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A peptide-based hydrogel sequence was computationally predicted from the Ala-rich cross-linked domains of elastin. Three candidate peptides were subsequently synthesised and characterised as potential drug delivery vehicles. The elastin-derived peptides are Fmoc-FFAAAAKAA-NH2, Fmoc-FFAAAKAA-NH2, and Fmoc-FFAAAKAAA-NH2. All three peptide sequences were able to self-assemble into nanofibers. However, only the first two could form hydrogels, which are preferred as delivery systems compared to solutions. Both of these peptides also exhibited favourable nanofiber lengths of at least 1.86 and 4.57 µm, respectively, which are beneficial for the successful delivery and stability of drugs. The shorter fibre lengths of the third peptide (maximum 0.649 µm) could have inhibited their self-assembly into the three-dimensional networks crucial to hydrogel formation.
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The interaction between genipin and a model protein bovine serum albumin (BSA), with and without the addition of acetic acid, has been studied experimentally and by modelling. The number of amino groups available to react was determined to be 5.6 % of the total number of amino acid building blocks on BSA. Fluorescence intensity was used to record the progress of the reaction over the 24 h, while the modelling study focused on capturing the kinetic profiles of the reaction. The experiments revealed a slow start to the BSA and genipin interaction, that subsequently accelerated in an S-shaped curve which the modelling study linked with the existence of the feedback cycle for both reactive amino groups and genipin. At BSA concentrations ≥30 mg/mL the reaction was accelerated in the presence of acid, while below 30 mg/mL the acidified conditions delayed the onset of the reaction. Contrary to the reaction mechanisms previously proposed, a degree of breakdown of the fluorescent links in the products formed was denoted both experimentally and in a modelling study. This indicated the reversibility of the processes forming fluorescent product/s and suggested feasibility of the successful release of the protein following prospective encapsulation within the genipin-crosslinked hydrogel structure.
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Iridoides , Albúmina Sérica Bovina , Iridoides/química , Albúmina Sérica Bovina/química , Animales , Bovinos , Cinética , Fluorescencia , Espectrometría de Fluorescencia/métodos , Modelos Teóricos , Unión ProteicaRESUMEN
We report a simple and reproducible micromoulding technique that dynamically fills microneedle moulds with a liquid formulation, using a plastic syringe, triggered by the application of vacuum ('vac-and-fill'). As pressure around the syringe drops, air inside the syringe pushes the plunger to uncover an opening in the syringe and fill the microneedle mould without manual intervention, therefore removing inter-operator variability. The technique was validated by monitoring the plunger movement and pressure at which the mould would be filled over 10 vacuum cycles for various liquid formulation of varying viscosity (water, glycerol, 20 % polyvinylpyrrolidone (PVP) solution or 40 % PVP solution). Additionally, the impact of re-using the disposable syringes on plunger movement, and thus the fill pressure, was investigated using a 20 % PVP solution. The fill pressure was consistent at 300-450 mbar. It produced well-formed and mechanically robust PVP, poly(methylvinylether/maleic anhydride) and hydroxyethylcellulose microneedles from liquid formulations. This simple and inexpensive technique of micromoulding eliminated the air entrapment and bubble formation, which prevent reproducible microneedle formation, in the resultant microneedle arrays. It provides a cost-effective alternative to the conventional micromoulding techniques, where the application of vacuum ('fill-and-vac') or centrifugation following mould-filling may be unsuitable, ineffective or have poor reproducibility.
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Sistemas de Liberación de Medicamentos , Jeringas , Vacio , Reproducibilidad de los Resultados , Sistemas de Liberación de Medicamentos/métodos , AgujasRESUMEN
Recent infectious disease outbreaks, such as COVID-19 and Ebola, have highlighted the need for rapid and accurate diagnosis to initiate treatment and curb transmission. Successful diagnostic strategies critically depend on the efficiency of biological sampling and timely analysis. However, current diagnostic techniques are invasive/intrusive and present a severe bottleneck by requiring specialist equipment and trained personnel. Moreover, centralised test facilities are poorly accessible and the requirement to travel may increase disease transmission. Self-administrable, point-of-care (PoC) microneedle diagnostic devices could provide a viable solution to these problems. These miniature needle arrays can detect biomarkers in/from the skin in a minimally invasive manner to provide (near-) real-time diagnosis. Few microneedle devices have been developed specifically for infectious disease diagnosis, though similar technologies are well established in other fields and generally adaptable for infectious disease diagnosis. These include microneedles for biofluid extraction, microneedle sensors and analyte-capturing microneedles, or combinations thereof. Analyte sampling/detection from both blood and dermal interstitial fluid is possible. These technologies are in their early stages of development for infectious disease diagnostics, and there is a vast scope for further development. In this review, we discuss the utility and future outlook of these microneedle technologies in infectious disease diagnosis.
