Exact Meromorphic Stationary Solutions of the Real Cubic Swift‐Hohenberg Equation

We show that all meromorphic solutions of the stationary reduction of the real cubic Swift‐Hohenberg equation are elliptic or degenerate elliptic. We then obtain them all explicitly by the subequation method, and one of them appears to be a new elliptic solution.     

pH‐ and Thiol‐Responsive BODIPY‐Based Photosensitizers for Targeted Photodynamic Therapy

A diiodo distyryl boron dipyrromethene (BODIPY) core was conjugated to two ferrocenyl quenchers through acid‐labile ketal and/or thiol‐cleavable disulfide linkers, of which the fluorescence and photosensitizing properties were significantly quenched through a photoinduced electron‐transfer process. The two symmetrical analogues that contained either the ketal or disulfide linkers could only be activated by a single stimulus, whereas the unsymmetrical analogue was responsive to dual stimuli. Upon interaction with acid and/or dithiothreitol (DTT), these linkers were cleaved selectively. The separation of the BODIPY core and the ferrocenyl moieties restored the photoactivities of the former in phosphate buffered saline and inside the MCF‐7 breast cancer cells, rendering these compounds as potential activable photosensitizers for targeted photodynamic therapy. The dual activable analogue exhibited the greatest enhancement in intracellular fluorescence intensity in both an acidic environment (pH 5) and the presence of DTT (4 mm ). Its photocytotoxicity against MCF‐7 cells also increased by about twofold upon preincubation with 4 mm of DTT. The activation of this compound was also demonstrated in nude mice bearing a HT29 human colorectal carcinoma. A significant increase in fluorescence intensity in the tumor was observed over 9 h after intratumoral injection.     

Synthesis of two-dimensional gallium nitride via spin coating method: influences of nitridation temperatures

This paper reports the synthesis and characterization of gallium nitride (GaN) thin films deposited on p-type silicon (100) substrates by using low cost spin coating method under various nitridation temperatures. This work demonstrated that spin coating with the new prepared precursor solution can be used as a versatile method for the successfully growth of GaN thin films. Furthermore, the influence of varying nitridation temperatures on the structural, morphological, and optical properties of synthesized GaN thin films were studied in this work. The GaN thin films were characterized by X-ray diffraction, field-emission scanning electron microscopy, atomic force microscopy, photoluminescence and Raman spectroscopy. All the characteristics of the GaN thin films were effectively improved with the increasing of the nitridation temperatures from 750 to 950 °C and degraded at temperature of 1,050 °C. The measured results show that nitridation temperature plays an important role in improving the crystalline quality of the GaN thin films and the most efficient nitridation temperature was at 950 °C.     

Photosynthetic Antenna‐Reaction Center Mimicry with a Covalently Linked Monostyryl Boron‐Dipyrromethene–Aza‐Boron‐Dipyrromethene–C60 Triad

An efficient functional mimic of the photosynthetic antenna‐reaction center has been designed and synthesized. The model contains a near‐infrared‐absorbing aza‐boron‐dipyrromethene (ADP) that is connected to a monostyryl boron‐dipyrromethene (BDP) by a click reaction and to a fullerene (C₆₀) using the Prato reaction. The intramolecular photoinduced energy and electron‐transfer processes of this triad as well as the corresponding dyads BDP‐ADP and ADP‐C₆₀ have been studied with steady‐state and time‐resolved absorption and fluorescence spectroscopic methods in benzonitrile. Upon excitation, the BDP moiety of the triad is significantly quenched due to energy transfer to the ADP core, which subsequently transfers an electron to the fullerene unit. Cyclic and differential pulse voltammetric studies have revealed the redox states of the components, which allow estimation of the energies of the charge‐separated states. Such calculations show that electron transfer from the singlet excited ADP (¹ADP*) to C₆₀ yielding ADP^.+‐C₆₀^.? is energetically favorable. By using femtosecond laser flash photolysis, concrete evidence has been obtained for the occurrence of energy transfer from ¹BDP* to ADP in the dyad BDP‐ADP and electron transfer from ¹ADP* to C₆₀ in the dyad ADP‐C₆₀. Sequential energy and electron transfer have also been clearly observed in the triad BDP‐ADP‐C₆₀. By monitoring the rise of ADP emission, it has been found that the rate of energy transfer is fast (≈10¹¹ s^?1). The dynamics of electron transfer through ¹ADP* has also been studied by monitoring the formation of C₆₀ radical anion at 1000 nm. A fast charge‐separation process from ¹ADP* to C₆₀ has been detected, which gives the relatively long‐lived BDP‐ADP^.+C₆₀^.? with a lifetime of 1.47 ns. As shown by nanosecond transient absorption measurements, the charge‐separated state decays slowly to populate mainly the triplet state of ADP before returning to the ground state. These findings show that the dyads BDP‐ADP and ADP‐C₆₀, and the triad BDP‐ADP‐C₆₀ are interesting artificial analogues that can mimic the antenna and reaction center of the natural photosynthetic systems.     

