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1.
Molecules ; 29(2)2024 Jan 22.
Artigo em Inglês | MEDLINE | ID: mdl-38276623

RESUMO

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.


Assuntos
Fotoquimioterapia , Neoplasias de Mama Triplo Negativas , Humanos , Neoplasias de Mama Triplo Negativas/tratamento farmacológico , Neoplasias de Mama Triplo Negativas/patologia , Rosa Bengala/farmacologia , Rosa Bengala/uso terapêutico , Oxigênio Singlete , Linhagem Celular Tumoral , Fármacos Fotossensibilizantes/farmacologia , Fármacos Fotossensibilizantes/uso terapêutico
2.
Photochem Photobiol ; 100(1): 115-128, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-37477110

RESUMO

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.


Assuntos
Quitosana , Onicomicose , Humanos , Trichophyton , Rosa Bengala/farmacologia , Projetos Piloto , Onicomicose/tratamento farmacológico
3.
Molecules ; 28(19)2023 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-37836744

RESUMO

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.


Assuntos
Neoplasias da Mama , Nanopartículas , Fotoquimioterapia , Neoplasias da Próstata , Masculino , Humanos , Rosa Bengala/farmacologia , Fármacos Fotossensibilizantes/farmacologia , Neoplasias da Próstata/tratamento farmacológico , Neoplasias da Mama/tratamento farmacológico , Microambiente Tumoral
7.
Phys Chem Chem Phys ; 25(10): 7170-7175, 2023 Mar 08.
Artigo em Inglês | MEDLINE | ID: mdl-36810448

RESUMO

Understanding and controlling the sintering behavior of gold nanoparticles is important for applications such as printed electronics, catalysis and sensing that utilise these materials. Here we examine the processes by which thiol-protected gold nanoparticles thermally sinter under a variety of atmospheres. We find that upon sintering, the surface-bound thiyl ligands exclusively form the corresponding disulfide species when released from the gold surface. Experiments conducted using air, hydrogen, nitrogen, or argon atmospheres revealed no significant differences between the temperatures of the sintering event nor on the composition of released organic species. When conducted under high vacuum, the sintering event occurred at lower temperatures compared to ambient pressures in cases where the resulting disulfide had relatively high volatility (dibutyl disulfide). Hexadecylthiol-stabilized particles exhibited no significant differences in the temperatures of the sintering event under ambient pressures compared to high vacuum conditions. We attribute this to the relatively low volatility of the resultant dihexadecyl disulfide product.

8.
Carbohydr Polym ; 291: 119659, 2022 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-35698423

RESUMO

Dietary fiber like konjac glucomannan (KGM) is important in maintaining good human health. There is no established method for quantifying the average degree of acetylation DA of this polysaccharide. Polysaccharides are notoriously difficult to dissolve. In this study, KGM could not be fully dissolved in common solvents and was characterized in the solid state. ATR-FTIR spectroscopy enabled a fast qualitative assessment of acetylation, selective to the outer layer of KGM particles, and identifying excipients like magnesium stearate. Average DA was quantified for the first time with solid-state 13C NMR in KGM: semi-quantitative measurements on the same arbitrary scale by cross polarization (1 to 2 days) were calibrated with a few longer single-pulse excitation measurements (approximately 1 week). DA values ranged from 4 to 8% of the hexoses in the backbone, in agreement with previously reported values. This method could be used for quality control and standardization of KGM products.


Assuntos
Mananas , Polissacarídeos , Acetilação , Proteínas Mutadas de Ataxia Telangiectasia , Humanos , Espectroscopia de Ressonância Magnética , Mananas/química , Espectroscopia de Infravermelho com Transformada de Fourier
9.
Lasers Surg Med ; 54(5): 758-766, 2022 07.
Artigo em Inglês | MEDLINE | ID: mdl-35195285

RESUMO

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.


