AGLUTININAS DE ALGAS ANTÁRTICAS.

Since the discovery of haemagglutinating activity in marine algal extracts in 1966, several algal haemagglutinins (lectins) have been detected, isolated and characterized. However, information is slowly emerging, concerning biochemical characteristics of lectins from Antarctic marine algae. Lectins are proteins or glycoproteins which bind, reversibly, to carbohydrates. Eighteen species of Antarctic marine algae have been tested for the presence of haemagglutinins against a several types of erythrocytes (rabbit, chicken, goat, sheep and ABO human blood groups). The protein extracts were prepared in phosphate buffered saline (PBS) pH 7.0. Serial doubling dilutions of extracts were prepared using 0.85% NaCl and an equal volume of 2% suspension of native or enzymatic treated erythrocytes was added to each tube, gentle mixed and left at 25 oC for 60 min before examination for agglutination. Fourteen species, among eighteen, produced haemagglutination of at least one type of blood cell tested. Protein extracts of three species were subjected to haemagglutination inhibition studies performed with a selection of sugars or glycoproteins. The activity of Adenocystis utriculares extracts was the only one inhibited by simple sugars. The other two extracts (Georgiella confluens and Gigartina skottsbergii) were not inhibited by mono- and polysaccharides, but were inhibited by glycoproteins.Desde a descoberta da presença de atividade hemaglutinante em extratos de algas marinhas em 1966, várias hemaglutininas (lectinas) de algas têm sido detectadas, isoladas e caracterizadas. Entretanto, novas informações surgem lentamente, em relação às características bioquímicas de lectinas de algas marinhas Antárticas. Hemaglutininas (lectinas) são proteínas ou glicoproteínas que se ligam, reversivelmente, a carboidratos. Dezoito espécies de algas marinhas Antárticas foram testadas quanto à presença de atividade hemaglutinante contra vários tipos de eritrócitos (coelho, galinha, carneiro, ovelha e humano dos grupos ABO). Os extratos protéicos foram preparados em tampão fosfato salino (PBS) pH 7,0. Diluições seriadas de extratos foram preparadas usando NaCl 0,85% e um volume igual de uma suspensão de eritrócitos a 2%, nativos ou tratados enzimaticamente, foi adicionada em cada tubo e incubada a 25 ºC por 60 minutos antes da análise da hemaglutinação. Quatorze espécies, entre dezoito, foram capazes de produzir hemaglutinação ao menos contra um tipo de células sangüíneas testadas. Extratos protéicos de três espécies foram submetidos a estudos de inibição da atividade hemaglutinante através da utilização de açúcares e glicoproteínas. A atividade do extrato de Adenocystis utriculares foi inibida somente por açúcares simples. Os outros dois extratos (Georgiella confluens e Gigartina skottsbergii) não foram inibidos por mono- e polissacarídeos, sendo inibidos somente por glicoproteínas.

Biomimetic Strontium Substituted Calcium Phosphate Coating for Bone Regeneration

Cellulose acetate (CA)/strontium phosphate (SrP) hybrid coating has been proposed as an effective strategy to build up novel bone-like structures for bone healing since CA is soluble in most organic solvents. Strontium (Sr2+) has been reported as a potential agent to treat degenerative bone diseases due to its osteopromotive and antibacterial effects. Herein, bioactive hybrid composite SrP-based coatings (CASrP) were successfully produced for the first time. CASrP was synthesized via a modified biomimetic method (for 7—CA7dSrP, and 14 days—CA14dSrP), in which the metal ion Sr2+ was used in place of Ca2+ in the simulated body fluid. Energy-dispersive X-ray (EDX) and Fourier transform infrared spectroscopy (FTIR) analysis confirmed the SrP incorporation chemically in the CASrP samples. Atomic absorption spectroscopy (AAS) supported EDX data, showing Sr2+ adsorption into CA, and its significant increase with the augmentation of time of treatment (ca. 92%—CA7dSrP and 96%—CA14dSrP). An increment in coating porosity and the formation of SrP crystals were evidenced by scanning electron microscopy (SEM) images. X-ray diffraction (XRD) evidenced a greater crystallinity than CA membranes and a destabilization of CA14dSrP structure compared to CA7dSrP. The composites were extremely biocompatible for fibroblast and osteoblast cells. Cell viability (%) was higher either for CA7dSrP (48 h: ca. 92% and 115%) and CA14dSrP (48 h: ca. 88% and 107%) compared to CA (48 h: ca. 70% and 51%) due to SrP formation and Sr2+ presence in its optimal dose in the culture media (4.6–9 mg·L−1). In conclusion, the findings elucidated here evidence the remarkable potential of CA7dSrP and CA14dSrP as bioactive coatings on the development of implant devices for inducing bone regeneration

