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...
