Mn-Doped ZnSe Quantum Dots as Fluorimetric Mercury Sensor

Quantum dots (QDs), because of their exciting optical properties, have been explored as alternative fluorescent sensors to conventional organic fluorophores which are routinely employed for the detection of various analytes via fluorometry. QD probes can detect toxic metal ions, anions, organic molecules with good selectivity and sensitivity. This chapter investigates the synthesis of Mn-doped ZnSe QDs using nucleation-doping strategy. The as-synthesized QDs were characterized by various analytical tools such as ultraviolet-visible (UV-vis) absorption, photoluminescence (PL) spectroscopy, X-ray diffractometry (XRD) and transmission electron microscopy (TEM). It was found that Mn doping of QDs significantly increases the PL intensity. The PL of the resulting QDs was examined in the presence of different metal ions to check its selective response. Among the various metal ions, Hg2+ exhibits a drastic quenching of the QD’s emission intensity. A Stern-Volmer plot of [Hg2+] sensing using the as-synthesized QDs showed linearity in the range of 0–30 × 10−6 ML−1 with the regression coefficient R2 = 0.99. The detection limit was found to be 6.63 × 10−7 ML−1. Thus, the present Mn-doped ZnSe QDs represent a simple, non-toxic fluorescent probe for the qualitative and quantitative detection of mercury ions in aqueous samples

NIR-II window absorbing graphene oxide-coated gold nanorods and graphene quantum dot-coupled gold nanorods for photothermal cancer therapy

Abstract: The graphene-based materials have been used as a potential coating material for nanoparticles due to their excellent passivation. Herein, we report for the first time the colloidal stability, photothermal profile, thermal stability, cytotoxicity, and photo-cytotoxicity of graphene quantum dots (GQDs) coupled with the second infrared window (NIR-II) absorbing gold nanorods (AuNRs/GQDs) and compare it to graphene oxide (GO)-coated NIR-II absorbing AuNRs (AuNRs/GO). The composites were achieved by electrostatic interaction of the GO or GQDs with AuNRs. The results revealed that (i) AuNRs/GQDs were more stable in the aqueous phosphate buffer and cell culture media than AuNRs/GO and AuNRs; (ii) GO enhanced the photothermal efficiency of the AuNRs, whereas GQDs reduced it; (iii) GQDs enhanced the photothermal stability of AuNRs than GO; (iv) both AuNRs/GO and AuNRs/GQDs were biocompatible with mouse colon carcinoma (C26) cell lines and malignant fibrous histiocytoma‐like, expressing a fusion of the luciferase and enhanced green fluorescent protein genes (KM-Luc/GFP) cell lines; and (v) photo-cytotoxicity of AuNRs/GO and AuNRs/GQDs conducted against C26 cell lines showed significantly improved cell death compared to laser irradiation alone; however, AuNRs/GO exhibited high photo-toxicity than AuNRs/GQDs. This study shows that AuNRs/GO and AuNRs/GQDs composites possess unique properties to improve AuNRs and be utilised in photothermal applications

Fabrication of Epoxy-CuInS-ZnS QDs- nanocomposite for fluorescent, transparent toughened coating applications

We herein report a simple method for preparing luminescent and highly toughened transparent epoxy/copper indium sulfide-zinc sulfide (CIS-ZnS) nanocomposite for coating applications. Briefly, fluorescent organically soluble dodecanethiol-capped CIS-ZnS core–shell quantum dots (QDs) was prepared via a solvothermal method. The as-synthesized QDs were small, spherical and highly crystalline, with an average particle diameter of 2.7 nm and improved photoluminescence quantum yields. The QDs were then dispersed in an epoxy matrix to produce a luminescent, transparent, and toughened nanocomposite with excellent mechanical properties: 5348.45 ± 58 J/m2 impact strength value (90 % better than epoxy system only), 34.6 ± 2.8 MPa tensile strength and 6.55 ± 0.31% elongation at break value (significant increment compared to the neat epoxy system). The proposed method is facile and efficient in preparing luminescent, transparent and toughened surface coating materials, which could be used for various physical and automobile applications

Preparation of β-Cyclodextrin Conjugated, Gelatin Stabilized SBA 15-CuInS2/ZnS Quantum Dot Nanocomposites for Camptothecin Release

Camptothecin (CPT) is a potential anticancer drug. However, it faces challenges due to its poor water solubility and the need for an efficient drug release system. Herein, we developed a novel system composed of gelatin stabilized, mesoporous silica SBA15 encapsulated CuInS2/ ZnS (CIS/ZnS) quantum dots (QDs) conjugated with β-cyclodextrin (β-CDs) for its potential use in the release of CPT. In this multifunctional system, β-CDs served as the drug carrier, SBA15 encapsulated QDs is capable of imaging and the gelatin was used to enhance the carrier-drug interaction. Fourier transform infrared (FTIR) analysis confirmed the successful conjugation of β-CDs to the Gel-SBA15 CIS/ZnS QDs, while optical analyses revealed excellent emission properties and high photostability. The β-CD-conjugated Gel-SBA15-CIS/ZnS QD nanocomposite was used to obtain the soluble derivate of CPT which further demonstrated a drug release profile following the triphasic model. Overall, the improved photostability and acceptable drug release profile of the β-CD conjugated Gel-SBA15-CIS/ZnS QD nanocomposite hold great promise for both imaging and therapeutic applications

