Polydopamine-like Coatings as Payload Gatekeepers for Mesoporous Silica Nanoparticles

We report the use of bis-catecholic polymers as candidates for obtaining effective, tunable gatekeeping coatings for mesoporous silica nanoparticles (MSNs) intended for drug release applications. In monomers, catechol rings act as adhesive moieties and reactive sites for polymerization, together with middle linkers which may be chosen to tune the physicochemical properties of the resulting coating. Stable and low-toxicity coatings (pNDGA and pBHZ) were prepared from two bis-catechols of different polarity (NDGA and BHZ) on MSN carriers previously loaded with rhodamine B (RhB) as a model payload, by means of a previously reported synthetic methodology and without any previous surface modification. Coating robustness and payload content were shown to depend significantly on the workup protocol. The release profiles in a model physiological PBS buffer of coated systems (RhB@MSN@pNDGA and RhB@MSN@pBHZ) showed marked differences in the "gatekeeping" behavior of each coating, which correlated qualitatively with the chemical nature of their respective linker moieties. While the uncoated system (RhB@MSN) lost its payload almost completely after 2 days, release from RhB@MSN@pNDGA was virtually negligible, likely due to the low polarity of the parent bis-catechol (NDGA). As opposed to these extremes, RhB@MSN@pBHZ presented the most promising behavior, showing an intermediate release of 50% of the payload in the same period of time

Mussel-inspired lego approach for controlling the wettability of surfaces with colorless coatings

The control of surface wettability with polyphenol coatings has been at the forefront of materials research since the late 1990s, when robust underwater adhesion was linked to the presence of L-DOPA-a catecholic amino acid-in unusually high amounts, in the sequences of several mussel foot proteins. Since then, several successful approaches have been reported, although a common undesired feature of most of them is the presence of a remnant color and/or the intrinsic difficulty in fine-tuning and controlling the hydrophobic character. We report here a new family of functional catechol-based coatings, grounded in the oxidative condensation of readily available pyrocatechol and thiol-capped functional moieties. The presence of at least two additional thiol groups in their structure allows for polymerization through the formation of disulfide bonds. The synthetic flexibility, together with its modular character, allowed us to: (I) develop coatings with applications exemplified by textiles for oil-spill water treatment; (II) develop multifunctional coatings, and (III) fine-tune the WCA for flat and textile surfaces. All of this was achieved with the application of colorless coating

Sonochemical synthesis, characterization, and effects of temperature, power ultrasound and reaction time on the morphological properties of two new nanostructured mercury(II) coordination supramolecule compounds

Two new mercury(II) coordination supramolecular compounds (CSCs) (1D and 0D), [Hg(L)(I)] (1) and [Hg(L')(SCN)]·2HO (2) (L = 2-amino-4-methylpyridine and L' = 2,6-pyridinedicarboxlic acid), have been synthesized under different experimental conditions. Micrometric crystals (bulk) or nano-sized materials have been obtained depending on using the branch tube method or sonochemical irradiation. All materials have been characterized by field emission scanning electron microscope (FESEM), scanning electron microscopy (SEM), powder X-ray diffraction (PXRD) and FT-IR spectroscopy. Single crystal X-ray analyses on compounds 1 and 2 show that Hg ions are 4-coordinated and 5-coordinated, respectively. Topological analysis shows that the compound 1 and 2 have 2C1, sql net. The thermal stability of compounds 1 and 2 in bulk and nano-size has been studied by thermal gravimetric (TG), differential thermal analyses (DTA) for 1 and differential scanning calorimetry (DSC) for 2, respectively. Also, by changing counter ions were obtained various structures 1 and 2 (1D and 0D, respectively). The role of different parameters like power of ultrasound irradiation, reaction time and temperature on the growth and morphology of the nano-structures are studied. Results suggest that increasing power ultrasound irradiation and temperature together with reducing reaction time and concentration of initial reagents leads to a decrease in particle size

Bioinspired Functional Catechol Derivatives through Simple Thiol Conjugate Addition

The combination of the surface-adhesive properties of catechol rings and functional moieties conveying specific properties is very appealing to materials chemistry, but the preparation of catechol derivatives often requires elaborate synthetic routes to circumvent the intrinsic reactivity of the catechol ring. In this work, functional catechols are synthesized straightforwardly by using the bioinspired reaction of several functional thiols with o-benzoquinone. With one exception, the conjugated addition of the thiol takes place regioselectively at the 3-position of the quinone, and is rationalized by DFT calculations. Overall, this synthetic methodology provides a general and straightforward access to functional and chain-extended catechol derivatives, which are later tested with regard to their hydro-/oleophobicity, colloidal stability, fluorescence, and metal-coordinating capabilities in proof-of-concept applications

