Yanpeng Jiao

Effects of the gene carrier polyethyleneimines on structure and function of blood components.

As a synthetic polycation, polyethylenimine (PEI) is currently one of the most effective non-viral gene carriers. For in vivo applications, PEI will enter systemic circulation and interact with various blood components and then affect their individual bio-functions. Up to now, overall and systematic investigation on the interaction of PEI with multiple blood components at cellular, membrane, and molecular levels is lacking, even though it is critically important for the in vivo safety of PEI. To learn a structure-activity relationship, we investigated the effects of PEI with different molecular weight (MW) and shape (branched or linear) on key blood components and function, specifically, on RBC aggregation and morphological change, platelet activation, conformation change of albumin (as a representative of plasma proteins), and blood coagulation process. Additionally, more proteins from plasma were screened and identified to have associations with PEI by a proteomic analysis. It was found that, the PEIs have severe impact on RBC membrane structure, albumin conformation, and blood coagulation process, but do not significantly activate platelets at low concentrations. Furthermore, 41 plasma proteins were identified to have some interaction with PEI. This indicates that, besides albumin, PEI does interact with a variety of blood plasma proteins, and could have unexplored effects on their structures and bio-functions. The results provide good insight into the molecular design and blood safety of PEI and other polycations for in vivo applications.

Interactions between solubilized polymer molecules and blood components

In biomedical field, a variety of natural or synthetic polymers are being exponentially developed and used in vivo to improve human health. In practical applications, these biopolymers would enter blood circulation directly or indirectly, positively or passively, rapidly or slowly. Blood is a special tissue of human body, which fulfills many important missions to sustain normal metabolism. The contact with blood of the biopolymers, which are seen as foreign substances by the body, would be harmful or even instantaneously lethal, depending on the nature and the dose of the biopolymers administered. Therefore, it is critical to clearly understand the potential influences of the foreign polymers on blood before the polymers are applied from the lab to bedside. In this review, we discuss the recent studies on the interactions of foreign, solubilized polymer molecules (excluding formed polymer materials) with blood constituents (red blood cells, white blood cells, platelets, plasma proteins, etc.), to gain insight into the potential in vivo applications of the biopolymers in the biomedical field.

Therapeutic efficacy of antibiotic-loaded gelatin microsphere/silk fibroin scaffolds in infected full-thickness burns

Despite advances in burn treatment, burn infection remains a major cause of morbidity and mortality. In this study, an antibacterial silk fibroin (SF) scaffold for burn treatment was designed; gelatin microspheres (GMs) were impregnated with the antibiotic gentamycin sulfate (GS), and the GS-impregnated GMs were then embedded in a SF matrix to fabricate GS/GM/SF scaffolds. The developed GS/GM/SF scaffolds could serve as a dermal regeneration template in full-thickness burns. The average pore size and porosity of the GS/GM/SF scaffolds were 40-80 μm and 85%, respectively. Furthermore, the drug release rate of the scaffolds was significantly slower than that of either GS/GM or GS/SF scaffolds. And the composite scaffold exhibited stronger antimicrobial activities against Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa. Hence, we evaluated the wound-healing effects and antibacterial properties of the GS/GM/SF scaffolds in a rat full-thickness burn infection model. Over 21 days, the GS/GM/SF scaffolds not only significantly reduced burn infection by P. aeruginosa but also accelerated the regeneration of the dermis and exhibited higher epithelialization rates than did GS/SF and SF scaffolds. Thus, GS/GM/SF scaffolds are potentially effective for treatment of full-thickness infected burns, and GS/GM/SF scaffolds are a promising therapeutic tool for severely burned patients.

Poly(l-lactide)/halloysite nanotube electrospun mats as dual-drug delivery systems and their therapeutic efficacy in infected full-thickness burns

In this study, poly(l-lactide) (PLLA)/halloysite nanotube (HNT) electrospun mats were prepared as a dual-drug delivery system. HNTs were used to encapsulate polymyxin B sulphate (a hydrophilic drug). Dexamethasone (a hydrophobic drug) was directly dissolved in the PLLA solution. The drug-loaded HNTs with optimised encapsulation efficiency were then mixed with the PLLA solution for subsequent electrospinning to form composite dual-drug-loaded fibre mats. The structure, morphology, degradability and mechanical properties of the electrospun composite mats were characterised in detail. The results showed that the HNTs were uniformly distributed in the composite PLLA mats. The HNTs content in the mats could change the morphology and average diameter of the electrospun fibres. The HNTs improved both the tensile strength of the PLLA electrospun mats and their degradation ratio. The drug-release kinetics of the electrospun mats were investigated using ultraviolet-visible spectrophotometry. The HNTs/PLLA ratio could be varied to adjust the release of polymyxin B sulphate and dexamethasone. The antibacterial activity in vitro of the mats was evaluated using agar diffusion and turbidimetry tests, which indicated the antibacterial efficacy of the dual-drug delivery system against Gram-positive and -negative bacteria. Healing in vivo of infected full-thickness burns and infected wounds was investigated by macroscopic observation, histological observation and immunohistochemical staining. The results indicated that the electrospun mats were capable of co-loading and co-delivering hydrophilic and hydrophobic drugs, and could potentially be used as novel antibacterial wound dressings.