Assuntos
Quitosana , Nanopartículas , Fotoquimioterapia , Quitosana/química , Quitosana/uso terapêutico , Café , Humanos , Nanopartículas/química , Tamanho da Partícula , Rosa Bengala/farmacologia , Rosa Bengala/uso terapêutico
10.
Physiol Plant ; 171(3): 358-370, 2021 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-32880970

RESUMO

Silicon (Si) has been widely reported to improve plant resistance to water stress via various mechanisms including cuticular Si deposition to reduce leaf transpiration. However, there is limited understanding of the effects of Si on stomatal physiology, including the underlying mechanisms and implications for resistance to water stress. We grew tall fescue (Festuca arundinacea Schreb. cv. Fortuna) hydroponically, with or without Si, and treated half of the plants with 20% polyethylene glycol to impose physiological drought (osmotic stress). Scanning electron microscopy in conjunction with X-ray mapping found that Si was deposited on stomatal guard cells and as a sub-cuticular layer in Si-treated plants. Plants grown in Si had a 28% reduction in stomatal conductance and a 23% reduction in cuticular conductance. When abscisic acid was applied exogenously to epidermal leaf peels to promote stomatal closure, Si plants had 19% lower stomatal aperture compared to control plants (i.e. increased stomatal sensitivity) and an increased efflux of guard cell K+ ions. However, the changes in stomatal physiology with Si were not substantial enough to improve water stress resistance, as shown by a lack of significant effect of Si on water potential, growth, photosynthesis and water-use efficiency. Our findings suggest a novel underlying mechanism for reduced stomatal conductance with Si application; specifically, that Si deposition on stomatal guard cells promotes greater stomatal sensitivity as mediated by guard cell K+ efflux.


Assuntos
Estômatos de Plantas , Silício , Ácido Abscísico , Secas , Fotossíntese , Silício/farmacologia
11.
J Mech Behav Biomed Mater ; 111: 103991, 2020 11.
Artigo em Inglês | MEDLINE | ID: mdl-32823075

RESUMO

Chitons are herbivorous invertebrates that use rows of ultrahard magnetite-based teeth connected to a flexible belt (radula) to rasp away algal deposits growing on and within rocky outcrops along coastlines around the world. Each tooth is attached to the radula by an organic structure (stylus) that provides mechanical support during feeding. However, the underlying structures within the stylus, and their subsequent function within the chiton have yet to be investigated. Here, we investigate the macrostructural architecture, the regional material and elemental distribution and subsequent nano-mechanical properties of the stylus from the Northern Pacific dwelling Cryptochiton stelleri. Using a combination of µ-CT imaging, optical and electron microscopy, as well as elemental analysis, we reveal that the stylus is a highly contoured tube, mainly composed of alpha-chitin fibers, with a complex density distribution. Nanoindentation reveals regiospecific and graded mechanical properties that can be correlated with both the elemental composition and material distribution. Finite element modeling shows that the unique macroscale architecture, material distribution and elemental gradients have been optimized to preserve the structural stability of this flexible, yet robust functionally-graded fiber-reinforced composite tube, providing effective function during rasping. Understanding these complex fiber-based structures offers promising blueprints for lightweight, multifunctional and integrated materials.


Assuntos
Poliplacóforos , Dente , Animais , Óxido Ferroso-Férrico , Microscopia Eletrônica
12.
Acta Biomater ; 101: 314-326, 2020 01 01.
Artigo em Inglês | MEDLINE | ID: mdl-31683016

RESUMO

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.


Assuntos
Quitosana/farmacologia , Di-Hidroxifenilalanina/farmacologia , Processos Fotoquímicos , Adesivos Teciduais/farmacologia , Animais , Materiais Biocompatíveis/farmacologia , Sobrevivência Celular/efeitos dos fármacos , Módulo de Elasticidade , Fibroblastos/efeitos dos fármacos , Humanos , Oxirredução , Porosidade , Ovinos , Resistência à Tração
13.
ACS Appl Mater Interfaces ; 11(36): 32613-32622, 2019 Sep 11.
Artigo em Inglês | MEDLINE | ID: mdl-31418544

RESUMO

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.


