“…Due to the metallic nature of PVP, calcium ions should interact more strongly with it than with the phosphorous present in TEP. It is known [25][26][27][28] that the carbonyl group of PVP interacts with cations when in solution, as illustrated in Figure 3 for calcium ions. Hence, composition A1 may have contained a large amount of polymer that interacted strongly with the calcium ions, causing a segregation in the reaction, which may have continued after the polymer was calcined, shifting the forming reaction to the production of β-TCP.…”
The purpose of this work was to produce submicrometric hydroxyapatite (HA) and beta-tricalcium phosphate (β-TCP) biphasic fibers by means of solution blow spinning (SBS). This method was chosen due to its lower cost and higher production rate than those of electrospinning, which is normally employed in ceramic fiber production. The fibers thus obtained were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and thermogravimetric analysis (TGA). The in vitro bioactivity and cytotoxicity of the fibers were also investigated. The XRD patterns indicated the formation of biphasic HA/βTCP fibers. SEM analysis revealed an interconnected cylindrical morphology with the presence of beads. Fiber diameters in the submicrometric range varied from 374 to 451 nm. TGA results indicated that organic losses occurred solely below 600ºC. All the fibers were non-cytotoxic, presenting an inhibitory concentration (IC) of > IC50. All the samples successfully formed acicular apatite layers when immersed in SBF, indicating a high potential for in vivo bone bioactivity.
“…Due to the metallic nature of PVP, calcium ions should interact more strongly with it than with the phosphorous present in TEP. It is known [25][26][27][28] that the carbonyl group of PVP interacts with cations when in solution, as illustrated in Figure 3 for calcium ions. Hence, composition A1 may have contained a large amount of polymer that interacted strongly with the calcium ions, causing a segregation in the reaction, which may have continued after the polymer was calcined, shifting the forming reaction to the production of β-TCP.…”
The purpose of this work was to produce submicrometric hydroxyapatite (HA) and beta-tricalcium phosphate (β-TCP) biphasic fibers by means of solution blow spinning (SBS). This method was chosen due to its lower cost and higher production rate than those of electrospinning, which is normally employed in ceramic fiber production. The fibers thus obtained were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and thermogravimetric analysis (TGA). The in vitro bioactivity and cytotoxicity of the fibers were also investigated. The XRD patterns indicated the formation of biphasic HA/βTCP fibers. SEM analysis revealed an interconnected cylindrical morphology with the presence of beads. Fiber diameters in the submicrometric range varied from 374 to 451 nm. TGA results indicated that organic losses occurred solely below 600ºC. All the fibers were non-cytotoxic, presenting an inhibitory concentration (IC) of > IC50. All the samples successfully formed acicular apatite layers when immersed in SBF, indicating a high potential for in vivo bone bioactivity.
“…Thus, PVP is shown to be a stabilizer of particle size, supporting nucleation, particle size growth, and particle regularity. PVP has been used previously to control particle size and prevent nanoparticle accretion [ 55 , 56 , 57 , 58 , 66 , 67 , 68 ]. The results illustrated in Table 1 allow for a comparison of the XRD and TEM analyses, further highlighting the relationship between calcination temperature and particle size (4–15.5 mm).…”
SnO2 nanoparticle production using thermal treatment with tin(II) chloride dihydrate and polyvinylpyrrolidone capping agent precursor materials for calcination was investigated. Samples were analyzed using X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), energy dispersive X-ray (EDX), transmission electron microscopy (TEM), Fourier Transform Infrared Spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), diffuse UV-vis reflectance spectra, photoluminescence (PL) spectra and the electron spin resonance (ESR). XRD analysis found tetragonal crystalline structures in the SnO2 nanoparticles generated through calcination. EDX and FT-IR spectroscopy phase analysis verified the derivation of the Sn and O in the SnO2 nanoparticle samples from the precursor materials. An average nanoparticle size of 4–15.5 nm was achieved by increasing calcination temperature from 500 °C to 800 °C, as confirmed through TEM. The valence state and surface composition of the resulting nanoparticle were analyzed using XPS. Diffuse UV-vis reflectance spectra were used to evaluate the optical energy gap using the Kubelka-Munk equation. Greater calcination temperature resulted in the energy band gap falling from 3.90 eV to 3.64 eV. PL spectra indicated a positive relationship between particle size and photoluminescence. Magnetic features were investigated through ESR, which revealed the presence of unpaired electrons. The magnetic field resonance decreases along with an increase of the g-factor value as the calcination temperature increased from 500 °C to 800 °C. Finally, Escherichia coli ATCC 25922 Gram (–ve) and Bacillus subtilis UPMC 1175 Gram (+ve) were used for in vitro evaluation of the tin oxide nanoparticle’s antibacterial activity. This work indicated that the zone of inhibition of 22 mm has good antibacterial activity toward the Gram-positive B. subtilis UPMC 1175.
“…1). This process complicates further when more than one absorption edge is observed, and, as we will show, straightforward use of the Tauc method in polyphasic samples could lead to systematic underestimation of the E g of those constituents with wider band gaps [15, 16]. Fig.…”
An automated method to determine the band gap energy (
E
g
) of pure and mixed powder compounds using diffuse reflectance spectroscopy is presented. This method is based on a five-step algorithm that mimics the judgment made by an expert analyst in identifying the linear segments in Tauc plots and subsequent estimation of the
E
g
value. It is demonstrated that the method to estimate
E
g
by intersecting the straight-line fit of the Tauc segment with the photon energy axis is not appropriate for those samples containing more than one optical absorbing phase because systematic underestimation of the
E
g
value results. The automated method accounts for such cases by introducing a base line function. The robustness of the implemented algorithm was tested using three model systems, ZnO-Al
2
O
3
, ZnO-CoO and ZnO-CdO. The estimated
E
g
's using the automated method differ in less than 1% than those obtained by its manual counterpart.
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