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One of the major biological functions of the retinal pigmented epithelium (RPE) is the clearance of shed photoreceptor outer segments (POS) through a multistep process resembling phagocytosis. RPE phagocytosis helps maintain the viability of photoreceptors that otherwise could succumb to the high metabolic flux and photo-oxidative stress associated with visual processing. The regulatory mechanisms underlying phagocytosis in the RPE are not fully understood, although dysfunction of this process contributes to the pathogenesis of multiple human retinal degenerative disorders, including age-related macular degeneration. Here, we present an integrated transcriptomic, proteomic, and phosphoproteomic analysis of phagocytosing RPE cells, utilizing three different experimental models: the human-derived RPE-like cell line ARPE-19, cultured murine primary RPE cells, and RPE samples from live mice. Our combined results indicated that early stages of phagocytosis in the RPE are mainly characterized by pronounced changes in the protein phosphorylation level. Global phosphoprotein enrichment analysis revealed involvement of PI3K/Akt, mechanistic target of rapamycin (mTOR), and MEK/ERK pathways in the regulation of RPE phagocytosis, confirmed by immunoblot analyses and in vitro phagocytosis assays. Most strikingly, phagocytosis of POS by cultured RPE cells was almost completely blocked by pharmacological inhibition of phosphorylation of Akt. Our findings, along with those of previous studies, indicate that these phosphorylation events allow the RPE to integrate multiple signals instigated by shed POS at different stages of the phagocytic process.

From the traditional Chinese medicine point of view, although Houttuynia cordata extract (HCE) possesses an incredible amount of phytonutrients and exhibits antioxidant activities, excessive doses of HCE can cause danger to organisms and lead to death. In this study, we first examine HCE's overall phenolic and flavonoid content, antioxidant efficacy, and antibacterial activity. Results show that HCE is suitable as a bio-reducing agent for the microwave-assisted synthesis of silver nanoparticles (HCE-AgNPs) with enhanced antioxidant and antimicrobial performance. Under an optimized microwave condition (i.e., 100 °C for 10 min), the HCE-stabilized AgNPs were confirmed with a UV-visible peak at 430 nm and 19.7 ± 4.2 nm in size. Physicochemical properties of HCE-AgNPs were extensively characterized by zeta-potential, FT-IR, XRD, and XPS measurements. Compared to the HC extract counterpart, HCE-AgNPs display superior antioxidant activity, higher DPPH scavenging efficiency, and enhanced broad-spectrum bactericidal activity to inhibit the growth of all tested bacterial strains at doses of 2 μg/mL. Biosafety evaluation indicated that HCE-AgNPs are noncytotoxic on human red blood cells. These data show that the microwave synthesis of AgNPs exhibits a great antioxidant ability, superior antibacterial activity, and a trivial hemolytic effect, providing another bactericidal therapy strategy to address the increasing healthcare-associated infections. [ABSTRACT FROM AUTHOR]

We have analyzed peptides, proteins, and protein--drug complexes through surface-assisted laser desorption/ ionization mass spectrometry (SALDI-MS) using HgTe nanostructures as matrixes. We investigated the effects of several parameters, including the concentration of the HgTe nanostructures, the pH of the buffer, and the concentration of salt, on the performance of this system. When HgTe nanostructures are used as matrixes, [[M + H].sup.+] ions were the dominant signals. Relative to other commonly used nanomaterials, HgTe nanostructures provided lower background signals from metal clusters, fewer fragment ions, less interference from alkali-adducted analyte ions, and a higher mass range (up to 150 000 Da). The present approach provides limits of detection for angiotensin I and bovine serum albumin of 200 pM and 14 nM, respectively, with great reproducibility (RSD: 10.1021/ac100550c

