A novel competitive 1,1'-oxalyldiimidazole (ODI) chemiluminescent enzyme immunoassay (CLEIA) was developed as a method for rapid and simple screening of melamine in milk. Fat existing in milk acts as an inhibitor in the competitive binding interaction of melamine and anti-melamine in the presence of melamine-conjugated horseradish peroxidase. Thus, the calibration curve and sensitivity of competitive ODI CLEIA for the quantification of melamine in fat free milk were wider and better than those in milk containing fat. However, a centrifuge is not a good method for removing the inhibitor because a portion of the melamine is also removed with the fat. The incubation time (20 min) for the competitive binding interaction of anti-melamine and melamine in 20% milk diluted with PBS buffer of pH 7.4 was longer than that (10 min) in 100% milk even though the sensitivity of the former was better than latter. The limit of detection (1.12 ppb) determined in rapid ODI CLEIA (dynamic range: 3.8-125 ppb) for the quantification of melamine in 20% milk not containing fat was lower than those (6.3 and 9.0 ppb) calculated in relatively time-consuming luminol CLEIA and enzyme-linked immunosorbent assay (ELISA). Also, we expect that ODI-CLEIA (dynamic range: 62.5-2000 ppb) capable of directly quantifying melamine in 100% milk without any pretreatment can be applied as a new and simple method for rapid screening of melamine in milk.

A seven-step asymmetric total synthesis of gymnothelignan N is detailed in the current report. The approach is based on an early-stage one-carbon homologative lactonization reaction, which we recently revisited and modified to construct the core γ-butyrolactone motif with the requisite β,γ-vicinal stereogenic centers. By design, the utilization of the same chiral γ-butyrolactone intermediate permitted the rapid and effective divergent assembly of optically active eupomatilones 1, 3, 4, and 7 in five or six steps from commercially available materials. This represents one of the shortest and highest-yielding syntheses reported to date.

A rapid hybridization method using graphene oxide and highly sensitive 1,1 0 -oxalyldiimidazole chemiluminescence (ODI-CL) detection was developed from an understanding of the chemical and physical interactions between single strand DNA (ssDNA) molecules and nanoparticles (e.g., multi-walled carbon nanotubes, graphene oxide, gold and silver nanoparticles). The efficiency of hybridization between mutated ssDNA and a complementary probe conjugated with TEX615 was dependent on four different variables: pH, temperature, incubation time, and properties of nanoparticles capable of capturing excess complementary probes remaining after the hybridization. A critical problem observed when mutated ssDNAs rapidly bound with complementary probe-conjugated TEX615 was that three different types of possible mismatched ssDNAs also slowly and competitively hybridized with complementary probe-conjugated TEX615. The problem was solved upon addition of three different types of complementary probes, not conjugated with TEX615, in the solution because mismatched DNAs hybridize with their complementary probes while mutated ssDNAs bind with complementary probe-conjugated TEX615. The new hybridization method using graphene oxide and ODI-CL detection quantified trace levels of mutated ssDNAs in a sample containing mismatched ssDNAs within 15 minutes without any interference from mismatched ssDNAs.

The first total synthesis of tetrahydrofuran dilignan gymnothelignan K is disclosed. The approach is based on implementing an early stage one-carbon homologative lactonization, which we recently disclosed, for constructing the γ-butyrolactone scaffold with the requisite β,γ-trans-vicinal stereocenters. Other salient features of the synthesis include the acid-promoted dimerization and the Suzuki–Miyaura cross-coupling reaction to install the challenging diaryl skeleton that permits the effective assembly of the optically active gymnothelignan K in 8 steps from commercially available materials.