Biocatalytic Synthesis of Fluorescent Conjugated Polyserotonin

Abstract

Polyserotonin was enzymatically synthesized using Horseradish peroxidase (HRP) as the catalyst. This novel conjugated polymer exhibited good fluorescent properties with significantly higher Stokes shift than its monomer. The enzymatic polymerization eliminated the need for extensive purification of the product (typically necessary for the removal of residual metal catalyst) allowing the product to be naturally fluorescent as synthesized. The reaction was monitored using UV-Vis spectrophotometry and the polymers were characterized using Fluorescence, Fourier Transform Infrared Spectroscopy (FTIR) and Thermogravimetry. The possibility of using polyserotonin for the detection of nitro-aromatic compounds, including 2,4dinitrotoluene (DNT) and trinitrotoluene (TNT), through fluorescence quenching at parts per million levels in solution has also been demonstrated.

Serotonin-Derived Fluorophore: A Novel Fluorescent Biomaterial for Copper Detection in Urine

“…The fluorescence quantum yield (Q) of the SEDF was estimated in water, as reported in the assay protocol, and the obtained value of 0.025 was higher than the Q reported for the PSE obtained enzymatically (0.017) [ 19 ] and here calculated also for the PDA (0.019) and PNE (0.008), indicating the good fluorescent properties of such conjugated serotonin.…”

“…To better understand the nature of the serotonin derivative obtained here, we performed mass spectrometry experiments by MALDI-TOF/TOF instrumentation. The peaks highlighted in Figure 2 ( m / z 176.689, 350.978, 502.098, and 672.180) are compatible with monomeric, dimeric, trimeric, and tetrameric structures, possibly obtained upon the linkage through the benzene ring ( Scheme 1 ) [ 19 ]. However, the determination of the SEDF structure is out of the scope of this study and requires a much deeper analysis.…”

“…SE is a neurotransmitter involved in multiple important physiological processes, such as memory, learning, anxiety, depression, cognition, vomiting, and vasoconstriction [ 15 ]. Very few studies describe the formation of SE oligomers [ 16 , 17 , 18 , 19 ], including polyserotonin (PSE) obtained using horseradish peroxidase (HRP) [ 19 ], and serotonin-based nanoparticles (PSE-NPs) [ 16 , 17 ] as multifunctional material for free radical scavenging, bioelectrical, and biomedical applications. In this paper, the highly emitting SE-derivative fluorophore (SEDF) was obtained by heating the SE monomer at an alkaline pH ( Scheme 1 a).…”

Buffer Components Incorporate into the Framework of Polyserotonin Nanoparticles and Films during Synthesis

“…The chemical composition of PSeNP was investigated using Fourier-transform infrared (FTIR) spectroscopy. The FTIR spectra of PSeNP synthesized in the different buffers display the characteristic peaks for PSeNP at >1500 cm −1 [15,26]. However, nanoparticles synthesized in HEPES showed additional peaks at 1369, 1056, and 838 cm −1 (Figure 2A).…”