Self-Assembling Peptides and Carbon Nanomaterials Join Forces for Innovative Biomedical Applications

Self-assembling peptides and carbon nanomaterials have attracted great interest for their respective potential to bring innovation in the biomedical field. Combination of these two types of building blocks is not trivial in light of their very different physico-chemical properties, yet great progress has been made over the years at the interface between these two research areas. This concise review will analyze the latest developments at the forefront of research that combines self-assembling peptides with carbon nanostructures for biological use. Applications span from tissue regeneration, to biosensing and imaging, and bioelectronics.     

Dipeptide and tripeptide conjugates as low-molecular-weight hydrogelators

Dipeptide and tripeptide conjugates are receiving significant current interest as LMWG, driven by the accessibility of these materials, their relatively low cost and also the large number of examples that successfully form hydrogels. Their behaviour can easily modified by changes in the amino acids or the aromatic end groups chosen. The assembly process has been relatively well described for a small subset of these gelators, giving a good idea of the behaviour of these molecules and allowing an understanding of the conditions under which assembly will occur. Here, we critically review the literature in this area and consider the importance of gelator choice and method of assembly on the outcome of the gelation. We also discuss the applications of these hydrogels.     

Methylene blue-conjugated hydrogel nanoparticles and tumor-cell targeted photodynamic therapy

Methylene blue‐conjugated polyacrylamide nanoparticles are prepared through a microemulsion polymerization, after conjugation of the dye with a monomer. The nanoparticles have a 50–60 nm diameter in solution. This conjugation method enables a large increase in loading of methylene blue per nanoparticle and also minimizes dye leaching out of the nanoparticle. Furthermore, the dye content can be controlled by variation of the dye amount, enabling a more refined control of the singlet oxygen production ability. The nanoparticles are coated with F3 peptides, which give specific targeting to selected tumor cells, 9L, MDA‐MB‐435, and F98, in vitro. In addition, MTT assays reveal that the nanoparticles have no dark toxicity but excellent PDT efficacy increasing with the nanoparticle dose and irradiation time.

     

Stiff,Multistimuli‐Responsive Supramolecular Hydrogels as Unique Molds for 2D/3D Microarchitectures of Live Cells

Supramolecular hydrogels constructed through molecular self‐assembly of small molecules have unique stimuli‐responsive properties; however, they are mechanically weak in general, relative to conventional polymer gels. Very recently, we developed a zwitterionic amino acid tethered amphiphilic molecule 1 , which gave rise to a remarkably stiff hydrogel comparable with polymer‐based agarose gel, retaining reversible thermal‐responsive properties. In this study, we describe that rational accumulation of multiple and orthogonal noncovalent interactions in the supramolecular nanofibers of 1 played crucial roles not only in the mechanical reinforcement but also in the multistimuli responsiveness. That is, the zwitterionic amino acid moiety and the C C double bond unit of the hydrogelator 1 can function as a pH‐responsive unit and a light‐responsive unit, respectively. We also demonstrated that this stiff and multistimuli‐responsive supramolecular hydrogel 1 is applied as a unique mold for 2D and 3D‐patterning of various substances. More significantly, we succeeded in the fabrication of a collagen gel for spatial patterning, culturing, and differentiation of live cells by using hydrogel 1 molds equipped with 2D/3D microspace channels (100–200 μm in diameter).     

pH敏感的聚(L-谷氨酸)-交联聚丙烯酸水凝胶的合成与性能研究

通过在聚L-谷氨酸侧链部分接枝甲基丙烯酸2-羟乙酯得到含有双键的聚(L-谷氨酸),将其与丙烯酸共聚得到由聚(L-谷氨酸)侧链接枝并交联聚丙烯酸的pH敏感水凝胶.研究水凝胶在不同pH的缓冲溶液中的溶胀性、溶胀动力学,并通过SEM观察水凝胶的微观结构.结果表明,水凝胶在低pH环境下的溶胀率明显低于高pH环境中的溶胀率,不同...     

NIPAM共聚物多孔水凝胶的光引发RAFT合成及其溶胀性能

采用光引发可逆加成-断裂链转移(RAFT)方法,在室温下先合成了链端含有三硫代碳酸酯基的大分子链转移剂聚(N,N'-二甲基丙烯酰胺)(PDMAM),然后与N-异丙基丙烯酰胺(NIPAM)、N,N'-二甲基双丙烯酰胺(BIS)交联共聚合,并通过聚乙二醇的制孔作用制得PNIPAM-g-PDMAM梳型/多孔水凝胶.采用FTI...     

Versatile functionalization of polyester hydrogels with electroactive aniline oligomers

Functionalizing aliphatic polyester hydrogels with an aniline oligomer is a means of achieving electrically conductive and degradable hydrogels. To lower the aniline oligomer content while maintaining a high conductivity and to overcome the acidic degradation product from polylactide reported in our previous work, a series of electroactive and degradable hydrogels based on polycaprolactone (PCL) hydrogels and carboxyl‐capped aniline pentamer (CCAP) were synthesized by a simple coupling reaction at room temperature. The reaction was carried out between the hydroxyl groups of hydroxyethylmethacrylate in a photopolymerized glycidyl methacrylate (GMA)‐functionalized PCL‐poly(ethylene glycol)‐PCL degradable network and carboxyl group of CCAP, using 1‐ethyl‐3‐(3‐dimethylaminopropyl) carbodiimide as water‐condensing agent and 4‐dimethylaminopyridine as catalyst. The electroactivity of the hydrogels was verified by cyclic voltammetry, which showed three pairs of redox peaks. The electrical conductivities and swelling ratios of these hydrogels were controlled by the CCAP content, the poly(ethylene glycol) molecular weight in the macromer, and the crosslinking density of the hydrogels. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Noncovalent binding interactions of polyacrylamide and clay in nanocomposite hydrogels

The interactions between organic and inorganic components in pregel solution for polyacrylamide (PAAm)/clay nanocomposite hydrogels (NC gels) and in prepared NC gels are investigated. Besides, a kind of self‐crosslinked PAAm gels with excellent mechanical properties is fabricated in the absence of any cross‐linking agents, the hydrogen bonding interactions among PAAm chains are acted as the cross‐linking force. It is revealed that the binding interactions of PAAm and clay in NC gels are owing to the noncovalent interactions between amide groups on PAAm chains and clay platelets, which afford the cross‐linking force for NC gels network formation. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2011     

A “self‐pinning” adhesive based on responsive surface wrinkles

Surface wrinkles are interesting since they form spontaneously into well‐defined patterns. The mechanism of formation is well‐studied and is associated with the development of a critical compressive stress that induces the elastic instability. In this work, we demonstrate surface wrinkles that dynamically change in response to a stimulus can improve interfacial adhesion with a hydrogel surface through the dynamic evolution of the wrinkle morphology. We observe that this control is related to the local pinning of the crack separation pathway facilitated by the surface wrinkles during debonding, which is dependent on the contact time with the hydrogel. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2010