therapeutics for the Eradication of Enterococci Dental Pathogens

Photodynamic therapy (PDT), as an advanced, alternative, and promising treatment, can inhibit dental pathogens. PDT employs the activation of photosensitizers via the light of a particular wavelength and molecular oxygen to inhibit dental pathogens. Herein, we present a comprehensive study on the synthesis and characterization of three chromone-porphyrins [Zn(II)-5-[4-chromone]-15-(4-phenyl)porphyrin (ZnCP), 5-[4-chromone]-15-(4-12 phenyl)porphyrin (DMCP), and Pd(II)-5-[4-chromone]-15-(4-phenyl)porphyrin (PdCP)]. Next, the computational study was also performed to establish the correlation between photophysical properties and theoretical calculations for those chromone-porphyrins using density functional theory and time-dependent density functional theory. Furthermore, chromone-porphyrins were encapsulated in starch nanoparticles to develop soluble nano-starch sensitizers (ZnCP-SNPs, DMCP-SNPs, and PdCP-SNPs) via the nanoprecipitation technique. Upon green light exposure, these nano-starch sensitizers exhibited excellent singlet oxygen generation ability. Moreover, final nanoformulations have been explored for pH responsiveness. Based on our intriguing findings, the chromone-porphyrin-loaded nano-starch sensitizers displayed great potential as prospective PDT to treat enterococci dental pathogens.

Extracellular matrix component-derived nanoparticles for drug delivery and tissue engineering

The extracellular matrix (ECM) consists of a complex combination of proteins, proteoglycans, and other biomolecules. ECM-based materials have been demonstrated to have high biocompatibility and bioactivity, which may be harnessed for drug delivery and tissue engineering applications. Herein, nanoparticles incorporating ECM-based materials and their applications in drug delivery and tissue engineering are reviewed. Proteins such as gelatin, collagen, and fibrin as well as glycosaminoglycans including hyaluronic acid, chondroitin sulfate, and heparin have been employed for cancer therapeutic delivery, gene delivery, and wound healing and regenerative medicine. Strategies for modifying and functionalizing these materials with synthetic and natural polymers or to enable stimuli-responsive degradation and drug release have increased the efficacy of these materials and nano-systems. The incorporation and modification of ECM-based materials may be used to drive drug targeting and increase tissue-specific cell differentiation more effectively.

In Situ Nanoarchitectonics of a MOF Hydrogel: A Self-Adhesive and pH-Responsive Smart Platform for Phototherapeutic Delivery

Metal-organic frameworks (MOFs) have dramatically changed the fundamentals of drug delivery, catalysis, and gas storage as a result of their porous geometry, controlled architecture, and ease of postsynthetic modification. However, the biomedical applications of MOFs still remain a less explored area due to the constraints associated with handling, utilizing, and site-specific delivery. The major drawbacks associated with the synthesis of nano-MOFs are related to the lack of control over particle size and inhomogeneous dispersion during doping. Therefore, a smart strategy for the in situ growth of a nano-metal-organic framework (nMOF) has been devised to incorporate it into a biocompatible polyacrylamide/starch hydrogel (PSH) composite for therapeutic applications. In this study, the post-treatment of zinc metal ion cross-linked PSH with the ligand solution generated the nZIF-8@PAM/starch composites (nZIF-8, nano-zeolitic imidazolate framework-8). The ZIF-8 nanocrystals thus formed have been found to be evenly dispersed throughout the composites. This newly designed nanoarchitectonics of an MOF hydrogel was found to be self-adhesive, which also exhibited improved mechanical strength, a viscoelastic nature, and a pH-responsive behavior. Taking advantage of these properties, it has been utilized as a sustained-release drug delivery platform for a potential photosensitizer drug (Rose Bengal). The drug was initially diffused into the in situ hydrogel, and then the entire scaffold was analyzed for its potential in photodynamic therapy against bacterial strains such as E. coli and B. megaterium. The Rose Bengal loaded nano-MOF hydrogel composite exhibited remarkable IC₅₀ values within the range of 7.37 ± 0.04 and 0.51 ± 0.05 μg/mL for E. coli and B. megaterium. Further, reactive oxygen species (ROS) directed antimicrobial potential was validated using a fluorescence-based assay. This smart in situ nanoarchitectonics hydrogel platform can also serve as a potential biomaterial for topical treatment including wound healing, lesions, and melanoma.

