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A green chemistry approach to synthesize biocompatible selenium nanoparticles is proposed in this work, using hydrogen selenite (NaHSeO3) as selenium precursor and lactose as reducing agent. The formation of nanoparticles was confirmed by dynamic light Scattering, revealing a gaussian size distribution, the maximum percentage being in the range of 20-40 nm. Zeta potential measurement indicates a negative charge -38.2 mV, the stability of selenium colloidal sol being also confirmed by UV-visible spectroscopy. TEM and AFM revealed the homogeneous, spherical shape, confirming the size of nanoparticles in the range of 20-40 nm. Structural investigations of powder selenium nanoparticles by FTIR spectroscopy and XRD patterns emphasise the presence of stretching and bending vibrations of Se-O bonds, respectively the amorphous structure of the synthesized selenium. The proposed method is suitable for biological applications such drug release, functional food or nutritional supplements.

New materials are required for bone healing in regenerative medicine able to temporarily substitute damaged bone and to be subsequently resorbed and replaced by endogenous tissues. Taking inspiration from basic composition of the mammalian bones, composed of collagen, apatite and a number of substitution ions, among them magnesium (Mg 2+ ), in this work, novel composite scaffolds composed of collagen(10%)-hydroxyapatite (HAp)(90%) and collagen(10%)-HAp(80%)-Mg(10%) were developed. The lyophilization was used for composites preparation. An insight into the nanostructural nature of the developed scaffolds was performed by Scanning Electron Microscopy coupled with Energy Dispersive X-Ray and Transmission Electron Microscopy coupled with Energy Dispersive X-Ray. The HAp nanocrystallite clusters and Mg nanoparticles were homogeneously distributed within the scaffolds and adherent to the collagen fibrils. The samples were tested for degradation in Simulated Body Fluid (SBF) solution by soaking for up to 28 days. The release of Mg from collagen(10%)-HAp(80%)-Mg(10%) composite during the period of up to 21 days was attested, this composite being characterized by a decreased degradation rate with respect to the composite without Mg. The developed composite materials are promising for applications as bone substitute materials favouring bone healing and regeneration.

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