Granular Disulfide-Crosslinked Hyaluronic Hydrogels: A Systematic Study of Reaction Conditions on Thiol Substitution and Injectability Parameters.

Granular polymer hydrogels based on dynamic covalent bonds are attracting a great deal of interest for the design of injectable biomaterials. Such materials generally exhibit shear-thinning behavior and properties of self-healing/recovery after the extrusion that can be modulated through the interactions between gel microparticles. Herein, bulk macro-hydrogels based on thiolated-hyaluronic acid were produced by disulphide bond formation using oxygen as oxidant at physiological conditions and gelation kinetics were monitored. Three different thiol substitution degrees (SD%: 65%, 30% and 10%) were selected for hydrogel formation and fully characterized as to their stability in physiological medium and morphology. Then, extrusion fragmentation technique was applied to obtain hyaluronic acid microgels with dynamic disulphide bonds that were subsequently sterilized by autoclaving. The resulting granular hyaluronic hydrogels were able to form stable filaments when extruded through a syringe. Rheological characterization and cytotoxicity tests allowed to assess the potential of these materials as injectable biomaterials. The application of extrusion fragmentation for the formation of granular hyaluronic hydrogels and the understanding of the relation between the autoclaving processes and the resulting particle size and rheological properties should expand the development of injectable materials for biomedical applications.

Multifunctional antibacterial chitosan-based hydrogel coatings on Ti6Al4V biomaterial for biomedical implant applications.

Among biomedical community, great efforts have been realized to develop antibacterial coatings that avoid implant-associated infections. To date, conventional mono-functional antibacterial strategies have not been effective enough for successful long-term implantations. Consequently, researchers have recently focused their attention on novel bifunctional or multifunctional antibacterial coatings, in which two or more antibacterial mechanisms interact synergistically. Thus, in this work different chitosan-based (CHI) hydrogel coatings were created on Ti6Al4V surface using genipin (Ti-CHIGP) and polyethylene glycol (Ti-CHIPEG) crosslinking agents. Hydrogel coatings demonstrated an exceptional in vivo biocompatibility plus a remarkable ability to promote cell proliferation and differentiation. Lastly, hydrogel coatings demonstrated an outstanding bacteria-repelling (17-28 % of S. aureus and 33-43 % of E. coli repelled) and contact killing (186-222 % of S. aureus and 72-83 % of E. coli damaged) ability. Such bifunctional antibacterial activity could be further improved by the controlled release of drugs resulting in powerful multifunctional antibacterial coatings.

Hyaluronic acid-based hydrogel coatings on Ti6Al4V implantable biomaterial with multifunctional antibacterial activity.

Today, the treatment of implant-associated infections with conventional mono-functional antibacterial coatings has not been effective enough for a prosperous long-term implantation. Therefore, biomedical industry is making considerable efforts on the development of novel antibacterial coatings with a combination of more than one antibacterial strategies that interact synergistically to reinforce each other. Therefore, in this work hyaluronic acid-based (HA) hydrogel coatings were created on the surface Ti6Al4V biomaterial with 1,4-butanediol diglycidyl ether (Ti-HABDDE) and divinyl sulfone (Ti-HADVS) crosslinking agents. Hydrogel coatings displayed an extraordinary in vivo biocompatibility, a remarkable ability to promote cell proliferation, differentiation and mineralization, and capability to sustainedly release drugs. Finally, HA-based hydrogel coatings demonstrated an outstanding multifunctional antibacterial activity: bacteria-repelling (51-55 % of S. aureus and 27-40 % of E. coli), bacteria-killing (82-119 % of S. aureus and 83-87 % of E. coli) and bactericide release killing (drug-loaded hydrogel coatings, R > 2).

Self-healing, antibacterial and anti-inflammatory chitosan-PEG hydrogels for ulcerated skin wound healing and drug delivery.

