Multifunctional theranostic Pluronic mixed micelles improve targeted photoactivity of Verteporfin in cancer cells

Nanotechnology development provides new strategies to treat cancer by integration of different treatment modalities in a single multifunctional nanoparticle. In this scenario, we applied the multifunctional Pluronic P123/F127 mixed micelles for Verteporfin-mediated photodynamic therapy in PC3 and MCF-7 cancer cells. Micelles functionalization aimed the targeted delivery by the insertion of biotin moiety on micelle surface and fluorescence image-based through rhodamine-B dye conjugation in the polymer chains. Multifunctional Pluronics formed spherical nanoparticulated micelles that efficiently encapsulated the photosensitizer Verteporfin maintaining its favorable photophysical properties. Lyophilized formulations were stable at least for 6months and readily reconstituted in aqueous media. The multifunctional micelles were stable in protein-rich media due to the dual Pluronic mixed micelles characteristic: high drug loading capacity provided by its micellar core and high kinetic stability due its biocompatible shell. Biotin surface functionalized micelles showed higher internalization rates due biotin-mediated endocytosis, as demonstrated by competitive cellular uptake studies. Rhodamine B-tagged micelles allowed monitoring cellular uptake and intracellular distribution of the formulations. Confocal microscopy studies demonstrated a larger intracellular distribution of the formulation and photosensitizer, which could drive Verteporfin to act on multiple cell sites. Formulations were not toxic in the dark condition, but showed high Verteporfin-induced phototoxicity against both cancer cell lines at low drug and light doses. These results point Verteporfin-loaded multifunctional micelles as a promising tool to further developments in photodynamic therapy of cancer.

Photosensitizer-based metal-organic frameworks for highly effective photodynamic therapy

Photodynamic therapy (PDT) uses a photosensitizer, molecular oxygen, and visible light as an alternative clinical protocol against located malignant tumors and other diseases. More recently, PDT has been combined to immunotherapy as a promising option to treat metastatic cancer. However, previous generations of photosensitizers (PSs) revealed clinical difficulties such as long-term skin photosensitivity (first generation), the need for drug delivery vehicles (second generation), and intracellular self-aggregation (third generation), which have generated a somewhat confusing scenario in PDT approaches and evolution. Recently, metal-organic frameworks (MOFs) with exceptionally high PS loading as a building unit of MOF framework have emerged as fourth-generation PS and presented outstanding outcomes under pre-clinical studies. For PS-based MOFs, the inorganic building unit (metal ions/clusters) plays an important role as a coadjuvant in PDT to alleviate hypoxia, to decrease antioxidant species, to yield ROS, or to act as a contrast agent for imaging-guided therapy. In this review, we intend to carry out a broad update on the recent history and the characteristics of PS-based MOFs from basic chemistry to the structure relationship with biological application in PDT. The details and variables that result in different photophysics, size, and morphology, are discussed. Also, we present an overview of the achievements on the pre-clinical assays in combination with other strategies, including alleviating hypoxia in solid tumors, chemotherapy, and the most recent immunotherapy for cancer.

Spectroscopic analysis of aluminum chloride phthalocyanine in binary water/ethanol systems for the design of a new drug delivery system for photodynamic therapy cancer treatment

This study evaluated the behavior of aluminum chloride phthalocyanine in a binary water/ethanol mixture using electronic absorption spectroscopy and static and time-resolved fluorescence spectroscopy. The electronic absorption spectra, resonance light scattering and fluorescence quenching of aluminum chloride phthalocyanine in water/ethanol mixtures were studied at several concentrations. The electronic absorption spectra and fluorescence quenching changed significantly at approximately 50% water (v/v). Below 50% water, the dimerization constant values were negative (-2609.2 M(-1) and -506.5 M(-1) at 30% and 40% of water, respectively), indicating that the formation of aggregates under these conditions is not favored. However, at 50% water, the dimerization constant value was estimated to be 559.7 M(-1), which indicates the presence of dimers. Above 60% water, the aggregation process was responsible for the balance between large complexes (such as trimers, tetramers or oligomers) formed in the medium under these conditions. The appearance of new absorption bands at 387 nm and 802 nm and their bathochromic shift relative to the monomer bands suggested that some J-type aggregates form. These results are relevant to understanding the behavior and use of aluminum chloride phthalocyanine in the design of new drug delivery systems for clinical application in photodynamic therapy as a new approach to treat skin cancer.

Evaluation of aluminum phthalocyanine chloride and DNA interactions for the design of an advanced drug delivery system in photodynamic therapy

The aim of this study was to evaluate the interaction of aluminum phthalocyanine chloride (AlClPc) with double-stranded DNA. Absorption and fluorescence spectra, resonance light scattering, and circular dichroism were evaluated in water and water/ethanol mixtures with different concentrations of DNA or AlClPc. AlClPc showed a high ability to bind to DNA in both water and 4/6 water/ethanol mixture (v/v), with a majority of monomeric and aggregated initial forms of AlClPc, respectively. In this interaction, AlClPc bound preferentially to the grooves of DNA. The monomeric/aggregate state of AlClPc in DNA was dependent on the AlClPc/DNA ratio. At low concentrations of AlClPc, the interaction of AlClPc with few DNA sites caused a curvature in the DNA structure that provided a favorable environment for the intercalation of AlClPc aggregates. Increase in AlClPc concentration induced interactions with a high number of binding sites on DNA, which prevented bending and therefore aggregation of AlClPc molecules throughout the double-stranded DNA. These results are relevant to the understanding of the behavior and interaction of AlClPc with double-stranded DNA in the design of novel drug delivery systems for clinical application in photodynamic therapy as a new approach to treat skin or oral cancer, scars, or wound healing.

