Plasmid DNA hydrogels for biomedical applications

In the last few years, our research group has focused on the design and development of plasmid DNA (pDNA) based systems as devices to be used therapeutically in the biomedical field. Biocompatible macro and micro plasmid DNA gels were prepared by a cross-linking reaction. For the first time, the pDNA gels have been investigated with respect to their swelling in aqueous solution containing different additives. Furthermore, we clarified the fundamental and basic aspects of the solute release mechanism from pDNA hydrogels and the significance of this information is enormous as a basic tool for the formulation of pDNA carriers for drug/gene delivery applications. The co-delivery of a specific gene and anticancer drugs, combining chemical and gene therapies in the treatment of cancer was the main challenge of our research. Significant progresses have been made with a new p53 encoding pDNA microgel that is suitable for the loading and release of pDNA and doxorubicin. This represents a strong valuable finding in the strategic development of systems to improve cancer cure through the synergetic effect of chemical and gene therapy.     

Photocrosslinkable chitosan hydrogels and their biomedical applications

Chitosan is a bioactive macromolecule with a wide variety of applications due to its excellent biological properties such as biodegradability, biocompatibility, and antibacterial activity, and so forth. This highlight focuses on the preparation of photoactive chitosans, the formation of photocrosslinkable chitosan hydrogels, and the related photopolymerization mechanisms. Moreover, the great potential applications of photocrosslinkable chitosan hydrogels for human tissues are also discussed. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 1862–1871     

Advances in nitric oxide-releasing hydrogels for biomedical applications

Hydrogels provide a plethora of advantages to biomedical treatments due to their highly hydrophilic nature and tissue-like mechanical properties. Additionally, the numerous and widespread endogenous roles of nitric oxide have led to an eruption in research developing biomimetic solutions to the many challenges the biomedical world faces. Though many design factors and fabrication details must be considered, utilizing hydrogels as nitric oxide delivery vehicles provides promising materials in several applications. Such applications include cardiovascular therapy, vasodilation and angiogenesis, antimicrobial treatments, wound dressings, and stem cell research. Herein, a recent update on the progress of NO-releasing hydrogels is presented in depth. In addition, considerations for the design and fabrication of hydrogels and specific biomedical applications of nitric oxide-releasing hydrogels are discussed.     

Injectable and biodegradable hydrogels: gelation, biodegradation and biomedical applications

Injectable hydrogels with biodegradability have in situ formability which in vitro/in vivo allows an effective and homogeneous encapsulation of drugs/cells, and convenient in vivo surgical operation in a minimally invasive way, causing smaller scar size and less pain for patients. Therefore, they have found a variety of biomedical applications, such as drug delivery, cell encapsulation, and tissue engineering. This critical review systematically summarizes the recent progresses on biodegradable and injectable hydrogels fabricated from natural polymers (chitosan, hyaluronic acid, alginates, gelatin, heparin, chondroitin sulfate, etc.) and biodegradable synthetic polymers (polypeptides, polyesters, polyphosphazenes, etc.). The review includes the novel naturally based hydrogels with high potential for biomedical applications developed in the past five years which integrate the excellent biocompatibility of natural polymers/synthetic polypeptides with structural controllability via chemical modification. The gelation and biodegradation which are two key factors to affect the cell fate or drug delivery are highlighted. A brief outlook on the future of injectable and biodegradable hydrogels is also presented (326 references).     

Polymeric gels and hydrogels for biomedical and pharmaceutical applications

Hydrogels are formed when a three‐dimensional polymeric network is loosely crosslinked. They are swollen by water but not dissolved in it. Hydrogels may display reversible sol–gel transitions, induced by changes in the environmental conditions such as temperature, pH, ionic strength, phase separation, wave length of light, crystallinity, etc. Hydrogel is described as smart or intelligent when sharp transition is induced by small change in such conditions. For the shape‐memory hydrogels, reversible change in shape may also be induced by such stimuli. The preparation and applications of the molecularly imprinted polymeric hydrogels (MIPs) are illustrated by a few examples. The use of shape sensitive hydrogels in microfluidic is mentioned. Application of hydrogels for chronobiology and chronotherapy is outlined. The conversion of hydrogels into aerogels and their respective properties is discussed. Copyright © 2009 John Wiley & Sons, Ltd.     

STING-activating drug delivery systems:Design strategies and biomedical applications

The stimulator of interferon genes(STING) shows promising clinical activity in infectious diseases and tumors.However,the lack of targeting capability and intracellular stability of STING agonists severely limits the therapeutic efficacy.Recently,drug delivery systems(DDSs) overcome these delivery barriers of STING agonists via passive or active cell targeting,prolonged blood circulation and drug release,and lysosome escape,etc.In this review,we will describe in detail how existing DDSs are designed to overcome delivery barriers and activate the STING pathway,and the current biomedical applications of STING-activating DDSs in the treatments of infectious diseases and tumors.Finally,the prospects and challenges of DDSs in STING activation are discussed.     

