In this work, the effects of solvation and desolvation on the β phase of poly­(9,9-dioctylfluorene) (PFO) are studied. The content of β phase is approximately calculated for comparison. The content of β phase can be enhanced up to 40% by the solvation effect and become a metastable state; the desolvation effect is a dynamic process and can enhance the content of β phase remarkably by 18%age units. It is found that the contents of β phase are always changing with the aggregation degrees of PFO chains. To fully understand it, the concepts of mesoscopic aggregates and macroscopic aggregates are proposed and well proved by the filtration experiment. In the solution (the ethanol content less than 30%), the mesoscopic aggregates are beneficial to enhance the content of β phase; in the solution (the ethanol content more than 40%), which is close to the condensed state of fabricated optoelectronic film, the macroscopic aggregates can make the content of β phase not only much higher but also stable. The content of β phase can be controlled by changing the aggregation characteristics of PFO chains in solution. This work will be significant in fabricating the optoelectronic devices from solutions to films with high carrier mobility and good stability.

3'-Deoxy-4-O-methylepisappanol, a new 3-benzylchroman derivative, was isolated from Sappan Lignum, together with thirteen known chemical compounds identified as protosappanin A, sappanchalcone, sappanone B, palmitic acid, (+)-(8S,8'S)-bisdihydrosiringenin, brazilein, 3-deoxysappanchalcone, (+)-lyoniresinol, 3-deoxy-sappanone B, protosappanin B, isoprotosappanin B, 3'-O-methylbrazilin and brazilin, respectively. Among these known compounds, this is the first time that (+)-(8S,8'S)-bis-dihydrosiringenin was obtained from the family Caesalpiniaceae.

In this work, the α-conformation (individual locally separated chain) of the conjugated polymer poly(9,9-dioctylfluorene) (PFO) in dilute solution is studied by the following three points: the Mark-Houwink exponent a, the fractal dimension D, and the form factor R(g)/R(h). From the result of a, the α-conformation of PFO is considered to have a semirigid chain conformation in dilute solution. We establish the mathematical relationship between the Mark-Houwink exponent a and the fractal dimension D in dilute solution. To prove the rationality of this mathematical relationship, the classic polymer polystyrene (PS) is used for comparison. According to the result of D, it can be known that the α-conformation of PFO has a relatively loose and extended chain conformation. Moreover, we use light scattering to get the form factor R(g)/R(h) of the PFO solution in which the α-conformation and β-conformation coexist. It is found that R(g)/R(h) increases with the proportion of α-conformation, which indicates that the α-conformation of PFO has a loose and extended chain conformation, and this result agrees well with the conclusions drawn from a and D. On the basis of the fact that the β-conformation (ordered conformation) and α-conformation of PFO can transform into each other in solution, this work is significant for the control of the β-conformation and will have a potential meaning to increase the charge carrier mobility and efficiency from the PFO solution to films.

Nanotechnology approaches play an important role in developing novel and efficient carriers for biomedical applications. Peptides are particularly appealing to generate such nanocarriers because they can be rationally designed to serve as building blocks for self-assembling nanoscale structures with great potential as therapeutic or diagnostic delivery vehicles. In this review, we describe peptide-based nanoassemblies and highlight features that make them particularly attractive for the delivery of nucleic acids to host cells or improve the specificity and sensitivity of probes in diagnostic imaging. We outline the current state in the design of peptides and peptide-conjugates and the paradigms of their self-assembly into well-defined nanostructures, as well as the co-assembly of nucleic acids to form less structured nanoparticles. Various recent examples of engineered peptides and peptide-conjugates promoting self-assembly and providing the structures with wanted functionalities are presented. The advantages of peptides are not only their biocompatibility and biodegradability, but the possibility of sheer limitless combinations and modifications of amino acid residues to induce the assembly of modular, multiplexed delivery systems. Moreover, functions that nature encoded in peptides, such as their ability to target molecular recognition sites, can be emulated repeatedly in nanoassemblies. Finally, we present recent examples where self-assembled peptide-based assemblies with “smart” activity are used in vivo. Gene delivery and diagnostic imaging in mouse tumor models exemplify the great potential of peptide nanoassemblies for future clinical applications.

