A Comprehensive Review on Current Advances in Peptide Drug Development and Design

Protein-protein interactions (PPIs) execute many fundamental cellular functions and have served as prime drug targets over the last two decades. Interfering intracellular PPIs with small molecules has been extremely difficult for larger or flat binding sites, as antibodies cannot cross the cell membrane to reach such target sites. In recent years, peptides smaller size and balance of conformational rigidity and flexibility have made them promising candidates for targeting challenging binding interfaces with satisfactory binding affinity and specificity. Deciphering and characterizing peptide-protein recognition mechanisms is thus central for the invention of peptide-based strategies to interfere with endogenous protein interactions, or improvement of the binding affinity and specificity of existing approaches. Importantly, a variety of computation-aided rational designs for peptide therapeutics have been developed, which aim to deliver comprehensive docking for peptide-protein interaction interfaces. Over 60 peptides have been approved and administrated globally in clinics. Despite this, advances in various docking models are only on the merge of making their contribution to peptide drug development. In this review, we provide (i) a holistic overview of peptide drug development and the fundamental technologies utilized to date, and (ii) an updated review on key developments of computational modeling of peptide-protein interactions (PepPIs) with an aim to assist experimental biologists exploit suitable docking methods to advance peptide interfering strategies against PPIs.

Strategies to engineer tendon/ligament-to-bone interface: Biomaterials, cells and growth factors

Integration between tendon/ligament and bone occurs through a specialized tissue interface called enthesis. The complex and heterogeneous structure of the enthesis is essential to ensure smooth mechanical stress transfer between bone and soft tissues. Following injury, the interface is not regenerated, resulting in high rupture recurrence rates. Tissue engineering is a promising strategy for the regeneration of a functional enthesis. However, the complex structural and cellular composition of the native interface makes enthesis tissue engineering particularly challenging. Thus, it is likely that a combination of biomaterials and cells stimulated with appropriate biochemical and mechanical cues will be needed. The objective of this review is to describe the current state-of-the-art, challenges and future directions in the field of enthesis tissue engineering focusing on four key parameters: (1) scaffold and biomaterials, (2) cells, (3) growth factors and (4) mechanical stimuli.

ADM guidance-Ceramics: guidance to the use of fractography in failure analysis of brittle materials

OBJECTIVES

To provide background information and guidance as to how to use fractography accurately, a powerful tool for failure analysis of dental ceramic structures.

METHODS

An extended palette of qualitative and quantitative fractography is provided, both for in vivo and in vitro fracture surface analyses. As visual support, this guidance document will provide micrographs of typical critical ceramic processing flaws, differentiating between pre- versus post sintering cracks, grinding damage related failures and occlusal contact wear origins and of failures due to surface degradation.

RESULTS

The documentation emphasizes good labeling of crack features, precise indication of the direction of crack propagation (dcp), identification of the fracture origin, the use of fractographic photomontage of critical flaws or flaw labeling on strength data graphics. A compilation of recommendations for specific applications of fractography in Dentistry is also provided.

SIGNIFICANCE

This guidance document will contribute to a more accurate use of fractography and help researchers to better identify, describe and understand the causes of failure, for both clinical and laboratory-scale situations. If adequately performed at a large scale, fractography will assist in optimizing the methods of processing and designing of restorative materials and components. Clinical failures may be better understood and consequently reduced by sending out the correct message regarding the fracture origin in clinical trials.

Bio-based polyurethane reinforced with cellulose nanofibers: a comprehensive investigation on the effect of interface

Novel bio-based polyurethane (PU) nanocomposites composed of cellulose nanofiller extracted from the rachis of date palm tree and polycaprolactone (PCL) diol based PU were prepared by casting/evaporation. Two types of nanofiber were used: cellulose nanofibrils (CNFs) and cellulose nanocrystals (CNCs). The mechanical and thermal properties of the nanocomposite films were studied by DMA, DSC, and tensile tests and the morphology was investigated by SEM. Bionanocomposites presented good mechanical properties in comparison to neat PU. While comparing both nanofillers, the improvement in mechanical and thermal properties was more pronounced for the nanocomposites based on CNF which could be explained, not only by the higher aspect ratio of CNF, but also by their better dispersion in the PU matrix. Calculation of the solubility parameters of the nanofiller surface polymers and of the PU segments portend a better interfacial adhesion for CNF based nanocomposites compared to CNC.

