Hydrothermally processed 1D hydroxyapatite: Mechanism of formation and biocompatibility studies

Recent developments in bone tissue engineering have led to an increased interest in one-dimensional (1D) hydroxyapatite (HA) nano- and micro-structures such as wires, ribbons and tubes. They have been proposed for use as cell substrates, reinforcing phases in composites and carriers for biologically active substances. Here we demonstrate the synthesis of 1D HA structures using an optimized, urea-assisted, high-yield hydrothermal batch process. The one-pot process, yielding HA structures composed of bundles of ribbons and wires, was typified by the simultaneous occurrence of a multitude of intermediate reactions, failing to meet the uniformity criteria over particle morphology and size. To overcome these issues, the preparation procedure was divided to two stages: dicalcium phosphate platelets synthesized in the first step were used as a precursor for the synthesis of 1D HA in the second stage. Despite the elongated particle morphologies, both the precursor and the final product exhibited excellent biocompatibility and caused no reduction of viability when tested against osteoblastic MC3T3-E1 cells in 2D culture up to the concentration of 2.6 mg/cm2. X-ray powder diffraction combined with a range of electron microscopies and laser diffraction analyses was used to elucidate the formation mechanism and the microstructure of the final particles. The two-step synthesis involved a more direct transformation of DCP to 1D HA with the average diameter of 37 nm and the aspect ratio exceeding 100:1. The comparison of crystalline domain sizes along different crystallographic directions showed no signs of significant anisotropy, while indicating that individual nanowires are ordered in bundles in the b crystallographic direction of the P63/m space group of HA. Intermediate processes, e.g., dehydration of dicalcium phosphate, are critical for the formation of 1D HA alongside other key aspects of this phase transformation, it must be investigated in more detail in the continuous design of smart HA micro- and nano-structures with advanced therapeutic potentials.This is the peer-reviewed version of the articleStojanović, Z.S., Ignjatović, N., Wu, V., Žunič, V., Veselinović, L., Škapin, S., Miljković, M., Uskoković, V., Uskoković, D., 2016. Hydrothermally processed 1D hydroxyapatite: Mechanism of formation and biocompatibility studies. Materials Science and Engineering: C 68, 746–757. [https://doi.org/10.1016/j.msec.2016.06.047

Hydrothermally processed 1D hydroxyapatite: Mechanism of formation and biocompatibility studies

Recent developments in bone tissue engineering have led to an increased interest in one-dimensional (1D) hydroxyapatite (HA) nano- and micro-structures such as wires, ribbons and tubes. They have been proposed for use as cell substrates, reinforcing phases in composites and carriers for biologically active substances. Here we demonstrate the synthesis of 1D HA structures using an optimized, urea-assisted, high-yield hydrothermal batch process. The one-pot process, yielding HA structures composed of bundles of ribbons and wires, was typified by the simultaneous occurrence of a multitude of intermediate reactions, failing to meet the uniformity criteria over particle morphology and size. To overcome these issues, the preparation procedure was divided to two stages: dicalcium phosphate platelets synthesized in the first step were used as a precursor for the synthesis of 1D HA in the second stage. Despite the elongated particle morphologies, both the precursor and the final product exhibited excellent biocompatibility and caused no reduction of viability when tested against osteoblastic MC3T3-E1 cells in 2D culture up to the concentration of 2.6 mg/cm2. X-ray powder diffraction combined with a range of electron microscopies and laser diffraction analyses was used to elucidate the formation mechanism and the microstructure of the final particles. The two-step synthesis involved a more direct transformation of DCP to 1D HA with the average diameter of 37 nm and the aspect ratio exceeding 100:1. The comparison of crystalline domain sizes along different crystallographic directions showed no signs of significant anisotropy, while indicating that individual nanowires are ordered in bundles in the b crystallographic direction of the P63/m space group of HA. Intermediate processes, e.g., dehydration of dicalcium phosphate, are critical for the formation of 1D HA alongside other key aspects of this phase transformation, it must be investigated in more detail in the continuous design of smart HA micro- and nano-structures with advanced therapeutic potentials.This is the peer-reviewed version of the articleStojanović, Z.S., Ignjatović, N., Wu, V., Žunič, V., Veselinović, L., Škapin, S., Miljković, M., Uskoković, V., Uskoković, D., 2016. Hydrothermally processed 1D hydroxyapatite: Mechanism of formation and biocompatibility studies. Materials Science and Engineering: C 68, 746–757. [https://doi.org/10.1016/j.msec.2016.06.047]Published version: [https://vinar.vin.bg.ac.rs/handle/123456789/7576

Antimicrobial activity of copper-polyaniline nanocomposite

By combining copper nanoparticles (CuNPs) as a good antimicrobial agent with polyaniline (PANI), which also shows some degree of antimicrobial activity, we were able to synthesize a novel promising antimicrobial material – copper-polyaniline (Cu-PANI) nanocomposite. It was prepared by simple in situ polymerization method, when thepolymer and metal nanoparticles (dav= 6 nm)are produced simultaneously.Quantitative (antimicrobial assay) and qualitative (atomic force microscopy – AFM) analyses showed that synergestic effect of CuNPs and PANI against bacteriaE. coli andS. aureus,and fungusC. albicans, provides its faster andhigher antimicrobial activity than any component acting alone.This makes it a great candidate for fast waste water treatment.Physical chemistry 2016 : 13th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 26-30 September 201

Nanomaterial with High Antimicrobial Efficacy-Copper/Polyaniline Nanocomposite

This study explores different mechanisms of antimicrobial action by designing hybrid nanomaterials that provide a new approach in the fight against resistant microbes. Here, we present a cheap copper-polyaniline (Cu-PANI) nanocomposite material with enhanced antimicrobial properties, prepared by simple in situ polymerization method, when polymer and metal nanoparticles are produced simultaneously. The copper nanoparticles (CuNPs) are uniformly dispersed in the polymer and have a narrow size distribution (dav = 6 nm). We found that CuNPs and PANI act synergistically against three strains, Escherichia coli, Staphylococcus aureus, and Candida albicans, and resulting nanocomposite exhibits higher antimicrobial activity than any component acting alone. Before using the colony counting method to quantify its time and concentration antimicrobial activity, different techniques (UV-visible spectroscopy, transmission electron microscopy, scanning electron microscope, field emission scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectrophotometry, and inductively coupled plasma optical emission spectrometry) were used to identify the optical, structural, and chemical aspects of the formed Cu-PANI nanocomposite. The antimicrobial activity of this nanocomposite shows that the microbial growth has been fully inhibited; moreover, some of the tested microbes were killed. Atomic force microscopy revealed dramatic changes in morphology of tested cells due to disruption of their cell wall integrity after incubation with Cu-PANI nanocomposite