Great efforts have been performed on the production of advanced biomaterials with the combination of self-healing and wound healing properties in implant/tissue engineering biomedical area. Inspired by this idea, chitosan (CHI) based hydrogels can be used to treat a less investigated class of harmful chronic wounds: ulcers or pressure ulcers. Thus, CHI was crosslinked with previously synthesized polyethylene glycol diacid (PEG-diacid) to obtain different CHI-PEG hydrogel formulations with high H-bonding tendency resulting in self-repair ability. Here presented results show biocompatible, antibacterial, anti-inflammatory, and self-healing CHI-PEG hydrogels with a promising future in the treatment of ulcerated wounds by a significant improvement in metabolic activity (94.51 ± 4.38 %), collagen and elastin quantities (2.12 ± 0.63 µg collagen and 4.97 ± 0.61 µg elastin per mg dermal tissue) and histological analysis. Furthermore, cefuroxime (CFX), tetracycline (TCN) and amoxicillin (AMX) antibiotics, and acetylsalicylic acid (ASA) anti-inflammatory agent were sustainedly released for enhancing antibacterial and anti-inflammatory activities of hydrogels.

Drug Delivery from Hyaluronic Acid-BDDE Injectable Hydrogels for Antibacterial and Anti-Inflammatory Applications.

Hyaluronic acid (HA) injectable biomaterials are currently applied in numerous biomedical areas, beyond their use as dermal fillers. However, bacterial infections and painful inflammations are associated with healthcare complications that can appear after injection, restricting their applicability. Fortunately, HA injectable hydrogels can also serve as drug delivery platforms for the controlled release of bioactive agents with a critical role in the control of certain diseases. Accordingly, herein, HA hydrogels were crosslinked with 1 4-butanediol diglycidyl ether (BDDE) loaded with cefuroxime (CFX), tetracycline (TCN), and amoxicillin (AMX) antibiotics and acetylsalicylic acid (ASA) anti-inflammatory agent in order to promote antibacterial and anti-inflammatory responses. The hydrogels were thoroughly characterized and a clear correlation between the crosslinking grade and the hydrogels' physicochemical properties was found after rheology, scanning electron microscopy (SEM), thermogravimetry (TGA), and differential scanning calorimetry (DSC) analyses. The biological safety of the hydrogels, expected due to the lack of BDDE residues observed in 1H-NMR spectroscopy, was also corroborated by an exhaustive biocompatibility test. As expected, the in vitro antibacterial and anti-inflammatory activity of the drug-loaded HA-BDDE hydrogels was confirmed against Staphylococcus aureus by significantly decreasing the pro-inflammatory cytokine levels.

Spontaneous Gelation of Adhesive Catechol Modified Hyaluronic Acid and Chitosan.

Spontaneously formed hydrogels are attracting increasing interest as injectable or wound dressing materials because they do not require additional reactions or toxic crosslinking reagents. Highly valuable properties such as low viscosity before external application, adequate filmogenic capacity, rapid gelation and tissue adhesion are required in order to use them for those therapeutic applications. In addition, biocompatibility and biodegradability are also mandatory. Accordingly, biopolymers, such as hyaluronic acid (HA) and chitosan (CHI), that have shown great potential for wound healing applications are excellent candidates due to their unique physiochemical and biological properties, such as moisturizing and antimicrobial ability, respectively. In this study, both biopolymers were modified by covalent anchoring of catechol groups, and the obtained hydrogels were characterized by studying, in particular, their tissue adhesiveness and film forming capacity for potential skin wound healing applications. Tissue adhesiveness was related to o-quinone formation over time and monitored by visible spectroscopy. Consequently, an opposite effect was observed for both polysaccharides. As gelation advances for HA-CA, it becomes more adhesive, while competitive reactions of quinone in CHI-CA slow down tissue adhesiveness and induce a detriment of the filmogenic properties.

Wound healing and antibacterial chitosan-genipin hydrogels with controlled drug delivery for synergistic anti-inflammatory activity.

