ABSTRACT
Spherical cellulose nanocrystals (SCNs) and rod-shaped cellulose nanocrystals (RCNs) were extracted from different cellulose materials. The two shape forms of cellulose nanocrystals (CNs) were designed with a combination of isothiocyanate (FITC), and both the obtained FITC-SCNs and FITC-RCNs exhibited high fluorescence brightness. The surfaces of SCNs and RCNs were subjected to a secondary imino group by a Schiff reaction and then covalently bonded to the isothiocyanate group of FITC through a secondary imino group to obtain fluorescent cellulose nanocrystals (FITC-CNs). The absolute ζ-potential and dispersion stability of FITC-CNs (FITC-SCNs and FITC-RCNs) were improved, which also promoted the increase in the fluorescence quantum yield. FITC-RCNs had a fluorescence quantum yield of 30.7%, and FITC-SCNs had a morphological advantage (better dispersion, etc.), resulting in a higher fluorescence quantum yield of 35.9%. Cell cytotoxicity experiments demonstrated that the process of FITC-CNs entering mouse osteoblasts (MC3T3) did not destroy the cell membrane, showing good biocompatibility. On the other hand, FITC-CNs with good dispersibility can significantly enhance poly(vinyl alcohol) (PVA) and poly(lactic acid) (PLA); their mechanical properties were improved (the highest sample reached to 243%) and their fluorescent properties were imparted. This study provides a simple surface functionalization method to produce high-luminance fluorescent materials for bioimaging, multifunctional nanoenhancement/dispersion marking, and anticounterfeiting materials.
Subject(s)
Cellulose/chemistry , Nanocomposites/chemistry , Nanoparticles/chemistry , Fluorescein-5-isothiocyanate/chemistryABSTRACT
An electrochemiluminescent (ECL) lead biosensor was developed based on GR-5 lead-dependent DNAzyme for lead recognition and intercalated ruthenium tris(1,10-phenanthroline) (Ru(phen)(3)(2+)) as the ECL probe. The thiol-modified substrate was first immobilized on the surface of the gold electrode via gold-sulfur self-assembly. Subsequently, the hybridization of DNAzyme and its substrate and the automatic intercalation of Ru(phen)(3)(2+) proceeded. Intercalated Ru(phen)(3)(2+) can transfer electrons through double-stranded DNA to the electrode and its electrochemiluminescence was excited with a potential step using tripropylamine as the coreactant. In the presence of lead, the substrate cleaves at the scissile ribo-adenine into two fragments. The dissociation of DNAzyme occurs, leading to the releasing of intercalated Ru(phen)(3)(2+) accompanied by a decrease in the intensity of electrochemiluminescence. A quantity of lead can be calculated from this decrease. The biosensor is highly sensitive and specific, along with an ultra-low limit of detection of 0.9 pM and a dynamic range from 2 to 1000 pM. It enables analysis of trace amounts of lead in serum samples. The combination of the intercalated-Ru(phen)(3)(2+) ECL probe and the cofactor-dependent DNAzyme may push the performance of cofactor-sensing tactics to the extreme.
Subject(s)
Biosensing Techniques/methods , DNA, Catalytic/metabolism , Lead/metabolism , Luminescent Measurements , Organometallic Compounds/chemistry , Phenanthrolines/chemistry , Base Sequence , DNA, Catalytic/genetics , Electrochemistry , Lead/chemistry , Limit of Detection , Oxidation-Reduction , Propylamines/chemistryABSTRACT
An electrochemiluminescent biosensor was designed for the detection of Ag(+) ions and cysteine as well as their interaction study. To this end, a functional nucleic acid was designed for target recognition and probe intercalation.
Subject(s)
Biosensing Techniques , Cysteine/analysis , DNA/chemistry , Silver/analysis , Coordination Complexes/chemistry , Glutathione/chemistry , Ions/chemistry , Luminescent Measurements , Ruthenium/chemistryABSTRACT
Tetrahedron-structured DNA (ts-DNA) in combination with a functionalized oligonucleotide was used to develop a "turn-on" biosensor for Hg(2+) ions. The ts-DNA provided an improved sensitivity and was used to block the active sites.
Subject(s)
Biosensing Techniques/methods , DNA/chemistry , Electrochemistry/methods , Mercury/analysis , Oligonucleotides/chemistry , Water Pollutants, Chemical/analysis , Rivers/chemistry , Sensitivity and Specificity , Water/analysisABSTRACT
A well-designed oligonucleotide functionalized for Hg(2+) identification and Ru(phen)(3)(2+) intercalation is used to develop a "turn-on" electrochemiluminescent (ECL) biosensor for the determination of Hg(2+) in a drop (10 µL) of sample.