The potential of protein-nanomaterial interaction for advanced drug delivery

Nanomaterials, like nanoparticles, micelles, nano-sheets, nanotubes and quantum dots, have great potentials in biomedical fields. However, their delivery is highly limited by the formation of protein corona upon interaction with endogenous proteins. This new identity, instead of nanomaterial itself, would be the real substance the organs and cells firstly encounter. Consequently, the behavior of nanomaterials in vivo is uncontrollable and some undesired effects may occur, like rapid clearance from blood stream; risk of capillary blockage; loss of targeting capacity; and potential toxicity. Therefore, protein-nanomaterial interaction is a great challenge for nanomaterial systems and should be inhibited. However, this interaction can also be used to functionalize nanomaterials by forming a selected protein corona. Unlike other decoration using exogenous molecules, nanomaterials functionalized by selected protein corona using endogenous proteins would have greater promise for clinical use. In this review, we aim to provide a comprehensive understanding of protein-nanomaterial interaction. Importantly, a discussion about how to use such interaction is launched and some possible applications of such interaction for advanced drug delivery are presented.

Heavy metal behaviour at mineral-organo interfaces: Mechanisms, modelling and influence factors

The mineral-organo composites control the speciation, mobility and bioavailability of heavy metals in soils and sediments by surface adsorption and precipitation. The dynamic changes of soil mineral, organic matter and their associations under redox, aging and microbial activities further complicate the fate of heavy metals. Over the past decades, the wide application of advanced instrumental techniques and modelling has largely extended our understanding on heavy metal behavior within mineral-organo assemblages. In this review, we provide a comprehensive summary of recent progress on heavy metal immobilization by mineral-humic and mineral-microbial composites, with a special focus on the interfacial reaction mechanisms of heavy metal adsorption. The impacts of redox and aging conditions on heavy metal speciations and associations with mineral-organo complexes are discussed. The modelling of heavy metals adsorption and desorption onto synthetic mineral-organo composites and natural soils and sediments are also critically reviewed. Future challenges and prospects in the mineral-organo interface are outlined. More in-depth investigations are warranted, especially on the function and contribution of microorganisms in the immobilization of heavy metals at the complex mineral-organo interface. It has become imperative to use the state-of-the-art methodologies to characterize the interface and develop in situ analytical techniques in future studies.

Irritable bowel syndrome: Relations with functional, mental, and somatoform disorders

This review describes the conceptual and clinical relations between irritable bowel syndrome (IBS), other functional, somatoform, and mental disorders, and points to appropriate future conceptualizations. IBS is considered to be a functional somatic syndrome (FSS) with a considerable symptom overlap with other FSSs like chronic fatigue syndrome or fibromyalgia syndrome. IBS patients show an increased prevalence of psychiatric symptoms and disorders, especially depression and anxiety. IBS is largely congruent with the concepts of somatoform and somatic symptom disorders. Roughly 50% of IBS patients complain of gastrointestinal symptoms only and have no psychiatric comorbidity. IBS concepts, treatment approaches, as well as health care structures should acknowledge its variability and multidimensionality by: (1) awareness of additional extraintestinal and psychobehavioral symptoms in patients with IBS; (2) general and collaborative care rather than specialist and separated care; and (3) implementation of “interface disorders” to abandon the dualistic classification of purely organic or purely mental disorders.

Nanostructured platinum grass enables superior impedance reduction for neural microelectrodes

Micro-sized electrodes are essential for highly sensitive communication at the neural interface with superior spatial resolution. However, such small electrodes inevitably suffer from high electrical impedance and thus high levels of thermal noise deteriorating the signal to noise ratio. In order to overcome this problem, a nanostructured Pt-coating was introduced as add-on functionalization for impedance reduction of small electrodes. In comparison to platinum black deposition, all used chemicals in the deposition process are free from cytotoxic components. The grass-like nanostructure was found to reduce the impedance by almost two orders of magnitude compared to untreated samples which was lower than what could be achieved with conventional electrode coatings like IrOx or PEDOT. The realization of the Pt-grass coating is performed via a simple electrochemical process which can be applied to virtually any possible electrode type and accordingly shows potential as a universal impedance reduction strategy. Elution tests revealed non-toxicity of the Pt-grass and the coating was found to exhibit strong adhesion to the metallized substrate.