Assuntos
Quitosana/farmacologia , Células-Tronco Mesenquimais/citologia , Cicatrização/efeitos dos fármacos , Animais , Forma Celular/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Módulo de Elasticidade , Humanos , Células-Tronco Mesenquimais/efeitos dos fármacos , Nanoporos/ultraestrutura , Porosidade , Ovinos , Suturas , Resistência à Tração , Adesivos Teciduais/farmacologia
14.
J Forensic Sci ; 63(6): 1809-1812, 2018 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-29601639

RESUMO

Raman spectroscopy has recently been investigated for use in the calculation of postmortem interval from skeletal material. The fluorescence generated by samples, which affects the interpretation of Raman data, is a major limitation. This study compares the effectiveness of two sample preparation techniques, chemical bleaching and scraping, in the reduction of fluorescence from bone samples during testing with Raman spectroscopy. Visual assessment of Raman spectra obtained at 1064 nm excitation following the preparation protocols indicates an overall reduction in fluorescence. Results demonstrate that scraping is more effective at resolving fluorescence than chemical bleaching. The scraping of skeletonized remains prior to Raman analysis is a less destructive method and allows for the preservation of a bone sample in a state closest to its original form, which is beneficial in forensic investigations. It is recommended that bone scraping supersedes chemical bleaching as the preferred method for sample preparation prior to Raman spectroscopy.


Assuntos
Osso e Ossos/patologia , Técnicas Histológicas , Análise Espectral Raman , Animais , Fluorescência , Modelos Animais , Suínos
15.
Biomed Eng Online ; 17(1): 7, 2018 Jan 22.
Artigo em Inglês | MEDLINE | ID: mdl-29357892

RESUMO

BACKGROUND: Extracellular matrices (ECMs) are often used in reconstructive surgery to enhance tissue regeneration and remodeling. Sutures and staples are currently used to fix ECMs to tissue although they can be invasive devices. Other sutureless and less invasive techniques, such as photochemical tissue bonding, cannot be coupled to ECMs because of their intrinsic opacity to light. RESULTS: We succeeded in fabricating a biocompatible and adhesive device that is based on ovine forestomach matrix (OFM) and a chitosan adhesive. The natural opacity of the OFM has been overcome by adding the adhesive into the matrix that allows for the light to effectively penetrate through it. The OFM-chitosan device is semitransparent (attenuation length ~ 106 µm) and can be photoactivated by green light to bond to tissue. This device does not require sutures or staples and guarantees a bonding strength of ~ 23 kPa. CONCLUSIONS: A new semitransparent and biocompatible bandage has been successfully fabricated and characterized for sutureless tissue bonding.


Assuntos
Bandagens , Quitosana/química , Matriz Extracelular/química , Fenômenos Ópticos , Processos Fotoquímicos , Adesividade , Animais , Feminino , Lasers , Teste de Materiais , Fenômenos Mecânicos , Ovinos
16.
ACS Omega ; 3(9): 10471-10480, 2018 Sep 30.
Artigo em Inglês | MEDLINE | ID: mdl-31459173

RESUMO

Herein, we report the synthesis and characterization of a chemosensor, 5-(diethylamino)-2-(2,3-dihydro-1H-perimidin-2-yl)phenol (HL), synthesized from a condensation between 4-(diethylamino)salicylaldehyde and 1,8-diaminonaphthalene. Upon investigation of the sensing properties of HL, it was found that this sensor may be employed for simple yet efficient detection of Cu2+ in aqueous methanol solutions. The selective and ratiometric response to Cu2+ yielded an outstandingly low limit of detection of 3.7 nM by spectrophotometry and is also useful as a naked-eye sensor from 2.5 µM. The system was studied by spectrophotometric pH titrations to determine Cu2+ binding constants and complex speciation. Binding of Cu2+ to HL occurs in 1:1 stoichiometry, in good agreement with high-resolution electrospray ionization mass spectrometry (ESI-HRMS) results, Cu2+ titrations, and Job's plot experiments, while the coordination geometry was tentatively assigned as square pyramidal by spectroscopic studies.