Photostable fluorescent Near-infrared colloidal Mn-doped CuInSe/ZnS quantum dots for cancer-bacteria dual imaging

Near-infrared quantum dots (NIR QDs) with tunable fluorescence emission are promising materials for bioimaging applications. However, they face several challenges, including low photostability, reduced brightness, and poor fluorescence emission. Herein, we report the synthesis of NIR emitting colloidal Mn-doped CuInSe/ZnS QDs synthesised via the hydrothermal method in a commercial pressure cooker. These fluorescent materials had a peak corresponding to photoluminescence maxima at 765 nm and had good photostability. The in vitro analysis showed that the assynthesised QDs displayed good cell viability against mouse colon carcinoma (C26) cells. They selectively screened Gram-positive bacteria from Gram-negative bacteria and effectively targeted prostate cancer cells compared to normal cells. Thus, they can be used for cancer-bacteria dual-imaging in the biomedical field

De novo assembly and transcriptome analysis of five major tissues of Jatropha curcas L. using GS FLX titanium platform of 454 pyrosequencing

<p>Abstract</p> <p>Background</p> <p><it>Jatropha curcas </it>L. is an important non-edible oilseed crop with promising future in biodiesel production. However, factors like oil yield, oil composition, toxic compounds in oil cake, pests and diseases limit its commercial potential. Well established genetic engineering methods using cloned genes could be used to address these limitations. Earlier, 10,983 unigenes from Sanger sequencing of ESTs, and 3,484 unique assembled transcripts from 454 pyrosequencing of uncloned cDNAs were reported. In order to expedite the process of gene discovery, we have undertaken 454 pyrosequencing of normalized cDNAs prepared from roots, mature leaves, flowers, developing seeds, and embryos of <it>J. curcas</it>.</p> <p>Results</p> <p>From 383,918 raw reads, we obtained 381,957 quality-filtered and trimmed reads that are suitable for the assembly of transcript sequences. <it>De novo </it>contig assembly of these reads generated 17,457 assembled transcripts (contigs) and 54,002 singletons. Average length of the assembled transcripts was 916 bp. About 30% of the transcripts were longer than 1000 bases, and the size of the longest transcript was 7,173 bases. BLASTX analysis revealed that 2,589 of these transcripts are full-length. The assembled transcripts were validated by RT-PCR analysis of 28 transcripts. The results showed that the transcripts were correctly assembled and represent actively expressed genes. KEGG pathway mapping showed that 2,320 transcripts are related to major biochemical pathways including the oil biosynthesis pathway. Overall, the current study reports 14,327 new assembled transcripts which included 2589 full-length transcripts and 27 transcripts that are directly involved in oil biosynthesis.</p> <p>Conclusion</p> <p>The large number of transcripts reported in the current study together with existing ESTs and transcript sequences will serve as an invaluable genetic resource for crop improvement in jatropha. Sequence information of those genes that are involved in oil biosynthesis could be used for metabolic engineering of jatropha to increase oil content, and to modify oil composition.</p

Last Men Standing: Chlamydatus Portraits and Public Life in Late Antique Corinth

Notable among the marble sculptures excavated at Corinth are seven portraits of men wearing the long chlamys of Late Antique imperial office. This unusual costume, contemporary portrait heads, and inscribed statue bases all help confirm that new public statuary was created and erected at Corinth during the 4th and 5th centuries. These chlamydatus portraits, published together here for the first time, are likely to represent the Governor of Achaia in his capital city, in the company of local benefactors. Among the last works of the ancient sculptural tradition, they form a valuable source of information on public life in Late Antique Corinth

Golden stripes: leadership on the high seas

In the first leadership book of its kind, Captain Parani weaves together his rich experience, cutting-edge insights and real-life stories in this book which has already garnered international acclaim. The reader will discover how to run a tight ship; enhance expertise; lead and communicate with a team; implement safety leadership; decide effectively in high-stake situations and be inspired by legendary sailors. It is a practical leadership action plan which can be applied at sea, or in any other workplace, anywhere

Graphene Oxide-Coated Gold Nanorods: Synthesis and Applications

The application of gold nanorods (AuNRs) and graphene oxide (GO) has been widely studied due to their unique properties. Although each material has its own challenges, their combination produces an exceptional material for many applications such as sensor, therapeutics, and many others. This review covers the progress made so far in the synthesis and application of GO-coated AuNRs (GO&ndash;AuNRs). Initially, it highlights different methods of synthesizing AuNRs and GO followed by two approaches (ex situ and in situ approaches) of coating AuNRs with GO. In addition, the properties of GO&ndash;AuNRs composite such as biocompatibility, photothermal profiling, and their various applications, which include photothermal therapy, theranostic, sensor, and other applications of GO&ndash;AuNRs are also discussed. The review concludes with challenges associated with GO&ndash;AuNRs and future perspectives