FloDots: luminescent nanoparticles

Abstract

Luminescent dye-doped silica nanoparticles (FloDots) have been developed for ultrasensitive bioanalysis and diagnosis in the past several years. Those novel nanoparticles are highly luminescent and extremely photostable. In this paper, we review the preparation, characterization, bioconjugation and bioapplication of FloDots. All the results clearly demonstrated that FloDots have many advantages over currently used luminescent probes, such as traditional fluorophores and quantum dots.

Nanomaterials in fluorescence-based biosensing

“…Another type of fluorescent nanomaterial which has been extensively tested as a labeling reagent in the detection of pathogens, nucleic acids, and proteins is silica nanoparticles doped with organic dyes [20][21][22][23][24][25]. This type of nanomaterial has the following advantages in biosensing: (1) silicon is abundant and nontoxic; (2) the high surface-to-volume ratio of the nanoparticles facilitates their binding to biomolecules; (3) the inclusion of a large number of fluorescent dye molecules inside each nanoparticle results in excellent photostability due to the ability of the silica matrix to shield from molecular oxygen, and the inclusion also dramatically increases the dye-to-biomolecule labeling ratio, leading to high signal amplification factors during detection; and (4) silica is relatively inert in chemical reactions, but still allows surface modification with wellestablished chemistries [20,21].…”

“…This type of nanomaterial has the following advantages in biosensing: (1) silicon is abundant and nontoxic; (2) the high surface-to-volume ratio of the nanoparticles facilitates their binding to biomolecules; (3) the inclusion of a large number of fluorescent dye molecules inside each nanoparticle results in excellent photostability due to the ability of the silica matrix to shield from molecular oxygen, and the inclusion also dramatically increases the dye-to-biomolecule labeling ratio, leading to high signal amplification factors during detection; and (4) silica is relatively inert in chemical reactions, but still allows surface modification with wellestablished chemistries [20,21]. Compared to QDs, fluorescent silica nanoparticles have a wider size range, spanning from a few to hundreds of nanometers; they require less strict size control, and exhibit better water solubility [20,21]. However, problems related to particle aggregation and nonspecific binding on the silica surface have been observed and will need to be solved before the full potential of silica nanoparticles in biosensing can be realized [20].…”

Fluorescent Dyes Used in Polymer Carriers as Imaging Agents in Anticancer Therapy

“…Different types of functional groups like e.g., amine in APTS and thiols in (3-mercaptopropyl)triethoxysilane (MPTS) can be introduced onto the surface of SiNPs and conjugated biomolecules and reactive dyes containing functional groups [375]. In addition, the properties of the silica surface makes SiNPs chemically inert and physically stable [374], so they are excellent labeling reagents for bioanalysis and bioimaging [381][382][383][384][385]. The second strategy of the preparation SiNPs [386] depends on the polycondensation of TEOS in a water-in-oil (W/O) microemulsion with the addition of surfactants (e.g., Triton X-100).…”

“…Depending on the lipophilicity of dyes they can be entrapped in an unaggregated form inside the silica pores like e.g., hydrophobic tertamethylrodamine (TMRA) linked to a hydrophilic dextran molecule (TMRA-dextran) [383]. Likewise, luminophore tris(2,2'-bipyridyl)dichlororuthenium (II) hexahydrate (Rubpy, λEx=458 nm λEm=594 nm) with methylene blue which formed a FRET pair of the model donor-aceptor [368,382] doped SiNPs. This model was used as a probe of leukemia cells [387].…”

Luminescent and Magnetic Nanoparticulates as Biomarkers

“…Amorphous silica nanoparticles have been extensively used to encapsulate dyes in order to enhance their stability and brightness for in vitro and in vivo applications 3,4) . Silica is an optically transparent material and allows emission and excitation light to pass through it without any alteration.…”