Chitosan (CHI) based hydrogels promote wound healing and relieve inflammations and chronic infections. However, in hardly healable ulcers with excessively painful inflammations, anti-inflammatory activity of hydrogels can be enhanced by the sustained release of non-steroidal anti-inflammatory drugs or combining them with antibiotics. Thus, CHI was crosslinked with genipin (GP) to obtain biocompatible hydrogels. Moreover, their antibacterial activity was confirmed against Staphylococcus aureus and Escherichia coli with an almost 100% bacteria reduction and a potential antibacterial efficacy (R > 2). Furthermore, hydrogels effective healing of ulcerated wounds was corroborated by a significant improvement in metabolic activity (95.58 ± 4.40%), collagen and elastin quantities (1.48 ± 0.07 µg collagen and 5.82 ± 0.73 µg elastin per mg dermal tissue) and histological analysis. Finally, the sustained release of acetylsalicylic acid (ASA), cefuroxime (CFX), tetracycline (TCN) and amoxicillin (AMX) were studied, as well as their anti-inflammatory activity. Results confirm the synergistic anti-inflammatory activity by the significant reduction in the amount of pro-inflammatory cytokines when ASA was combined with CFX (5.39 ± 0.81 ng·mL-1 TNF-α), TCN (4.70 ± 0.21 ng·mL-1 TNF-α and 49.06 ± 9.64 ng·mL-1 IL-8), and AMX (2.28 ± 0.36 ng·mL-1 TNF-α, 14.84 ± 5.57 ng·mL-1 IL-8, and total IL-6 removal).

Hyaluronic Acid Hydrogels Crosslinked in Physiological Conditions: Synthesis and Biomedical Applications.

Hyaluronic acid (HA) hydrogels display a wide variety of biomedical applications ranging from tissue engineering to drug vehiculization and controlled release. To date, most of the commercially available hyaluronic acid hydrogel formulations are produced under conditions that are not compatible with physiological ones. This review compiles the currently used approaches for the development of hyaluronic acid hydrogels under physiological/mild conditions. These methods include dynamic covalent processes such as boronic ester and Schiff-base formation and click chemistry mediated reactions such as thiol chemistry processes, azide-alkyne, or Diels Alder cycloaddition. Thermoreversible gelation of HA hydrogels at physiological temperature is also discussed. Finally, the most outstanding biomedical applications are indicated for each of the HA hydrogel generation approaches.

Biocompatible hyaluronic acid-divinyl sulfone injectable hydrogels for sustained drug release with enhanced antibacterial properties against Staphylococcus aureus.

Hyaluronic acid (HA) solutions were crosslinked with divinyl sulfone (DVS) and subsequently loaded with antibiotic molecules to obtain biocompatible and antibacterial injectable hydrogels. The crosslinking degree of the hydrogels was modulated by varying the reaction time and the HA:DVS weight ratio. Synthesized HA-DVS hydrogels were characterized by their rheological properties, pore size, swelling capacity and hydrolytic and thermal degradation. Biocompatibility was assessed by measuring pH, osmolality and by in vitro cytotoxic assay. Acetyl salicylic (AAS) loaded hydrogels display anti-inflammatory properties in vitro, whereas cefuroxime (CFX), tetracycline (TCN) and amoxicillin (AMX) loaded hydrogels show in vitro antibacterial activity against Staphylococcus aureus. The combine use of antibiotics and AAS produces a synergic effect that reduces the S. aureus population up to a log10 reduction (R) of 5.55. Overall results show that antibiotic/AAS loaded HA-DVS hydrogels could be effectively used to combat S. aureus infections and to increase the antibacterial activity of antibiotics commonly used against S. aureus.

Reproductive aspects of Grapsus grapsus (Decapoda: Grapsidae) on islands of the southeastern Gulf of California / Aspectos reproductivos de Grapsus grapsus (Decapoda: Grapsidae) en islas del sureste del Golfo de California