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Transmucosal drug delivery includes the administration of drugs via various mucous membranes, such as gastrointestinal, nasal, ocular, and vaginal mucosa. The use of nanoparticles in transmucosal drug delivery has several advantages, including the protection of drugs against the harsh environment of the mucosal lumens and surfaces, increased drug residence time, and enhanced drug absorption. Due to their relatively simple synthetic methods for preparation, safety profile, and possibilities of surface functionalisation, silica nanoparticles are highly promising for transmucosal drug delivery. This review provides a description of silica nanoparticles and outlines the preparation methods for various core and surface-functionalised silica nanoparticles. The relationship between the functionalities of silica nanoparticles and their interactions with various mucous membranes are critically analysed. Applications of silica nanoparticles in transmucosal drug delivery are also discussed.
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Minimally invasive, reliable and low-cost in vivo biosensors that enable real-time detection and monitoring of clinically relevant molecules and biomarkers can significantly improve patient health care. Microneedle array (MNA)-based electrochemical sensors offer exciting prospects in this respect, as they can sample directly from the skin. However, their acceptability is dependent on developing a highly scalable and cost-effective fabrication strategy. In this work, we evaluated the potential for poly(lactic acid)/carboxyl-multiwalled carbon nanotube (PLA/ f-MWCNT) composites to be developed into MNAs and their effectiveness for dermal biosensing. Our results show that MNAs are easily made from solvent-cast nanocomposite films by micromolding. A maximum carbon nanotube (CNT) loading of 6 wt % was attained with the current fabrication method. The MNAs were mechanically robust, being able to withstand axial forces up to 4 times higher than necessary for skin insertion. Electrochemical characterization of these MNAs by differential pulse voltammetry (DPV) produced a linear current response toward ascorbic acid, with a limit of detection of 180 µM. In situ electrochemical performance was assessed by DPV measurements in ex vivo porcine skin. This showed active changes characterized by two oxidative peaks at 0.23 and 0.69 V, as a result of the diffusion of phosphate-buffered saline. The diagnostic potential of this waveform was further evaluated through a burn wound model. This showed an attenuated oxidative response at 0.69 V. Importantly, the impact of the burn could be measured at progressive distances from the burn site. Overall, alongside the scalable fabrication strategy, the DPV results promise efficient electrochemical biosensors based on CNT nanocomposite MNAs.
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Técnicas Biosensibles/métodos , Dermis/química , Nanotubos de Carbono/química , Poliésteres/química , Animales , Técnicas Biosensibles/instrumentación , Quemaduras/diagnóstico , Dermis/patología , Técnicas Electroquímicas/instrumentación , Técnicas Electroquímicas/métodos , Nanocompuestos/química , Agujas , Oxidación-Reducción , PorcinosRESUMEN
In this study, we synthesised thiolated silica nanoparticles using 3-mercaptopropyltrimethoxysilane and functionalised them with either 5â¯kDa methoxy polyethylene glycol maleimide (PEG) or 5â¯kDa alkyne-terminated poly(2-ethyl-2-oxazoline) (POZ). The main objectives of this study are to investigate the effects of pH on the size and ξ-potential of these nanoparticles and evaluate their mucoadhesive properties ex vivo using rat intestinal mucosa. The sizes of thiolated, PEGylated and POZylated silica nanoparticles were 53⯱â¯1, 68⯱â¯1 and 59⯱â¯1â¯nm, respectively. The size of both thiolated and POZylated nanoparticles significantly increased at pHâ¯≤â¯2, whereas no size change was observed at pHâ¯2.5-9 for both these two types of nanoparticles. On the other hand, the size of PEGylated nanoparticles did not change over the studied pH range (1.5-9). Moreover, thiolated nanoparticles were more mucoadhesive in the rat small intestine than both PEGylated and POZylated nanoparticles. After 12â¯cycles of washing (with a total of 20â¯mL of phosphate buffer solution pHâ¯6.8), a significantly greater amount of thiolated nanoparticles remained on the intestinal mucosa than FITC-dextran (non-mucoadhesive polymer, pâ¯<â¯0.005) and both PEGylated and POZylated nanoparticles (pâ¯<â¯0.05 both). However, both PEGylated and POZylated nanoparticles showed similar retention to FITC-dextran (pâ¯>â¯0.1 for both). Thus, this study indicates that thiolated nanoparticles are mucoadhesive, whereas PEGylated and POZylated nanoparticles are non-mucoadhesive in the ex vivo rat intestinal mucosa model. Each of these nanoparticles has potential applications in mucosal drug delivery.
