Encapsulated Rose Bengal Enhances the Photodynamic Treatment of Triple-Negative Breast Cancer Cells.

Among breast cancer subtypes, triple-negative breast cancer stands out as the most aggressive, with patients facing a 40% mortality rate within the initial five years. The limited treatment options and unfavourable prognosis for triple-negative patients necessitate the development of novel therapeutic strategies. Photodynamic therapy (PDT) is an alternative treatment that can effectively target triple-negative neoplastic cells such as MDA-MB-231. In this in vitro study, we conducted a comparative analysis of the PDT killing rate of unbound Rose Bengal (RB) in solution versus RB-encapsulated chitosan nanoparticles to determine the most effective approach for inducing cytotoxicity at low laser powers (90 mW, 50 mW, 25 mW and 10 mW) and RB concentrations (50 µg/mL, 25 µg/mL, 10 µg/mL and 5 µg/mL). Intracellular singlet oxygen production and cell uptake were also determined for both treatment modalities. Dark toxicity was also assessed for normal breast cells. Despite the low laser power and concentration of nanoparticles (10 mW and 5 µg/mL), MDA-MB-231 cells experienced a substantial reduction in viability (8 ± 1%) compared to those treated with RB solution (38 ± 10%). RB nanoparticles demonstrated higher singlet oxygen production and greater uptake by cancer cells than RB solutions. Moreover, RB nanoparticles display strong cytocompatibility with normal breast cells (MCF-10A). The low activation threshold may be a crucial advantage for specifically targeting malignant cells in deep tissues.

Rose bengal-encapsulated chitosan nanoparticles for the photodynamic treatment of Trichophyton species.

Rose bengal (RB) solutions coupled with a green laser have proven to be efficient in clearing resilient nail infections caused by Trichophyton rubrum in a human pilot study and in extensive in vitro experiments. Nonetheless, the RB solution can become diluted or dispersed over the tissue and prevented from penetrating the nail plate to reach the subungual area where fungal infection proliferates. Nanoparticles carrying RB can mitigate the problem of dilution and are reported to effectively penetrate through the nail. For this reason, we have synthesized RB-encapsulated chitosan nanoparticles with a peak distribution size of ~200 nm and high reactive oxygen species (ROS) production. The RB-encapsulated chitosan nanoparticles aPDT were shown to kill more than 99% of T. rubrum, T. mentagrophytes, and T. interdigitale spores, which are the common clinically relevant pathogens in onychomycosis. These nanoparticles are not cytotoxic against human fibroblasts, which promotes their safe application in clinical translation.

Photodynamic Treatment of Human Breast and Prostate Cancer Cells Using Rose Bengal-Encapsulated Nanoparticles.

Cancer, a prominent cause of death, presents treatment challenges, including high dosage requirements, drug resistance, poor tumour penetration and systemic toxicity in traditional chemotherapy. Photodynamic therapy, using photosensitizers like rose bengal (RB) with a green laser, shows promise against breast cancer cells in vitro. However, the hydrophilic RB struggles to efficiently penetrate the tumour site due to the unique clinical microenvironment, aggregating around rather than entering cancer cells. In this study, we have synthesized and characterized RB-encapsulated chitosan nanoparticles with a peak particle size of ~200 nm. These nanoparticles are readily internalized by cells and, in combination with a green laser (λ = 532 nm) killed 94-98% of cultured human breast cancer cells (MCF-7) and prostate cancer cells (PC3) at a low dosage (25 µg/mL RB-nanoparticles, fluence ~126 J/cm2, and irradiance ~0.21 W/cm2). Furthermore, these nanoparticles are not toxic to cultured human normal breast cells (MCF10A), which opens an avenue for translational applications.

Fabrication and characterization of chitosan nanoparticles using the coffee-ring effect for photodynamic therapy.

