This research has successfully synthesized highly flexible and conductive nanohybrid electrode films. Nanodispersion and stabilization of silver nanoparticles (AgNPs) were achieved via non-covalent adsorption and with an organic polymeric dispersant and inorganic carbon-based nanomaterials—nano-carbon black (CB), carbon nanotubes (CNT), and graphene oxide (GO). The new polymeric dispersant—polyisobutylene-b-poly(oxyethylene)-b-polyisobutylene (PIB-POE-PIB) triblock copolymer—could stabilize AgNPs. Simultaneously, this stabilization was conducted through the addition of mixed organic/inorganic dispersants based on zero- (0D), one- (1D), and two-dimensional (2D) nanomaterials, namely CB, CNT, and GO. Furthermore, the dispersion solution was evenly coated/mixed onto polymeric substrates, and the products were heated. As a result, highly conductive thin-film materials (with a surface electrical resistance of approximately 10−2 Ω/sq) were eventually acquired. The results indicated that 2D carbon-based nanomaterials (GO) could stabilize AgNPs more effectively during their reductNion and, hence, generate particles with the smallest sizes, as the COO− functional groups of GO are evenly distributed. The optimal AgNPs/PIB-POE-PIB/GO ratio was 20:20:1. Furthermore, the flexible electrode layers were successfully manufactured and applied in wearable electronic sensors to generate electrocardiograms (ECGs). ECGs were, thereafter, successfully obtained.

Dye effluent causes serious pollution and damage to the environment and needs a series of treatments before it can be discharged. Among the numerous effluent treatment methods, adsorption is the simplest and does not cause secondary pollution. Bio-adsorbents are especially advantageous in the treatment of low-concentration dye effluent. In this study, the adsorption and removal capacities of unmodified α- and β-chitosan and modified β-chitosan (β-chitosan cross-linked with triethylenetetramine, BCCT) on C.I. Reactive Blue 221 (RB221) dye were compared. The experiments were performed on the adsorption of the RB221 dye by unmodified α- and β-chitosan and cross-linkage–modified BCCT at different temperatures and for different durations, which are presented along with the relevant adsorption kinetics calculations. According to the results, as the temperature increased from 303 to 333 K, the initial adsorption rates of the adsorbents, α-chitosan, β-chitosan, and BCCT, for the RB221 dye, changed from 1.01 × 102, 4.74 × 102, and 1.48 × 106 mg/g min to 5.98 × 104, 4.23 × 108, and 1.52 × 1013 mg/g min, respectively. BCCT thus showed the best adsorption for the dye at all temperatures from the Elovich model. These results confirmed the successful introduction of a polyaminated and cross-linked extended structure as a modification for the BCCT adsorbent, which makes it resistant to acid hydrolysis and gives it the functional amine group for dye adsorption, thereby promoting the ability of BCCT to adsorb dyes under strongly acidic conditions. The compound synthesized in this study is expected to be a good choice in the future for purifying strongly acidic effluent containing anionic organic dyes.

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A hybrid material obtained by blending β-chitosan (CS) with triethylenetetramine-functionalized graphene oxide (TFGO) (CSGO), was used as an adsorbent for a reactive dye (C.I. Reactive Blue 221 Dye, RB221), and the adsorption and removal performances of unmodified CS and mix-modified CSGO were investigated and compared systematically at different pH values (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, and 12). The adsorption capacities of CS and CSGO were 45.5 and 56.1 mg/g, respectively, at a pH of 2 and 5.4 and 37.2 mg/g, respectively, at a pH of 12. This indicates that TFGO was successfully introduced into CSGO, enabling π–π interactions and electrostatic attraction with the dye molecules. Additionally, benzene ring-shaped GO exhibited a high surface chemical stability, which was conducive to maintaining the stability of the acid and alkali resistance of the CSGO adsorbent. The RB221 adsorption performance of CS and CSGO at acidic condition (pH 3) and alkaline condition (pH 12) and different temperatures was investigated by calculating the adsorption kinetics and isotherms of adsorbents. Overall, the adsorption efficiency of CSGO was superior to that of CS; thus, CSGO is promising for the treatment of dye effluents in a wide pH range.

In this study, coaxial electrospinning was used to prepare novel core/shell composite nanofiber films for use as substrates in surface-enhanced Raman spectroscopy (SERS). The shell layer was composed of Au@silicate nanohybrids, i.e., Au nanoparticles (AuNPs) immobilized in silicate nanosheets via electrostatic attraction. The core layer consisted of polyvinyl alcohol (PVA), which functioned as the mechanical support of the composite nanofibers. By using coaxial electrospinning to form the Au@silicate/PVA core/shell composite nanofibers, the Au@silicate nanohybrids were uniformly dispersed on the PVA nanofibers. Transmission electron microscopy revealed that the AuNPs immobilized on the silicate nanosheets had particle sizes of 25–30 nm and uniform spherical shapes. Furthermore, the core/shell composite nanofiber film had a three-dimensional network structure owing to its formation via random deposition. Compared with the uniaxially electrospun nanofibers, the core/shell composite nanofibers required a significantly lower AuNP content to achieve the same SERS sensitivity. Furthermore, the Au@silicate nanohybrid shell layer increased the ultimate tensile strength by a factor of almost 1.5. In SERS experiments, the uniaxially electrospun nanofiber had an enhancement factor (EF) of 4.1 × 104, whereas the coaxially electrospun nanofiber had an EF of 1.7 × 105. It was demonstrated that our nanofiber can be used for environmental, food safety, and biomedical applications, as it has a detection limit of 10-7 M and EF of 2.5 × 105 for Direct Blue 200 (an industrial dye) and detection limits lower than 10-6 M for paraquat (a pesticide) and adenine (a biomolecule). Therefore, Au@silicate/PVA core/shell composite nanofibers can be used to prepare portable, flexible, freestanding, and stable SERS substrates that are amenable to large-scale fabrication. Furthermore, films prepared using Au@silicate/PVA core/shell composite nanofibers are less susceptible to the “coffee ring” effect observed in conventional droplet coatings, which improves the reproducibility and uniformity of SERS analysis. The developed SERS substrate has a wide range of applications, and the findings of this study are expected to improve sensor technologies for environmental, food safety, and biomedical applications.