Browsing by Author "Qiao, Zheng"
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- An exploratory study to evaluate the potential of nanohydroxyapatite as a powerful sorbent for efficient extraction of volatile organic metabolites, potential biomarkers of cancerPublication . Qiao, Zheng; Perestrelo, Rosa; Shi, Xiangyang; Rodrigues, João; Câmara, José S.Developing early-stage diagnostic methods which are specific, highly sensitive and non-invasive for cancer has received much attention. In this paper, nanohydroxyapatite (NHA) was for the first time used as a sorbent to extract volatile organic metabolites (VOMs) which are considered as potential biomarkers of cancer, such as hexanal, heptanal, decanal, benzaldehyde, 4-heptanone, phenol, undecane, and 5-methyl-2-furfural. The extraction process was performed by simply dispersing nanohydroxyapatite into working solution containing targeted VOMs and then eluting the centrifuged sorbent with an organic solvent. Batch techniques were performed to optimize the experimental variables affecting the extraction of targeted VOMs such as the sorbent amount, adsorption time, elution time and types of elution solvent. The eluent was collected, concentrated and analyzed by gas chromatography-mass spectrometry (GC-qMS). Under optimized conditions, the results obtained demonstrated a good linearity (r2 ≥ 0.993), over the linear dynamic range, for all urinary volatile metabolites investigated. The proposed strategy provided limits of detection (LODs) ranging from 9.8 ng L−1 to 69.5 ng L−1 and limits of quantification (LOQs) from 32.5 ng L−1 to 231.6 ng L−1. The method also afforded satisfactory results in terms of the matrix effect (72.8–96.1%) and recoveries (accuracy) higher than 70% for most of the studied VOMs. The intra-day and inter-day precision was lower than 3% and 13%, respectively. The established method has been successfully applied to the determination of the target urinary VOMs, from cancer patients, described as potential cancer biomarkers.
- Octadecyl functionalized core–shell magnetic silica nanoparticle as a powerful nanocomposite sorbent to extract urinary volatile organic metabolitesPublication . Qiao, Zheng; Perestrelo, Rosa; Reyes-Gallardo, Emilia M.; Lucena, R.; Cárdenas, S.; Rodrigues, João; Câmara, José S.In this present study, magnetic Fe3O4@SiO2 nanoparticles (MNPs) functionalized with octadecyl groups (Fe3O4@SiO2-C18 NPs) were synthesized, characterized and employed, for the first time, as powerful nanosorbent to extract endogenous volatile organic metabolites (EVOMs) namely, hexanal, heptanal, decanal, benzaldehyde, 4-heptanone, 5-methyl-2-furfural and phenol, described as potential biomarkers of cancer, from human urine. By using co-precipitation, surface modification methods, the carbon-ferromagnetic nanocomposite was synthesized and characterized by infrared spectrum (IR) and transmission electron microscopy (TEM). By coupling with gas chromatography-mass spectrometry (GC-qMS), a reliable, sensitive and cost-effective method was validated. To test the extraction efficiency of the carbon-ferromagnetic nanocomposite toward urinary EVOMs experimental variables affecting the extraction performance, including nanosorbent amount, adsorption time, elution time, and nature of elution solvent, were investigated in detail. The extraction process was performed by dispersing Fe3O4@SiO2-C18 NPs into working solution containing targeted VOMs, and into urine samples, and then eluted with an adequate organic solvent. The eluate was collected, concentrated and analyzed by GC-qMS. Under the optimized conditions, the LODs and LOQs achieved were in the range of 9.7-57.3 and 32.4-190.9ng/mL, respectively. Calibration curves were linear (r(2)≥0. 988) over the concentration ranges from 0.25 to 250ng/mL. In addition, a satisfying reproducibility was achieved by evaluating the intra- and inter-day precisions with relative standard deviations (RSDs) less than 3 and 11%, respectively. The method also afforded satisfactory results in terms of the matrix effect (72.8-96.1%) and recoveries (accuracy) higher than 75.1% for most of the studied EVOMs. The Fe3O4@SiO2-C18 NPs-based sorbent extraction combined with GC-qMS revealed that the new nanosorbent had a strong ability to retain the target metabolites providing a new, reliable and high throughput strategy for isolation of targeted EVOMs in human urine, suggesting their potential to be applied in other EVOMs.