New approaches to the building of supramolecular radiofullerenes for possible biomedical and toxicological applications

The paper demonstrates that water insoluble pristine C₆₀ can be easily solubilized by a mechanochemical solid-solid reaction in a special ball mill with g-cyclodextrin or calix-[8]-arene. It also shows that nuclear recoil after neutron capture provides a new means for the preparation of endohedral radiofullerenes by nuclear implosion. The radiofullerenes built by mechanochemically activated supramolecular reactions are soluble in water and can be used in biomedical and toxicological studies. This revised version was published online in August 2006 with corrections to the Cover Date.     

Melanin-based nanoparticles in biomedical applications: From molecular imaging to treatment of diseases

The melanin-based nanoparticles preparation methods were summarized here. Biomedical applications of melanin-based nanoparticles were also reviewed, including molecular imaging (magnetic resonance, positron emission tomography, and photoacoustic imaging) and treatment of diseases (drug delivery, photothermal therapy, antioxidant therapy, and iron overload therapy).     

D-glucosamine-based supramolecular hydrogels to improve wound healing

A simple supramolecular hydrogel based on D-glucosamine, a naturally occurring aminosaccharide, promises new biomaterials for applications such as wound healing.     

From polymeric particles to multifunctional nanocapsules for biomedical applications using the miniemulsion process

The miniemulsions process represents a versatile tool for the formation of polymeric nanoparticles consisting of different kinds of polymer as obtained by a variety of polymerization types ranging from radical, anionic, cationic, enzymatic polymerization to polyaddition, and polycondensation. The process perfectly allows the encapsulation of hydrophilic and hydrophobic liquids and solids in polymeric shells, molecularly dissolved dyes or other components. In combination with a specific functionalization of the nanoparticles' or nanocapsules' surfaces and the possibility to release substances in a defined way from the interior, complex nanoparticles or nanocapsules are obtained, which are ideally suited for application in biomedical application as marker and targeted drug‐delivery system. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 493–515, 2010     

Smart and green interfaces: From single bubbles/drops to industrial environmental and biomedical applications

Interfaces can be called Smart and Green (S&G) when tailored such that the required technologies can be implemented with high efficiency, adaptability and selectivity. At the same time they also have to be eco-friendly, i.e. products must be biodegradable, reusable or simply more durable. Bubble and drop interfaces are in many of these smart technologies the fundamental entities and help develop smart products of the everyday life.     

Aldehyde responsive supramolecular hydrogels: towards biomarker-specific delivery systems

A reactive supramolecular hydrogel sensitive to the presence of aldehydes is reported. Its fast disassembly in the presence of hydrophobic aldehydes allows the use for the release of substances (i.e. drugs) entrapped within the gel network.     

A DNA-based piezoelectric biosensor: strategies for coupling nucleic acids to piezoelectric devices

A DNA-based piezoelectric biosensor has been here studied in terms of probe immobilisation and DNA sample pre-treatment. The biosensor is specific for the detection of the mecA gene of methicillin-resistant Staphylococcus aureus (MRSA).Methicillin-resistant S. aureus is responsible of several infections in humans, like pneumonia, meningitis and endocarditic. MRSA is also a major cause of hospital-acquired infections worldwide. The antibiotics resistance is conferred by the gene mecA, codifying for an anomalous protein.Two different immobilisation procedures of the probe specific for mecA gene are reported: immobilisation via streptavidin-biotin interaction and direct immobilisation of thiolated probes.After the study with synthetic oligonucleotides, the system has been applied to the analysis of bacterial DNA from MRSA, amplified by polymerase chain reaction. These samples were pre-treated with two different denaturation procedures and the performances of the sensor in the two cases were compared.The two immobilisation methods and denaturation protocols were here used to study the influences of these parameters on the performances of the sensor, applied here to the detection of the mecA gene. Better results in terms of sensitivity and reproducibility were obtained when using the biotinylated probe and the PCR-amplified samples treated by a denaturation procedures involving the use of high temperature and blocking oligonucleotides.     

Engineered hydrogen-bonded polymer multilayers: from assembly to biomedical applications

Over the last two decades the layer-by-layer (LbL) assembly technique has become a highly versatile platform for the synthesis of nanoengineered thin films and particles. The widespread need for highly functional and responsive materials for applications in biomedicine-such as drug and gene delivery-has recently led to considerable efforts in the assembly of LbL materials, particularly films that can be subsequently stabilised and functionalised through a range of chemistries. In this tutorial review, recent developments in hydrogen-bonded LbL-assembled materials will be discussed, focusing on the design of materials with enhanced stimuli-responsive characteristics. Emphasis will be given to materials engineered for biomedical applications, specifically films/capsules that afford controlled loading and release of therapeutic cargo for application in vitro and in vivo.     

Programming supramolecular peptide materials by modulating the intermediate steps in the complex assembly pathway: Implications for biomedical applications

Self-assembling peptides form a prominent class of supramolecular materials with in general good biocompatibility. To afford better control over the material properties, tremendous progress has been made in studying the supramolecular organization of the peptide assemblies. This knowledge has helped us to understand the correlation between the molecular structure of the peptide building blocks and the properties of the supramolecular products. However, peptide self-assembly consists of a complex pathway rather than a spontaneous thermodynamic process. This implies that the outcome of the self-assembly is critically governed by the assembly pathway. Here, we are going to discuss how peptide self-assembly can be modulated at the intermediate steps in the self-assembly pathway. The focus will be to demonstrate this engineering approach on the example of zero-dimensional/one-dimensional nanostructure selectivity over the β-sheet assembly pathway. In addition, we provide examples of biomedical applications of such steered peptide assemblies in the field of drug delivery and tissue engineering.     

