Nylon 6–Gold Nanoparticle Composite Fibers for Colorimetric Detection of Urinary 1-Hydroxypyrene

Abstract

A one-step in situ synthesis of nylon 6 nanofi bers fi lled with gold nanoparticles for the colorimetric probe of 1-hydroxypyrene, a biomarker associated with the largest class of cancer-causing chemical compounds polycyclic aromatic hydrocarbons (PAHs) is proposed in this study. The gold nanoparticles (AuNPs) were successfully embedded on the surface of the nylon 6 fi bers where the gold particles were chemisorbed onto the amide groups in the nylon 6 backbones. By electrospinning the nylon 6/gold nanocomposite, the gold nanoparticles were uniformly dispersed on the polymer fi bers to give a photostable reddish white fi ber which turned purple/blue when brought in contact with a standard solution of the biomarker. The TEM revealed the formation of spherical AuNPs with an average diameter of 8 nm well arrayed within the nanofi bers, but no signifi cant change in the morphology of the nanofi bers was observed. The thermal properties of the composite fi bers were greatly improved compared to the electrospun nylon 6 fi ber. The developed method described herein is simple, effective, requires no post-treatments, and is highly sensitive (100 ng/ ml) hence the nanocomposite fi bers can be employed as a test strip for the colorimetric detection of 1-hydroxypyrene in human urine or other diagnostic probe biosensors.Introduction. Metal nanoparticles are of great scientifi c interest as they are effectively a bridge between bulk materials and atomic/molecular structures. Nanoparticles often have unexpected visible properties because they are small enough to confi ne their electrons and produce quantum confi nement effect [1][2][3][4]. Their high surface activity and freely moving electrons can bring about the enhanced Raman scattering effect and agglomeration [1,[5][6][7][8]. The high surface area to volume ratio reduces their incipient melting temperature. They often possess high molar extinction values, which makes them far more sensitive and stable than other conventional colorimetric probes [2]. A prominent spectroscopic feature of the noble metal nanoparticles is surface plasmon resonance (SPR), which arises from the collective resonance oscillations of the free electrons of the conduction band of the metal and often gives rise to a sharp and intense absorption band in the visible range [5,[9][10][11][12]. A combination of these unique properties makes the metal nanoparticles highly promising as the ultimate miniature devices with potential applications in optometrics [1,2,5,13], sensing (biological colorimetric probes) [2, 13-16], catalysis [14,15], labeling, pharmacy (controlled drug release, therapeutic) and modern medicine [2,[14][15][16][17].A gold nanoparticle (AuNP) is one of the few metal nanoparticles that are increasingly drawing huge scientifi c attention as colorimetric probes due to their unique physical and chemical properties. Beside the numerous applications of the AuNPs in catalysis, diagnostics (biomarkers), photo thermal cancer therapy, antibacterials, biology [17][18][19][20], they exhibit an observ...

Towards the development of solid-state platform optical sensors: aggregation of gold nanoparticles on polyurethane foam

“…The second approach is much more promising regarding this task, however it requires a quite complicated synthetic procedure. An alternative approach has been developed by Torto and co-workers [25][26][27]. It is based on application of AuNPs-polymer fiber nanocomposites synthesized by the electrospinning technique as colorimetric probes that change their color due to aggregation of AuNPs on surface of the fibers in the presence of analytes.…”

“…It is based on application of AuNPs-polymer fiber nanocomposites synthesized by the electrospinning technique as colorimetric probes that change their color due to aggregation of AuNPs on surface of the fibers in the presence of analytes. The authors ascribed this phenomenon to competitive displacing AuNPs from adsorption sites of the polymer chain under influence of the analyte due to its stronger interaction, which causes AuNP aggregation [27].…”

The Place of Electrospinning in Separation Science and Biomedical Engineering

“…Their large surface area makes them equally applicable as wonderful sensing tools as applied in test strips and other colorimetric probes. Hence, significant effort has been made to increase the surface area of the sensing interface in chemical sensors [58].…”

“…To this end, equipment-free sensor systems such as colorimetric detection by naked eye would be among the best and most practically useful methods as this could easily be fabricated into a test strip. Colorimetric biosensing does not require expensive or sophisticated instrumentation and maybe applied to field analysis and point of care diagnosis since color changes can be read by naked eye [58].…”

“…They often possess high molar extinction values, which makes them far more sensitive and stable than other conventional colorimetric probes [58]. Surface plasmon resonance (SPR) is a conspicuous property of metal nanoparticles that results from the combined resonance oscillations of the free electrons of the conduction band of the metal [58]. A sharp and intense absorption band is observed in the visible range [58].…”