Abstract: Designer self-assembling peptides are a category of emerging nanobiomaterials which have been widely investigated in the past decades. In this field, amphiphilic peptides have received special attention for their simplicity in design and versatility in application. This review focuses on recent progress in designer amphiphilic peptides, trying to give a comprehensive overview about this special type of self-assembling peptides. By exploring published studies on several typical types of amphiphilic peptides in recent years, herein we discuss in detail the basic design, self-assembling behaviors and the mechanism of amphiphilic peptides, as well as how their nanostructures are affected by the peptide characteristics or environmental parameters. The applications of these peptides as potential nanomaterials for nanomedicine and nanotechnology are also summarized. Keywords: amphiphilic peptides, self-assembly, nanomaterials
With the popular use of the laryngeal mask airway (LMA), recurrent laryngeal nerve injury associated with the LMA, which might cause serious complications, has recently been reported. The true mechanism, however, remains unclear, which makes effective prevention and treatment of this disorder difficult. On the basis of the anatomical relationship of the laryngopharynx and the laryngeal mask and the progressive recovery in most reported cases, we hypothesize that demyelinating neuropraxia resulting from direct mechanical compression contributes to the recurrent nerve injury associated with the LMA. A series of clinical cases which showed that recurrent nerve palsy may occur as a result of cuff over-inflation and/or prolonged LMA insertion period support the hypothesis. Several animal studies also reveal that high laryngeal mask airway intra-cuff pressure might cause laryngopharyngeal mucosa damage, but there is no experimental research about LMA-related recurrent nerve injury. Therefore, further investigation by establishing an animal model might disclose the definite mechanism of the injury and evaluate the process of nerve recovery. The potential implications arising from this testable hypothesis might be helpful in developing clinical therapeutic approaches for this complication.
To investigate the immunomodulatory effect of Armillariella polysaccharide purified from Armillariella tabescens (Scop.ex Fr.)Sing. The effect of Armillariella polysaccharide on mice immunological function was studied by means of determining the production of the hemolysin antibody, the function of macrophage and the production of IL-2. Armillariella polysaccharide had markedly enhanced phagocytic function, and significantly increased the production of the hemolysin antibody on immunosuppression mice caused by cyclophosphamide and the mice's IL-2 production induced by Con A. These results suggest that Armillariella polysaccharide has potent enhancement on immunity.
Purpose Relatively small radial artery may be challenging for cannulation. We investigated whether a distal tourniquet would inflate the proximal radial artery and therefore facilitate cannulation in adults. Methods There were two stages of the study. The first was to measure the characteristics of radial artery by ultrasound imaging before and after tourniquet in volunteers. The second was a prospective, randomized, double blind study. Forty patients (American Society of Anesthesiologists I-III) who needed artery cannulation during operation were enrolled. Patients were assigned into two groups: loosen or tightened tourniquet for proximal radial artery cannulation by traditional palpation technique. The primary endpoints were the success rates and time of first attempt success by traditional palpation technique. The time of success after two to three attempts, failure rates and complications were collected. Results For volunteers, the distal tourniquet significantly expanded the cross-sectional up-forward diameter (p<0.001) and the area (p<0.05), but had no effect on cross-sectional lateral-lateral diameter or circumference of proximal radial artery (p>0.05). The success rate of first attempt was higher in the tighten group (75%) than in the loosen group (15%, p<0.05), but the time for success of first attempt/two to three attempts was similar (19.33 ± 1.12/62.11 ± 37.03 sec loosen group vs. 19.07 ± 12.75/45.55 ± 8.98 sec tightened group, p>0.05). Both groups had same failure rates of 10%. No complication was observed. Conclusions Distal tourniquet could inflate the proximal radial artery and facilitate palpation of radial artery cannulation.
In the prevailing phenomenon of peptide fibrillization, β-strand conformation has long been believed to be an important structural basis for peptide assembly. According to a widely accepted theory, in most peptide fibrillization processes, peptide monomers need to intrinsically take or transform to β-strand conformation before they can undergo ordered packing to form nanofibers. In this study, we reported our findings on an alternative peptide fibrillization pathway starting from a disordered secondary structure, which could then transform to β-strand after fibrillization. By using circular dichroism, thioflavin-T binding test, and transmission electron microscopy, we studied the secondary structure and assembly behavior of Ac-RADARADARADARADA-NH2 (RADA16-I) in a low concentration range. The effects of peptide concentration, solvent polarity, pH, and temperature were investigated in detail. Our results showed that at very low concentrations, even though the peptide was in a disordered secondary structure, it could still form nanofibers through intermolecular assembly, and under higher peptide concentrations, the transformation from the disordered structure to β-strand could happen with the growth of nanofibers. Our results indicated that even without ordered β-strand conformation, driving forces such as hydrophobic interaction and electrostatic interaction could still play a determinative role in the self-assembly of peptides. At least in some cases, the formation of β-strand might be the consequence rather than the cause of peptide fibrillization.
We propose a general formalism beyond Weisskopf-Wigner approximation to efficiently calculate the coupling matrix element, evolution spectrum and population evolution of two quantum emitters in arbitrary metallic nanostructures. We demonstrate this formalism to investigate the radiative coupling and decay dynamics of two quantum emitters embedded in the two hot spots of three silver nano-spheroids. The vacuum Rabi oscillation in population evolution and the anti-crossing behavior in evolution spectrum show strong radiative coupling is realized in this metallic nanostructure despite its strong plasmon damping. Our formalism can serve as a flexible and efficient calculation tool to investigate the distant coherent interaction in a large variety of metallic nanostructures, and may be further developed to handle the cases for multiple quantum emitters and arbitrary dielectric-metallic hybrid nanostructures.
Supercontinuum generation in anomalous dispersion_flattened fibers through higher_order soliton compression effect is simulated and analyzed in detail. The results show that the second order differential constant of the dispersion parameter， dispersion parameter of the fiber and the pulse width, and peak power of the pump pulse are crucial to flat wideband supercontinuum generation, and the fiber length should also be dissimilarly chosen. It further shows that supercontinuum generation in the fiber mainly results from the interaction of self_phase modulation and group_velocity dispersions, and the higher_order nonlinear effects can be ignored.
Photon-mediated coherent interaction determines the decay dynamics of quantum emitters and facilitates on-chip quantum manipulation for quantum information processing. We derive a general formalism to efficiently and flexibly simulate the radiative coupling between two two-level quantum emitters in arbitrary dielectric nanostructures, based on which, the decay dynamics of the two quantum emitters can be obtained. We demonstrate this formalism to investigate the two quantum dots embedded in the photonic crystal L3 cavity. The anticrossing behavior in the evolution spectrum and the vacuum Rabi oscillation in the populations of the two quantum dots can be simulated in both zero and small dot-dot detuning case. Our formalism can serve as a flexible and efficient theoretical tool and may be further developed to handle the cases for different initial states, multiple quantum emitters, and arbitrary metallic nanostructures.
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