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The enhanced electroluminescence of GaN-based light-emitting diodes (LEDs) with noble metallic nanoparticles (MNPs) is demonstrated. The sample with well-designed Ag MNPs has shown the best performance enhancement of 126% in electroluminescent intensity compared with a conventional LED sample, even though the MNPs are placed at least 200 nm away from the quantum-well active layer. The MNPs provide enhanced photon scattering and coupling between localized surface plasmon resonance (LSPR) modes and photon modes internally trapped in a device. To investigate this effect, the peculiarities of the LSPR and the corresponding structural properties of the MNPs are discussed through the effective medium approach.

Phosphorylation of proteins by kinases plays an important role in regulating cellular processes including melanin production in the skin cells. Protein kinase C β (PKCβ) is known to be involved in phosphorylating tyrosinase, the key enzyme of melanin production, regulating the skin pigmentation process. In melanogenesis, PKCβ activates the tyrosinase by phosphorylation of its two serine residues. In this study, phosphorylation activity by PKCβ was monitored on a protein chip for the screening of depigmenting agents. As a tyrosinase mimic, 11 or 30 amino acids of the C-terminal of tyrosinase was fused with maltose-binding protein (MBP). After immobilizing the MBP-fused PKCβ substrate peptide on epoxy-treated slide surface, PKCβ reaction mix was applied over the immobilized MBP-fused PKCβ substrate peptide. Phosphorylation was detected with anti-phosphoSer/Thr antibodies, followed by fluorescence-labeled second antibodies. Phosphorylation of MBP-30aa was observed on a protein chip, and this phosphorylation was inhibited by the PKC inhibitor (GF109203X). These results indicate the potential of PKCβ protein chip as a high-throughput screening tool in the screening of depigmenting agents.

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