A Seedless, Surfactant-Free Synthesis of Gold Nanospheres, Nanosheets, and Nanostars Based on Functionalized Tryptophan

Abstract

Three kinds of morphological gold nanoparticles (Au NPs), including gold nanospheres, gold nanosheets, and gold nanostars were easily synthesized using Tryptophan (Trp) modified with glutaraldehyde (GA) as reducing agent and stabilizer. This method can avoid using of seed and surfactant during the whole preparation process. The molar ratio of Trp-GA to chloroaurate ions plays a significant role in controlling the morphology of the Au NPs in aqueous environment. By adjusting the molar ratio of Trp-GA to chloroaurate ions, gold nanospheres, nanosheets, and nanostars can be easily obtained. Moreover, the as-prepared gold nanosheets and nanostars possess excellent SERS efficiency, demonstrating their potential as SERS tags for practical application.

Design and synthesis of gold nanostars-based SERS nanotags for bioimaging applications

“…However, it was shown that by using a similar molecule, L-DOPA, one can also obtain nanostars of less than 100 nm size (Figure 5f) [74]. Using an adduct of tryptophan and glutaraldehyde, Ma and colleagues have synthesized nanostars of several different shapes and relatively large sizes (>200 nm; Figure 5g) [75]. Finally, star-like structures could also be obtained from solely star fruit juice and gold salt (Figure 5h) [76].…”

“…Finally, star-like structures could also be obtained from solely star fruit juice and gold salt (Figure 5h) [76]. [74] with permission from The Royal Society of Chemistry; (g) tryptophan [75]; (h) star fruit juice, adapted from ref. [76] with permission from The Royal Society of Chemistry.…”

“…under a Creative Commons Attribution (CC BY) license; (f) L-DOPA, adapted from ref [74]. with permission from The Royal Society of Chemistry; (g) tryptophan[75]; (h) star fruit juice, adapted from ref [76]. with permission from The Royal Society of Chemistry.…”

Synthesis of tuneable gold nanostars: the role of adenosine monophosphate

“…The limitations of this strategy are that it requires the tight control of different synthetic factors, the colloidal stability, and the presence of other Au NPs as subproducts with some Good's buffers. Finally, biomolecules (albumin, 31 gelatin protein, 32 l -DOPA, 33 and tryptophan–glutaraldehyde (Trp–GA) 34 ) have also been employed for AuNS synthesis although the reported results show broad plasmonic responses or limited plasmon tuning. Overall, different synthetic protocols can be classified into seedless or seed-mediated.…”

Adenosine Monophosphate as Shape-inducing Agent: The Case of Gold Nanostars

“…The limitations of this strategy are that requires tight control of different synthetic factors, the colloidal stability, or the presence of other Au NPs as subproducts with some Good´s buffers. Finally, biomolecules (albumin, [29] gelatin protein, [30] L-DOPA, [31] tryptophan-glutaraldehyde (Trp-GA) [32]) has been also employed for AuNSs synthesis although the reported results show broad plasmonic responses or limited plasmon tunning. Table S1 summarizes different synthesis protocols of AuNSs and their main properties.…”