BACKGROUND AND OBJECTIVES: Biocompatible nanoparticles have been increasingly used in a variety of medical applications, including photodynamic therapy. Although the impact of synthesis parameters and purification methods is reported in previous studies, it is still challenging to produce a reliable protocol for the fabrication, purification, and characterization of nanoparticles in the 200-300 nm range that are highly monodisperse for biomedical applications. STUDY DESIGN/MATERIALS AND METHODS: We investigated the synthesis of chitosan nanoparticles in the 200-300 nm range by evaluating the chitosan to sodium tripolyphosphate (TPP) mass ratio and acetic acid concentration of the chitosan solution. Chitosan nanoparticles were also crosslinked to rose bengal and incubated with human breast cancer cells (MCF-7) to test photodynamic activity using a green laser (λ = 532 nm, power = 90 mW). RESULTS: We established a simple protocol to fabricate and purify biocompatible nanoparticles with the most frequent size occurring between 200 and 300 nm. This was achieved using a chitosan to TPP mass ratio of 5:1 in 1% v/v acetic acid at a pH of 5.5. The protocol involved the formation of nanoparticle coffee rings that showed the particle shape to be spherical in the first approximation. Photodynamic treatment with rose bengal-nanoparticles killed ~98% of cancer cells. CONCLUSION: A simple protocol was established to prepare and purify spherical and biocompatible chitosan nanoparticles with a peak size of ~200 nm. These have remarkable antitumor activity when coupled with photodynamic treatment.

Surfactant-Mediated and Morphology-Controlled Nanostructured LiFePO4/Carbon Composite as a Promising Cathode Material for Li-Ion Batteries.

The synthesis of morphology-controlled carbon-coated nanostructured LiFePO4 (LFP/Carbon) cathode materials by surfactant-assisted hydrothermal method using block copolymers is reported. The resulting nanocrystalline high surface area materials were coated with carbon and designated as LFP/C123 and LFP/C311. All the materials were systematically characterized by various analytical, spectroscopic and imaging techniques. The reverse structure of the surfactant Pluronic® 31R1 (PPO-PEO-PPO) in comparison to Pluronic® P123 (PEO-PPO-PEO) played a vital role in controlling the particle size and morphology which in turn ameliorate the electrochemical performance in terms of reversible specific capacity (163 mAh g-1 and 140 mAh g-1 at 0.1 C for LFP/C311 and LFP/C123, respectively). In addition, LFP/C311 demonstrated excellent electrochemical performance including lower charge transfer resistance (146.3 Ω) and excellent cycling stability (95 % capacity retention at 1 C after 100 cycles) and high rate capability (163.2 mAh g-1 at 0.1 C; 147.1 mAh g-1 at 1 C). The better performance of the former is attributed to LFP nanoparticles (<50 nm) with a specific spindle-shaped morphology. Further, we have also evaluated the electrode performance with the use of both PVDF and CMC binders employed for the electrode fabrication.

Porous chitosan adhesives with L-DOPA for enhanced photochemical tissue bonding.

L-3,4-dihydroxyphenylalanine (L-DOPA) is a naturally occurring catechol that is known to increase the adhesive strength of various materials used for tissue repair. With the aim of fortifying a porous and erodible chitosan-based adhesive film, L-DOPA was incorporated in its fabrication for stronger photochemical tissue bonding (PTB), a repair technique that uses light and a photosensitiser to promote tissue adhesion. The results showed that L-DOPA did indeed increase the tissue bonding strength of the films when photoactivated by a green LED, with a maximum strength recorded of approximately 30 kPa, 1.4 times higher than in its absence. The addition of L-DOPA also did not appreciably change the swelling, mechanical and erodible properties of the film. This study showed that strong, porous and erodible adhesive films for PTB made from biocompatible materials can be obtained through a simple inclusion of a natural additive such as L-DOPA, which was simply mixed with chitosan without any chemical modifications. In vitro studies using human fibroblasts showed no negative effect on cell proliferation indicating that these films are biocompatible. The films are convenient for various surgical applications as they can provide strong tissue support and a microporous environment for cellular infusion without the use of sutures. STATEMENT OF SIGNIFICANCE: Tissue adhesives are not as strong as sutures on wounds under stress. Our group has previously demonstrated that strong sutureless tissue repair can be realised with chitosan-based adhesive films that photochemically bond to tissue when irradiated with green light. The advantage of this technique is that films are easier to handle than glues and sutures, and their crosslinking reactions can be controlled with light. However, these films are not optimal for high-tension tissue regenerative applications because of their non-porous structure, which cannot facilitate cell and nutrient exchange at the wound site. The present study resolves this issue, as we obtained a strong and porous photoactivated chitosan-based adhesive film, by simply using freeze drying and adding L-DOPA.

Porous Chitosan Films Support Stem Cells and Facilitate Sutureless Tissue Repair.

