Remote‐Controlled Release of Singlet Oxygen by the Plasmonic Heating of Endoperoxide‐Modified Gold Nanorods: Towards a Paradigm Change in Photodynamic Therapy

The photodynamic therapy of cancer is contingent upon the sustained generation of singlet oxygen in the tumor region. However, tumors of the most metastatic cancer types develop a region of severe hypoxia, which puts them beyond the reach of most therapeutic protocols. More troublesome, photodynamic action generates acute hypoxia as the process itself diminishes cellular oxygen reserves, which makes it a self‐limiting method. Herein, we describe a new concept that could eventually lead to a change in the 100 year old paradigm of photodynamic therapy and potentially offer solutions to some of the lingering problems. When gold nanorods with tethered endoperoxides are irradiated at 808 nm, the endoperoxides undergo thermal cycloreversion, resulting in the generation of singlet oxygen. We demonstrate that the amount of singlet oxygen produced in this way is sufficient for triggering apoptosis in cell cultures.     

Rhodamine urea derivatives as fluorescent chemosensors for Hg

New rhodamine derivatives bearing urea group have been synthesized for the detection of metal ions. Especially, the dimeric system 2 displayed a selective fluorescent enhancement and colorimetric change upon the addition of Hg²⁺, in which the spirolactam (nonfluorescent) to ring opened amide (fluorescent) process was utilized. The association constant of 2 with Hg²⁺ was calculated as 3.2 × 10⁵ M⁻¹.     

A permutation test for the two-sample right-censored model

The paper presents a novel approach to solve a classical two-sample problem with right-censored data. As a result, an efficient procedure for verifying equality of the two survival curves is developed. It generalizes, in a natural manner, a well-known standard, that is, the log-rank test. Under the null hypothesis, the new test statistic has an asymptotic Chi-square distribution with one degree of freedom, while the corresponding test is consistent for a wide range of the alternatives. On the other hand, to control the actual Type I error rate when sample sizes are finite, permutation approach is employed for the inference. An extensive simulation study shows that the new test procedure improves upon classical solutions and popular recent developments in the field. An analysis of the real datasets is included. A routine, written in R, is attached as Supplementary Material.

     

A new fluorescein derivative bearing a boronic acid group as a fluorescent chemosensor for fluoride ion

A new fluorescein derivative 1 bearing a boronic acid group was investigated as a fluorescent chemosensor for F-. An off-on type fluorescence enhancement was observed by the blocking of the photoinduced electron transfer mechanism, which was induced by the interaction between fluoride and boronic acid moiety.     

Recent progress in fluorescent and colorimetric chemosensors for detection of amino acids

Due to the biological importance of amino acids, the development of optical probes for these molecules has been an active research area in recent years. This tutorial review focuses on recent contributions since the year 2000 concerning the fluorescent or colorimetric sensors for amino acids, and is organized according to their structural classification and reaction types. For reaction based chemosensors, the works are classified according to the mechanisms between sensors and amino acids, including imine formation, Michael addition, thiazinane or thiazolidine formation, cleavage of a sulfonate ester, cleavage of disulfide, metal complexes-displace coordination and others.     

Rational design of biologically important chemosensors: a novel receptor for selective recognition of acetylcholine over ammonium cations

[structure: see text] In consideration of competition between cation-pi and hydrogen bond interaction forces, we designed a novel receptor, 1,3,5-tris(pyrrolyl)benzene, which shows high selectivity for acetylcholine (ACh). The selectivity of the receptor for ACh over other ammonium cations is demonstrated by the ion-selective electrode (ISE) method in buffer solution. The binding free energy of the receptor with ACh in chloroform solution is measured to be 3.65 kcal/mol in the presence of chloride anion by nuclear magnetic resonance spectroscopy, and that in water is estimated to be much greater ( approximately 6 kcal/mol).     

Unique blue shift due to the formation of static pyrene excimer: highly selective fluorescent chemosensor for Cu

New binaphthyl derivatives bearing pyrene groups have been synthesized and studied as fluorescent chemosensors for Cu²⁺ ions. A unique blue shift along with fluorescent enhancement in pyrene excimer emission was observed, which were induced by the formation of a static pyrene excimer.     

Highly effective fluorescent sensor for H2PO4(-)

A new anthracene dimer connected by two imidazolium moieties has been systematically designed and synthesized as a fluorescent chemosensor for selective binding of H(2)PO(4)(-) over other anions, which have been examined using fluorescence and (1)H NMR and rationalized with ab initio study.     

A fluorescein derivative for nanomolar aqueous copper and monitoring copper ion uptake by transferrin and amyloid precursor protein

A new fluorescent chemosensor based on the fluorescein derivative effectively recognizes Cu²⁺ in nanomolar range at pH 7.4. The Cu²⁺ ion uptake by transferrin and amyloid precursor protein was monitored using the title fluorescent chemosensor.     

A new fluoride selective fluorescent as well as chromogenic chemosensor containing a naphthalene urea derivative

A new naphthalene derivative containing a urea group at the 1,8-position of naphthalene was synthesized and showed a unique absorption and fluorescence peak with a fluoride ion. Calculations suggested that a new peak was attributed to the increased anion character of urea nitrogen due to the strong interaction of the fluoride and N-H protons.