Catechol Poly(disulfide)s : a new platform for adhesives in the medical industry

Los catecoles están ampliamente presentes en la naturaleza y participan en mecanismos cruciales en algunos organismos. Las fascinantes propiedades de los catecoles en términos de adhesión, actividad redox y propiedades quelantes han suscitado el reciente interés por los polímeros que contienen catecoles para el desarrollo de nuevos materiales funcionales. Un área de investigación activa es el diseño de nuevos adhesivos bioinspirados que contengan catecoles. La presencia de la funcionalidad catecol ha permitido conseguir materiales con adhesión sobre múltiples sustratos y, además, ha mejorado la adhesión en condiciones de humedad. Esta adhesión en condiciones húmedas ha abierto la posibilidad de utilizar estos materiales en el campo biomédico como adhesivos para dispositivos médicos y adhesivos/sellantes tisulares. A pesar de los grandes avances en este campo durante las últimas décadas, todavía se necesitan nuevos enfoques para conseguir adhesivos basados en catecoles con propiedades de adhesión/despegue 'a demanda' y con potencial de biodegradabilidad. Los polidisulfuros, que se caracterizan por la presencia de enlaces disulfuro (-S-S-), son polímeros con un comportamiento dinámico especialmente interesante debido a su reversibilidad mediante el intercambio tiol-disulfuro y la escisión homolítica con la luz y la temperatura. Dentro de este contexto, en la presente tesis se introduce una nueva familia de polidisulfuros de catecol para combinar las características más interesantes de las funcionalidades de los catecoles y los disulfuros. Durante el trabajo se lleva a cabo la síntesis de un nuevo compuesto que contiene un catecol y dos tioles para su posterior polimerización. A continuación, se optimiza la polimerización con yodo a través de la oxidación de los tioles libres buscando un enfoque modular adecuado con un ajuste del peso molecular de los polidisulfuros de catecol. Buscando la potencial aplicación en el campo biomédico, se evalúa la adhesión sobre diversos sustratos y el uso de estos materiales como adhesivo y sellador tisulares. Además, para estudiar la completa biocompatibilidad de estos materiales, se realizan estudios in vitro e in vivo siguiendo la norma ISO 10993, así como la evaluación de la posible degradación en diferentes medios.Catechols are widely present in nature taking part on crucial mechanisms in some organisms. The fascinating properties of catechols in terms of adhesion, redox activity and chelating properties have raised the recent interest in catechol containing polymers for the development of new functional materials. An area of active research is the design of new bioinspired catechol containing adhesives. The presence of catechol functionality has allowed to achieve materials with adhesion on multiple substrates and, furthermore, has enhanced the adhesion on wet conditions. This adhesion on wet conditions has opened the possibility of using these materials in the biomedical field as adhesives for medical devices and tissue adhesives/sealants. Despite the great advances in the field during last decades, new approaches to achieve adhesives based on catechols with bonding/debonding on demand properties and biodegradability potential are still required. Poly(disulfide)s, which are characterized by the presence of disulfide bonds (-S-S-), are polymers with special interesting dynamic behavior due to their reversibility through thiol-disulfide exchange and homolytic cleavage with light and temperature. Within this context, in the present thesis a new family of catechol poly(disulfide)s is introduced to combine the most interesting features of catechols and disulfides functionalities. During the work the synthesis of a novel catechol containing compound bearing two thiols readily for polymerization is performed. Then, polymerization with iodine through the oxidation of free thiols is optimized looking for a proper modular approach with fine-tuning of the molecular weight of final catechol poly(disulfide)s. Seeking for the potential application in the biomedical field, the adhesion on diverse substrates and the use of these materials as tissue adhesive and sealant is evaluated. Furthermore, to study the full biocompatibility of these materials, in vitro and in vivo studies following ISO 10993 are carried out, as well as the assessment of the feasible degradation on different media

Supporting Information Reversible Tissue Sticker Inspired by Chemistry in Plant-Pathogen Relationship

11 pages. -- Materials and methods: 1.1 Molecular weight determined by gel permeation chromatography. -- 1.2 Film bursting tests by monitoring pressure given on the GMTA film. -- 1.3 An in vitro degradation profile of GMTA films in fetal bovine serum. -- 1.4 Cytotoxicity tests by agar diffusion methods. -- 1.5 Subcutaneous implantation and histology staining. -- Figures S1-S7. -- Movie S1. TA spray curing on an uncured GM film showing enhanced interfacial adhesion on a freshly prepared porcine heart.Peer reviewe

Synthesis of Polydopamine-Like Nanocapsules via Removal of a Sacrificial Mesoporous Silica Template with Water

Hollow polymeric polydopamine (PDA) micro-/nanocapsules have been obtained through a very simple, mild, and straightforward method that involves coating of silica mesoporous nanoparticles through an ammonia-triggered polymerization of PDA and the posterior removal of the sacrificial template simply by dispersion in water, without the need of any harsh chemical reagent, either in the presence or absence of active principles, from doxorubicin to iron oxide nanoparticles. To demonstrate the potential of the nanocapsules obtained with this new approach, they have been successfully used as nanocarriers for drug delivery