Expanding the Limits of Photodynamic Therapy: The Design of Organelles and Hypoxia-Targeting Nanomaterials for Enhanced Photokilling of Cancer

Photodynamic therapy (PDT) is a minimally invasive clinical protocol that combines a nontoxic photosensitizer (PS), appropriate visible light, and molecular oxygen for cancer treatment. This triad generates reactive oxygen species (ROS) in situ, leading to different cell death pathways and limiting the arrival of nutrients by irreversible destruction of the tumor vascular system. Despite the number of formulations and applications available, the advancement of therapy is hindered by some characteristics such as the hypoxic condition of solid tumors and the limited energy density (light fluence) that reaches the target. As a result, the use of PDT as a definitive monotherapy for cancer is generally restricted to pretumor lesions or neoplastic tissue of approximately 1 cm in size. To expand this limitation, researchers have synthesized functional nanoparticles (NPs) capable of carrying classical photosensitizers with self-supplying oxygen as well as targeting specific organelles such as mitochondria and lysosomes. This has improved outcomes in vitro and in vivo. This review highlights the basis of PDT, many of the most commonly used strategies of functionalization of smart NPs, and their potential to break the current limits of the classical protocol of PDT against cancer. The application and future perspectives of the multifunctional nanoparticles in PDT are also discussed in some detail.

Theoretical and experimental studies concerning monomer/aggregates equilibrium of zinc phthalocyanine for future photodynamic action

Monomeric zinc phthalocyanine has been studied as a promising active photosensitizer in photodynamic therapy against cancer, in which its aggregate form is non-active. This paper aimed to describe the monomer/aggregates equilibrium of zinc phthalocyanine in binary water/DMSO mixtures. To reach this aim theoretical calculation, electronic absorption, static and time-resolved fluorescence, and resonance light scattering was used. Zinc phthalocyanine shows a complex water dependence behavior in the mixture. At least three distinct steps were observed: (i) until 30% water zinc phthalocyanine is essentially in the monomeric form, changing to (ii) small slipped cofacial-aggregates around 30% to 40% water and finally to (iii) a staircase arrangement of large aggregates at higher water percent. The staircase arrangement is driven by the intermolecular coordination between the pyrrolic nitrogen lone-pairs and the central metal zinc. The water-Zn coordination governs the fluorescence quenching by a static mechanism. These results have direct relevance in the better understanding on the behavior of zinc phthalocyanine in vivo and when incorporated in drug delivery systems for clinical applications in photodynamic therapy.

Type-I Collagen/Collagenase Modulates the 3D Structure and Behavior of Glioblastoma Spheroid Models

Multicellular tumor spheroids have emerged as well-structured, three-dimensional culture models that resemble and mimic the complexity of the dense and hypoxic cancer microenvironment. However, in brain tumor studies, a variety of glioblastoma multiforme (GBM) cell lines only self-assemble into loose cellular aggregates, lacking the properties of actual glioma tumors in humans. In this study, we used type-I collagen as an extracellular matrix component to promote the compaction of GBM aggregates forming tight spheroids to understand how collagen influences the properties of tumors, such as their growth, proliferation, and invasion, and collagenase to promote collagen degradation. The GBM cell lines U87MG, T98G, and A172, as well as the medulloblastoma cell line UW473, were used as standard cell lines that do not spontaneously self-assemble into spheroids, and GBM U251 was used as a self-assembling cell line. According to the findings, all cell lines formed tight spheroids at collagen concentrations higher than 15.0 μg mL^-1. Collagen was distributed along the spheroid, similarly to that observed in invasive GBM tumors, and decreased cell migration with no effect on the cellular uptake of small active molecules, as demonstrated by uptake studies using the photosensitizer verteporfin. The enzymatic cleavage of collagen affected spheroid morphology and increased cell migration while maintaining cell viability. Such behaviors are relevant to the physiological models of GBM tumors and are useful for better understanding cell migration and the in vivo infiltration path, drug screening, and kinetics of progression of GBM tumors.

