ORCID Profile
0000-0003-0698-4162
Current Organisation
Xiamen University
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Publisher: Wiley
Date: 27-10-2017
Abstract: Structure-property relationships of silk is an intriguing topic for silk-based biomaterials research since these features are related to biomimicking the processing in natural silk fiber formation which results in excellent mechanical properties. Strain-stiffening is common for spider silks and nonmulberry silkworm silks. However, the structural origin of strain-stiffening remains unclear. In this paper, the strain-dependent structural change of Antheraea pernyi silkworm silk is studied by X-ray fiber diffraction and Fourier transform infrared spectroscopy under stretching. Based on a combination of mechanical and structural analysis, the molecular origins of strain-stiffening in A. pernyi silk were determined. The relatively high content of the β-sheets within the amorphous domains in A. pernyi silk is responsible for strain-stiffening, where "molecular spindles" enhance the extensibility and toughness of the fiber.
Publisher: Wiley
Date: 17-08-2016
Publisher: American Chemical Society (ACS)
Date: 30-11-2006
DOI: 10.1021/JP065101J
Abstract: A new approach of engineering of molecular gels was established on the basis of a nucleation-initiated network formation mechanism. A variety of gel network structures can be obtained by regulating the starting temperature of the sol-gel transition. This enables us to tune the network from the spherulitic domains pattern to the extensively interconnected fibrillar network. As the consequence of fibrous network structure turning, desirable rheological and other in-use properties of the materials can be obtained accordingly. This approach of micro-/nanostructural fabrication may open up a new route for micro-/nanofunctional materials engineering in general.
Publisher: American Chemical Society (ACS)
Date: 12-05-2010
DOI: 10.1021/CG100188W
Publisher: Royal Society of Chemistry (RSC)
Date: 2012
DOI: 10.1039/C2SM25073J
Publisher: American Chemical Society (ACS)
Date: 31-05-2011
DOI: 10.1021/LA200196K
Abstract: We present a new generic strategy to fabricate nanoparticles in the "cages" within the fibrous networks of supramolecular soft materials. As the cages can be acquired by a design-and-production manner, the size of nanoparticles synthesized within the cages can be tuned accordingly. To implement this idea, both selenium and silver were chosen for the detailed investigation. It follows that the sizes of selenium and silver nanoparticles can be controlled by tuning the pore size of the fiber networks in the material. When the concentration of the gelator is high enough, monodisperse nanoparticles can be prepared. More interestingly, the morphology of the nanoparticles can be altered: silver disks can be formed when the concentrations of both the gelator and silver nitrate are sufficiently low. As the fiber network serves as a physical barrier and semisolid support for the nanoparticles, the stability in the aqueous media and the ease of application of these nanoparticles can be substantially enhanced. This robust surfactant-free approach will not only allow the controlled fabrication of nanoparticles, but also can be applied to the fabrication of composite materials for robust applications.
Publisher: Elsevier BV
Date: 02-2009
DOI: 10.1016/J.CANLET.2008.09.024
Abstract: Gold nanoparticles were conjugated with transferrin molecules for targeting, imaging and therapy of breast cancer cells (Hs578T, ATCC). Results show that, the transferrin-transferrin receptor-mediated cellular uptake of gold nanoparticles is six times of that in the absence of this interaction. As a consequence, the laser power effective for photothermal therapy of the cancer cells was reduced to values of two orders of magnitude lower. To demonstrate the efficiency of the conjugated gold nanoparticles in selectively targeting cancer cells, the cellular uptake of the gold nanoparticles by noncancerous cells (3T3, ATCC) was also investigated. The cellular uptake by the normal cells is only one fourth of that by the cancerous cells indicating that the transferrin-transferrin receptor interaction plays an important role in controlling the cellular uptake of the gold nanoparticles.
Publisher: Elsevier BV
Date: 08-2013
Publisher: American Chemical Society (ACS)
Date: 12-2005
DOI: 10.1021/JP054676Y
Abstract: The architecture of a biocompatible organogel formed by gelation of a small molecule organic gelator, N-lauroyl-L-glutamic acid di-n-butylamide, in isostearyl alcohol was investigated based on a supersaturation-driven crystallographic mismatch branching mechanism. By controlling the supersaturation of the system, the correlation length that determines the mesh size of the fiber network was finely tuned and the rheological properties of the gel were engineered. This approach is of considerable significance for many gel-based applications, such as controlled release of drugs that requires precise control of the mesh size. A direct cryo-transmission electron microscopy (TEM) imaging technique capable of preserving the network structure was used to visualize its nanostructure.