Bacterial cellulose nanocrystals produced under different hydrolysis conditions: properties and morphological features

Bacterial cellulose (BC) is a polymer with interesting physical properties owing to the regular and uniform structure of its nanofibers, which are formed by amorphous (disordered) and crystalline (ordered) regions. Through hydrolysis with strong acids, it is possible to transform BC into a stable suspension of cellulose nanocrystals, adding new functionality to the material. The aim of this work was to evaluate the effects of inorganic acids on the production of BC nanocrystals (BCNCs). Acid hydrolysis was performed using different H2SO4 concentrations and reaction times, and combined hydrolysis with H2SO4 and HCl was also investigated. The obtained cellulose nanostructures were needle-like with lengths ranging between 622 and 1322 nm, and diameters ranging between 33.7 and 44.3 nm. The nanocrystals had a crystallinity index higher than native BC, and all BCNC suspensions exhibited zeta potential moduli greater than 30 mV, indicating good colloidal stability. The mixture of acids resulted in improved thermal stability without decreased crystallinity.The authors would like to thank Coordination for the Improvement of Higher Education Personnel (CAPES), National Counsel of Technological and Scientific Development (CNPq), and the Embrapa Tropical Agroindustry for funding this research and Strategic Technologies Center Northeast (CETENE) for supporting the transmission electron microscopy analysis

Virucidal PVP-Copper Salt Composites against Coronavirus Produced by Electrospinning and Electrospraying

Electrospinning technology was used to produced polyvinylpyrrolidone (PVP)-copper salt composites with structural differences, and their virucidal activity against coronavirus was investigated. The solutions were prepared with 20, 13.3, 10, and 6.6% w/v PVP containing 3, 1.0, 0.6, and 0.2% w/v Cu (II), respectively. The rheological properties and electrical conductivity contributing to the formation of the morphologies of the composite materials were observed by scanning electron microscopy (SEM). SEM images revealed the formation of electrospun PVP-copper salt ultrafine composite fibers (0.80 ± 0.35 µm) and electrosprayed PVP-copper salt composite microparticles (1.50 ± 0.70 µm). Energy-dispersive X-ray spectroscopy (EDS) evidenced the incorporation of copper into the produced composite materials. IR spectra confirmed the chemical composition and showed an interaction of Cu (II) ions with oxygen in the PVP resonant ring. Virucidal composite fibers inactivated 99.999% of coronavirus within 5 min of contact time, with moderate cytotoxicity to L929 cells, whereas the virucidal composite microparticles presented with a virucidal efficiency of 99.999% within 1440 min of exposure, with low cytotoxicity to L929 cells (mouse fibroblast). This produced virucidal composite materials have the potential to be applied in respirators, personal protective equipment, self-cleaning surfaces, and to fabric coat personal protective equipment against SARS-CoV-2, viral outbreaks, or pandemics

Characterisation of microbial attack on archaeological bone

As part of an EU funded project to investigate the factors influencing bone preservation in the archaeological record, more than 250 bones from 41 archaeological sites in five countries spanning four climatic regions were studied for diagenetic alteration. Sites were selected to cover a range of environmental conditions and archaeological contexts. Microscopic and physical (mercury intrusion porosimetry) analyses of these bones revealed that the majority (68%) had suffered microbial attack. Furthermore, significant differences were found between animal and human bone in both the state of preservation and the type of microbial attack present. These differences in preservation might result from differences in early taphonomy of the bones. © 2003 Elsevier Science Ltd. All rights reserved