Three pairs of spirocyclic diketopiperazine enantiomers, variecolortins A-C (1-3), were isolated from marine-derived fungus Eurotium sp. SCSIO F452. Compound 1 possesses an unprecedented highly functionalized seco-anthronopyranoid carbon skeleton featuring a 2-oxa-7-azabicyclo[3.2.1]octane core. Compounds 2 and 3 represent rare examples of a 6/6/6/6 tetracyclic cyclohexene-anthrone carbon scaffold. Their structures were determined by spectroscopic analyses, X-ray diffraction, and ECD calculations. Their enantiomers exhibited different antioxidative and cytotoxic activities, and their modes of action were investigated.

On the basis of the structural features of (fluoro)quinolones (FQs), pazufloxacin was first used as a generic immunizing hapten to raise a broad-specificity antibody. The obtained polyclonal antibody exhibited broad cross-reactivity ranging from 5.19% to 478.77% with 21 FQs. Furthermore, the antibody was able to recognize these FQs below their maximum residue limits (MRLs) in an indirect competitive chemiluminescence enzyme immunoassay (ic-CLEIA), with the limit of detection (LOD) ranging from 0.10 to 33.83 ng/mL. For simply pretreated milk samples with spiked FQs, the ic-CLEIA exhibited an excellent recovery with a range of 84.6-106.9% and an acceptable coefficient of variation below 15%, suggesting its suitability and reliability for the use of a promising tool to detect FQs. Meanwhile, comparative molecular field analysis (CoMFA) and comparative molecular similarity indices analysis (CoMSIA) models, with statistically significant correlation coefficients (q(2)CoMFA = 0.559, r(2)CoMFA = 0.999; q(2)CoMSIA = 0.559, r(2)CoMSIA = 0.994), were established to investigate the antibody recognition mechanism. These two models revealed that in the antibody, the active cavity binding FQs' 7-position substituents worked together with another cavity (binding FQs' 1-position groups) to crucially endow the high cross-reactivity. This investigation will be significant for better exploring the recognition mechanism and for designing new haptens.

Ochratoxins A, B, and C (OTA, OTB, and OTC) can be found in cereals and feeds; the simultaneous detection of these ochratoxins holds a great need in food safety. In this study, four antibodies raised from two ochrotoxin haptens and two coating antigens were compared, and then a sensitive and broad-specificity enzyme-linked immunosorbent assay (ELISA) was established for the simultaneous determination of three ochratoxins, where the detection limits were 0.005, 0.001, and 0.001 ng/mL for OTA, OTB, and OTC, respectively, and recoveries of three ochratoxins were between 84.3% and 111.7%. This developed method had been successfully applied to detect ochratoxins in both millet and maize. Molecular modeling revealed that the broad-specificity was related with the chlorine electronegativity on OTA and OTC and the potential of the acetyl ester group on OTC. The proposed ELISA can be used for simultaneous detection of three ochratoxins.

Antibody-based immunoassay methods have been important tools for monitoring drug residues in animal foods. However, because of limited knowledge about the quantitative structure-activity relationships between a hapten and its resultant antibody specificity, antibody production with the desired specificity is still a huge challenge. In this study, the three-dimensional quantitative structure-activity relationship (3D QSAR) was analyzed in accordance with the cross-reactivity of quinolone drugs reacting with the antibody raised by pipemidic acid as the immunizing hapten and compared with the reported cross-reactivity data and their hapten structures. It was found that the specificity of a quinolone antibody was strongly related to the conformation of the hapten used and that hapten conformations shaped like the letters "I", "P", and "Φ" were essential for the desired high specificity with low cross-reactivity, but that the hapten conformation shaped like the letter "Y" led to an antibody with broad specificity and high cross-reactivity. Almost all of the antibodies against quinolones could result from these four hapten conformations. It was first found that the concrete conformations dominated the specificity of the antibody to quinolone, which will be of significance for the accurate hapten design, predictable antibody specificity, and better understanding the recognition mechanism between haptens and the antibodies for immunoassays.