Ester-Derivatized Indoles as Fluorescent and Infrared Probes for Hydration Environments

Tryptophan derivatives have long been used as site-specific biological probes. 4-Cyanotrypto- phan emits in the visible region and is the smallest blue fluorescent amino acid probe for bio- logical applications. Other indole or tryptophan analogs may emit at even longer wavelengths than 4-cyanotryptophan. We performed FTIR, UV-Vis, and steady-state and time-resolved fluorescence spectroscopy on six ester-derivatized indoles in different solvents. Methyl indole- 4-carboxylate emits at 450 nrn with a long fluorescence lifetirne, and is a promising candidate for a fluorescent probe. The ester-derivatized indoles could be used as spectroscopic probes to study local protein environments. Our measurements provide a guide for choosing esterderivatized indoles to use in practice and data for computational modeling of the effect of substitution on the electronic transitions of indole.

NONINVASIVE OPTICAL IMAGING OF STAPHYLOCOCCUS AUREUS INFECTION IN VIVO USING AN ANTIMICROBIAL PEPTIDE FRAGMENT BASED NEAR-INFRARED FLUORESCENT PROBES

The diagnosis of bacterial infections remains a major challenge in medicine.Optical imaging of bacterial infection in living animals is usually conducted with genetic reporters such as lightemitting encymes or fluorescent proteins.However,there are many circumstances where genetic reporters are not applicable,and there is an urgent need for exogenous synthetic probes that can selectively target bacteria.Optical imaging of bacteria in vivo is much less developed than methods such as ndioimaging and MRI.Furthermore near infrared(NIR)dyes with emision wavelengths in the region of 650-900 rm can propagate through two or more centimeters of tissue and may enable deeper tisue imaging if sensitive detection techniques are employed.Here we constructed an antimicrobial peptide fragment UBI29-41-based near infrared fuorescent imaging probe.The probe is composed of UBI2941 conjugated to a near infraured dye ICG Der-02.UBI29-41 is a cationic antimicrobial peptide that targets the anionic surfaces of bacterial cells.The probe allows detection of Staphylococcus aureus infection(5×10^(7)cells)in a mouse local infection model using whole animal nearinfrared fuorescence imaging.Furthermore,we demonstrate that the UBI29-41-based imaging probe can selectively accumulate within bacteria.The significantly higher accumulation in bacterial infection suggests that UBI29-41-based imaging probe may be a promising imaging agent to detect bacterial infections.

Synthesis and Characterization of Dendrimer-Encapsulated Bimetallic Core-Shell PdPt Nanoparticles

Using a successive method, PAMAM dendrimer-encapsulated bimetallic PdPt nanoparticles have been successfully prepared with core-shell structures （Pd@Pt DENs）. Evidenced by UV-vis spectra, high resolution trans- mission electron microscopy, and X-ray energy dispersive spectroscopy （EDS）, the obtained Pd@Pt DENs are monodispersed and located inside the cavity of dendrimers, and they show a different structure from monometallic Pt or Pd and alloy PdPt DENs. The core-shell structure of Pd@Pt DENs is further confirmed by infrared measure- ments with carbon monoxide （IR-CO） probe. In order to prepare Pd@Pt DENs, a required Pd/Pt ratio of 1 ： 2 is de- termined for the Pt shell to cover the Pd core completely. Finally, a mechanism for the formation of Pd@Pt DENs is proposed.