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Mucosa Intestinal/metabolismo , Nanopartículas/administración & dosificación , Poliaminas/administración & dosificación , Polietilenglicoles/administración & dosificación , Silanos/administración & dosificación , Dióxido de Silicio/administración & dosificación , Compuestos de Sulfhidrilo/administración & dosificación , Adhesividad , Animales , Femenino , Nanopartículas/química , Compuestos de Organosilicio , Poliaminas/química , Polietilenglicoles/química , Ratas Sprague-Dawley , Silanos/química , Dióxido de Silicio/química , Dióxido de Silicio/farmacocinética , Compuestos de Sulfhidrilo/químicaRESUMEN
This special issue, which is entitled “Penetration Enhancement of Topical Formulations”, presents a selection of the latest research that elucidates the challenges facing topical formulations for human skin in addition to proposing interesting solutions.[…].
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Immunodiagnostic microneedles provide a novel way to extract protein biomarkers from the skin in a minimally invasive manner for analysis in vitro. The technology could overcome challenges in biomarker analysis specifically in solid tissue, which currently often involves invasive biopsies. This study describes the development of a multiplex immunodiagnostic device incorporating mechanisms to detect multiple antigens simultaneously, as well as internal assay controls for result validation. A novel detection method is also proposed. It enables signal detection specifically at microneedle tips and therefore may aid the construction of depth profiles of skin biomarkers. The detection method can be coupled with computerised densitometry for signal quantitation. The antigen specificity, sensitivity and functional stability of the device were assessed against a number of model biomarkers. Detection and analysis of endogenous antigens (interleukins 1α and 6) from the skin using the device was demonstrated. The results were verified using conventional enzyme-linked immunosorbent assays. The detection limit of the microneedle device, at ≤10 pg/mL, was at least comparable to conventional plate-based solid-phase enzyme immunoassays.
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Biomarcadores/análisis , Técnicas para Inmunoenzimas , Pruebas Inmunológicas , Microinyecciones , Agujas , Enfermedades de la Piel/diagnóstico , Animales , Anticuerpos Inmovilizados , Equipo para Diagnóstico , Diseño de Equipo , Humanos , Técnicas para Inmunoenzimas/instrumentación , Técnicas para Inmunoenzimas/métodos , Pruebas Inmunológicas/instrumentación , Pruebas Inmunológicas/métodos , Interleucina-1alfa/análisis , Interleucina-6/análisis , Ratones , Microinyecciones/instrumentación , Microinyecciones/métodos , Enfermedades de la Piel/metabolismoRESUMEN
Porcine ear skin is widely used to study skin permeation and absorption of ester compounds, whose permeation and absorption profiles may be directly influenced by in situ skin esterase activity. Importantly, esterase distribution and activity in porcine ear skin following common protocols of skin handling and storage have not been characterised. Thus, we have compared the distribution and hydrolytic activity of esterases in freshly excised, frozen, heated and explanted porcine ear skin. Using an esterase staining kit, esterase activity was found to be localised in the stratum corneum and viable epidermis. Under frozen storage and a common heating protocol of epidermal sheet separation, esterase staining in the skin visibly diminished. This was confirmed by a quantitative assay using HPLC to monitor the hydrolysis of aspirin, in freshly excised, frozen or heated porcine ear skin. Compared to vehicle-only control, the rate of aspirin hydrolysis was approximately three-fold higher in the presence of freshly excised skin, but no different in the presence of frozen or heated skin. Therefore, frozen and heat-separated porcine ear skin should not be used to study the permeation of ester-containing permeants, in particular co-drugs and pro-drugs, whose hydrolysis or degradation can be modulated by skin esterases.