Publisher: Royal Society of Chemistry (RSC)
Date: 2015
DOI: 10.1039/C4RA09482D
Abstract: Both the physical and physiochemical properties of domestic and wild silkworm silk fibroin were studied, including surface energy and surface energy heterogeneity.
Publisher: American Chemical Society (ACS)
Date: 26-12-2015
DOI: 10.1021/MP500542A
Abstract: Controlled release plays an essential role in formulating topical and transdermal drug delivery systems. In this study, we correlated the skin permeation of Sesamin, a lipophilic drug, with the rheological properties of two different organogel carriers, i.e., low molecular weight gelling agent N-lauroyl-l-glutamic acid di-n-butylamide (GP-1) and Carbopol polymeric gels. Although these two gels have distinct network structures, they share the same trend: the more rigid the gel network and the higher the gelator concentration, the lower the steady flux of Sesamin through skin. This negative correlation lies in the fact that organogel network hinders the diffusion of drug to the gel-skin interface as a result, the depletion zone near the interface is non-negligible and contributes to the resistance of the whole diffusion system, and thus, the permeation flux is reduced. More interestingly, the dependence of the steady flux against gel complex modulus at the linear viscoelastic region followed a "universal" power law regardless of the gel types, i.e., 1/J = 1/J0 + a(G*)(ε)/C0 with a = 11.25, ε = 0.21 ± 0.03 for GP-1 gels, and a = 0.16, ε = 1.05 ± 0.06 for Carbopol gels, J0 is the steady flux without gel (G* = 0), and C0 is the initial concentration of drug in gels. The empirical formulae are crucial in developing transdermal organogel systems with controlled release of drug content through readily obtainable data of their rheological properties. The explanation for the power law dependence of the steady flux on gel complex modulus is discussed.
Publisher: Elsevier BV
Date: 12-2016
DOI: 10.1016/J.FOODCHEM.2016.05.162
Abstract: Konjac glucomannan - tungsten (KGM-T) gels were successfully prepared under DC electric fields, in the presence of sodium tungstate. The textural properties and microstructure of the gels were investigated by Texture Analyzer, Rheometer and SEM. Based on the response surface methodology (RSM) results, the optimum conditions for KGM-T gel springiness is 0.32% sodium tungstate concentration, 0.54% KGM concentration, 24.66V voltage and 12.37min treatment time. Under these conditions, the maximum springiness value of KGM-T gel is 1.21mm. Steady flow measurement indicated that KGM-T gel showed characteristic non-Newtonian pseudoplastic behaviour, with low flow behaviour indexes in the shear thinning region. SEM demonstrated the porosity of the freeze-dried s les. These findings may pave the way to use DC electric fields for the design and development of KGM gels and to apply KGM gels for practical applications.
Publisher: American Chemical Society (ACS)
Date: 17-03-2009
DOI: 10.1021/JP8035023
Abstract: A finite element method based on ABAQUS is employed to examine the correlation between the microstructure and the elastic response of planar Cayley treelike fiber networks. It is found that the elastic modulus of the fiber network decreases drastically with the fiber length, following the power law. The power law of elastic modulus G' vs the correlation length xi obtained from this simulation has an exponent of -1.71, which is close to the exponent of -1.5 for a single-domain network of agar gels. On the other hand, the experimental results from multidomain networks give rise to a power law index of -0.49. The difference between -1.5 and -0.49 can be attributed to the multidomain structure, which weakens the structure of the overall system and therefore suppresses the increase in G'. In addition, when the aspect ratio of the fiber is smaller than 20, the radius of the fiber cross-section has a great impact on the network elasticity, while, when the aspect ratio is larger than 20, it has almost no effect on the elastic property of the network. The stress distribution in the network is uniform due to the symmetrical network structure. This study provides a general understanding of the correlation between microscopic structure and the macroscopic properties of soft functional materials.
Publisher: Royal Society of Chemistry (RSC)
Date: 2013
DOI: 10.1039/C2SM27065J
Publisher: AIP Publishing
Date: 21-08-2006
DOI: 10.1063/1.2338007
Abstract: An understanding of the physical hydrogel network formation has been obtained by dynamic rheological experiments. The evidence shows that the network formation turns out to be a nucleation-controlled process. It was found that there exists a critical temperature Tc fiber branching is greatly enhanced when the network formation is performed in the regime of T& Tc (T, the final setting temperature). This finding enables the authors to build significantly enhanced gel networks. So far G′ (elastic modulus) of the hydrogel network has been enhanced by 187% while the formation period can be greatly shortened to only 1∕20 of the previous process.
