Recovering and Exploiting Aragonite and Calcite Single Crystals with Biologically Controlled Shapes from Mussel Shells

Control over the shape and morphology of single crystals is a theme of great interest in fundamental science and for technological application. Many synthetic strategies to achieve this goal are inspired by biomineralization processes. Indeed, organisms are able to produce crystals with high fidelity in shape and morphology utilizing macromolecules that act as modifiers. An alternative strategy can be the recovery of crystals from biomineralization products, in this case, seashells. In particular, waste mussel shells from aquaculture are considered. They are mainly built up of single crystals of calcite fibers and aragonite tablets forming an outer and an inner layer, respectively. A simple mechanochemical treatment has been developed to separate and recover these two typologies of single crystals. The characterization of these single crystals showed peculiar properties with respect to the calcium carbonate from quarry or synthesis. We exploited these biomaterials in the water remediation field using them as substrate adsorbing dyes. We found that these substrates show a high capability of adsorption for anionic dye, such as Eosin Y, but a low capability of adsorption for cationic dyes, such as Blue Methylene. The adsorption was reversible at pH 5.6. This application represents just an example of the potential use of these biogenic single crystals. We also envision potential applications as reinforcing fillers and optical devices

One-step hydrothermal transformation of oyster shell Mg-calcite to biomimetic nanocrystalline apatite

Comunicación oral del The International Conference on Crystal Growth and Epitaxy-ICCGE-20. Naples(Italy), 30 july-4 august 2023Seashells are hierarchical bio-organic/mineral composites made of calcium carbonate (CaCO3) and an organic matrix (1-5 wt. %) composed mainly of proteins and polysaccharides. Fishery industry waste containing seashells from mussels, scallops, and oysters, represents an important environmental issue. The process is ecologically harmful and implies the loss of potentially useful biomaterials [1]. The valorization of seashell waste by transforming the CaCO3 crystals into biomimetic apatite micro/nanoparticles for biomedical applications may have a positive environmental impact besides economic profitability since the global market (including nano-sized, micron-sized, and higher sizes) is expected to grow in the next years. Different methods to transform biogenic CaCO3 into apatite nano/microparticles have been developed recently. They are mainly two-step processes involving calcination to CaO at 900-1000 °C followed by the reaction of a phosphate reagent (typically H3PO4) with the Ca(OH)2 produced by hydration of the CaO [2]. In this work, we have developed a one-step hydrothermal process to obtain biomimetic carbonated-apatite using oyster shells (Mg-calcite, 5 wt.% Mg) from the species Crassostrea gigas as model raw material. Shells were treated with NaClO 5% v/v to remove surface organic residues, crushed by a hammer mill, milled in a ball mill and sieved using a <45 ¿m mesh. The so obtained particles were submitted to hydrothermal treatment. Different experimental parameters were tested: P reagents (H3PO4, KH2PO4, and K2HPO4); P/Ca molar ratios (0.24, 0.6, and 0.96); temperature (25-200°C) and time (from 1 week to 2 months), without any pH adjustment. Characterization was performed by XRD, FTIR, Raman, SEM, TEM, DLS and TGA. The apatite/calcite ratio (wt.%) of the final precipitates was determined by Rietveld analysis using TOPAS 6.0 software. Among the many results, it is worth of mentioning that at the lowest experimental time used (1 week), the temperatures to obtain full transformation depend on the P reagent and P/Ca mol ratio, the lowest one being 80 ºC when using KH2PO4 as reagent, and a P/Ca molar ratio 0.96 (excess of P). The obtained precipitates (Mg2+-doped carbonated-apatite micro/nanoparticles) with biomimetic features are the result of a dissolution/reprecipitation mechanism driven by pH variation. Compared to the previous two-step processes, the one reported here is straightforward, one-pot, and can be operated at relatively low temperatures without any pH adjustment, and specially avoiding the use of expensive hydrothermal autoclaves. Acknowledgements: Grant ref. PCI2020-112108 is funded by MCIN/AEI/10.13039 /501100011033 (Spain) and the European Union "NextGenerationEU"/PRTR". PCI2020-112108 is part of the project CASEAWA of ERA-NET Cofund BlueBio H2020

TP52*P72 allele influences negatively female life expectancy in a population of central Italy: cross-sectional study and genetic-demographic approch.

The association of TP53 P72R (rs1042522) with longevity remains uncertain and varies with ethnicity. Here, we tested its association with longevity in a cross-sectional population of Central Italy (18-106 years, N = 1,072), by integrating demographic information and frequency data to account for the different survival rates between sexes through the application of a genetic-demographic approach. rs1042522 affects females longevity, showing significant associations in Comparison 2 (Age Class 3 [>91 years] vs Age Class 2 [73-91 years]) under both additive (odds ratio [OR] 0.574; p = .006) and dominant (OR 0.513; p = .006) models. The TP53*P72 allele is significantly underrepresented in Age Class 3 only in women (OR 0.575; p = .008). The genetic-demographic approach demonstrated that the frequency of female TP53*P72 carriers underwent a significant reduction after 82 years (OR 0.586; p = .002). The same analyses gave nonsignificant results in men. The discrepancies among the results obtained on rs1042522 for longevity could result from the pleiotropic effects of p53 and the potential ethnic variation of its functional variants

Microbiological characterization of Gioddu, an Italian fermented milk

Gioddu, also known as “Miciuratu”, “Mezzoraddu” or “Latte ischidu” (literally meaning acidulous milk), is the sole variety of traditional Italian fermented milk. The aim of the present study was to elucidate the microbiota and the mycobiota occurring in artisan Gioddu sampled from three Sardinian producers by combining the results of viable counting on selective culture media and high-throughput sequencing. Physico-chemical parameters were also measured. The overall low pH values (3.80–4.22) recorded in the analyzed Gioddu samples attested the strong acidifying activity carried out by lactic acid bacteria during fermentation. Viable counts revealed the presence of presumptive lactococci, presumptive lactobacilli and non-Saccharomyces yeasts. A complex (kefir-like) microbiota of bacteria and yeasts was unveiled through sequencing. In more detail, Lactobacillus delbrueckii was found to dominate in Gioddu together with Streptococcus thermophilus, thus suggesting the establishment of a yogurt-like protocooperation. Unexpectedly, in all the three analyzed batches from two out of the three producers Lactobacillus kefiri was also detected, thus representing an absolute novelty, which suggests the presence of bioactive compounds (e.g. exopolysaccharides) similar to those characterizing milk kefir beverage. Mycobiota population, studied for the very first time in Gioddu, revealed a more complex composition, with Kluyveromyces marxianus, Galactomyces candidum and Geotrichum galactomyces constituting the core species. Further research is needed to disclose the eventual occurence in Gioddu of probiotic cultures and bioactive compounds (e.g. exopolysaccharides, angiotensin-converting enzyme inhibitory peptides and antimicrobial compounds) with potential health-benefits for the consumers

Le Rotte della Filosofia

Enciclopedia Multimediale delle Scienze Filosofiche in collaborazione con l'Istituto Italiano per gli Studi Filosofici. Una coproduzione RAI Educational e Paravi