Analyst 100 spectrophotometer

Polyethylenimine (25000 Da) was purchased from BASF, phosphorous acid, formaldehyde, hydrochloric acid and sodium hydroxide were obtained from VWR and dyes (methylene blue, MB, and methyl orange, MO) from Sigma-Aldrich. Dialysis tubings were bought from Roth. Absorbance was measured by using a UV–visible Perkin-Elmer Analyst 100 spectrophotometer. The microwave used was a Prolabo Synthewave. A Varian SpectrAA 55 AAS was used to detect potential traces of iron in the supernatants after collecting nanoparticles. Zeta potential measurements were determined by DLS analysis using a Malvern Zetasizer nanoZS model.

Serum levels of calcium and phosphorus were determined by colorimetric analysis using a calcium reagent set and a phosphorus reagent set (Nanjing Jiancheng Bioengineering Institute) with a spectrophotometer (Shimadzu).
To determine the mass of bone mineral, the right tibia sample was weighed (wet weight), and then dried at 640°C for 12 hours in a muffle furnace. The dried sample was ground into powder and weighed (dry weight). The ratio of the bone mineral mass to the bone mass was determined. One hundred milligrams of bone powder was then dissolved in 6 M HCl and diluted with distilled water. The calcium and phosphorus contents were measured using atomic absorption spectrophotometry (Analyst 100 Spectrophotometer, PerkinElmer, Waltham, MA, USA).