Spectroscopic Investigations of Porphyrin-TiO2 Nanoparticles Complexes

This study presents the spectral characterization of TiO₂ nanoparticles (NPs) functionalized with three porphyrin derivatives: 5,10,15,20-(Tetra-4-aminophenyl) porphyrin (TAPP), 5,10,15,20-(Tetra-4-methoxyphenyl) porphyrin (TMPP), and 5,10,15,20-(Tetra-4-carboxyphenyl) porphyrin (TCPP). UV-Vis absorption and Fourier transform infrared spectroscopy-attenuated total reflection (FTIR-ATR) spectroscopic studies of these porphyrins and their complexes with TiO₂ NPs were performed. In addition, the efficiency of singlet oxygen generation, the key species in photodynamic therapy, was investigated. UV-Vis absorption spectra of the NPs complexes showed the characteristic bands of porphyrins. These allowed us to determine the loaded porphyrins on TiO₂ NPs functionalized with porphyrins. FTIR-ATR revealed the formation of porphyrin-TiO₂ complexes, suggesting that porphyrin adsorption on TiO₂ may involve the pyrroles in the porphyrin ring, or the radicals of the porphyrin derivative. The quantum yield for singlet oxygen generation by the studied porphyrin complexes with TiO₂ was higher compared to bare porphyrins for TAPP and TMPP, while for the TCPP-TiO₂ NPs complex, a decrease was observed, but still maintained a good efficiency. The TiO₂ NPs conjugates can be promising candidates to be tested in photodynamic therapy in vitro assays.

Recent Trends and Developments in Multifunctional Nanoparticles for Cancer Theranostics

Conventional anticancer treatments, such as radiotherapy and chemotherapy, have significantly improved cancer therapy. Nevertheless, the existing traditional anticancer treatments have been reported to cause serious side effects and resistance to cancer and even to severely affect the quality of life of cancer survivors, which indicates the utmost urgency to develop effective and safe anticancer treatments. As the primary focus of cancer nanotheranostics, nanomaterials with unique surface chemistry and shape have been investigated for integrating cancer diagnostics with treatment techniques, including guiding a prompt diagnosis, precise imaging, treatment with an effective dose, and real-time supervision of therapeutic efficacy. Several theranostic nanosystems have been explored for cancer diagnosis and treatment in the past decade. However, metal-based nanotheranostics continue to be the most common types of nonentities. Consequently, the present review covers the physical characteristics of effective metallic, functionalized, and hybrid nanotheranostic systems. The scope of coverage also includes the clinical advantages and limitations of cancer nanotheranostics. In light of these viewpoints, future research directions exploring the robustness and clinical viability of cancer nanotheranostics through various strategies to enhance the biocompatibility of theranostic nanoparticles are summarised.

Novel archetype in cancer therapeutics: exploring prospective of phytonanocarriers