Surface modified halloysite nanotubes: A flexible interface for biological, environmental and catalytic applications

Halloysite Nanotubes (HNTs) are clay minerals that possess unique chemical composition and a tubular structure due to which, they have recently emerged as a potential nanomaterial for umpteen applications. Over the years, the myriad applications of HNT have been realized through the surface modification of HNT, which involves the modification of nanotube's inner lumen and the outer surface with different functional compounds. The presence of aluminum and silica groups on the inner and outer surface of HNT enhance the interfacial relationship of the nanotube with different functional agents. Compounds such as alkalis, organosilanes, polymers, compounds of biological origin, surfactants and nanomaterials have been used for the modification of the inner lumen and the outer surface of HNT. The strategies change the constitution of HNT's surface either through micro-disintegration of the surface or by introducing additional functional groups on the surface, which further enhances their potential to be used as a flexible interface for different applications. In this review, the different surface modification strategies of the outer surface and the inner lumen that have been employed over the years have been discussed. The biological, environmental and catalytic applications of these surface modified HNTs with such versatile interface in the past two years have been elaborately discussed as well.

A critical review of modeling Poly- and Perfluoroalkyl Substances (PFAS) in the soil-water environment

Due to their health effects and the recalcitrant nature of their CF bonds, Poly- and Perfluoroalkyl Substances (PFAS) are widely investigated for their distribution, remediation, and toxicology in ecosystems. However, very few studies have focused on modeling PFAS in the soil-water environment. In this review, we summarized the recent development in PFAS modeling for various chemical, physical, and biological processes, including sorption, volatilization, degradation, bioaccumulation, and transport. PFAS sorption is kinetic in nature with sorption equilibrium commonly quantified by either a linear, the Freundlich, or the Langmuir isotherms. Volatilization of PFAS depends on carbon chain length and ionization status and has been simulated by a two-layer diffusion process across the air water interface. First-order kinetics is commonly used for physical, chemical, and biological degradation processes. Uptake by plants and other biota can be passive and/or active. As surfactants, PFAS have a tendency to be sorbed or concentrated on air-water or non-aqueous phase liquid (NAPL)-water interfaces, where the same three isotherms for soil sorption are adopted. PFAS transport in the soil-water environment is simulated by solving the convection-dispersion equation (CDE) that is coupled to PFAS sorption, phase transfer, as well as physical, chemical, and biological transformations. As the physicochemical properties and concentration vary greatly among the potentially thousands of PFAS species in the environment, systematic efforts are needed to identify models and model parameters to simulate their fate, transport, and response to remediation techniques. Since many process formulations are empirical in nature, mechanistic approaches are needed to further the understanding of PFAS-soil-water-plant interactions so that the model parameters are less site dependent and more predictive in simulating PFAS remediation efficiency.

Continuous positive airway pressure and noninvasive ventilation adherence in children

BACKGROUND

Adherence to continuous positive airway pressure (CPAP) and noninvasive ventilation (NIV) is crucial for the successful treatment of sleep-disordered breathing. The aim of our study was to analyze the adherence of children to long-term home CPAP/NIV treatment.

METHODS

We analyzed data from all consecutive patients older than the age of 2years, in whom CPAP/NIV treatment was initiated in a specialized pediatric NIV and in those who were receiving CPAP/NIV treatment at home for at least 1month. Data of the memory cards of the ventilators and nocturnal gas exchange were analyzed during a routine CPAP/NIV overnight control in the hospital. CPAP/NIV adherence during the previous month was analyzed according to patient's age, ventilatory mode, type of interface, nocturnal gas exchange, and duration of treatment.

