Covalent bonding of quaternary ammonium compounds and zwitterionic polymer functional layers on polydimethylsiloxane against Escherichia Coli adhesion.

Quaternary ammonium compounds (QACs) are recognized by the World Health Organization as a useful disinfectant against microbes. The synergistic effect of zwitterionic polymers with QACs as antimicrobial agents rather than QACs alone is yet to be investigated. A potential strategy is the use of covalent bonding to halt the release of minute antibacterials and a hierarchy of functional layers to detain and annihilate microbes. The strategy was tested on a polydimethylsiloxane (PDMS) surface on which quaternized poly(2-dimethylaminoethyl methacrylate) (qDMA+) and sulfobetaine (SBMA) were hierarchically functionalized. Attenuated total reflectance Fourier transform infrared analysis confirmed the quaternization of DMA to qDMA+, grafting of qDMA + on PDMS (PDMS-qDMA+), and grafting of the SBMA overlayer on PDMS-qDMA+ (PDMS-qDMA+-SB). Contact angle measurement showed that PDMS-qDMA + exhibited the lowest contact angle (26.2 ± 2.9°) compared with the hydrophobic PDMS (115.2 ± 1.6°), but that of PDMSqDMA+-SB increased to 56.3 ± 1.3°. The Escherichia coli survival count revealed that PDMS-qDMA+ and PDMS-qDMA+-SB exhibited significantly greater bactericidal ability than PDMS. Confocal laser scanning microscopy revealed fewer dead bacteria on PDMS-qDMA+-SB than on PDMS-qDMA+. Scanning electron microscopy demonstrated that E. coli was disintegrated on the functionalized surface via dual-end cell lysis. To the best of our knowledge, this is the first observation of this type of process. The results confirmed the potent antibacterial and cell disruption activities of the qDMA+ and SBMA modified PDMS surface.

Towards Macroscopically Anisotropic Functionality: Oriented Metallo-supramolecular Polymeric Materials Induced by Magnetic Fields.

Based on the predesigned self-selective complexation, metallo-supramolecular P3HT-b-PEO diblock copolymers with varying block ratios were synthesized, and their oriented polymer films generated during solvent evaporation in a 9 T magnetic field were investigated. An anisotropic, ordered layer structure was achieved using [P3HT20 -Zn-PEO107 ] and carefully characterized by polarized optical microscopy (POM), AFM, polarized UV/Vis spectroscopy, and GI-SAXS/WAXS. The PEO-removed [P3HT20 -Zn-PEO107 ] film was obtained after decomplexation with TEA-EDTA under mild conditions, and the selective removal of PEO domains was evidenced by UV/Vis and ATR-FTIR spectroscopy. Anisotropic photoconductivity of the magnetically aligned film was evaluated by flash-photolysis time-resolved microwave conductivity (FP-TRMC) measurements. The results indicated that the presence of insulating crystalline PEO segments diminished the photoconductivity along the P3HT backbone direction.

Synthesis of Terpyridine End-Modified Polystyrenes through ATRP for Facile Construction of Metallo-Supramolecular P3HT-b-PS Diblock Copolymers.

Complementary complexation between 2,2':6',2″-terpyridine (tpy) and 6,6″-dianthracenyl-substituted tpy in the presence of Zn(II) ions provided an efficient strategy for construction of metallo-supramolecular diblock copolymers. To synthesize well-defined tpy-modified polystyrenes (PSs), an Fe(II) bis(tpy) complex bearing α-bromoester as a metallo-initiator was applied to atom transfer radical polymerization (ATRP) to avoid poisoning the Cu(I) catalyst. Subsequently, a series of tpy-functionalized PSs was obtained after the decomplexation of junction by tetrakis(triethylammonium) ethylenediaminetetraacetate (TEA-EDTA) under mild conditions. The metallo-supramolecular poly(3-hexylthiophene) (P3HT)-block-PS diblock copolymers were prepared by simply mixing the corresponding terminally tpy-modified homopolymers with Zn(II) ions, and further characterized by 1H NMR and diffusion ordered spectroscopy (DOSY) experiments. The approach using metallo-initiators for ATRP offers an opportunity to construct tpy-functionalized polymers with controllable molecular weights and low polydispersities. Through the spontaneous heteroleptic complexation, a variety of metallo-supramolecular diblock copolymers with tunable block ratios can be easily constructed.

Multicomponent Metallo-Supramolecular Nanocapsules Assembled from Calix[4]resorcinarene-Based Terpyridine Ligands.

Tetrafunctionalized calix[4]resorcinarene cavitands commonly serve as supramolecular scaffolds for construction of coordination-driven self-assembled capsules. However, due to the calix-like shape, the structural diversity of assemblies is mostly restricted to dimeric and hexameric capsules. Previously, we reported a spontaneous heteroleptic complexation strategy based on a pair of self-recognizable terpyridine-based ligands and CdII ions. Building on this complementary ligand pairing system, herein three types of nanocapsules, including a dimeric capsule, a Sierpinski triangular prism, and a cubic star, could be readily obtained through dynamic complexation reactions between a tetratopic cavitand-based ligand and various multitopic counterparts in the presence of CdII ions. The dimeric capsular assemblies display the spacer-length-dependent self-sorting behavior in a four-component system. Moreover, the precise multicomponent self-assembly of a Sierpinski triangular prism and a cubic star possessing three and six cavitand-based motifs, respectively, demonstrates that such self-assembly methodology is able to efficiently enhance architectural complexity for calix[4]resorcinarene-containing metallo-supramolecules.

