外围由小分子修饰的树枝状聚酰胺的合成及其荧光性能研究

合成了1－5代外围由小分子荧光体修饰的树枝状聚酰胺，通过红外，紫外，核磁等表征了其结构，并对其荧光性能进行了研究，修饰后的固体产物的荧光较修饰前粘稠体产物的荧光强得多，树枝状高分子荧光受组分比，代数，溶液浓度，溶剂等因素的影响，有机硅对树状高分子的端氨基与3，5二羟基苯甲酸按1／1摩尔比反应时，其产物荧光最强，对于端氨基与3，5－二羟基苯甲酸摩尔比为1／1的不同代树枝状聚酰胺而言，2代产物荧光最强。     

Gene delivery using functional dendritic polymers

Objective: This review describes a strategy for the development of multifunctional dendritic polymers for application as gene delivery systems. These polymers can address the low transfection efficiency usually encountered by synthetic non-viral vectors. Methods: Employing appropriate, well-characterized and mainly commercially available dendritic polymers, the emphasis is placed primarily on step-wise molecular engineering of their surface for providing gene carriers of low toxicity, specificity to certain cells and transport ability through their membranes, with the ultimate objective of enhanced transfection efficiency. Cationic dendritic polymers interact with appropriate genetic material, affording complexes that are employed for cell transfection. Conclusion: Multifunctionalization of dendritic polymers provides gene vectors of low toxicity, significant transfection efficiency, specificity to certain biological cells and transport ability through their membranes.     

Modified Dendrimer Cross-Linked Collagen-Based Matrices

Abstract

Dendrimer cross-linking has been achieved with pepsin digested over 80% type-I bovine collagen to create strong hydrogels with good cell compatibility. Herein we investigate the use of commercially available collagen-based products with the dendrimer cross-linking technology. Specifically PureCol^® (PC), a 97% bovine type-I collagen, human collagen (HC) and human extracellular matrix (hECM) were concentrated, and then cross-linked with polypropyleneimine octaamine generation two dendrimers using 1-ethyl-3-(3-dimethyl aminopropyl) carbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS) chemistry. PC gels with 30 and 20 mg/ml bovine collagen were fabricated, and despite similar concentrations to >80% type-I bovine collagen dendrimer cross-linked gels (CG), PC gels demonstrated increased swelling and decreased stability, as determined with collagenase digestion. The highly purified bovine (PC) and human sourced-collagen (HC) gels were similar in performance, but not as stable as the CG gels, which may correlate to the manufacturer’s collagen purification and storage. Finally, the addition of hECM components to PC to create PC-hECM gels, resulted in a looser gel network, compared to heparinized dendrimer cross- linked bovine >80% type-I collagen gels (CHG). However, all collagen-based gels supported 3T3 fibroblast cell growth over 4 days, indicating these gels may be suitable for tissue-engineering applications.     

Role of nanostructures in allergy: Diagnostics,treatments and safety

Nanotechnology is science, engineering and technology conducted at the nanoscale, which is about 1–100 nm. It has led to the development of nanomaterials, which behave very differently from materials with larger scales and can have a wide range of applications in biomedicine. The physical and chemical properties of materials of such small compounds depend mainly on the size, shape, composition and functionalization of the system. Nanoparticles, carbon nanotubes, liposomes, polymers, dendrimers and nanogels, among others, can be nanoengineeried for controlling all parameters, including their functionalization with ligands, which provide the desired interaction with the immunological system, that is dendritic cell receptors to activate and/or modulate the response, as well as specific IgE, or effector cell receptors. However, undesired issues related to toxicity and hypersensitivity responses can also happen and would need evaluation. There are wide panels of accessible structures, and controlling their physico-chemical properties would permit obtaining safer and more efficient compounds for clinical applications goals, either in diagnosis or treatment. The application of dendrimeric antigens, nanoallergens and nanoparticles in allergy diagnosis is very promising since it can improve sensitivity by increasing specific IgE binding, mimicking carrier proteins or enhancing signal detection. Additionally, in the case of immunotherapy, glycodendrimers, liposomes, polymers and nanoparticles have shown interest, behaving as platforms of allergenic structures, adjuvants or protectors of allergen from degradation or having a depot capacity. Taken together, the application of nanotechnology to allergy shows promising facts facing important goals related to the improvement of diagnosis as well as specific immunotherapy.     

Convenient Synthesis of a Polyester‐co‐Polyether Block for Assembling Biocompatible Hyperbranched Macromolecules

Synthesis of a novel multifunctional block based on asymmetrically substituted pentaerythritol, succinic acid, and tetraethylene glycol is reported. The proposed reaction conditions allow selective preparation of the product in high overall yield. The block can be used in the assembly of biocompatible polyester‐co‐polyether (PEPE) hyperbranched macromolecules, which allows the product to be considered as a promising intermediate for the development of new biomedical dendrimers. As an example, the use of the “block by block” strategy is employed to obtain a second‐generation dendron. It is shown that the approach is much more efficient than the pathway of step‐by‐step grafting of separate molecular fragments.

     

树枝状大分子的抗菌作用研究进展

目的 对各种树枝状大分子抗菌效能及其毒性的研究进展进行总结,为该类物质的进一步开发及应用提供参考。方法 查阅国内外相关文献,进行分析、归纳和综述。结果 具有抗菌活性的树枝状大分子主要包括糖、阳离子、肽、阴离子类及聚酰胺-胺类等树枝状大分子,上述大分子抗菌谱广,活性高,不容易诱导细菌耐药且生物相容性较好。 结论 树枝状大分子是一类潜在的抗菌候选分子及抗菌涂层材料,有良好的应用前景。     

Emerging concepts in dendrimer‐based nanomedicine: from design principles to clinical applications

Dendrimers are discrete nanostructures/nanoparticles with ‘onion skin‐like’ branched layers. Beginning with a core, these nanostructures grow in concentric layers to produce stepwise increases in size that are similar to the dimensions of many in vivo globular proteins. These branched tree‐like concentric layers are referred to as ‘generations’. The outer generation of each dendrimer presents a precise number of functional groups that may act as a monodispersed platform for engineering favourable nanoparticle–drug and nanoparticle–tissue interactions. These features have attracted significant attention in medicine as nanocarriers for traditional small drugs, proteins, DNA/RNA and in some instances as intrinsically active nanoscale drugs. Dendrimer‐based drugs, as well as diagnostic and imaging agents, are emerging as promising candidates for many nanomedicine applications. First, we will provide a brief survey of recent nanomedicines that are either approved or in the clinical approval process. This will be followed by an introduction to a new ‘nanoperiodic’ concept which proposes nanoparticle structure control and the engineering of ‘critical nanoscale design parameters’ (CNDPs) as a strategy for optimizing pharmocokinetics, pharmocodynamics and site‐specific targeting of disease. This paradigm has led to the emergence of CNDP‐directed nanoperiodic property patterns relating nanoparticle behaviour to critical in vivo clinical translation issues such as cellular uptake, transport, elimination, biodistribution, accumulation and nanotoxicology. With a focus on dendrimers, these CNDP‐directed nanoperiodic patterns are used as a strategy for designing and optimizing nanoparticles for a variety of drug delivery and imaging applications, including a recent dendrimer‐based theranostic nanodevice for imaging and treating cancer. Several emerging preclinical dendrimer‐based nanotherapy concepts related to inflammation, neuro‐inflammatory disorders, oncology and infectious and ocular diseases are reviewed. Finally we will consider challenges and opportunities anticipated for future clinical translation, nanotoxicology and the commercialization of nanomedicine.