Publisher: American Chemical Society (ACS)
Date: 18-03-2006
DOI: 10.1021/JP054531R
Abstract: Low-molecular mass organic gelators self-organizing into three-dimensional fiber networks within organic solvents have attracted much attention in recent years. However, to date, how the microstructure of fiber network is formed in a gelation process and the key factors that govern the topological structure of a gel network remain to be determined. In this work, we address these issues by investigating the in situ formation of the gel networks in the N-lauroyl-l-glutamic acid di-n-butylamide (GP-1) ropylene glycol (PG) system. By using optical microscopy, the time evolution of the gel network microstructure was investigated under various supersaturation conditions. It is found that supersaturation is one of the key factors that govern the topological structure of a gel network. In particular, the creation of the junctions turns out to be supersaturation-dependent. The rheological experiments further revealed the correlation between topological structure and mechanical properties. It suggests that the rheological properties can be effectively modified by tuning the microstructure topology of the gel network. Our results reported here provide new physical insight into the formation kinetics of a molecular gel. Furthermore, this work could be important in constructing and engineering a supramolecular structure for the purpose of applications.
Publisher: Informa UK Limited
Date: 12-2009
Publisher: American Chemical Society (ACS)
Date: 02-11-2009
DOI: 10.1021/JP907963T
Abstract: The engineering of soft functional materials based on the construction of three-dimensional interconnecting self-organized nanofiber networks is reported. The system under investigation is an organogel formed by N-lauroyl-L-glutamic acid di-n-butylamide (GP-1) in propylene glycol. The engineering of soft functional materials is implemented by controlling primary nucleation kinetics of GP-1, which can be achieved by both reducing thermodynamic driving force and/or introducing a tiny amount of specific copolymers (i.e., poly(methyl methacrylate comethacrylic acid)). The primary nucleation rate of GP-1 is correlated to the number density of GP-1 spherulites, which determines the overall rheological properties of soft functional materials. The results show that the presence of a tiny amount of the polymer (0.01-0.06%) can effectively inhibit the nucleation of GP-1 spherulites, which leads to the formation of integrated fiber networks. It follows that with the additive approach, the viscoelasticity of the soft functional material is significantly enhanced (i.e., more than 1.5 times at 40 degrees C). A combination of the thermal and additive approach led to an improvement of 3.5 times in the viscosity of the gel.
Publisher: AIP Publishing
Date: 06-09-2005
DOI: 10.1063/1.2042552
Abstract: Three-dimensional fiber networks were created from an organogel system consisting mainly of elongated fibrils by using a nonionic surfactant as an additive. The presence of the surfactant molecules manipulates the network structure by enhancing the mismatch nucleation on the growing fiber tips. Both the fiber network structure and the rheological properties of the material can be finely tuned by changing the surfactant concentration, which provides a robust approach to the engineering of supramolecular soft functional materials.
Publisher: American Chemical Society (ACS)
Date: 23-03-2009
DOI: 10.1021/JP811215T
Abstract: The formation of most organogels requires the compatibility of both the gelator and solvent. It is very desirable if the rheological properties of a gel can be manipulated to achieve the desired performance. In this paper, a novel organogel was developed and its rheological properties and fiber network were engineered by controlling the thermal processing conditions. The gel was formed by the gelation of 12-hydroxystearic acid as a gelator in benzyl benzoate. It was observed that the degree of supercooling for gel formation has a significant effect on the rheological properties and fiber network structure. By increasing supercooling, the elasticity of the gel was enhanced, and the correlation length of the fibers was shortened, leading to the formation of denser fiber networks. The good biocompatibility of both the gelator and solvent makes this gel a promising vehicle for a variety of bioapplications such as controlled transdermal drug release and in vivo tissue repair.