ABSTRACT Objective. The sex ratio, proportion of ovigerous females, length at sexual maturity and fecundity of Grapsus grapsus crabs in the Lobos, Venados and Pajaros islands (southeastern Gulf of California) were analyzed. Materials and methods. Sampling was conducted monthly between March 2011 and February 2012, during the night at low tide. Thirty crabs were collected in a quadrant (25 m2) at each sampling site on each island. cw (mm) and w (g) were determined. The sex ratio and size at sexual maturity (cw50%) were estimated, and for ovigerous females, embryonic stages and fecundity (gravimetric method) were determined. Results. The sex ratio (M:F) was 1:1.3. The average size at sexual maturity (cw50%) was 34.9 mm. The majority of females were ovigerous (71.3%), and 48% of the embryos of ovigerous females were at the red-orange phase. Egg diameter ranged from 1.1 to 5 µm, with an average of 2.05 µm. The mean fecundity was 24339.3 eggs. The maximum and minimum weight of ovigerous females was 69.9 and 15.2 g. Conclusions. The studied characteristics of sex ratio, proportion of ovigerous females, length at sexual maturity and fecundity of G. grapsus, indicate the effective administration and management of this resource in this area.

RESUMEN Objetivo. Se analizó la proporción de sexos, hembras ovígeras, talla de primera madurez sexual y fecundidad del cangrejo roca Grapsus grapsus en islas Lobos, Venados y Pájaros (sureste del Golfo de California). Material y métodos. Los muestreos fueron mensuales entre marzo 2011 y febrero 2012, las colectas fueron nocturnas durante la bajamar, se obtuvieron en un cuadrante (25 m2) por isla 30 organismos al azar, se les determinó el AN (mm) y PT (g). Se estimó la proporción de sexos y talla de primera madurez sexual (AN50%), se analizaron en hembras grávidas, las fases embrionarias y la fecundidad (método gravimétrico). Resultados. La proporción de M:H fue 1:1.3. La talla media de primera madurez fue AN50% 34.9 mm. Es evidente la presencia de hembras ovígeras (71.3%) y todas las fases embrionarias, la fase rojo-naranja fue la mayor representada en 48%. La variación del diámetro del huevo fue 1.1 a 5 µm y el promedio de 3.05 µm. La fecundidad media fue 24339.3 cigotos. El máximo y mínimo peso de hembras ovígeras fue 69.9 y 15.2 g, respectivamente. Conclusiones. Con base a las características biológicas del recurso tales como la proporción de sexos, hembras ovígeras, talla de primera madurez sexual y fecundidad en la población de G. grapsus, representa un efecto favorable en su posterior administración y manejo de este recurso en esta zona.

Injectable Hydrogels: From Laboratory to Industrialization.

The transfer of some innovative technologies from the laboratory to industrial scale is many times not taken into account in the design and development of some functional materials such as hydrogels to be applied in the biomedical field. There is a lack of knowledge in the scientific field where many aspects of scaling to an industrial process are ignored, and products cannot reach the market. Injectable hydrogels are a good example that we have used in our research to show the different steps needed to follow to get a product in the market based on them. From synthesis and process validation to characterization techniques used and assays performed to ensure the safety and efficacy of the product, following regulation, several well-defined protocols must be adopted. Therefore, this paper summarized all these aspects due to the lack of knowledge that exists about the industrialization of injectable products with the great importance that it entails, and it is intended to serve as a guide on this area to non-initiated scientists. More concretely, in this work, the characteristics and requirements for the development of injectable hydrogels from the laboratory to industrial scale is presented in terms of (i) synthesis techniques employed to obtain injectable hydrogels with tunable desired properties, (ii) the most common characterization techniques to characterize hydrogels, and (iii) the necessary safety and efficacy assays and protocols to industrialize and commercialize injectable hydrogels from the regulatory point of view. Finally, this review also mentioned and explained a real example of the development of a natural hyaluronic acid hydrogel that reached the market as an injectable product.

Synthesis and Characterization of Covalently Crosslinked pH-Responsive Hyaluronic Acid Nanogels: Effect of Synthesis Parameters.

