Surfactant-Induced Modulation of Nanometal Surface Energy Transfer from Silicon Quantum Dots to Silver Nanoparticles

Abstract

In the present study, we have demonstrated the excitation energy transfer (EET) from silicon quantum dots (Si QDs) to silver nanoparticles (Ag NPs) and its modulation in the presence of cetyltrimethylammonium bromide (CTAB) surfactant by means of steady-state and time-resolved photoluminescence (PL) spectroscopy. Significant spectral overlap between the emission spectrum of Si QDs and localized surface plasmon resonance of Ag NPs results in a substantial amount of PL quenching of Si QDs. In addition, the PL lifetime of Si QDs is shortened in the presence of Ag NPs. The origin of this PL quenching has been rationalized on the basis of increased nonradiative decay rate due to excitation energy transfer from Si QDs to Ag NPs surface. The observed energy-transfer efficiency correlates well with the nanometal surface energy transfer theory with a 1/d 4 distance dependence rather than conventional Forster resonance energy transfer theory. It has also been observed that the EET efficiency drastically reduces in the presence of 0.5 mM CTAB. Dynamic light scattering and single-particle PL microscopy results indicate the formation of large surfactant-induced aggregates of Ag NPs. Finally, the energy-transfer efficiency values obtained from experiment have been used to calculate the distance between Si QDs and Ag NPs in the absence and presence of CTAB, which correlates well with the proposed model.

Ferritin-Based Electrochemiluminescence Nanosurface Energy Transfer System for Procalcitonin Detection Using HWRGWVC Heptapeptide for Site-Oriented Antibody Immobilization

“…Therefore, the radius d 0 can be calculated by where Φ ET is the energy-transfer efficiency, d is the separation distance between Au NPs and proximal ABEI, n is the power that owns a value of 6 for FRET (r 0 = R 0 ) or 4 for NSET (r 0 = d 0 ), respectively. 13 When Φ ET was 56%, the estimated separation distances between Au NPs and proximal ABEI based on FRET and NSET mechanisms were calculated to be 13.29 and 3.33 nm, respectively. However, it should be highlighted that in a qualified ECL quenching system based on FRET theory, the Forster distance R 0 value should be in the range of 2−6 nm and the distance should be no longer than 10 nm.…”

“…17 Due to the long steric distance between the primary amino group and benzene ring, ABEI exhibits favorable reducibility and has been used for in situ preparation of Au NPs in ECL sensing systems. 17,18 For improving the biocompatibility of biosensors, some nanosized biomaterials such as DNA nanoscaffolds 13,19 and protein nanocages 20 have been explored as ECL nanocarriers. Ferritin is a ubiquitous iron-storage protein which encapsulates a ferric nanocore within a nanocage composed of 24 subunits.…”

“…Electrochemiluminescence (ECL), a light-emission process generated from excited luminous species, has received considerable attention due to high sensitivity, low background noise, wide dynamic response range, and favorable controllability. − To date, ECL systems based on energy transfer theory has become a growing focus in bioanalysis, clinical diagnosis, and pharmaceutical analysis. − Notably, gold nanoparticles (Au NPs) have been employed as energy acceptors to quench ECL emission of various luminophores. − However, some of the involved mechanisms still remain unspecified despite Förster resonance energy transfer (FRET) being used to verify the quenching process, thus making it essential to establish other qualified models to infer the possible mechanisms. As a nonradiative excitation energy transfer from molecular dipole to nanometal surface, nanometal surface energy transfer (NSET) is gaining attention in nanometer distance measurements, cell apoptosis monitoring, and fluorescence quenching. − Recently, NSET has been utilized to reveal and demonstrate the quenching effects of nanometals toward fluorescence dyes. , Though similar to FRET, NSET theory has not yet been applied to determine ECL quenching mechanisms and measure the distance between ECL donors and acceptors. Herein, the concept of ECL-NSET is first introduced in this work, aimed at building a new quenching model for specific energy-transfer mechanism determinations between various ECL donors and nanometal-based ECL acceptors.…”

“…It is known that N -(aminobutyl)- N -(ethylisoluminol) (ABEI) with high and stable ECL efficiency can generate ECL signals with hydrogen peroxide (H 2 O 2 ) as coreactant in alkaline solutions . Due to the long steric distance between the primary amino group and benzene ring, ABEI exhibits favorable reducibility and has been used for in situ preparation of Au NPs in ECL sensing systems. , For improving the biocompatibility of biosensors, some nanosized biomaterials such as DNA nanoscaffolds , and protein nanocages have been explored as ECL nanocarriers. Ferritin is a ubiquitous iron-storage protein which encapsulates a ferric nanocore within a nanocage composed of 24 subunits. , With unique structural features, a pH-tolerant property, biocompatibility, and an enzyme-mimic property, ferritin has been extensively utilized as nanoreactors for the synthesis of nanomaterials, fabrication of nanodevices, controllable delivery of bioactive molecules, etc. − It should be highlighted that the ferric nanocore with enzyme-mimic activity can efficiently catalyze the oxidation of ECL luminophores in the presence of H 2 O 2 .…”

Fluorescence, Phosphorescence, and Chemiluminescence

“…263 There has been continued use of plasmonic substrates for enhancing the photophysical properties of luminescent particles. 264,265 To this list, quantum dots have been extensively studied, not only to enhance their luminescence but to additionally improve quantum dot photostability. 265 In addition, a recent report has appeared on the use of plasmonic substrates to enhance the intrinsic emission of carbon nanodots, 266 small amorphous carbon nanoparticles formed from burning hydrocarbons.…”