Dual action of pyroligneous acid in the eco-friendly synthesis of bactericidal silver nanoparticles

Silver-nanoparticle-modified nanocellulose synthesized by pyroligneous acid: cytotoxicity towards HaCat cells

“…Afterwards, AgNPs were produced through reduction of Ag + by PA in alkaline medium. In accordance with the study by Medeiros et al [16], a UV-vis band peaking at 420 nm upon mixing alkaline PA with AgNO 3 indicated the formation of AgNPs (figure 1(a)). The yellow color emerges from the surface plasmon band (SPB) resulting from the resonant coherent dipolar oscillations of the electron gas (electrons of the conduction band) at the surface of nanoparticles [21].…”

“…The synthesis of PA yielded a pale-yellow smoky-odor liquid with density and pH of 1.05 g cm −3 and 2.80, respectively. In agreement with results found in literature [16], gas chromatography-mass spectrometry analysis revealed the main components to be furfural, guaiacol and p-cresol, showing PA to be constituted of a variety of highly oxygenated species responsible for the reduction of silver ions into metallic silver. Afterwards, AgNPs were produced through reduction of Ag + by PA in alkaline medium.…”

“…The intensity of the band increased during the following 10 d, remaining stable up to 150 d. The zeta potential of −56.0 mv attested the excellent stability of the solution. TEM images (figure 1(b)) revealed the AgNPs to be spherical in shape and 16.7 ± 4.62 nm in size, thus in accordance with previous results [16].…”

“…In addition to exhibiting bactericidal and bacteriostatic properties [16,[30][31][32], silver nanoparticles (AgNPs) are known to present dose-and-time-dependent cytotoxicity in vitro and in vivo [33,34]. Herein, we set out to discovering the conditions under which the NC-AgNPs toxicity emerges.…”

“…Herein, we employed pyroligneous acid (PA), a highlyoxygenated environmentally-benign organic liquid originated from the pyrolysis of biomass [15], simultaneously as reducing and capping agents to synthesize AgNPs directly anchored on NC-AgNPs. An important advantage of using PA is that no other agent was required to stabilize the AgNPs, an aspect that renders AgNPs environmentally friendlier in comparison with those obtained from typical routes [16]. Not only does the use of PA in the synthesis of AgNPs impacts positively pollution mitigation, it also helps decrease greenhouse gases emissions because PA derives from the condensation of pyrolysis vapors that would otherwise be discarded into the environment [17][18][19].…”