Melanoma spheroid-containing artificial dermis as an alternative approach to in vivo models

Melanoma spheroid-loaded 3D skin models allow for the study of crucial tumor characteristics and factors at a superior level because the neoplastic cells are integrated into essential human skin components, permitting tumor-skin model communication. Herein, we designed a melanoma-containing artificial dermis by inserting multicellular tumor spheroids from the metastatic phase of WM 1617 melanoma cells into an artificial dermis. We cultured multicellular melanoma spheroids by hanging drop method (250 cells per drop) with a size of 420 μm in diameter after incubation for 14 days. These spheroids were integrated into the dermal equivalents that had been previously preparedwith a type-I collagen matrix and healthy fibroblasts. The melanoma spheroid cells invaded and proliferated in the artificial dermis. Spheroids treated with a 1.0 μmol/L aluminum chloride phthalocyanine nanoemulsion in the absence of light showed high cell viability. In contrast, under irradiation with visible red light (660 nm) at 25 J/cm2, melanoma cells were killed and the healthy tissue was preserved, indicating that photodynamic therapy is effective in such a model. Therefore, the 3D skin melanoma model has potential to promote research in full-thickness skin model targeting optimized preclinical assays.

Photo-responsive polymeric micelles for the light-triggered release of curcumin targeting antimicrobial activity

Nanocarriers have been successfully used to solubilize, deliver, and increase the bioavailability of curcumin (CUR), but slow CUR release rates hinder its use as a topical photosensitizer in antimicrobial photodynamic therapy. A photo-responsive polymer (PRP) was designed for the light-triggered release of CUR with an effective light activation-dependent antimicrobial response. The characterization of the PRP was compared with non-responsive micelles comprising Pluronics™ P123 and F127. According to the findings, the PRP formed photo-responsive micelles in the nanometric scale (< 100 nm) with a lower critical micelle concentration (3.74 × 10^-4 M^-1, 5.8 × 10^-4 M^-1, and 7.2 × 10^-6 M^-1 for PRP, F127, P123, respectively, at 25°C) and higher entrapment efficiency of CUR (88.7, 77.2, and 72.3% for PRP, F127, and P123 micelles, respectively) than the pluronics evaluated. The PRP provided enhanced protection of CUR compared to P123 micelles, as demonstrated in fluorescence quenching studies. The light-triggered release of CUR from PRP occurred with UV light irradiation (at 355 nm and 25 mW cm^-2) and a cumulative release of 88.34% of CUR within 1 h compared to 80% from pluronics after 36 h. In vitro studies showed that CUR-loaded PRP was non-toxic to mammal cell, showed inactivation of the pathogenic microorganisms Candida albicans, Pseudomonas aeruginosa, and methicillin-resistant Staphylococcus aureus, and decreased biofilm biomass when associated with blue light (455  nm, 33.84 J/cm²). The findings show that the CUR-loaded PRP micelle is a viable option for antimicrobial activity.

Renal proximal tubule-on-a-chip in PDMS: fabrication, functionalization, and RPTEC:HUVEC co-culture evaluation

'On-a-chip' technology advances the development of physiologically relevant organ-mimicking architecture by integrating human cells into three-dimensional microfluidic devices. This method also establishes discrete functional units, faciliting focused research on specific organ components. In this study, we detail the development and assessment of a convoluted renal proximal tubule-on-a-chip (PT-on-a-chip). This platform involves co-culturing Renal Proximal Tubule Epithelial Cells (RPTEC) and Human Umbilical Vein Endothelial Cells (HUVEC) within a polydimethylsiloxane microfluidic device, crafted through a combination of 3D printing and molding techniques. Our PT-on-a-chip significantly reduced high glucose level, exhibited albumin uptake, and simulated tubulopathy induced by amphotericin B. Remarkably, the RPTEC:HUVEC co-culture exhibited efficient cell adhesion within 30 min on microchannels functionalized with plasma, 3-aminopropyltriethoxysilane, and type-I collagen. This approach significantly reduced the required incubation time for medium perfusion. In comparison, alternative methods such as plasma and plasma plus polyvinyl alcohol were only effective in promoting cell attachment to flat surfaces. The PT-on-a-chip holds great promise as a valuable tool for assessing the nephrotoxic potential of new drug candidates, enhancing our understanding of drug interactions with co-cultured renal cells, and reducing the need for animal experimentation, promoting the safe and ethical development of new pharmaceuticals.

Interaction of triblock copolymers (Pluronic®) with DMPC vesicles: a photophysical and computational study

Pluronic/lipid mix promises stealth liposomes with long circulation time and long-term stability for pharmaceutical applications. However, the influence of Pluronics on several aspects of lipid membranes has not been fully elucidated. Herein it was described the effect of Pluronics on the structured water, alkyl chain conformation, and kinetic stability of dimyristoylphosphatidylcholine (DMPC) liposomes using interfacial and deeper fluorescent probes along with computational molecular modeling data. Interfacial water changed as a function of Pluronics' hydrophobicity with polypropylene oxide (PPO) anchoring the copolymers in the lipid bilayer. Pluronics with more than 30-40 PO units had facilitated penetration at the bilayer while shorter PPO favored a more interfacial interaction. Low Pluronic concentrations provided long-term stability of vesicles by steric effects of polyethylene oxide (PEO), but high amounts destabilized the vesicles as a sum of water-bridge cleavage at the polar head group and the reduced alkyl-alkyl interactions among the lipids. The high kinetic stability of Pluronic/DMPC vesicles is a proof-of-concept of its advantages and applicability in nanotechnology over conventional liposome-based pharmaceutical products for future biomedical applications.