Polydopamine-like Coatings as Payload Gatekeepers for Mesoporous Silica Nanoparticles

We report the use of bis-catecholic polymers as candidates for obtaining effective, tunable gatekeeping coatings for mesoporous silica nanoparticles (MSNs) intended for drug release applications. In monomers, catechol rings act as adhesive moieties and reactive sites for polymerization, together with middle linkers which may be chosen to tune the physicochemical properties of the resulting coating. Stable and low-toxicity coatings (pNDGA and pBHZ) were prepared from two bis-catechols of different polarity (NDGA and BHZ) on MSN carriers previously loaded with rhodamine B (RhB) as a model payload, by means of a previously reported synthetic methodology and without any previous surface modification. Coating robustness and payload content were shown to depend significantly on the workup protocol. The release profiles in a model physiological PBS buffer of coated systems (RhB@MSN@pNDGA and RhB@MSN@pBHZ) showed marked differences in the "gatekeeping" behavior of each coating, which correlated qualitatively with the chemical nature of their respective linker moieties. While the uncoated system (RhB@MSN) lost its payload almost completely after 2 days, release from RhB@MSN@pNDGA was virtually negligible, likely due to the low polarity of the parent bis-catechol (NDGA). As opposed to these extremes, RhB@MSN@pBHZ presented the most promising behavior, showing an intermediate release of 50% of the payload in the same period of time

Reversible tissue sticker inspired by chemistry in plant-pathogen relationship

Plants release phenolic molecules to protect against invading pathogens. In plant-microorganism relationships, phenolics bind to surface oligosaccharides, inactivating microorganism activities. Inspired by phenol-saccharide interactions in plant defense systems, we designed an adhesive sealant. By screening 16 different saccharides, the O-acetyl group, rich in glucomannan (GM), exhibited rapid, robust binding with the galloyl moiety of a model phenolic molecule, tannic acid (TA). Furthermore, the interaction showed both pH and temperature (upper critical solution temperature) sensitivities. Utilizing O-acetyl-galloyl interactions, materials of all dimensions from beads (0D) to strings (1D), films (2D), and objects (3D) could be prepared, as a suitable platform for printing techniques. GMTA films are elastic, adhesive, water-resistant, and effectively sealed perforations, as demonstrated by (1) a lung incision followed by an air inflation model and (2) a thoracic diaphragm model. Statement of significance: In nature, phenolic molecules are 'nearly always' physically bound with polysaccharides, indicating that the phenolics widen the functions of polysaccharides. An example includes that phenolic-polysaccharide interactions are key defense mechanisms against microbial infection in plants whereas polysaccharide alone functions poorly. Despite the ubiquitous biochemistry of polysaccharide-phenolic interactions, efforts on understanding binding chemistry focusing on phenol/polysaccharide interactions is little. This study is important because we found for the first time that O-acetyl group is the moiety in polysaccharides to which phenolic cis-diol and/or cis-triol is spontaneously bound. The phenol-polysaccharide interaction is non-covalent yet robust, kinetically fast, and reversible. Inspired by the interaction chemistry, a simple mixture of phenolic molecules and O-acetyl group containing polysaccharides such as glucomannan opens a promising fabrication strategy toward functional polysaccharide-based material

Sonochemical synthesis, characterization, and effects of temperature, power ultrasound and reaction time on the morphological properties of two new nanostructured mercury(II) coordination supramolecule compounds

Two new mercury(II) coordination supramolecular compounds (CSCs) (1D and 0D), [Hg(L)(I)] (1) and [Hg(L')(SCN)]·2HO (2) (L = 2-amino-4-methylpyridine and L' = 2,6-pyridinedicarboxlic acid), have been synthesized under different experimental conditions. Micrometric crystals (bulk) or nano-sized materials have been obtained depending on using the branch tube method or sonochemical irradiation. All materials have been characterized by field emission scanning electron microscope (FESEM), scanning electron microscopy (SEM), powder X-ray diffraction (PXRD) and FT-IR spectroscopy. Single crystal X-ray analyses on compounds 1 and 2 show that Hg ions are 4-coordinated and 5-coordinated, respectively. Topological analysis shows that the compound 1 and 2 have 2C1, sql net. The thermal stability of compounds 1 and 2 in bulk and nano-size has been studied by thermal gravimetric (TG), differential thermal analyses (DTA) for 1 and differential scanning calorimetry (DSC) for 2, respectively. Also, by changing counter ions were obtained various structures 1 and 2 (1D and 0D, respectively). The role of different parameters like power of ultrasound irradiation, reaction time and temperature on the growth and morphology of the nano-structures are studied. Results suggest that increasing power ultrasound irradiation and temperature together with reducing reaction time and concentration of initial reagents leads to a decrease in particle size