17.
Nanotechnology ; 28(26): 265602, 2017 Jun 30.
Artigo em Inglês | MEDLINE | ID: mdl-28510531

RESUMO

Highly oriented epitaxial rutile titanium dioxide (TiO2) nanowire arrays have been hydrothermally grown on polycrystalline TiO2 templates with their orientation dependent on the underlying TiO2 grain. Both the diameter and areal density of the nanowires were tuned by controlling the precursor concentration, and the template surface energy and roughness. Nanowire tip sharpness was influenced by precursor solubility and diffusivity. A new secondary ion mass spectrometer technique has been developed to install additional nucleation sites in single crystal TiO2 templates and the effect on nanowire growth was probed. Using the acquired TiO2 nanowire synthesis knowhow, an assortment of nanowire arrays were installed upon the surface of undoped TiO2 photo-electrodes and assessed for their photo-electrochemical water splitting performance. The key result obtained was that the presence of short and dispersed nanowire arrays significantly improved the photocurrent when the illumination intensity was increased from 100 to 200 mW cm-2. This is attributed to the alignment of the homoepitaxially grown nanowires to the [001] direction, which provides the fastest charge transport in TiO2 and an improved pathway for photo-holes to find water molecules and undertake oxidation. This result lays a foundation for achieving efficient water splitting under conditions of concentrated solar illumination.

18.
Adv Mater ; 28(32): 6835-44, 2016 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-27238289

RESUMO

A fibrous herringbone-modified helicoidal architecture is identified within the exocuticle of an impact-resistant crustacean appendage. This previously unreported composite microstructure, which features highly textured apatite mineral templated by an alpha-chitin matrix, provides enhanced stress redistribution and energy absorption over the traditional helicoidal design under compressive loading. Nanoscale toughening mechanisms are also identified using high-load nanoindentation and in situ transmission electron microscopy picoindentation.

19.
Anal Bioanal Chem ; 407(9): 2543-55, 2015 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-25680633

RESUMO

Chitosan, being antimicrobial and biocompatible, is attractive as a cell growth substrate. To improve cell attachment, arginine-glycine-aspartic acid-serine (RGDS) peptides were covalently grafted to chitosan films, through the widely used coupling agents 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC-HCl) and N-hydroxysuccinimide (NHS), via the carboxylic acid function of the RGDS molecule. The grafting reaction was monitored, for the first time, in real time using free-solution capillary electrophoresis (CE). This enabled fast separation and determination of the peptide and all other reactants in one separation with no sample preparation. Covalent RGDS peptide grafting onto the chitosan film surface was demonstrated using solid-state NMR of swollen films. CE indicated that oligomers of RGDS, not simply RGDS, were grafted on the film, with a likely hyperbranched structure. To assess the functional properties of the grafted films, cell growth was compared on control and peptide-grafted chitosan films. Light microscopy and polymerase chain reaction (PCR) analysis demonstrated greatly improved cell attachment to RGDS-grafted chitosan films.


Assuntos
Materiais Biocompatíveis/síntese química , Quitosana/química , Eletroforese Capilar/métodos , Peptídeos/química , Materiais Biocompatíveis/química , Adesão Celular , Linhagem Celular , Proliferação de Células , Sobrevivência Celular , Células/citologia , Humanos
20.
J Biophotonics ; 7(11-12): 948-55, 2014 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-24395818

RESUMO

A range of chitosan-based biomaterials have recently been used to perform sutureless, laser-activated tissue repair. Laser-activation has the advantage of bonding to tissue through a non-contact, aseptic mechanism. Chitosan adhesive films have also been shown to adhere to sheep intestine strongly without any chemical modification to chitosan. In this study, we continue to investigate chitosan adhesive films and explore the impact on the tissue repair strength and tensile strength characteristics of four types of adhesive film based on chitosan with different molecular weight and degree of deacetylation. Results showed that adhesives based on chitosan with medium molecular weight achieved the highest bonding strength, tensile strength and E-modulus when compared to the other adhesives.


Assuntos
Materiais Biocompatíveis/química , Quitosana/química , Cicatrização , Acetilação , Adesivos , Animais , Reagentes de Ligações Cruzadas/química , Lasers , Microscopia de Força Atômica , Microscopia Eletrônica de Varredura , Peso Molecular , Ovinos , Temperatura , Resistência à Tração , Termogravimetria , Raios X
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