RESULTS

The data of 62 children (mean age, 10±5years) with obstructive sleep apnea (n=51) treated with CPAP and neuromuscular disease (n=6) or lung diseases (n=5) treated with NIV were analyzed. Mean adherence was 8:17±2:30h:min per night, and the results did not significantly differ between CPAP and NIV adherence. Seventy-two percent of the patients used their device >8h per night. The mean number of nights of CPAP/NIV use during the last month was 26±5 nights per month. Treatment adherence was not correlated to age, the type of underlying disease, the type of interface (nasal, facial mask, or nasal cannula), nocturnal gas exchange, and duration of CPAP/NIV treatment.

CONCLUSION

Long-term CPAP/NIV adherence at home was extremely high in this group of children followed in a pediatric NIV unit. This finding may explain the lack of effect of the interface, nocturnal gas exchange, and duration of CPAP/NIV treatment.

The flotation and adsorption of mixed collectors on oxide and silicate minerals

The analysis of flotation and adsorption of mixed collectors on oxide and silicate minerals is of great importance for both industrial applications and theoretical research. Over the past years, significant progress has been achieved in understanding the adsorption of single collectors in micelles as well as at interfaces. By contrast, the self-assembly of mixed collectors at liquid/air and solid/liquid interfaces remains a developing area as a result of the complexity of the mixed systems involved and the limited availability of suitable analytical techniques. In this work, we systematically review the processes involved in the adsorption of mixed collectors onto micelles and at interface by examining four specific points, namely, theoretical background, factors that affect adsorption, analytical techniques, and self-assembly of mixed surfactants at the mineral/liquid interface. In the first part, the theoretical background of collector mixtures is introduced, together with several core solution theories, which are classified according to their application in the analysis of physicochemical properties of mixed collector systems. In the second part, we discuss the factors that can influence adsorption, including factors related to the structure of collectors and environmental conditions. We summarize their influence on the adsorption of mixed systems, with the objective to provide guidance on the progress achieved in this field to date. Advances in measurement techniques can greatly promote our understanding of adsorption processes. In the third part, therefore, modern techniques such as optical reflectometry, neutron scattering, neutron reflectometry, thermogravimetric analysis, fluorescence spectroscopy, ultrafiltration, atomic force microscopy, analytical ultracentrifugation, X-ray photoelectron spectroscopy, Vibrational Sum Frequency Generation Spectroscopy and molecular dynamics simulations are introduced in virtue of their application. Finally, focusing on oxide and silicate minerals, we review and summarize the flotation and adsorption of three most widely used mixed surfactant systems (anionic-cationic, anionic-nonionic, and cationic-nonionic) at the liquid/mineral interface in order to fully understand the self-assembly progress. In the end, the paper gives a brief future outlook of the possible development in the mixed surfactants.

Interfaces with the peripheral nerve for the control of neuroprostheses

Nervous system injuries lead to loss of control of sensory, motor, and autonomic functions of the affected areas of the body. Provided the high amount of people worldwide suffering from these injuries and the impact on their everyday life, numerous and different neuroprostheses and hybrid bionic systems have been developed to restore or partially mimic the lost functions. A key point for usable neuroprostheses is the electrode that interfaces the nervous system and translates not only motor orders into electrical outputs that activate the prosthesis but is also able to transform sensory information detected by the machine into signals that are transmitted to the central nervous system. Nerve electrodes have been classified with regard to their invasiveness in extraneural, intraneural, and regenerative. The more invasive is the implant the more selectivity of interfacing can be reached. However, boosting invasiveness and selectivity may also heighten nerve damage. This chapter provides a general overview of nerve electrodes as well as the state-of-the-art of their biomedical applications in neuroprosthetic systems.

A Zn-doped etch-and-rinse adhesive may improve the mechanical properties and the integrity at the bonded-dentin interface

OBJECTIVE

The objective of the study was to determine if zinc-doped etch-and-rinse dentin adhesive may induce therapeutic effects within the resin-dentin interface.

METHODS

Human acid-etched dentin was infiltrated with Adper™ Single Bond Plus (SB, 3M ESPE, St. Paul, MN, USA), SB doped with 10wt.% ZnO nanoparticles (ZnO-SB) or SB doped with 2wt.% ZnCl2 (ZnCl2-SB). AFM/nanoindentation analysis was performed on fully hydrated specimens to evaluate the nanomechanical properties (Hi: hardness; Ei: modulus of elasticity) across the resin-dentin interface after different SBF storage periods (24h, 1m, 3m). Confocal laser microscopy (CLSM) was used to evaluate the ultramorphology and micropermeability at 24h and 3m of SBF storage.