Stable hyaluronic acid nanogels were obtained following the water-in-oil microemulsion method by covalent crosslinking with three biocompatible crosslinking agents: Divinyl sulfone, 1,4-butanediol diglycidyl ether (BDDE), and poly(ethylene glycol) bis(amine). All nanoparticles showed a pH-sensitive swelling behavior, according to the pKa value of hyaluronic acid, as a consequence of the ionization of the carboxylic moieties, as it was corroborated by zeta potential measurements. QELS studies were carried out to study the influence of the chemical structure of the crosslinking agents on the particle size of the obtained nanogels. In addition, the effect of the molecular weight of the biopolymer and the degree of crosslinking on the nanogels dimensions was also evaluated for BDDE crosslinked nanoparticles, which showed the highest pH-responsive response.

Morbilidad materna extremadamente grave, un problema actual / Extremely severe mother morbidity, a current problem

La morbilidad materna extremadamente grave es la complicación que ocurre durante el embarazo, el parto y el puerperio, que pone en riesgo la vida de la mujer y requiere de una atención inmediata con el fin de evitar la muerte. Como parte de la primera etapa de un proyecto de investigación relacionado con la morbilidad materna extremadamente grave se realizó la actualización sobre este tema, para lo cual se efectuó una revisión bibliográfica. Fueron consultadas las bases de datos LILACS, EBSCO e HINARI, con el uso de los siguientes descriptores: bienestar materno, mortalidad materna y morbilidad. También se utilizo el lenguaje libre con palabras clave aportadas por los autores, tales como: calidad de los cuidados maternos, morbilidad materna y morbilidad materna extremadamente grave. Se utilizaron los operadores booleanos correspondientes y las referencias bibliográficas, acotadas según la norma Vancouver 2010. Los resultados de la búsqueda se limitaron a los últimos cinco años y a los idiomas inglés, español y portugués. El análisis de la morbilidad materna extremadamente grave emerge como complemento o alternativa a la investigación de las muertes maternas y se considera actualmente el indicador de calidad de los cuidados maternos. La incorporación de este indicador a los reportes epidemiológicos y a los servicios obstétricos aportará nuevos conocimientos sobre una base científica del problema y permitirá de forma oportuna la toma de decisiones para la atención materna en el futuro.

The extremely severe mother morbidity is a complication occurring during pregnancy, delivery and the puerperium risking the woman's life and that require of an immediate care to avoid death. As part of the first stage of a research project related to extremely severe mother morbidity an updating on this subject was carried out and a bibliography review. The databases LILACS, EBSCO AND HINARI database were consulted with the use of following descriptors: mother wellbeing, morbidity and mortality as well as a free language using words provided by authors including: quality of mother cares, mother morbidity and extremely severe mother morbidity. The corresponding operators were used and the references selected according to the Vancouver standards, 2010. Results from search were limited to the last 5 years and to English, Spanish and Portuguese languages. The analysis of extremely severe mother morbidity emerges as a complement or alternative to research of mother deaths and nowadays is considered an indicator of mother cares. The addition of this indicator to epidemiologic reports and to obstetric services will supply new knowledges on the scientific basis of problem and will allow in a timely way the decisions-making for the future mother care.

Morbilidad materna extremadamente grave, un problema actual / Extremely severe mother morbidity, a current problem

La morbilidad materna extremadamente grave es la complicación que ocurre durante el embarazo, el parto y el puerperio, que pone en riesgo la vida de la mujer y requiere de una atención inmediata con el fin de evitar la muerte. Como parte de la primera etapa de un proyecto de investigación relacionado con la morbilidad materna extremadamente grave se realizó la actualización sobre este tema, para lo cual se efectuó una revisión bibliográfica. Fueron consultadas las bases de datos LILACS, EBSCO e HINARI, con el uso de los siguientes descriptores: bienestar materno, mortalidad materna y morbilidad. También se utilizo el lenguaje libre con palabras clave aportadas por los autores, tales como: calidad de los cuidados maternos, morbilidad materna y morbilidad materna extremadamente grave. Se utilizaron los operadores booleanos correspondientes y las referencias bibliográficas, acotadas según la norma Vancouver 2010. Los resultados de la búsqueda se limitaron a los últimos cinco años y a los idiomas inglés, español y portugués. El análisis de la morbilidad materna extremadamente grave emerge como complemento o alternativa a la investigación de las muertes maternas y se considera actualmente el indicador de calidad de los cuidados maternos. La incorporación de este indicador a los reportes epidemiológicos y a los servicios obstétricos aportará nuevos conocimientos sobre una base científica del problema y permitirá de forma oportuna la toma de decisiones para la atención materna en el futuro(AU)

