Immature cotton fibers upcycled into advanced natural nanoparticle synthesizers

As a key agricultural commodity, cotton fibers play a vital role in the global economy. However, unpredictable growing conditions often result in immature cotton fibers, leading to substantial economic losses for both cotton growers and industries. This study revealed the untapped commercial potential of immature cotton fibers-their superior ability to synthesize antimicrobial silver nanoparticles (Ag NPs). Without external reducing or stabilizing agents, immature cotton fibers produced Ag NPs (ca. 10 nm in diameter) at a concentration (2 wt% based on the dry fiber weight) more than three times higher than that of mature cotton fibers. This enhanced nanoparticle synthesis was attributed to structural and morphological characteristics of immature cotton fibers, which are defects in traditional textile applications. High Volume Instrument (HVI), Advanced Fiber Information system (AFIS), and fiber cross-sectional analysis showed that immature cotton fibers have a greater surface area for the infusion of Ag precursor ions and higher concentrations of natural reducing agents per unit weight due to their smaller amounts of secondary cell walls and larger amounts of primary cell walls and lumens. The resulting Ag NP-filled fibers are expected to open new market opportunities in filtration systems and biomedical applications.