Feasible and pure P2O5-CaO nanoglasses: An in-depth NMR study of synthesis for the modulation of the bioactive ion release

Abstract

The use of bioactive glasses (e.g. silicates, phosphates, borates) has demonstrated to be an effective therapy for the restoration of bone fractures, wound healing and vascularization.Their partial dissolution towards the surrounding tissue has shown to trigger positive bioactive responses, without the necessity of using growth factors or cell therapy, which reduces moneycosts, side effects and increases their translation to the clinics. However, bioactive glasses often need from stabilizers (e.g. SiO4 4-, Ti 4+ , Co 2+ , etc.) that are not highly abundant in the body and which metabolization is not fully understood. In this study, we were focused on synthesizing pure calcium phosphate glasses without the presences of such stabilizers. We combined a mixture of ethyphosphate and calcium 2-methoxyethoxide to synthesize nanoparticles with different compositions and degradability. Synthesis was followed by an in-depth nuclear magnetic resonance characterization, complemented with other techniques that helped us to correlate the chemical structure of the glasses with their physiochemical properties and reaction mechanism.After synthesis, the organically modified xerogel (i.e. calcium monoethylphosphate) was treated at 200 or 350 ºC and its solubility was maintained and controlled due to the elimination of organics, increase of phosphate-calcium interactions and phosphate polycondensation. To the best of our knowledge, we are reporting the first sol-gel synthesis of binary (P2O5-CaO) calcium phosphate glass nanoparticles in terms of continuous poycondensated phosphate chains structure without the

A Review of Phosphate and Borate Sol–Gel Glasses for Biomedical Applications

“…Recent work examined a series of sol–gel‐derived binary P 2 O 5 –CaO compositions. [ 50 ] Under basic processing conditions using ammonia, a suspension of particles formed, which were centrifuged, washed, dried, and calcined to temperatures of 200 and 350 °C. While not all compositions remained amorphous after calcination and some particles were undissolved after 2 weeks in a 0.05 m HEPES buffer solution, pH 7.4 solution, this study represented the first step to simplified, binary bioactive phosphate sol–gel glasses.…”

“…Gallium has demonstrated antibiofilm properties, [55] leading it to be incorporated into sol-gel glasses. [56] Glasses in the system (50)…”

“…55)P 2 O 5 -(30)CaO-(15)Na 2 O -Marti-Muñoz et al[50] 2019 (100-x)P 2 O 5 -(x)CaO x 0, 25, 45, 70, 100…”

“…55)P 2 O 5 -(30)CaO-(15)Na 2 O -Marti-Muñoz et al[50] 2019 (100-x)P 2 O 5 -(x)CaO x 0, 25, 45, 70, 100 Foroutan et al [70] 2020 (45)P 2 O 5 -(35)CaO-(20)Na 2 O -Foroutan et al [71] 2020 (55)P 2 O 5 -(30)CaO-(15-x)Na 2 O-(x)SrO 0, 1, 3, 5…”