Biominerals Formed by DNA and Calcium Oxalate or Hydroxyapatite: A Comparative Study.

Biominerals formed by DNA and calcium oxalate (CaOx) or hydroxyapatite (HAp), the most important and stable phase of calcium phosphate) have been examined and compared using a synergistic combination of computer simulation and experimental studies. The interest of this comparison stems from the medical observation that HAp- and CaOx-based microcalcifications are frequently observed in breast cancer tissues, and some of their features are used as part of the diagnosis. Molecular dynamics simulations show that (1) the DNA double helix remains stable when it is adsorbed onto the most stable facet of HAp, whereas it undergoes significant structural distortions when it is adsorbed onto CaOx; (2) DNA acts as a template for the nucleation and growth of HAp but not for the mineralization of CaOx; and (3) the DNA double helix remains stable when it is encapsulated inside HAp nanopores, but it becomes destabilized when the encapsulation occurs into CaOx nanopores. Furthermore, CaOx and HAp minerals containing DNA molecules inside and/or adsorbed on the surface have been prepared in the lab by mixing solutions containing the corresponding ions with fish sperm DNA. Characterization of the formed minerals, which has been focused on the identification of DNA using UV-vis spectroscopy, indicates that the tendency to adsorb and, especially, encapsulate DNA is much smaller for CaOx than for HAp, which is in perfect agreement with results from molecular dynamics simulations. Finally, quantum mechanical calculations have been performed to rationalize these results in terms of molecular interactions, evidencing the high affinity of Ca2+ toward oxalate anions in an aqueous environment.

Unravelling the Encapsulation of DNA and Other Biomolecules in HAp Microcalcifications of Human Breast Cancer Tissues by Raman Imaging.

Microcalcifications are detected through mammography screening and, depending on their morphology and distribution (BI-RADS classification), they can be considered one of the first indicators of suspicious cancer lesions. However, the formation of hydroxyapatite (HAp) calcifications and their relationship with malignancy remains unknown. In this work, we report the most detailed three-dimensional biochemical analysis of breast cancer microcalcifications to date, combining 3D Raman spectroscopy imaging and advanced multivariate analysis in order to investigate in depth the molecular composition of HAp calcifications found in 26 breast cancer tissue biopsies. We demonstrate that DNA has been naturally adsorbed and encapsulated inside HAp microcalcifications. Furthermore, we also show the encapsulation of other relevant biomolecules in HAp calcifications, such as lipids, proteins, cytochrome C and polysaccharides. The demonstration of natural DNA biomineralization, particularly in the tumor microenvironment, represents an unprecedented advance in the field, as it can pave the way to understanding the role of HAp in malignant tissues.

Clinical Feasibility of Large Gastrotomy Closure Using a Flexible Tissue Glue Based on N-Butyl-2-Cyanoacrylate: Experimental Study in Pigs.

BACKGROUND: The use of synthetic adhesives such as cyanoacrylates has been established previously for a wide range of clinical indications. However, more research is necessary to evaluate their use in digestive closures or anastomosis. New chemical formulations developed to achieve more flexibility of synthetic adhesives (i.e., based on n-butyl-2-cyanoacrylate) could be an alternative to achieve this purpose. The aim of this study was to investigate the feasibility of using flexible cyanoacrylate adhesives for large gastric incision closure in an animal model. METHODS: Twelve farm pigs were divided in two groups depending on the type of closure method applied. In all cases, extra-large seven centimeters gastrostomies were performed. Braided absorbable hand-sewn interrupted suture versus n-butyl-2-cyanoacrylate with softener closure were compared during a 3-week follow-up period. Histopathological aspects, hematologic and inflammatory biomarkers, and endoluminal pressure tolerated until leakage were assessed. The time spent on both closing procedures was compared. RESULTS: No differences between the two groups were found in any of the histopathological and inflammatory variables evaluated. The glued group tolerated a significantly higher pressure than the manual suture group. A reduction of surgery time was also observed. CONCLUSIONS: Our results suggest that flexible cyanoacrylates could be a feasible alternative to improve the clinical outcome of the closure of hollow viscera through more efficient sutureless procedures.

Loading of Antibiotic into Biocoated Hydroxyapatite Nanoparticles: Smart Antitumor Platforms with Regulated Release.

In this research we propose a nanoplatform for anticancer therapy that is based on the combination of three components: (1) an antibiotic to target selectively the mitochondria of cancer cells, inhibiting their functions; (2) mineral nanoparticles (NPs) able to encapsulate the antibiotic and to enter into the cells across the cell membrane; and (3) a biocoating to protect the antibiotic during and/or after its regulated release, increasing its therapeutic efficacy. Chloramphenicol (CAM), a prototypical wide-spectrum antibiotic, has been used to induce mitochondrial-dysfunctions in cancer cells. Different in situ synthetic strategies have been tested to load such antibiotic into both crystalline hydroxyapatite (cHAp) and amorphous calcium phosphate (ACP) NPs. cHAp NPs showed higher loading capacity, in terms of encapsulation and superficial adsorption of CAM, and slower antibiotic release than ACP NPs. On the other hand, the protecting role played by biocoatings based on pyrophosphate and, especially, triphosphate was greater than that of biophosphonates, the anticancer therapeutic efficacy of CAM being maximized by the former. In vitro studies using healthy and cancer cell lines have demonstrated that in situ CAM-loaded cHAp NPs coated with triphosphate selectively kill a great population of cancer cells, evidencing the potential of this nanoplatform in cancer treatment.