A surface molecularly imprinted electrospun polyethersulfone (PES) fiber mat for selective removal of bilirubin

Electrospinning has been widely recognized as a facile and scalable method for fabricating fibrous materials, which could be used as adsorption materials because of their high surface area. Surface molecular imprinting based on adsorption materials has shown excellent adsorption performance, including large binding capacity, a fast adsorption rate and selective adsorption. In this study, electrospinning and surface molecular imprinting were used together to prepare a surface molecularly imprinted electrospun polyethersulfone (PES) fiber mat (PES@MIP). The mat was prepared by self-polymerization of dopamine (as a functional monomer) on the electrospun PES fiber mat surface in weak alkaline aqueous solution in the presence of a template, bilirubin. The results indicated that a polydopamine coating was formed on the PES fiber mat surface successfully, and the template bilirubin could be removed. The adsorption performance of PES@MIP was investigated in detail, showing a higher adsorption capacity (184.24 mg g-1), faster adsorption kinetics and a short adsorption equilibrium time of 2 h, as well as a good selectivity toward bilirubin with an imprinting factor (IF) of 1.4. In addition, the selectivity coefficient (α) of PES@MIP toward cholesterol and testosterone could be calculated to be 1.11 and 1.43. Also, both adsorption kinetic and isotherm models were used to analyze the adsorption process. Besides, the dynamic adsorption indicated that PES@MIP adsorbed much more bilirubin, and had a shorter equilibrium time of about 40 minutes for bilirubin removal. In addition, PES@MIP had a much lower hemolysis ratio and exhibited a little anticoagulant property compared to the original PES fiber mat. Therefore, this work provided a new strategy to build practical PES@MIP for bilirubin adsorption.

Collagen films with stabilized liquid crystalline phases and concerns on osteoblast behaviors.

To duplicate collagens in vivo liquid crystalline (LC) phase and investigate the relationship between the morphology of LC collagen and osteoblast behavior, a self-assembly method was introduced for preparing collagen films with a stabilized LC phase. The LC texture and topological structure of the films before and after stabilization were observed with polarizing optical microscopy, scanning electron microscopy (SEM), and atomic force microscopy (AFM). The relationship between the collagen films and osteoblast behavior was studied with the 3-(4,5)-dimethylthiahiazo(-z-y1)-3,5-di-phenytetrazoliumromide method, proliferation index detection, alkaline phosphatase measurements, osteocalcin assay, inverted microscopy, SEM observation, AFM observation, and cytoskeleton fluorescence staining. The results showed that the LC collagen film had continuously twisting orientations in the cholesteric phase with a typical series of arced patterns. The collagen fibers assembled in a well-organized orientation in the LC film. Compared to the non-LC film, the LC collagen film can promote cell proliferation, and increase ALP and osteocalcin expression, revealing a contact guide effect on osteoblasts.

Improving cytoactive of endothelial cell by introducing fibronectin to the surface of poly L-Lactic acid fiber mats via dopamine.

A simple but straightforward approach was reported to prepare fiber mats modified with fibronectin (Fn) protein for endothelial cells activity study. Based on the self-polymerization and strong adhesion feature of dopamine, poly L-Lactic acid (PLLA) fibers mat was modified via simply immersing them into dopamine solution for 16h. Subsequently, Fn was immobilized onto the fiber mats surface by the coupling reactive polydopamine (PDA) layer and Fn. Attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS) were used to determine the chemical compositions of fiber mats surface, which confirmed the successful immobilization of PDA and Fn molecules on the fiber surface. Scanning electronic microscopy (SEM) was used to observe the surface morphology changes after modification with PDA and Fn. The data of water contact angle showed that the hydrophilicity of the fiber mats was improved after surface modification. The data of in vitro cell culture proved that the PDA and Fn modified surface significantly enhanced the adhesion, proliferation and cell activity of endothelial cells on the fiber mats. And the release of tumor necrosis factor-α (TNF-α) by endothelial cells on the modified surface was suppressed compared to that on culture plate and PLLA film at 2 and 4days, while the secretion of interleukin-1β (IL-1β) was increased compared to that on culture plate and PLLA film at 2days.