Integrated Hollow Mesoporous Silica Nanoparticles for Target Drug/siRNA Co‐Delivery

A hollow mesoporous silica nanoparticle (HMSNP) based drug/siRNA co‐delivery system was designed and fabricated, aiming at overcoming multidrug resistance (MDR) in cancer cells for targeted cancer therapy. The as‐prepared HMSNPs have perpendicular nanochannels connecting to the internal hollow cores, thereby facilitating drug loading and release. The extra volume of the hollow core enhances the drug loading capacity by two folds as compared with conventional mesoporous silica nanoparticles (MSNPs). Folic acid conjugated polyethyleneimine (PEI‐FA) was coated on the HMSNP surfaces under neutral conditions through electrostatic interactions between the partially charged amino groups of PEI‐FA and the phosphate groups on the HMSNP surfaces, blocking the mesopores and preventing the loaded drugs from leakage. Folic acid acts as the targeting ligand that enables the co‐delivery system to selectively bind with and enter into the target cancer cells. PEI‐FA‐coated HMSNPs show enhanced siRNA binding capability on account of electrostatic interactions between the amino groups of PEI‐FA and siRNA, as compared with that of MSNPs. The electrostatic interactions provide the feasibility of pH‐controlled release. In vitro pH‐responsive drug/siRNA co‐delivery experiments were conducted on HeLa cell lines with high folic acid receptor expression and MCF‐7 cell lines with low folic acid receptor expression for comparison, showing effective target delivery to the HeLa cells through folic acid receptor meditated cellular endocytosis. The pH‐responsive intracellular drug/siRNA release greatly minimizes the prerelease and possible side effects of the delivery system. By simultaneously delivering both doxorubicin (Dox) and siRNA against the Bcl‐2 protein into the HeLa cells, the expression of the anti‐apoptotic protein Bcl‐2 was successfully suppressed, leading to an enhanced therapeutic efficacy. Thus, the present multifunctional nanoparticles show promising potentials for controlled and targeted drug and gene co‐delivery in cancer treatment.     

Synthesis and characterization of dithienobenzothiadiazole-based donor–acceptor conjugated polymers for organic solar cell applications

New donor–acceptor conjugated polymers (P1 and P2) containing a fused-ring dithienobenzothiadiazole (DT-BTD building block) were synthesized by using the Stille copolymerization method. The synthesized polymers were characterized by ¹H NMR, GPC, and elemental analysis. The optical band gaps of the polymers were found to be 1.86 and 1.9 eV, respectively, as calculated from their film onset absorption edge. Upon annealing both produced a distinct shoulder peak in their film absorption spectra. The electrochemical studies of P1 and P2 revealed that the HOMO and LUMO energy levels of the polymer were −5.3, −5.1 eV, and −3.4, −3.2 eV, respectively. The polymers are thermally stable up to 250–350 °C.     

Macrocycle Dynamics in a Branched [8]Catenane Controlled by Three Different Stimuli in Three Different Regions

A branched [8]catenane from an efficient one-pot synthesis (72 % HPLC yield, 59 % isolated yield) featuring the simultaneous use of three kinds of templates and cucurbit[6]uril-mediated azide–alkyne cycloaddition (CBAAC) for ring-closing is reported. Design and assembly of the [8]catenane precursors are unexpectedly complex that can involve cooperating, competing and non-influencing interactions. Due to the branched structure, dynamics of the [8]catenane can be modulated in different extent by rigidifying/loosening the mechanical bonds at different regions by using solvent polarity, acid-base and metal ions as the stimuli. This work not only highlights the importance of understanding the delicate interplay of the weak and non-obvious supramolecular interactions in the synthesis of high-order [n]catenane, but also demonstrates a complex control of dynamics and flexibility for exploiting [n]catenanes applications.