PH-Induced aggregated melanin nanoparticles for photoacoustic signal amplification

Kuk Youn Ju, Jeeun Kang, Jung Pyo, Joohyun Lim, Jin Ho Chang, Jin Kyu Lee

Research output: Contribution to journalArticlepeer-review

71 Scopus citations

Abstract

We present a new melanin-like nanoparticle (MelNP) and its performance evaluation results. This particle is proposed as an exogenous contrast agent for photoacoustic (PA) imaging. Conventional PA contrast agents are based on non-biological materials. In contrast, the MelNPs are organic nanoparticles inspired by natural melanin. Melanin is an endogenous chromophore that has the ability to produce a PA signal in vivo. The developed MelNPs are capable of aggregating with one another under mildly acidic conditions after introducing hydrolysis-susceptible citraconic amide on the surface of bare MelNPs. We ascertained that the physical aggregation of the MelNPs resulted in an increased PA signal strength in the near-infrared window of biological tissue (i.e., 700 nm) without absorption tuning. This phenomenon is likely because of the overlapping thermal fields of the developed MelNPs. The PA signal produced from the developed MelNPs, after exposure to mildly acidic conditions (i.e., pH 6), is 8.1 times stronger than under neutral conditions. This unique characteristic found in this study can be utilized in a practical strategy for highly sensitive in vivo cancer target imaging in response to its acidic microenvironment. This approach to amplify the PA response of MelNPs in clusters could accelerate the use of MelNPs as an alternative to non-biological nanoprobes, so that MelNPs may be applicable in PA imaging and functional PA imaging such as stimuli sensitive, multimodal, and theranostic imaging.

Original languageEnglish
Pages (from-to)14448-14456
Number of pages9
JournalNanoscale
Volume8
Issue number30
DOIs
StatePublished - 14 Aug 2016

Bibliographical note

Publisher Copyright:
© 2016 The Royal Society of Chemistry.

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