Effect of halloysite nanotubes on the structure and function of important multiple blood components

Many researchers have investigated the application of halloysite nanotubes (HNTs) in biomedicine, because of their special nanoscale hollow tubular structure. Although the cytocompatibility of HNTs has been studied, their blood compatibility has not been systematically investigated. In this work, the effect of HNTs on the structure and function of different blood components has been studied, including the morphology and hemolysis of red blood cells (RBCs). Based on scanning electron microscopy (SEM) observations, optical density test and flow cytometry analysis, we found that HNTs can affect the morphology and membrane integrity of RBCs in phosphate buffered saline (PBS) in a content-dependent way. In particular, based on UV-vis absorption spectra, fluorescence spectra and circular dichroism (CD) spectra, HNTs can alter the secondary structure and conformation of human fibrinogen and γ-globulins. In addition, the detection of biomarker molecules C3a and C5a in plasma suggests that HNTs can trigger complement activation. In the blood clotting assay, HNTs were found to significantly prolong the activated partial thromboplastin time (APTT), shorten the prothrombin time (PT) of platelet-poor plasma (PPP), and change the thromboelastography (TEG) parameters of whole blood coagulation. Furthermore, confocal laser scanning microscopy and flow cytometry analysis were used to test intracellular uptake by macrophages, and the cellular uptake of HNTs in the RAW 264.7 was found to be content-dependent, but not time-dependent. These findings provide insight for the potential use of HNTs as biofriendly nanocontainers for biomaterials in vivo.

Fabrication of macroporous reduced graphene oxide composite aerogels reinforced with chitosan for high bilirubin adsorption

Numerous adsorbents have been reported for the removal of bilirubin, which is a well-known endogenous toxin. Three-dimensional graphene sponges and aerogels have been fully studied in the adsorption field but little in hemoperfusion especially for bilirubin adsorption. In this study, macroporous reduced graphene oxide (GO) aerogels were fabricated by a chemical reduction method. Besides, chitosan was introduced in the aerogels during the reduction process to improve their mechanical properties. The graphene oxide composite aerogels reinforced with chitosan (rGO/CS) were investigated using scanning electron microscopy (SEM), Fourier Transform Infrared Spectrometry (FTIR), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and Brunauer–Emmett–Teller (BET). Furthermore, the mechanical properties test showed the reinforced mechanical strength of the rGO/CS aerogels. The adsorption performance of the aerogels for bilirubin was studied in detail, showing a high adsorption capacity (458.9 mg g−1) and a fast adsorption rate. Moreover, the low hemolysis ratio and negligible anticoagulant activity of rGO/CS aerogels suggested good blood compatibility. The mesoporous structure of the aerogels can provide good mechanical strength, and the macroporous structure of the rGO/CS aerogels shows a good adsorption capacity, which would have potential applications in bilirubin adsorption.

Construction and characterization of an antibacterial/anticoagulant dual-functional surface based on poly l-lactic acid electrospun fibrous mats

In this study, a poly l-lactic acid (PLLA) fibrous mat was prepared by electrospinning, followed by surface modification with polydopamine (PDA), based on its strong adhesion performance and self-polymerization of dopamine. The PDA coating on the fibrous mat surface provided a reaction platform for heparin via a Michael-type addition reaction and a reductive surface for Ag+ in situ formation of silver nanoparticles (AgNPs) in AgNO3 solution. The structure and chemical composition of the fibrous mats were determined by scanning electronic microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy. All the results confirmed the successful immobilization of heparin and AgNPs on the PLLA fibrous mats. Thermogravimetric analysis (TGA) and energy dispersive X-ray spectrum (EDS) analysis were used to determine the content of AgNPs and their distribution on the fibrous mat surface. Water contact angle measurements showed the hydrophilic improvement after modification. The antibacterial investigation indicated that the fibrous mats could inhibit the growth of both Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). Protein adsorption, the hemolysis test, the coagulation test, complement activation, and platelet activation were used to confirm the compatibility with blood and the anticoagulation property of the fibrous mats. Finally, cell proliferation and live/dead assays, conducted with cultured fibroblasts on the fibrous mats, showed that the modified fibrous mat surface had good cell compatibility. This antibacterial/anticoagulant dual-functional surface, based on poly l-lactic acid electrospun fibrous mats, would have potential application in blood contacting materials.