A colorimetric, label-free, and nonaggregation-based gold nanoparticles (Au NPs) probe has been developed for the detection of [Pb.sup.2+] in aqueous solution, based on the fact that [Pb.sup.2+] ions accelerate the leaching rate of An NPs by thiosulfate ([S.sub.2][O.sub.3.sup.2-]) and 2-mereaptoethanol (2-ME). Au NPs reacted with [S.sub.2][O.sub.3.sup.2-] ions in solution to form Au[([S.sub.2][O.sub.3]).sub.2.sup.3-] complexes on the All NP surfaces, leading to slight decreases in their surface plasmon resonance (SPR) absorption. Surface-assisted laser desorption/ ionization time-of-flight ionization mass spectrometry (SALDI-TOF MS) data reveals the formation of Pb--Au alloys on the surfaces of the Au NPs in the presence of [Pb.sup.2+] ions and 2-ME. The formation of Pb--Au alloys accelerated the Au NPs rapidly dissolved into solution, leading to dramatic decreases in the SPR absorption. The 2-ME/[S.sub.2][O.sub.3.sup.2-]-Au NP probe is highly sensitive (LOD = 0.5 nM) and selective (by at least 1000-fold over other metal ions) toward [Pb.sup.2+] ions, with a linear detection range (2.5 nM-10 [micro]M) over nearly 4 orders of magnitude. The cost-effective probe allows rapid and simple determination of the concentrations of [Pb.sup.2+] ions in environmental samples (Montana soil and river), with results showing its great practicality for the detection of lead in real samples. 10.1021/ac9018268

In this paper we unveil a new homogeneous assay--using TOTO-3 and the polythymine oligonueleotide [T.sub.33]--for the highly selective and sensitive detection of [Hg.sup.2+] in aqueous solution. The fluorescence of TOTO-3 is weak in the absence or presence of randomly coiled [T.sub.33]. After [T.sub.33] interacts specifically with [Hg.sup.2+] ions through T-[Hg.sup.2+]--T bonding, however, its conformation changes to form a folded structure that preferably binds to TOTO-3. As a result, the fluorescence of a mixture of [T.sub.33] and TOTO-3 increases in the presence of [Hg.sup.2+]. Our data from fluorescence polarization spectroscopy, capillary electrophoresis with laser-induced fluorescence detection, circular dichroism spectroscopy, and melting temperature measurements confirm the formation of folded [T.sub.33]--[Hg.sup.2+] complexes. Under optimum conditions, the TOTO-3/[T.sub.33] probe exhibited a high selectivity ([greater than or equal to] 265-fold) toward [Hg.sup.2+] over other metal ions, with a limit of detection of 0.6 ppb. We demonstrate the practicality of this TOTO-3/[T.sub.33] probe for the rapid determination of [Hg.sup.2+] levels in pond water and in batteries. This approach offers several advantages, including rapidity (< 15 min), simplicity (label-free), and low cost.

This study describes the first instance of the use of two differently sized Au nanoparticles (Au NPs), acting separately as donor and acceptor, in homogeneous photoluminescence quenching assays developed for the analysis of proteins. Introduction of a breast cancer marker protein, platelet-derived growth factor AA (PDGF AA), to a solution of 11-mercaptoundecanoic acid-protected, 2.0-nm photoluminescent Au nanodots ([L.sub.AuND]) led to the preparation of PDGF AA-[L.sub.AuND] as the donor. Thiol-derivative PDGF binding aptamers (Apt) and 13-nm spherical Au NPs were used to synthesize the Apt-[Q.sub.AuNP] acceptor. The photoluminescence of PDGF AA-[L.sub.AuND] at 520 nm decreased when photoluminescence quenching occurred between Apt-[Q.sub.AuNP] and PDGF AA-[L.sub.AuND]. We used the PDGF AA-[L.sub.AuND]/Apt-[Q.sub.AuNP]-based molecular light switching system to analyze PDGFs and PDGF [alpha]-receptor in separate homogeneous solutions. In the presence of PDGFs, the interaction between Apt-[Q.sub.AuNP] and PDGF AA-[L.sub.AuND] decreased as a result of competitive reactions between the PDGFs and Apt-[Q.sub.AuNP]. Similarly, the interaction between Apt-[Q.sub.AuNP] and PDGF AA-[L.sub.AuND] reduced as a result of competitive reactions between PDGF [alpha]-receptor and PDGF AA-[L.sub.AuND]. The limits of detection (LODs) for PDGF AA and PDGF [alpha]-receptor were 80 pM and 0.25 nM, respectively, resulting from a low background photoluminescence signal. When using the Apt-[Q.sub.AuNP] as selectors for (a) the enrichment of PDGF AA and (b) the removal of matrixes possessing intense background fluorescence from cell media and urine samples, the LOD for PDGF AA decreased to 10 pM. Unlike quantum dots, the [L.sub.AuND] provide the advantages of biocompatibility, ease of bioconjugation, and minimal toxicity.