This paper reports various types of cancer, their incidence, and prevalence all over the globe. Along with the discovery of novel natural drugs for cancer treatment, these present a promising option which are eco-friendly, safe, and provide better acceptability in comparison to synthetic agents that carries multiple side effects. This paper provides an idea about various nanocarriers and phytochemicals, along with how their solubility and bioavailability can be enhanced in nanocarrier system. This report combines the data from various literature available on public domain including PubMed on research articles, reviews, and along with report from various national and international sites. Specialized metabolites (polyphenols, alkaloids, and steroids etc) from medicinal plants are promising alternatives to existing drugs. Studies have suggested that the treatment of cancer using plant products could be an alternative and a safe option. Studies have shown with the several cell lines as well as animal models, that phytomolecules are important in preventing/treating cancer. Phytochemicals often outperform chemical treatments by modulating a diverse array of cellular signaling pathways, promoting cell cycle arrest, apoptosis activation, and metastatic suppression, among others. However, limited water solubility, bioavailability, and cell penetration limit their potential clinical manifestations. The development of plant extract loaded nanostructures, rendering improved specificity and efficacy at lower concentrations could prove effective. Nanocarriers, such as liposomes, nanostructured lipids, polymers, and metal nanoparticles, have been tested for the delivery of plant products with enhanced effects. Recent advances have achieved improvement in the the stability, solubility, bioavailability, circulation time, and target specificity by nanostructure-mediated delivery of phytochemicals. Nanoparticles have been considered and attempted as a novel, targeted, and safe option. Newer approaches such as phyto-nanocarriers with carbohydrates, lignin, and polymers have been considered even more selective and effective modes of drug delivery in biomedical or diagnostic applications.

Polymeric Nanomaterials for Efficient Delivery of Antimicrobial Agents

Bacterial infections have threatened the lives of human beings for thousands of years either as major diseases or complications. The elimination of bacterial infections has always occupied a pivotal position in our history. For a long period of time, people were devoted to finding natural antimicrobial agents such as antimicrobial peptides (AMPs), antibiotics and silver ions or synthetic active antimicrobial substances including antimicrobial peptoids, metal oxides and polymers to combat bacterial infections. However, with the emergence of multidrug resistance (MDR), bacterial infection has become one of the most urgent problems worldwide. The efficient delivery of antimicrobial agents to the site of infection precisely is a promising strategy for reducing bacterial resistance. Polymeric nanomaterials have been widely studied as carriers for constructing antimicrobial agent delivery systems and have shown advantages including high biocompatibility, sustained release, targeting and improved bioavailability. In this review, we will highlight recent advances in highly efficient delivery of antimicrobial agents by polymeric nanomaterials such as micelles, vesicles, dendrimers, nanogels, nanofibers and so forth. The biomedical applications of polymeric nanomaterial-based delivery systems in combating MDR bacteria, anti-biofilms, wound healing, tissue engineering and anticancer are demonstrated. Moreover, conclusions and future perspectives are also proposed.

Photodynamic therapy for leishmaniasis: Recent advances and future trends

Leishmaniasis has infected more than 12 million people worldwide. This neglected tropical disease, causing 20,000-30,000 deaths per year, is a global health problem. The emergence of resistant parasites and serious side effects of conventional therapies has led to the search for less toxic and non-invasive alternative treatments. Photodynamic therapy is a promising therapeutic strategy to produce reactive oxygen species for the treatment of leishmaniasis. In this regard, natural and synthetic photosensitizers such as curcumin, hypericin, 5-aminolevulinic acid, phthalocyanines, phenothiazines, porphyrins, chlorins and nanoparticles have been applied. In this review, the recent advances on using photodynamic therapy for treating Leishmania species have been reviewed.

Insights on the polypyrrole based nanoformulations for photodynamic therapy

This review is written to endow updated information on polypyrrole based photosensitizers for the treatment of deadly diseases such as cancer and microbial infection. Tetrapyrrolic macromolecules such as porphyrins and phthalocyanines hold unique photophysical properties which make them very useful compounds for various biomedical applications. Besides their properties, they also have some limitations such as low water solubility, bioavailability, biocompatibility and lack of specificity, etc. Researchers are trying to overcome these limitations by incorporating photosensitizers into the different types of nanoparticles and improve the quality of photodynamic therapy. We have contributed to this field by synthesizing and developing polypyrrolic photosensitizer based nanoparticles for potential applications in antimicrobial and anticancer photodynamic activity. Throughout this review, newly synthesized and existing PSs conjugated/encapsulated/doped/incorporated with nanoparticles are emphasized, which are essential for current and future research themes. Also in this review, we briefly summarized the research work carried over the past few years by considering the porphyrin based photosensitizers as alternative therapeutic entities for the treatment of microbial infections, cancers, and many other diseases.