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Aspirina/farmacocinética , Esterasas/metabolismo , Absorción Cutánea , Piel/metabolismo , Animales , Aspirina/química , Cromatografía Líquida de Alta Presión , Congelación , Calor , Hidrólisis , Permeabilidad , Piel/enzimología , Porcinos , Distribución TisularRESUMEN
A novel topical codrug, naproxyl-dithranol (Nap-DTH), in which dithranol and naproxen are linked via an ester in a 1:1 ratio to form a single chemical entity, was synthesized. The antiproliferative, anti-inflammatory and toxic effects of Nap-DTH were assessed, at the cellular level, using various in vitro methods. Cultured HaCaT keratinocytes were treated with Nap-DTH, and the cellular effects were compared with those of the parent compounds, individually and as a 1:1 mixture of naproxen:dithranol to mimic 1:1 in situ liberation from Nap-DTH. The results demonstrate that Nap-DTH did not modify proliferation and only exhibited slight toxic effects after 24 h at concentrations >21 µM. At a lower concentration (3.4 µM), Nap-DTH did not alter cell proliferation or inflammation, which suggests that the codrug is therapeutically inert. Relating to this, the 1:1 mixture of naproxen:dithranol exhibited the lowest toxic effect and the highest antiproliferative effect on HaCaT keratinocytes compared to dithranol at the same concentration. Moreover, the 1:1 mixture exhibited a reduced inflammatory effect compared to dithranol alone, as reflected by the upregulation of cyclooxygenase-2 by 45% and 136%, respectively. In spite of the 1:1 mixture showing a greater downregulation of Ki-67 and a 2-fold reduction of proliferating cell nuclear antigen (both cellular markers of proliferation) than dithranol, dithranol showed a much greater induction of cleaved caspase-3 protein expression (upregulated by 287%, compared to 85% for the 1:1 mixture). This suggests that when dithranol was administered with naproxen, inhibition of cell growth plays a more important role in the antiproliferation effects than the induction of apoptotic cell death. These results confirm that the codrug would lead to a better therapeutic profile and fewer adverse effects compared to its parent compounds.
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Antralina/farmacología , Antiinflamatorios/farmacología , Ésteres/farmacología , Naproxeno/farmacología , Antralina/síntesis química , Antralina/química , Línea Celular , Proliferación Celular/efectos de los fármacos , Ciclooxigenasa 2/metabolismo , Ésteres/síntesis química , Ésteres/química , Citometría de Flujo , Humanos , Inmunohistoquímica , Estructura Molecular , Naproxeno/síntesis química , Naproxeno/químicaRESUMEN
RATIONALE: Children with congenital heart disease are at risk of gut barrier dysfunction and translocation of gut bacterial antigens into the bloodstream. This may contribute to inflammatory activation and organ dysfunction postoperatively. OBJECTIVES: To investigate the role of intestinal injury and endotoxemia in the pathogenesis of organ dysfunction after surgery for congenital heart disease. METHODS: We analyzed blood levels of intestinal fatty acid binding protein and endotoxin (endotoxin activity assay) alongside global transcriptomic profiling and assays of monocyte endotoxin receptor expression in children undergoing surgery for congenital heart disease. MEASUREMENTS AND MAIN RESULTS: Levels of intestinal fatty acid binding protein and endotoxin were greater in children with duct-dependent cardiac lesions. Endotoxemia was associated with severity of vital organ dysfunction and intensive care stay. We identified activation of pathogen-sensing, antigen-processing, and immune-suppressing pathways at the genomic level postoperatively and down-regulation of pathogen-sensing receptors on circulating immune cells. CONCLUSIONS: Children undergoing surgery for congenital heart disease are at increased risk of intestinal mucosal injury and endotoxemia. Endotoxin activity correlates with a number of outcome variables in this population, and may be used to guide the use of gut-protective strategies.
