3D Printable Composite Biomaterials Based on GelMA and Hydroxyapatite Powders Doped with Cerium Ions for Bone Tissue Regeneration.

The main objective was to produce 3D printable hydrogels based on GelMA and hydroxyapatite doped with cerium ions with potential application in bone regeneration. The first part of the study regards the substitution of Ca2+ ions from hydroxyapatite structure with cerium ions (Ca10-xCex(PO4)6(OH)2, xCe = 0.1, 0.3, 0.5). The second part followed the selection of the optimal concentration of HAp doped, which will ensure GelMA-based scaffolds with good biocompatibility, viability and cell proliferation. The third part aimed to select the optimal concentrations of GelMA for the 3D printing process (20%, 30% and 35%). In vitro biological assessment presented the highest level of cell viability and proliferation potency of GelMA-HC5 composites, along with a low cytotoxic potential, highlighting the beneficial effects of cerium on cell growth, also supported by Live/Dead results. According to the 3D printing experiments, the 30% GelMA enriched with HC5 was able to generate 3D scaffolds with high structural integrity and homogeneity, showing the highest suitability for the 3D printing process. The osteogenic differentiation experiments confirmed the ability of 30% GelMA-3% HC5 scaffold to support and efficiently maintain the osteogenesis process. Based on the results, 30% GelMA-3% HC5 3D printed scaffolds could be considered as biomaterials with suitable characteristics for application in bone tissue engineering.

Stochastic microsensors for the assessment of DNA damage in cancer.

Three stochastic microsensors based on graphite powder modified with three different oleamides: N-(2-piperidin-1-ylethyl)oleamide, N-(3,4-dihydroxyphenethyl)oleamide and N-(2-morpholinoethyl)oleamide, were designed, characterized, and used to assess DNA damage in cancer by assaying two biomarkers namely 8-nitroguanine and 8-hydroxy-2'-deoxyguanosine. The two biomarkers were determined from urine and whole blood samples. The characterization of the microsensors was done at two pHs 7.40 and 3.00. The best microsensor for the simultaneous determination of biomarkers in whole blood and urine samples was the one based on the graphite paste modified with N-(3,4-dihydroxyphenethyl)oleamide. The results indicated that the proposed microsensors can be reliably used for pattern recognition and quantitative determination of 8-nitroguanine and 8-hydroxy-2'-deoxyguanosine in whole blood and urine, and accordingly, for the assessment of DNA damage in cancer patients.

Advances in immunosensors for clinical applications.

Immunoassay technique performs a fast, simple, reliable, and sensitive analysis of different compounds, being applied in several areas of interest such as clinical analysis for medical diagnosis, as well as in environmental analysis, and food quality control. The latest research activities in this field are represented by the attempts to achieve a low limit of detection by developing of new signal amplification strategies, eliminate the interferences, and decrease the cost of analysis.

Pattern recognition of 8-hydroxy-2'-deoxyguanosine in biological fluids.

8-Hydroxy-2'-deoxyguanosine (8-OHdG), a product of oxidative DNA damage, which has been used as a sensitive and reliable marker of oxidative stress and carcinogenesis, is found in high levels in biological fluids of leukemia patients. A reliable screening method based on pattern recognition of 8-OHdG using stochastic sensors designed with graphene materials decorated with nanoparticles of TiO2Ag or TiO2Au was developed. 5,10,15,20-Tetraphenyl-21H,23H porphyrin (P), 2,6-bis((E)-2-(furan-2-yl)vinyl)-4-(4,6,8-trimethylazulen-1-yl)pyridine (Py1), and 2,6-bis((E)-2-(thiophen-3-yl)vinyl)-4-(4,6,8-trimethylazulen-1-yl)pyridine (Py2) were used as modifiers of the graphene paste in the design of sensors. The screening method used for pattern recognition was developed for two pH values accordingly with the nature of the biological fluid to be screened: pH = 3.02 for urine samples and pH = 7.49 for whole blood samples. High sensitivities and low limits of determination for 8-OHdG obtained at both pH values favored the early detection of leukemia. Recoveries over 98.00% with RSD (%) values lower than 1.00% proved the reliability of the proposed screening method. Graphical abstract Graphene based sensors detect 8-hydroxy-2'-deoxyguanosine in biological fluids.

3D Printed Composite Scaffolds of GelMA and Hydroxyapatite Nanopowders Doped with Mg/Zn Ions to Evaluate the Expression of Genes and Proteins of Osteogenic Markers.

As bone diseases and defects are constantly increasing, the improvement of bone regeneration techniques is constantly evolving. The main purpose of this scientific study was to obtain and investigate biomaterials that can be used in tissue engineering. In this respect, nanocomposite inks of GelMA modified with hydroxyapatite (HA) substituted with Mg and Zn were developed. Using a 3D bioprinting technique, scaffolds with varying shapes and dimensions were obtained. The following analyses were used in order to study the nanocomposite materials and scaffolds obtained by the 3D printing technique: Fourier transform infrared spectrometry and X-ray diffraction (XRD), scanning electron microscopy (SEM), and micro-computed tomography (Micro-CT). The swelling and dissolvability of each scaffold were also studied. Biological studies, osteopontin (OPN), and osterix (OSX) gene expression evaluations were confirmed at the protein levels, using immunofluorescence coupled with confocal microscopy. These findings suggest the positive effect of magnesium and zinc on the osteogenic differentiation process. OSX fluorescent staining also confirmed the capacity of GelMA-HM5 and GelMA-HZ5 to support osteogenesis, especially of the magnesium enriched scaffold.

Cellulose Nanofiber-Based Hydrogels Embedding 5-FU Promote Pyroptosis Activation in Breast Cancer Cells and Support Human Adipose-Derived Stem Cell Proliferation, Opening New Perspectives for Breast Tissue Engineering.

The structure and biocompatibility analysis of a hydrogel based on cellulose nanofibers (CNFs) combined with alginate/pectin (A.CNF or P.CNF) and enriched with 1% or 5% 5-FU revealed more favorable properties for the cellular component when pectin was dispersed within CNFs. 5-Fluorouracil (5-FU) is an antimetabolite fluoropyrimidine used as antineoplastic drug for the treatment of multiple solid tumors. 5-FU activity leads to caspase-1 activation, secretion and maturation of interleukins (IL)-1, IL-18 and reactive oxygen species (ROS) generation. Furthermore, the effects of embedding 5-FU in P.CNF were explored in order to suppress breast tumor cell growth and induce inflammasome complex activation together with extra- and intracellular ROS generation. Exposure of tumor cells to P.CNF/5-FU resulted in a strong cytotoxic effect, an increased level of caspase-1 released in the culture media and ROS production-the latter directly proportional to the concentration of anti-tumor agent embedded in the scaffolds. Simultaneously, 5-FU determined the increase of p53 and caspase-1 expressions, both at gene and protein levels. In conclusion, P.CNF/5-FU scaffolds proved to be efficient against breast tumor cells growth due to pyroptosis induction. Furthermore, biocompatibility and the potential to support human adipose-derived stem cell growth were demonstrated, suggesting that these 3D systems could be used in soft tissue reconstruction post-mastectomy.