The extremely severe mother morbidity is a complication occurring during pregnancy, delivery and the puerperium risking the woman's life and that require of an immediate care to avoid death. As part of the first stage of a research project related to extremely severe mother morbidity an updating on this subject was carried out and a bibliography review. The databases LILACS, EBSCO AND HINARI database were consulted with the use of following descriptors: mother wellbeing, morbidity and mortality as well as a free language using words provided by authors including: quality of mother cares, mother morbidity and extremely severe mother morbidity. The corresponding operators were used and the references selected according to the Vancouver standards, 2010. Results from search were limited to the last 5 years and to English, Spanish and Portuguese languages. The analysis of extremely severe mother morbidity emerges as a complement or alternative to research of mother deaths and nowadays is considered an indicator of mother cares. The addition of this indicator to epidemiologic reports and to obstetric services will supply new knowledges on the scientific basis of problem and will allow in a timely way the decisions-making for the future mother care(AU)

Propuesta de indicadores de resultado, primera etapa para la medición de la eficiencia del policlínico / Proposal of outcome indicators, the first stage of measuring polyclinics efficiency

Se realizó un estudio descriptivo con la finalidad de identificar indicadores de resultado del policlínico, como primer paso para una futura medición de su eficiencia productiva. Se hizo una revisión bibliográfica y consulta a expertos a través del método Delphi. Se efectuó el análisis de las variables del estudio a partir de las bases de datos creadas mediante el empleo de porcentajes. La propuesta final está compuesta por 6 indicadores (índice de mortalidad infantil evitable, índice de cumplimiento del esquema de vacunación, índice de satisfacción de la población, índice de bajo peso al nacer, índice de casos bacilófilos positivos diagnosticados en el policlínico e índice de enfermos crónicos controlados). Los indicadores seleccionados abarcan tanto la dimensión de la salud percibida como de la salud objetiva.

A descriptive study was made to identify outcome indicators of the polyclinics, as a first step for measurement of productive efficiency in the future. A literature review was made and experts were consulted through the Delphi method. The study variables were analyzed, through percentages, from developed databases. The definite proposal consisted of six indicators (preventable infant mortality index, vaccination schedule fulfillment index, population satisfaction index, low birthweight index, index of positive bacilophilic cases diagnosed by the polyclinics and controlled chronic patient index). The selected indicators cover both the perceived health dimension and the objective health dimension.

Propuesta de indicadores de resultado, primera etapa para la medición de la eficiencia del policlínico / Proposal of outcome indicators, the first stage of measuring polyclinics efficiency

Se realizó un estudio descriptivo con la finalidad de identificar indicadores de resultado del policlínico, como primer paso para una futura medición de su eficiencia productiva. Se hizo una revisión bibliográfica y consulta a expertos a través del método Delphi. Se efectuó el análisis de las variables del estudio a partir de las bases de datos creadas mediante el empleo de porcentajes. La propuesta final está compuesta por 6 indicadores (índice de mortalidad infantil evitable, índice de cumplimiento del esquema de vacunación, índice de satisfacción de la población, índice de bajo peso al nacer, índice de casos bacilófilos positivos diagnosticados en el policlínico e índice de enfermos crónicos controlados). Los indicadores seleccionados abarcan tanto la dimensión de la salud percibida como de la salud objetiva(AU)

A descriptive study was made to identify outcome indicators of the polyclinics, as a first step for measurement of productive efficiency in the future. A literature review was made and experts were consulted through the Delphi method. The study variables were analyzed, through percentages, from developed databases. The definite proposal consisted of six indicators (preventable infant mortality index, vaccination schedule fulfillment index, population satisfaction index, low birthweight index, index of positive bacilophilic cases diagnosed by the polyclinics and controlled chronic patient index). The selected indicators cover both the perceived health dimension and the objective health dimension(AU)