Photochemical tissue bonding with chitosan-based adhesive films is an experimental surgical technique that avoids the risk of thermal tissue injuries and the use of sutures to maintain strong tissue connection. This technique is advantageous over other tissue repair methods as it is minimally invasive and does not require mixing of multiple components before or during application. To expand the capability of the film to beyond just a tissue bonding device and promote tissue regeneration, in this study, we designed bioadhesive films that could also support stem cells. The films were modified with oligomeric chitosan to tune their erodibility and made porous through freeze-drying for better tissue integration. Of note, porous adhesive films (pore diameter ∼110 µm), with 10% of the chitosan being oligomeric, could retain similar tissue bonding strengths (13-15 kPa) to that of the nonporous chitosan-based adhesives used in previous studies when photoactivated. When tested in vitro, these films exhibited a mass loss of ∼20% after 7 days, swelling ratios of ∼270-300%, a percentage elongation of ∼90%, and both a tensile strength and Young's modulus of ∼1 MPa. The physical properties of the films were suitable for maintaining the viability and multipotency of bone-marrow-derived human mesenchymal stem cells over the duration of culture. Thus, these biocompatible, photoactivated porous, and erodible adhesive films show promise for applications in controlled cell delivery and regenerative medicine.

Impact of industrial-age climate change on the relationship between water uptake and tissue nitrogen in eucalypt seedlings.

This study explored reductions in tissue nitrogen concentration ([N]) at elevated CO2 concentrations ([CO2]), and changes in plant water and N uptake. Eucalyptus saligna Sm. seedlings were grown under three [CO2] levels (preindustrial (280µLL-1), current (400µLL-1) or projected (640µLL-1)) and two air temperatures (current, (current+4°C)). Gravimetric water use, leaf gas exchange and tissue dry mass and %N were determined. Solid-state 15N-NMR spectroscopy was used for determining the partitioning of N chemical groups in the dry matter fractions. Water use efficiency (WUE) improved with increasing [CO2] at ambient temperature, but strong leaf area and weak reductions in transpiration rates led to greater water use at elevated [CO2]. High temperature increased plant water use, such that WUE was not significantly stimulated by increasing [CO2] at high temperature. Total N uptake increased with increasing [CO2] but not temperature, less than the increase recorded for plant biomass. Tissue [N] decreased with rising [CO2] and at high temperature, but N use efficiency increased with rising [CO2]. Total N uptake was positively correlated with total water use and root biomass under all treatments. Growth [CO2] and temperature did not affect the partitioning of 15N among the N chemical groups. The reductions of tissue [N] with [CO2] and temperature were generic, not specific to particular N compounds. The results suggest that reductions in tissue [N] are caused by changes in root N uptake by mass flow due to altered transpiration rates at elevated [CO2] and temperature.

Stigma by association: the effects of caring for HIV/AIDS patients in South Africa.

The shortage of healthcare workers caring for South Africa's 5-6 million persons living with HIV/AIDS (PLHA) calls for inquiry into workers' challenges and experiences. This exploratory study examines one little-studied challenge: stigmatisation of HIV/AIDS healthcare workers based on their association with PLHA. The authors tested the hypotheses that HIV/AIDS healthcare workers experience stigmatisation due to their association with PLHA, and that such association stigma is correlated with thoughts of leaving the HIV/AIDS field. A sample of 100 participants who provided direct care to PLHA was recruited from a variety of public and private HIV/AIDS care centres in Eastern Cape province, South Africa. Participants attended one of 12 focus groups held between June and August, 2008. They completed a 17-item questionnaire and discussed each item. Findings exhibit the presence of an adverse differentiation and labelling of HIV/AIDS healthcare workers, leading to status loss and discrimination, creating an impetus for HIV/AIDS healthcare workers to leave AIDS work altogether. A significant relationship (χ(2) (TREND) = 3.86, df = 1, P = 0.049) was found between contemplation of leaving AIDS work and perception of others' responses to their work with PLHA. In addition, associations emerged between type of AIDS worker and contemplation of working in AIDS care outside of South Africa (Kruskal-Wallis χ(2) = 6.96, df = 2, P = 0.031), with doctors and nurses reporting higher frequency of contemplating leaving South Africa to work with PLHA elsewhere (Mann-Whitney z = -2.53, P = 0.011). The study lays the foundation for additional research on the effects of association stigma. In turn, increased efforts to retain and recruit new HIV/AIDS healthcare workers will expand the pool of healthcare personnel to PLHA.