From supramolecular block copolymers to advanced nano-objects

The formation of asymmetric bis-complexes, based on terpyridine ligands and ruthenium ions, is described as a powerful tool for the self-assembly of polymer blocks end-functionalized with terpyridine units. This is illustrated in this contribution for the synthesis of amphiphilic metallo-supramolecular block copolymers, which are further used to produce aqueous micelles. Finally, the reversibility of the supramolecular bond opens new avenues for the preparation and manipulation of these nano-objects.     

热稳定单原子催化剂的理性构筑:从原子级结构到实际应用

80%以上的工业生产过程涉及催化,如化工生产、能源转换、制药和废物处理等等.催化剂的使用显著提高了生产效率,降低了生产成本,为国民经济、地球环境和人类文明的可持续发展做出了很大贡献.为了满足日益增长的生产需求和最大的经济效益,开发高效、稳定、低成本的新型催化剂已成为当务之急.金属中心负载在载体上的负载型金属催化剂因其较好的催化活性和相对较低的金属用量而受到广泛关注.研究发现,负载型结构可增强传热和传质并增加活性金属中心的分散度,从而影响催化性能.此外,负载金属的颗粒尺寸对催化剂的性能有很大影响.迄今为止,科学家们一直在通过减小金属颗粒尺寸和提高原子利用效率来提高催化剂的活性.原子级尺寸的颗粒通常表现出与大尺寸颗粒显着不同的物理和化学性质,而当活性位点的尺寸缩小到单个原子时,单原子催化剂的概念应运而生.对于单原子催化剂,金属原子中心通过配位被载体中的缺陷锚定,从而调整金属原子的电子云分布.这种配位调整使得单原子催化剂拥有与传统催化剂不同的性能.作为催化领域的新前沿,单原子催化剂已经在许多催化反应中表现出前所未有的活性和选择性.然而,许多报道的单原子催化剂在高温环境或长期催化应用中容易受到奥斯特瓦尔德熟化过程的影响,从而导致催化剂烧结和失活.而烧结的原因在于金属原子和载体之间较弱的相互作用.失活催化剂的再生和回收将大大增加工业生产的时间和经济成本.因此,开发具有优异热稳定性的单原子催化剂以满足工业需求是十分必要的.本综述首先总结了近年来关于热稳定型单原子催化剂合成方法的基础研究,并从原子尺度上分析了这些方法所构建的金属中心的结构形态和配位环境.此外,结合近些年的研究中新的表征技术与理论计算手段解释了热稳定性的来源.重点讨论了热稳定单原子催化剂的实际催化应用.分析了热稳定单原子催化剂在热催化应用中的独特作用机理、并尝试为确定催化过程中真正的活性中心以及通过原子级调控手段进行高活性热稳定单原子催化剂的合成提供理论指导.最后总结了热稳定单原子催化剂发展的主要问题,并简要分析了单原子催化领域的研究挑战和发展前景.     

Single-molecule and single-nanoparticle SERS: from fundamental mechanisms to biomedical applications

This tutorial review discusses a new class of colloidal metal nanoparticles that is able to enhance the efficiencies of surface-enhanced Raman scattering (SERS) by as much as 10(14)-10(15) fold. This enormous enhancement allows spectroscopic detection and identification of single molecules located on the nanoparticle surface or at the junction of two particles under ambient conditions. Considerable progress has been made in understanding the enhancement mechanisms, including definitive evidence for the single-molecule origin of fluctuating SERS signals. For applications, SERS nanoparticle tags have been developed based on the use of embedded reporter molecules and a silica or polymer encapsulation layer. The SERS nanoparticle tags are capable of providing detailed spectroscopic information and are much brighter than semiconductor quantum dots in the near-infrared spectral window. These properties have raised new opportunities for multiplexed molecular diagnosis and in vivo Raman spectroscopy and imaging.     

Coordination chemistry of phosphole ligands: From supramolecular assemblies to OLEDs

The synthesis and properties of organophosphorus π-conjugated chromophores incorporating metallic ions are described. Their optical and electrochemical properties depend on the metal centre linked to the organophosphorus atom. Moreover, the introduction of metallic ions induces a control of the supramolecular organization of the organophosphorus π-conjugated systems. The specific properties of these complexes make them valuable materials for organic light-emitting diodes and interesting building blocks for the tailoring of novel NLO-phores.     

From metal-organic squares to porous zeolite-like supramolecular assemblies

We report the synthesis, structure, and characterization of two novel porous zeolite-like supramolecular assemblies, ZSA-1 and ZSA-2, having zeolite gis and rho topologies, respectively. The two compounds were assembled from functional metal-organic squares (MOSs) via directional hydrogen-bonding interactions and exhibited permanent microporosity and thermal stability up to 300 °C.