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Endotoxemia/microbiología , Cardiopatías Congénitas/cirugía , Enfermedades Intestinales/microbiología , Mucosa Intestinal/lesiones , Mucosa Intestinal/microbiología , Regulación hacia Abajo/inmunología , Endotoxemia/sangre , Endotoxemia/inmunología , Ensayo de Inmunoadsorción Enzimática , Proteínas de Unión a Ácidos Grasos/sangre , Proteínas de Unión a Ácidos Grasos/inmunología , Femenino , Humanos , Lactante , Inflamación/sangre , Inflamación/inmunología , Inflamación/microbiología , Enfermedades Intestinales/sangre , Enfermedades Intestinales/inmunología , Mucosa Intestinal/inmunología , Tiempo de Internación/estadística & datos numéricos , Masculino , Insuficiencia Multiorgánica/sangre , Insuficiencia Multiorgánica/inmunología , Insuficiencia Multiorgánica/microbiología , Complicaciones Posoperatorias/sangre , Complicaciones Posoperatorias/inmunología , Complicaciones Posoperatorias/microbiología , Índice de Severidad de la EnfermedadRESUMEN
The presence of resident Langerhans cells (LCs) in the epidermis makes the skin an attractive target for DNA vaccination. However, reliable animal models for cutaneous vaccination studies are limited. We demonstrate an ex vivo human skin model for cutaneous DNA vaccination which can potentially bridge the gap between pre-clinical in vivo animal models and clinical studies. Cutaneous transgene expression was utilised to demonstrate epidermal tissue viability in culture. LC response to the culture environment was monitored by immunohistochemistry. Full-thickness and split-thickness skin remained genetically viable in culture for at least 72 h in both phosphate-buffered saline (PBS) and full organ culture medium (OCM). The epidermis of explants cultured in OCM remained morphologically intact throughout the culture duration. LCs in full-thickness skin exhibited a delayed response (reduction in cell number and increase in cell size) to the culture conditions compared with split-thickness skin, whose response was immediate. In conclusion, excised human skin can be cultured for a minimum of 72 h for analysis of gene expression and immune cell activation. However, the use of split-thickness skin for vaccine formulation studies may not be appropriate because of the nature of the activation. Full-thickness skin explants are a more suitable model to assess cutaneous vaccination ex vivo.
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Células de Langerhans/citología , Técnicas de Cultivo de Órganos , Piel/citología , Supervivencia Tisular , Adulto , Anciano , Células Epidérmicas , Femenino , Expresión Génica , Técnicas de Transferencia de Gen , Humanos , Inyecciones Intradérmicas , Células de Langerhans/inmunología , Persona de Mediana Edad , Plásmidos , Piel/inmunología , Transgenes , VacunaciónRESUMEN
Small interfering RNA (siRNA), antisense oligonucleotides (ODNs), ribozymes and DNAzymes have emerged as sequence-specific inhibitors of gene expression that may have therapeutic potential in the treatment of a wide range of diseases. Due to their rapid degradation in vivo, the efficacy of naked gene silencing nucleic acids is relatively short lived. The entrapment of these nucleic acids within biodegradable sustained-release delivery systems may improve their stability and reduce the doses required for efficacy. In this study, we have evaluated the potential in vitro and in vivo use of biodegradable poly (D,L-lactide-co-glycolide) copolymer (PLGA) microspheres as sustained delivery devices for ODNs, ribozyme, siRNA and DNA enzymes. In addition, we investigated the release of ODN conjugates bearing 5'-end lipophilic groups. The in vitro sustained release profiles of microsphere-entrapped nucleic acids were dependent on variables such as the type of nucleic acid used, the nature of the lipophilic group, and whether the nucleic acid used was single or double stranded. For in vivo studies, whole body autoradiography was used to monitor the bio-distribution of either free tritium-labelled ODN or that entrapped within PLGA microspheres following subcutaneous administration in Balb-c mice. The majority of the radioactivity associated with free ODN was eliminated within 24 h whereas polymer-released ODN persisted in organs and at the site of administration even after seven days post-administration. Polymer microsphere released ODN exhibited a similar tissue and cellular tropism to the free ODN. Micro-autoradiography analyses of the liver and kidneys showed similar bio-distribution for polymer-released and free ODNs with the majority of radioactivity being concentrated in the proximal convoluted tubules of the kidney and in the Kupffer cells of the liver. These findings suggest that biodegradable PLGA microspheres offer a method for improving the in vivo sustained delivery of gene silencing nucleic acids, and hence are worthy of further investigation as delivery systems for these macromolecules.