Highly biocompatible, nanocrystalline hydroxyapatite synthesized in a solvothermal process driven by high energy density microwave radiation.

International journal of nanomedicine · 2013 · Benefit · Low evidence

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BenefitLow evidencePaper 6549

Study snapshot

PublicationInternational journal of nanomedicine · 2013

Study typein_vitro

Reported directionBenefit

Evidence ratingLow

Abstract

A microwave, solvothermal synthesis of highly biocompatible hydroxyapatite (HAp) nanopowder was developed. The process was conducted in a microwave radiation field having a high energy density of 5 W/mL and over a time less than 2 minutes. The sample measurements included: powder X-ray diffraction, density, specific surface area, and chemical composition. The morphology and structure were investigated by scanning electron microscopy as well as transmission electron microscopy (TEM). The thermal behavior analysis was conducted using a simultaneous thermal analysis technique coupled with quadruple mass spectrometry. Additionally, Fourier transform infrared spectroscopy tests of heated samples were performed. A degradation test and a biocompatibility study in vitro using human osteoblast cells were also conducted. The developed method enables the synthesis of pure, fully crystalline hexagonal HAp nanopowder with a specific surface area close to 240 m(2)/g and a Ca/P molar ratio equal to 1.57. TEM measurements showed that this method results in particles with an average grain size below 6 nm. A 28-day degradation test conducted according to the ISO standard indicated a 22% loss of initial weight and a calcium ion concentration at 200 μmol/dm(3) in the tris(hydroxymethyl)aminomethane hydrochloride test solution. The cytocompatibility of the obtained material was confirmed in a culture of human bone derived cells, both in an indirect test using the material extract, and in direct contact. A quantitative analysis was based on the 2,3-bis-(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide. Viability assay as well as on DNA content measurements in the PicoGreen test. Indirect observations were performed at one point in time according to the ISO standard for in vitro cytotoxicity (ie, after 24 hours of cell exposure to the extracts). The direct contact tests were completed at three time points: after 24 hours, on day 7, and on day 14 of a culture in an osteogenic medium. All of the tests revealed good tolerance of cells toward the material; this was also shown by means of live/dead fluorescent staining. Both quantitative results and morphological observations revealed much better cell tolerance toward the obtained HAp compared to commercially available HAp NanoXIM, which was used as a reference material.

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AI evidence extraction

Structured fields below were generated from the paper’s abstract and metadata to make the evidence easier to inspect. Automated extraction may be incomplete or incorrect; verify important details against the original paper.

Study typein_vitro

Effect directionbenefit

Populationhuman osteoblast cells (in vitro)

Sample sizeNot supplied

Exposure< 2 minutes (synthesis time)

Evidence strengthLowConfidence: 74% · Peer reviewed: yes

Main findings

A microwave-driven solvothermal method (high energy density 5 W/mL, <2 minutes) produced pure, fully crystalline hexagonal hydroxyapatite nanopowder with specific surface area ~240 m^2/g, Ca/P ratio 1.57, and average grain size <6 nm. In vitro testing with human bone-derived cells indicated good cytocompatibility in both extract and direct-contact assays, with better cell tolerance than a commercial HAp reference (NanoXIM).

Outcomes measured

hydroxyapatite nanopowder crystallinity/purity
particle/grain size
specific surface area
Ca/P molar ratio
28-day degradation (weight loss, calcium ion concentration)
in vitro cytocompatibility/viability (XTT, DNA content/PicoGreen, live/dead staining)
cell tolerance vs commercial reference (HAp NanoXIM)

Limitations

Microwave exposure parameters beyond energy density and time (eg, frequency) not reported in the abstract.
In vitro study; findings may not generalize to in vivo or human health outcomes.
Cell observations in the indirect extract test were performed at a single time point (24 hours) per ISO standard (as described in abstract).

View raw extracted JSON

{
  "study_type": "in_vitro",
  "exposure": {
    "band": null,
    "source": "microwave radiation (solvothermal synthesis process)",
    "frequency_mhz": null,
    "sar_wkg": null,
    "duration": "< 2 minutes (synthesis time)"
  },
  "population": "human osteoblast cells (in vitro)",
  "sample_size": null,
  "outcomes": [
    "hydroxyapatite nanopowder crystallinity/purity",
    "particle/grain size",
    "specific surface area",
    "Ca/P molar ratio",
    "28-day degradation (weight loss, calcium ion concentration)",
    "in vitro cytocompatibility/viability (XTT, DNA content/PicoGreen, live/dead staining)",
    "cell tolerance vs commercial reference (HAp NanoXIM)"
  ],
  "main_findings": "A microwave-driven solvothermal method (high energy density 5 W/mL, <2 minutes) produced pure, fully crystalline hexagonal hydroxyapatite nanopowder with specific surface area ~240 m^2/g, Ca/P ratio 1.57, and average grain size <6 nm. In vitro testing with human bone-derived cells indicated good cytocompatibility in both extract and direct-contact assays, with better cell tolerance than a commercial HAp reference (NanoXIM).",
  "effect_direction": "benefit",
  "limitations": [
    "Microwave exposure parameters beyond energy density and time (eg, frequency) not reported in the abstract.",
    "In vitro study; findings may not generalize to in vivo or human health outcomes.",
    "Cell observations in the indirect extract test were performed at a single time point (24 hours) per ISO standard (as described in abstract)."
  ],
  "evidence_strength": "low",
  "confidence": 0.74,
  "peer_reviewed_likely": "yes",
  "keywords": [
    "microwave radiation",
    "solvothermal synthesis",
    "hydroxyapatite",
    "nanopowder",
    "biocompatibility",
    "in vitro",
    "human osteoblast cells",
    "cytocompatibility",
    "degradation test",
    "XTT",
    "PicoGreen"
  ],
  "suggested_hubs": []
}

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AI-extracted fields are generated from the abstract and metadata and may be incomplete or incorrect. This material is for informational purposes and is not medical advice.

Identifiers and source

DOI: 10.2147/ijn.s39299
PubMed: 23431124

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