A Ratiometric Fluorescent Probe Based on Carbon Dots and Bimetallic Nanoclusters for the Assay of Copper Gluconate and Copper Sulfate

Doping Ag-enhanced and glutathione-stabilized Au nanoclusters (GSH–Ag/AuNCs) were prepared by the one-step ultraviolet radiation combined with microwave heating method. The effects of the molar ratio of Au–Ag and different types of energy suppliers on the fluorescent performance of GSH–Ag/AuNCs were studied in detail. After that, a new ratio fluorescent probe (RF-probe) based on the mixing of GSH–Ag/AuNCs with carbon dots (CDs) was designed for sensitive and selective determination of copper gluconate (CG) and cupric sulfate (CS). For the CDs–GSH–Ag/AuNCs RF-probe, the fluorescence (FL) of CDs (at 440[Formula: see text]nm) and that of alloy nanoclusters (NCs) (at 605[Formula: see text]nm) were, respectively, unaffected and strongly quenched in the presence of CG/CS at [Formula: see text][Formula: see text]nm coming from the dynamic quenching process. Corresponding linear ranges and limit of detection (LOD) of the RF-probe for the CG/CS assay were estimated to be 0.17–6.20/0.17–5.62[Formula: see text][Formula: see text]mol/L and 16.80/15.95[Formula: see text]nmol/L, respectively. Furthermore, the proposed RF-probe was successfully used for the assays of CG in CG tablets and CG additive, and CS in infant formula and CS additive, respectively.

Screening of cultivars for tissue culture response and establishment of genetic transformation in a high-yielding and disease-resistant cultivar of Theobroma cacao

A highly efficient transformation protocol is a prerequisite to developing genetically modified and genome-edited crops. A tissue culture system spanning culture initiation from floral material to conversion of embryos to plants has been tested and improved in Theobroma cacao. Nine cultivars were screened for their tissue culture response and susceptibility to Agrobacterium transfer-DNA delivery as measured through transient expression. These key factors were used to determine the genetic transformability of various cultivars. The high-yielding, disease-resistant cultivar INIAPG-038 was selected for stable transformation and the method was further optimized. Multiple transgenic events were produced using two vectors containing both yellow fluorescent protein and neomycin phosphotransferase II genes. A two-fold strategy to improve both T-DNA delivery and secondary somatic embryogenesis rates was conducted to improve overall transformation frequency. The use of Agrobacterium strain AGL1 and cotyledon tissue derived from secondary somatic embryos ranging in size between 4 to 10 mm resulted in the highest T-DNA delivery efficiency. Furthermore, the use of higher concentrations of basal salts and cupric sulfate in the medium increased the frequency of explants producing greater than ten embryos by five-fold and four-fold during secondary somatic embryogenesis, respectively. Consequently, an optimal combination of all these components resulted in a successful transformation of INIAPG-038 with 3.7% frequency at the T0 plant-level. Grafting transgenic scions with undeveloped roots to non-transgenic seedlings with healthy roots helped make plantlets survive and facilitated quick transplantation to the soil. The presented strategy can be applied to improve tissue culture response and transformation frequency in other Theobroma cacao cultivars.