RESULTS

SB control specimens exhibited a decrease in Hi in the hybrid layer (HL) and bottom of the hybrid layer (BHL) and a decrease in Ei in the HL after 3m of SBF storage, indicating that severe degradation occurred in the control interface. ZnO-SB bonded specimens preserved the initial Hi and Ei at the HL and BHL subsequent SBF storage; ZnCl2-SB bonded specimens showed a decrease in Ei, in the HL over time. CLSM analysis confirmed that both Zn-doped adhesives were able to preserve the integrity of the HL.

SIGNIFICANCE

Specific formulation of Zn-doped etch-and-rinse adhesives may offer the possibility to maintain the nano-mechanical properties along the dentin-bonded interface by inhibiting dentin MMPs and by protective mineral crystals formation within the resin-dentin interface. Clinical advantages may be expected by preserving and improving the integrity of the hybrid layer when Zn-doped adhesives are employed.

Basic science of osteoarthritis

Osteoarthritis (OA) is a prevalent, disabling disorder of the joints that affects a large population worldwide and for which there is no definitive cure. This review provides critical insights into the basic knowledge on OA that may lead to innovative end efficient new therapeutic regimens. While degradation of the articular cartilage is the hallmark of OA, with altered interactions between chondrocytes and compounds of the extracellular matrix, the subchondral bone has been also described as a key component of the disease, involving specific pathomechanisms controlling its initiation and progression. The identification of such events (and thus of possible targets for therapy) has been made possible by the availability of a number of animal models that aim at reproducing the human pathology, in particular large models of high tibial osteotomy (HTO). From a therapeutic point of view, mesenchymal stem cells (MSCs) represent a promising option for the treatment of OA and may be used concomitantly with functional substitutes integrating scaffolds and drugs/growth factors in tissue engineering setups. Altogether, these advances in the fundamental and experimental knowledge on OA may allow for the generation of improved, adapted therapeutic regimens to treat human OA.

Analysis of high-throughput screening reveals the effect of surface topographies on cellular morphology

Surface topographies of materials considerably impact cellular behavior as they have been shown to affect cell growth, provide cell guidance, and even induce cell differentiation. Consequently, for successful application in tissue engineering, the contact interface of biomaterials needs to be optimized to induce the required cell behavior. However, a rational design of biomaterial surfaces is severely hampered because knowledge is lacking on the underlying biological mechanisms. Therefore, we previously developed a high-throughput screening device (TopoChip) that measures cell responses to large libraries of parameterized topographical material surfaces. Here, we introduce a computational analysis of high-throughput materiome data to capture the relationship between the surface topographies of materials and cellular morphology. We apply robust statistical techniques to find surface topographies that best promote a certain specified cellular response. By augmenting surface screening with data-driven modeling, we determine which properties of the surface topographies influence the morphological properties of the cells. With this information, we build models that predict the cellular response to surface topographies that have not yet been measured. We analyze cellular morphology on 2176 surfaces, and find that the surface topography significantly affects various cellular properties, including the roundness and size of the nucleus, as well as the perimeter and orientation of the cells. Our learned models capture and accurately predict these relationships and reveal a spectrum of topographies that induce various levels of cellular morphologies. Taken together, this novel approach of high-throughput screening of materials and subsequent analysis opens up possibilities for a rational design of biomaterial surfaces.

Dynamic and viscoelastic interfacial behavior of β-lactoglobulin microgels of varying sizes at fluid interfaces

HYPOTHESIS

Microgel particles formed from the whey protein β-lactoglobulin are able to stabilize emulsion and foam interfaces, yet their interfacial properties have not been fully characterized. Smaller microgels are expected to adsorb to and deform at the interface more rapidly, facilitating the development of highly elastic interfaces.

METHODS

Microgels were produced by thermal treatment under controlled pH conditions. Dynamic surface pressure and dilatational interfacial rheometry measurements were performed on heptane-water droplets to examine microgel interfacial adsorption and behavior. Langmuir compression and atomic force microscopy were used to examine the changes in microgel and monolayer characteristics during adsorption and equilibration.

