Chemiluminescence and fluorescence of the europium ions-adenine nucleotides system and its possible biological significance

Aggregation-induced structure transition of protein-stabilized zinc/copper nanoclusters for amplified chemiluminescence

A stable, water-soluble fluorescent Zn/Cu nanocluster (NC) capped with a model protein, bovine serum albumin (BSA), was synthesized and applied to the reaction of hydrogen peroxide and sodium hydrogen carbonate. A significantly amplified chemiluminescence (CL) from the accelerated decomposition of peroxymonocarbonate (HCO4(-)) by the nanosluster was observed. The CL reaction led to a structure change of BSA and aggregation of Zn/Cu NCs. In the presence of H2O2, Zn/Cu-S bonding between BSA scaffolds and the encapsulated Zn/Cu@BSA NC was oxidized to form a disulfide product. Zn/Cu@BSA NCs were prone to aggregate to form larger nanoparticles without the protection of scaffolds. It is revealed that the strong CL emission was initiated from the catalysis of Zn/Cu@BSA NC and the surface plasmon coupling of the formed Zn/Cu nanoparticles in a single chemical reaction. This amplified CL was successfully exploited for selective sensing of hydrogen peroxide in environmental samples.

Determination of ammonia in water based on chemiluminescence resonance energy transfer between peroxymonocarbonate and branched NaYF4:Yb3+/Er3+ nanoparticles

The ultraweak chemiluminescence (CL) from the reaction of hydrogen peroxide and carbonate is strongly enhanced by the branched NaYF(4):Yb(3+)/Er(3+) nanoparticle (NP) in the presence of aqueous ammonia. It was explained that ammonia catalyzes the decomposition of peroxymonocarbonate, which is the product of hydrogen peroxide mixing with bicarbonate, making the formation of (CO(2))(2)*, (O(2))(2)*, and (1)O(2). The excitation energy, carried by these emitter intermediates, can be transferred to NaYF(4):Yb(3+)/Er(3+) NP. The CL intensity is directly proportional to the concentration of ammonia present in the solution. A flow-injection CL system with high sensitivity, selectivity, and reproducibility is proposed for the determination of aqueous ammonia. The proposed method exhibited advantages in a larger linear range from 0.5 μmol L(-1) to 50 μmol L(-1) and a lower detection limit of 1.1 × 10(-8) mol L(-1) (S/N = 3). This method has been successfully applied to the evaluation of ammonia in water samples with recoveries from 95% to 108%. The relative standard deviations are 1.8% and 4.1% for intra-assay and inter-assay precision, respectively.

Chemiluminescence Energy Transfer Reaction for the On-Line Preparation of Peroxymonocarbonate and Eu(II)−Dipicolinate Complex

In this work, an on-line preparation of peroxymonocarbonate was formed innovatively, which offered a reliable intermediate for further investigation. The forming conditions of on-line peroxymonocarbonate ions were investigated in detail. Meanwhile, the energy transfer chemiluminescent reaction of peroxymonocarbonate and the Eu(II)-dipicolinate complex was studied. Through UV-visible absorption spectra, CL method, ESR spin-trapping technique, and mass spectrum experiments, it can be concluded that peroxymonocarbonate oxidizes Eu(II) to Eu(III), and simultaneously creates radicals. The bond rearrangement within radicals formed the singlet molecular oxygen. The energy originating from the singlet oxygen was accepted by the (Eu(III)dipic)- complex. The excited (Eu(III)dipic)- ions underwent radiative deactivation and emitted the chemiluminescence. The peroxymonocarbonate system was a simple, inexpensive, and relatively nontoxic alternative to other oxidants, and it can be used in a mild, neutral-pH environment.