Presentation Information
[P04-558]Bifunctional Peptide-Mediated Control of Gold Nanoparticle Assembly for Selective Nanoplastic Detection
○Daiki Sakamoto1, Yohei Shinozaki2, Masayoshi Tanaka1 (1. Science Tokyo (Japan), 2. KIKKOMAN CORPORATION (Japan))
Keywords:
Gold nanoparticle,Polystyrene,Nano plastic,Peptide
[Purpose] Peptides capable of interacting with multiple materials provide a powerful platform for regulating nanoparticle assembly toward simple and rapid sensing applications. Currently, analytical techniques such as Raman spectroscopy are employed for the analysis of nanoplastics (< 100 nm), however, these methods require expensive instrumentation and highly skilled operation, creating a demand for the development of rapid and simple detection methods. In this study, targeting a 50 nm polystyrene nanoparticle (PSNP), we used peptide array technology to identify a bifunctional peptide capable of binding to both PSNP and a library of approximately 1,000 gold nanoparticle (AuNP, 20 nm)-binding peptides available in our laboratory. Using the identified peptide sequence, we constructed a colorimetric detection system in which the aggregation and dispersion states of gold nanoparticles in solution change depending on the presence of PSNP, leading to a visible color change.
[Method] To screen bifunctional peptides for AuNPs and PSNPs, a peptide array approach was used to evaluate PSNP-binding from a library of ~1,000 AuNP-binding peptides. Based on PS characteristics (negative charge, hydrophobicity, and aromaticity), 34 candidate sequences were selected. Using the identified peptides (Au-PS-BPs), optimal assay conditions were determined, followed by evaluation of the limit of detection (LOD) and specificity against various plastic and inorganic particles.
[Results] We screened a library of AuNP-binding peptides using a peptide array and identified several bifunctional peptide sequences that bind polystyrene nanoparticles and AuNPs. Among these, the peptide GWWARTLSKR (Au-PS-BPs) exhibited the strongest PSNP-binding affinity. In the absence of PSNPs, this peptide (0.8 μM) induced aggregation of AuNPs (1.15 nM), resulting in a blue-colored solution. In contrast, in the presence of PSNPs, AuNP aggregation was suppressed and the particles remained dispersed, maintaining a red color. These results indicate that PSNPs competitively interact with the peptide, suppressing peptide-mediated AuNP assembly. PSNPs were detected within 3–5 min because the use of free peptides enhanced diffusion and increased the collision frequency with PSNPs compared to peptide-modified AuNPs. The LOD was 0.033 mg/mL, demonstrating the practical sensitivity for nanoplastic detection.
[Consideration] Binding assays using fluorescent PSNPs were performed on membrane-synthesized peptides consisting of five residues, each composed of a single amino acid, to identify which residues contribute to PSNP binding. Arginine (R), Phenylalanine (F), and Tryptophan (W) were found to play crucial roles. The guanidinium group of arginine and aromatic residues (F and W) likely contribute via cation–π and π–π interactions with the polystyrene surface with the enrichment of these residues in high-affinity sequences.
[Conclusion] We developed a rapid and simple colorimetric detection system for nanoplastics based on bifunctional peptide-mediated control of nanoparticle assembly. This study demonstrates that peptide design enables regulation of nanoparticle interactions, providing a versatile strategy for selective sensing without the need for sophisticated instrumentation. Future work will focus on detection in real samples such as seawater and freshwater toward the development of practical sensors.
[Method] To screen bifunctional peptides for AuNPs and PSNPs, a peptide array approach was used to evaluate PSNP-binding from a library of ~1,000 AuNP-binding peptides. Based on PS characteristics (negative charge, hydrophobicity, and aromaticity), 34 candidate sequences were selected. Using the identified peptides (Au-PS-BPs), optimal assay conditions were determined, followed by evaluation of the limit of detection (LOD) and specificity against various plastic and inorganic particles.
[Results] We screened a library of AuNP-binding peptides using a peptide array and identified several bifunctional peptide sequences that bind polystyrene nanoparticles and AuNPs. Among these, the peptide GWWARTLSKR (Au-PS-BPs) exhibited the strongest PSNP-binding affinity. In the absence of PSNPs, this peptide (0.8 μM) induced aggregation of AuNPs (1.15 nM), resulting in a blue-colored solution. In contrast, in the presence of PSNPs, AuNP aggregation was suppressed and the particles remained dispersed, maintaining a red color. These results indicate that PSNPs competitively interact with the peptide, suppressing peptide-mediated AuNP assembly. PSNPs were detected within 3–5 min because the use of free peptides enhanced diffusion and increased the collision frequency with PSNPs compared to peptide-modified AuNPs. The LOD was 0.033 mg/mL, demonstrating the practical sensitivity for nanoplastic detection.
[Consideration] Binding assays using fluorescent PSNPs were performed on membrane-synthesized peptides consisting of five residues, each composed of a single amino acid, to identify which residues contribute to PSNP binding. Arginine (R), Phenylalanine (F), and Tryptophan (W) were found to play crucial roles. The guanidinium group of arginine and aromatic residues (F and W) likely contribute via cation–π and π–π interactions with the polystyrene surface with the enrichment of these residues in high-affinity sequences.
[Conclusion] We developed a rapid and simple colorimetric detection system for nanoplastics based on bifunctional peptide-mediated control of nanoparticle assembly. This study demonstrates that peptide design enables regulation of nanoparticle interactions, providing a versatile strategy for selective sensing without the need for sophisticated instrumentation. Future work will focus on detection in real samples such as seawater and freshwater toward the development of practical sensors.
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