Publisher: Elsevier BV
Date: 06-2008
DOI: 10.1016/J.IJPHARM.2008.02.021
Abstract: It is accepted that terpenes are effective penetration enhancers to promote the passage of drugs or chemicals through the human skin barrier. However the physical and chemical changes of a pharmaceutical vehicle induced by the incorporation of terpenes have not been explored. Thus, this study examines the effects of three terpenes (linalool, cineole, limonene) on the rheology and chemical stability of an organogel composed of dibutyllauroylglutamide (GP1) and propylene glycol (PG). At a given GP1 concentration, oxygen-containing linalool and cineole decreased gel moduli (elastic and viscous) and brittleness, and the reverse was obtained for hydrocarbon limonene. Probably, linalool and cineole interfered with hydrogen bonding between GP1 molecules while limonene could have initiated a phase separation-mediated gelation, changing the gel morphology. Microcalorimetry detected minute heat endotherms for gels (with and without terpenes) subjected to accelerated heat testing. These heat changes could arise from a small degree of structural disruption of the gel network. Heat endotherms normalized with respect to GP1 content were used to assess gel chemical stability. Although the terpenes altered rheology, they did not significantly affect the chemical stability of the gels. This is the first in the literature that reports the effect of penetration enhancers, such as terpenes, on the physical, rheological and chemical characteristics of a model pharmaceutical formulation for topical and transdermal drug delivery.
Publisher: Royal Society of Chemistry (RSC)
Date: 2011
DOI: 10.1039/C0CC04488A
Abstract: The formation of fiber networks and the resulting rheological properties of supramolecular soft materials are dramatically influenced when the volume of the system is reduced to a threshold. Unlike un-confined systems, the formation of fiber networks under volume confinement is independent of temperature and solute concentration.
Publisher: Royal Society of Chemistry (RSC)
Date: 2013
DOI: 10.1039/C2CC38779D
Abstract: Silk scaffolds having biomimetic hierarchical porous structures were achieved by carefully tuning liquid-liquid separation in regenerated silk fibroin solutions. Such scaffolds show greatly enhanced cellular responses.
Publisher: American Scientific Publishers
Date: 05-2008
DOI: 10.1166/JNN.2008.502
Abstract: Selenium-polypyrrole core–shell nanoparticles are fabricated by an in-situ polymerization process and functionalized with transferrin for targeting and imaging of human cervical cancer cells. The shell thickness and chemical composition of the as-synthesized particles can be manipulated by controlling the precursor concentration. The presence of the polymer layer can greatly increase the thermal stability of the selenium nanoparticles. The presence of transferrin molecules on the surface of the core–shell nanoparticles can significantly enhance their cellular uptake. The tranferrin-conjugated core–shell nanoparticles can be potentially used for the targeting and imaging of cancer cells.
Publisher: Royal Society of Chemistry (RSC)
Date: 2013
DOI: 10.1039/C2CP43747C
Abstract: Understanding the role of kinetics in fiber network microstructure formation is of considerable importance in engineering gel materials to achieve their optimized performances/functionalities. In this work, we present a new approach for kinetic-structure analysis for fibrous gel materials. In this method, kinetic data is acquired using a rheology technique and is analyzed in terms of an extended Dickinson model in which the scaling behaviors of dynamic rheological properties in the gelation process are taken into account. It enables us to extract the structural parameter, i.e. the fractal dimension, of a fibrous gel from the dynamic rheological measurement of the gelation process, and to establish the kinetic-structure relationship suitable for both dilute and concentrated gelling systems. In comparison to the fractal analysis method reported in a previous study, our method is advantageous due to its general validity for a wide range of fractal structures of fibrous gels, from a highly compact network of the spherulitic domains to an open fibrous network structure. With such a kinetic-structure analysis, we can gain a quantitative understanding of the role of kinetic control in engineering the microstructure of the fiber network in gel materials.
Publisher: Elsevier BV
Date: 08-2013
DOI: 10.1016/J.MSEC.2013.03.051
Abstract: As a protective shell against environmental damage and attack by natural predators, the silkworm cocoon has outstanding mechanical properties. In particular, this multilayer non-woven composite structure can be exceptionally tough to enhance the chance of survival for silkworms while supporting their metabolic activity. Peel, out-of-plane compression and nano-indentation tests and micro-structure analysis were performed on four types of silkworm cocoon walls (domesticated Bombyx mori, semi-domesticated Antheraea assamensis and wild Antheraea pernyi and Antheraea mylitta silkworm cocoons) to understand the structure and mechanical property relationships. The wild silkworm cocoons were shown to be uniquely tough composite structures. The maximum work-of-fracture for the wild cocoons (A. pernyi and A. mylitta) was approximately 1000 J/m(2), which was almost 10 times the value for the domesticated cocoon (Bombyx mori) and 3~4 times the value for the semi-domesticated cocoon (A. assamensis). Calcium oxalate crystals were found to deposit on the outer surfaces of the semi-domesticated and wild cocoons. They did not show influence in enhancing the interlaminar adhesion between cocoon layers but exhibited much higher hardness than the cocoon pelades.