Chemical mimicry of viral capsid self-assembly via corannulene-based pentatopic tectons.

Self-assembly of twelve pentatopic tectons, which have complementary edges or can be linked using either digonal or trigonal connectors, represents the optimal synthetic strategy to achieve spherical objects, such as chemical capsids. This process requires conditions that secure uninterrupted equilibria of binding and self-correction en route to the global energy minimum. Here we report the synthesis of a highly soluble, deca-heterosubstituted corannulene that bears five terpyridine ligands. Spontaneous self-assembly of twelve such tectons with 30 cadmium(II) cations produces a giant icosahedral capsid as a thermodynamically stable single product in high yield. Nuclear magnetic resonance (NMR) methods, mass spectrometry analyses, small-angle X-ray scattering, transmission electron microscopy, and atomic force microscopy indicate that this spherical capsid has an external diameter of nearly 6 nm and shell thickness of 1 nm, in agreement with molecular modeling. NMR and liquid chromatography evidences imply that chiral self-sorting complexation generates a racemic mixture of homochiral capsids.

Exposure to Second-Generation Antipsychotics and Risk of Type 2 Diabetes Mellitus in Adolescents and Young Adults: A Nationwide Study in Taiwan.

BACKGROUND: The association between second-generation antipsychotics (SGAs) and type 2 diabetes mellitus (T2DM) has been well investigated in adults. However, T2DM risk has been less examined among adolescents with SGA exposure, and the risk remains uncertain in this population. METHODS: A total of 91,185 adolescents and young adults within the Taiwan National Health Insurance system who were exposed to SGAs were enrolled into this study between 2000 and 2011.The patients were divided into 4 subgroups on the basis of cumulative defined daily doses (cDDDs) of SGAs taken by them in the study period: < 30 cDDDs, 30-179 cDDDs, 180-364 cDDDs, and ≥ 365 cDDDs. Those who developed T2DM (ICD-9-CM) during follow-up, which was the period from enrollment to the end of 2011, were identified. RESULTS: Compared with those in the < 30 cDDD group, adolescents and young adults in the 30-179, 180-364, and ≥ 365 cDDD groups exhibited a high risk of T2DM in later life that increased dose dependently (hazard ratio [HR] = 1.15, 95% CI, 0.98-1.34; HR = 1.54, 95% CI, 1.28-1.84; HR = 1.91, 95% CI, 1.67-2.18, respectively) after adjustment for demographic data, medical comorbidities, and psychiatric disorders. DISCUSSION: Our study results showed a significant relationship between SGA exposure and T2DM risk among adolescents and young adults. These results raise further concern about the use of SGAs in pediatric populations, and on the basis of these results, clinicians should monitor the metabolic condition of their patients.

Micelles Protect Intact Metallo-supramolecular Block Copolymer Complexes from Solution to Gas Phase during Electrospray Ionization.

Supramolecular diblock copolymers using metal-ligand coordination can be synthesized under ambient conditions by delicate design of the end groups of the homopolymer chains. However, mass spectrometric analysis of such metallo-supramolecular copolymers is challenging. One of the reasons is the nonpolarity of the polymer chains, making it hard to disperse the complexes in electrospray ionization (ESI)-friendly environments. The other difficulty is the noncovalent nature of such copolymers, which is easily disrupted during the ionization. Here, we demonstrate that the intact metallo-supramolecular diblock copolymers can be maintained sufficiently during the ESI process in aqueous solution within micelles. The high-resolution mass spectrometric evidence revealed that the surfactant molecules effectively protect the noncovalent binding of the complexes into gaseous ions. Intriguingly, surfactant molecules were sufficiently detached away from the copolymer complexes, giving unambiguous mass spectra that were predominated by intact diblock copolymers. This ESI-based approach allowed us to investigate the relative bond strengths of metal-to-ligand complexation using collision-induced dissociation (CID) in the ion trap mass spectrometry. Conformational features and collision cross sections of the copolymers were thus obtained using subsequent ion mobility spectrometry mass spectrometry (IMS-MS). Remarkable environment-dependent conformations of the denoted diblock copolymers were found using this mass spectrometric platform.

Facile Construction of Metallo-supramolecular Poly(3-hexylthiophene)-block-Poly(ethylene oxide) Diblock Copolymers via Complementary Coordination and Their Self-Assembled Nanostructures.

Complementary coordination of two predesigned 2,2':6',2″-terpyridine-based ligands to a ZnII ion led to the exclusive formation of a heteroleptic bis(terpyridine) complex under ambient conditions. This highly self-selective process was facilitated by 9-anthracenyl substituents at the 6,6″-positions of a terpyridine, which not only decelerated the formation rate of its homoleptic complex, but also provided π-stacking stabilization in the heteroleptic complex. Facile construction of metallo-supramolecular poly(3-hexylthiophene) (P3HT)-block-poly(ethylene oxide) (PEO) diblock copolymers was realized using the complementary ligand pair. The morphological studies of the amphiphilic block copolymers in solution were conducted by atomic force microscopy and transmission electron microscopy, indicating that the self-assembled core-shell morphology such as spherical and fibrillar nanostructures could be controlled by adjusting the rod-coil block ratios. The heteroleptic complexes residing at the junction between two polymer blocks could be readily dissociated by EDTA to afford the unshelled P3HT nanofiber networks, and restored by treatment of bifunctional ZnII-terpyridine-capped PEO to redisperse the aggregates. The presented supramolecular methodology highlights the merits of complementary metal-ligand coordination, and offers a new approach to engineering nanostructures assembled from rod-coil block copolymers.