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The availability of colloidal nano-materials with high efficiency, stability, and non-toxicity in the near infrared-II range is beneficial for biological diagnosis and therapy. Rare earth doped nanoparticles are ideal luminescent agents for bio-applications in the near infrared-II range due to the abundant energy level distribution. Among them, both excitation and emission range of Er3+ ions can be tuned into second biological window range. Herein, we report the synthesis of ∼15 nm LiYF4, NaYF4, and NaGdF4 nanoparticles doped with Er3+ ions and their core-shell structures. The luminescent properties are compared, showing that Er3+ ions with single-doped LiYF4 and NaYF4 nanoparticles generate stronger luminescence than Er3+ ions with doped NaGdF4, despite the difference in relative intensity at different regions. By epitaxial growth an inert homogeneous protective layer, the surface luminescence of the core-shell structure is further enhanced by about 5.1 times, 6.5 times, and 167.7 times for LiYF4, NaYF4, and NaGdF4, respectively. The excellent luminescence in both visible and NIR range of these core-shell nanoparticles makes them potential candidate for bio-applications.

A novel cationic water-soluble polythiophene derivative, the poly [N,N,N-trimethyl-3-(thiophen-3-yl)propenaminium chloride] (PTPA-Cl) was chosen as a sensitive colorimetric and fluorescent probe to differentiate adenosine triphosphate (ATP), the present work shows for the first time that the difference between ATP and coenzyme A (CoA). ATP has much stronger colorimetric and fluorescent than CoA. When bound to different charged analytes, the polythiophene derivative probe emitted light with different colors due to the unique spectral properties of the conformation sensitive probe, and the sensing interaction can be apparently observed by naked eyes. Moreover, the cationic water-soluble polythiophene shows selectivity to ATP in the presence of other charged analytes and as well a high sensitivity with the detection limit at 10 À8 M by using fluorometry at aqueous solution. IntroductionAdenosine triphosphate (ATP) is a high-energy phosphate compound. The energy is stored in the covalent bonds between phosphates, with the greatest amount of energy in the bond between the second and third phosphate groups. The mutual transformation of ATP and ADP can achieve energy storage and energy release in a cell, so as to ensure the cells of the life activities of the energy supply. On the other hand, ATP is not only a universal energy source but also an extracellular signaling mediator in many biological metabolic processes.[1] ATP can modulate ion channels and activate signaling cascades,[2,3] and the detection and quantification of ATP is essential in biochemistry and clinic diagnosis. So it is important to use fluorescent or colorimetric sensors to monitor the concentration of ATP in aqueous solution. Although several intriguing techniques have been developed to differentiate ATP from other nucleotide phosphates, such as synthetic Host-guest receptors,[4] combinatorial library-based sensors,[5] multicomponent indicator displacement assays [6] and RNA aptamers, [7] it still remains a challenge to find new approaches that could identify and classify more species of nucleotides and improve the simplicity, selectivity, and sensitivity of ATP detection.Water-soluble conjugated polyelectrolytes (CPEs) are a kind of water-soluble macromolecules which possess excellent optical, hydrophobic or cooperative, and

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as an oxidizing agent. In P3BLMT and P3BRMT, substituted piperidine rings are connected with the polythiophene backbone through carbon-carbon double bond. While in the two polythiophenes, the significant difference is the substituent linked to the N-atom of the piperidine effectively. Structures of the monomers and the corresponding soluble polymers were elucidated by 1 H NMR, 13 C NMR, and IR. Average molecular weights have been determined by gel permeation chromatography. Photoluminescence spectra and ultraviolet-visible spectra of the two polythiophenes in both solution and solid states were also investigated, and all peaks were bathochromically shifted when they were measured in the solid state. The results of optical and electrochemical measurements indicate that the carbonyl group on the sidechain has obvious influence on the electrochemical properties of the conjugated polythiophenes. In addition, the polymers were also characterized by cyclic voltammetry and scanning electron microscopy.