Publisher: Royal Society of Chemistry (RSC)
Date: 2013
DOI: 10.1039/C3SM50879J
Publisher: Elsevier BV
Date: 08-2005
DOI: 10.1016/J.JCONREL.2005.04.017
Abstract: Small molecule gelling agent (SMGA) gels were developed using the gelator GP-1 in the solvents, namely, isostearyl alcohol (ISA) and propylene glycol (PG), to deliver haloperidol through the skin. The concentrations of the drug, haloperidol, the enhancer, farnesol and the gelator, GP-1 are 3 mg/ml, 5% (w/v) and 5% (w/v), respectively. The study employed a three-factor full factorial statistical design to investigate the influence of factor level changes on the permeability coefficient and permeation lag-time of haloperidol. Gels were prepared by raising temperature to 120 degrees C, followed by natural cooling under room temperature of 22+/-1 degrees C. The rheological properties of the gels were examined with a strain-controlled dynamic mechanical method. The in vitro permeation study was conducted with automated flow-through type cells. The gels successfully incorporated the drug and enhancer without losing their aesthetic properties. The in vitro human skin permeation study showed the permeation of the drug in ISA-based gels reached the pseudo steady state faster than PG-based gels and were less affected by gelator. PG-based gels delivered the drug at a faster rate with the incorporation of the enhancer. GP-1 did not influence the drug permeation rate but it increased permeation lag-time. The co-existence of gelator or enhancer increased the lag-time to a larger extent than when used separately. The novel SMGA gels are suitable for topical or transdermal delivery.
Publisher: American Chemical Society (ACS)
Date: 14-05-2009
DOI: 10.1021/CG9000494
Publisher: Elsevier BV
Date: 03-2006
DOI: 10.1016/J.IJPHARM.2005.12.042
Abstract: Penetration enhancers are a classical means for improving transdermal drug delivery (TDD). Enhancers permeate into the skin and reversibly decrease the barrier resistance. Basically, our aim is to formulate a transdermal gel containing an appropriate enhancer for a controlled drug release. Terpenes, namely limonene, linalool and cineole, in propylene glycol (PG) were first investigated in vitro for their capacity to enhance the percutaneous release of an anti-psychotic drug, haloperidol (HP). Relative to oxygenated linalool and cineole, hydrocarbon limonene was more effective as a skin enhancer it increased human skin permeability and decreased lag time. Limonene was thus incorporated in an organogel comprised of gelator GP1 and PG. This skin-friendly gel in a transdermal patch could act as a long-acting formulation that delivers HP at a sustained percutaneous rate. The microscopic framework of the organogel is a branched network of interlocking fibres. Varying the gelator content modulates the fibre density and gel stiffness, and presents different degrees of resistance to drug diffusion on the vehicle side. Rheological and permeation studies demonstrated that an increase in gelator concentration increased gel moduli and decreased drug flux simultaneously. The rheology of the gel matrix influenced drug release rate in a manner described by several experimentally-derived correlations.
Publisher: Wiley
Date: 04-10-2006
Publisher: American Chemical Society (ACS)
Date: 27-08-2013
DOI: 10.1021/LA4023085
Abstract: This paper describes a strategy of fabricating a new class of nano hybrid particles in terms of the "nanocages" of reactive molecular matrices/networks. The concept is to design molecular matrices functionalized with particular reactive groups, which can on-site synthesize and fix nanoparticles at the designated positions of the molecular networks. The cages of the molecular networks impose the confinement and protection to the nanoparticles so that the size and the stability of nano hybrid particles can be better controlled. To this end, polyamide network polymers (PNP) were synthesized and adopted as the reactive molecular cages for the control of silver nanoparticles formation. It follows that the silver nano hybrid particles fabricated by this method have an average diameter of 4.34 nm much smaller than any other or similar methods ie by a hyperbranched polyamide polymer (HB-PA). As per our design, the size of the silver nano hybrid particles can also be tuned by controlling the molar ratio between silver ions and the functional groups in the polymeric matrices. The silver nano hybrid particles reveal the substantially enhanced stability in aqueous solutions, which gives rise to the long stable performance of localized surface plasmon resonance. As the nano hybrid particles display long eminent nanoeffects, they exert broad implications for a wide range of applications such as biomedicine, catalysis, and optoelectronics.
Publisher: Royal Society of Chemistry (RSC)
Date: 2011
DOI: 10.1039/C0SM00873G
Publisher: Royal Society of Chemistry (RSC)
Date: 2014
DOI: 10.1039/C4CE00096J
Publisher: Wiley
Date: 23-08-2010
Location: China
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Xiang Yang Liu.