Facile Preparation of Fe3O4/C Nanocomposite and Its Application for Cost-Effective and Sensitive Detection of Tryptophan

Abstract

In this study, we reported facile synthesis of Fe3O4/C composite and its application for the cost-effective and sensitive determination of tryptophan (Trp) in human serum samples. Fe3O4/C composites were prepared by a simple one-pot hydrothermal method followed by a mild calcination procedure, using FeCl3∙6H2O as Fe3O4 precursor, and glucose as reducing agent and carbon source simultaneously. The Fe3O4/C composite modified glassy carbon electrode (Fe3O4/C/GCE) was prepared by drop-casting method. The microstructure and morphology of Fe3O4/C composite was characterized by powder X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. Due to large specific surface area and synergistic effect from Fe3O4 nanoparticles and carbon coating, Fe3O4/C composite showed excellent electrocatalytic activity toward the oxidation of Trp. As a result, the proposed Fe3O4/C/GCE displayed superior analytical performances toward Trp determination, with two wide detection ranges (1.0–80 μM and 80–800 μM) and a low detection limit (0.26 μM, S/N = 3). Moreover, successful detection of Trp in human serum samples further validate the practicability of the proposed sensor.

Comparison of the Surface Properties of Hydrothermally Synthesised Fe3O4@C Nanocomposites at Variable Reaction Times

“…The nanocomposites show varying degrees of distributions in particle size, uniformity, and aggregation [ 46 ]. The nanocomposites possess larger distribution of particle size (11–91 nm) than the parent Fe 3 O 4 NPs (21–39 nm), as indicated by supporting information from EFTEM, which is comparable to the observation reported by Liu et al [ 44 ].…”

“…The gasification rate of the encapsulating carbon layer per minute in Fe 3 O 4 @C-T 190 t 3 and Fe 3 O 4 @C-T 190 t 5 was higher than in Fe 3 O 4 @C-T 190 t 4 (as shown in red by plots in Figure 3 ) due to the higher carbon content in the composites. Further weight loss at higher temperatures, i.e., 450–900 °C, for Fe 3 O 4 @C-T 190 t 3 (27.63%), Fe 3 O 4 @C-T 190 t 4 (23.34%), and Fe 3 O 4 @C-T 190 t 5 (28.54%), could be assigned to intensified carbonisation of the nanocomposite topmost layer and probable total exposure of the magnetite core of the nanocomposites [ 44 ]. Based on the overall weight loss throughout the entire heating profile of 30–900 °C, Fe 3 O 4 @C-T 190 t 4 (36.5%) is the most stable sample in agreement with the carbon content shown in EDX analysis below.…”

“…This observed deviation can be attributed to the fact that EDX is a semiquantitative analytical technique. Previously, based on EDX analysis, Liu et al [ 44 ] reported that their as-synthesised Fe 3 O 4 @C nanocomposites contained 15.4% carbon, which is in agreement with Fe 3 O 4 @C-T 190 t 4 (14.1%) but far lower than those observed for Fe 3 O 4 @C-T 190 t 3 (64.3%) and Fe 3 O 4 @C-T 190 t 5 (72.4%). This observation indicates that the deposition of the encapsulating carbon layer onto the parent Fe 3 O 4 NPs was more favourable at 5 h, and the least favourable reaction time was at 4 h.…”

Potensi Nanokomposit Fe3O4@C dari Bijih Besi Sebagai Pendeteksi Kadar Glukosa

“…Penelitian tentang Fe3O4@C telah dilakukan oleh beberapa peneliti. Liu, et al, (2019) menyintesis Fe3O4@C menggunakan bahan FeCl3.6H2O sebagai prekursor Fe3O4 dan glukosa sebagai sumber karbon [21]. Penelitian yang sejenis juga telah dilakukan oleh Wu, et al, (2014) [2].…”

“…Penelitian tentang sintesis dan karakterisasi nanopartikel Fe3O4 dila-pisi karbon dari glukosa telah dilakukan oleh Trisnawati, et al, dengan metode hidrotermal untuk mendapatkan ukuran partikel 10,055 nm [19]. Hasil uji TEM menunjukkan bahwa karbon dapat melindungi nanopartikel Fe3O4 sehingga meminimalisir terjadinya aglomerasi [19,21]. Nanokomposit magnetit karbon ini dapat meningkatkan kinerja adsorbsi sehingga sangat berpotensi menjadi adsorben magnetik untuk pengolahan air limbah [15], adsorben pewarna organik [20], adsorben pewarna tekstil serta memperbaiki sifat stabilitas kimia sehingga tidak mudah teroksidasi [19,24].…”