FINDINGS

Microgel interfacial adsorption was influenced by bulk concentration and particle size, with smaller particles adsorbing faster. Microgel-stabilized interfaces were dominantly elastic, and elasticity increased more rapidly when smaller microgels were employed as stabilizers. Interfacial compression increased surface pressure but not elasticity, possibly due to mechanical disruption of inter-particle interactions. Monolayer images showed the presence of small aggregates, suggesting that microgel structure can be disrupted at low interfacial loadings. The ability of β-lactoglobulin microgels to form highly elastic interfacial layers may enable improvements in the colloidal stability of food, pharmaceutical and cosmetic products in addition to applications in controlled release and flavor delivery systems.

Polysaccharides at fluid interfaces of food systems

Fabrication of next generation polysaccharides with interfacial properties is driven by the need to create high performance surfactants that operate at extreme environments, as for example in complex food formulations or in the gastrointestinal tract. The present review examines the behaviour of polysaccharides at fluid food interfaces focusing on their performance in the absence of any other intentionally added interfacially active components. Relevant theoretical principles of colloidal stabilisation using concepts that have been developed for synthetic polymers at interfaces are firstly introduced. The role of protein that in most cases is present in polysaccharide preparations either as contaminant or as integral part of the structure is also discussed. Critical assessment of the literature reveals that although protein may contribute to emulsion formation mostly as an anchor for polysaccharides to attach, it is not the determinant factor for the long-term emulsion stability, irrespectively of polysaccharide structure. Interfacial performance of key polysaccharides is also assessed revealing shared characteristics in their modes of adsorption. Conformation of polysaccharides, as affected by the composition of the aqueous solvent needs to be closely controlled, as it seems to be the underlying fundamental cause of stabilisation events and appears to be more important than the constituent polysaccharide sugar-monomers. Finally, polysaccharide adsorption is better understood by regarding them as copolymers, as this approach may assist to better control their properties with the aim to create the next generation biosurfactants.

Recent advances in coupling capillary electrophoresis-based separation techniques to ESI and MALDI-MS

Coupling CE-based separation techniques to MS creates a powerful platform for analysis of a wide range of biomolecules from complex samples because it combines the high separation efficiency of CE and the sensitivity and selectivity of MS detection. ESI and MALDI, as the most common soft ionization techniques employed for CE and MS coupling, offer distinct advantages for biomolecular characterization. This review is focused primarily on technological advances in combining CE and chip-based CE with ESI and MALDI-MS detection in the past five years. Selected applications in the analyses of metabolites, peptides, and proteins with recently developed CE-MS platforms are also highlighted.

Calcium orthophosphate coatings, films and layers

In surgical disciplines, where bones have to be repaired, augmented or improved, bone substitutes are essential. Therefore, an interest has dramatically increased in application of synthetic bone grafts. As various interactions among cells, surrounding tissues and implanted biomaterials always occur at the interfaces, the surface properties of the implants are of the paramount importance in determining both the biological response to implants and the material response to the physiological conditions. Hence, a surface engineering is aimed to modify both the biomaterials, themselves, and biological responses through introducing desirable changes to the surface properties of the implants but still maintaining their bulk mechanical properties. To fulfill these requirements, a special class of artificial bone grafts has been introduced in 1976. It is composed of various mechanically stable (therefore, suitable for load bearing applications) biomaterials and/or bio-devices with calcium orthophosphate coatings, films and layers on their surfaces to both improve interactions with the surrounding tissues and provide an adequate bonding to bones. Many production techniques of calcium orthophosphate coatings, films and layers have been already invented and new promising techniques are continuously investigated. These specialized coatings, films and layers used to improve the surface properties of various types of artificial implants are the topic of this review.

Structure-Function Relationships in Pectin Emulsification

The emulsifying characteristics of pectins isolated from six different okra genotypes were investigated and their structure-function relationships have been evaluated. Emulsion formation and stabilization of acidic oil-in-water emulsions (pH 2.0, φ = 0.1) were studied by means of droplet size distribution, ζ-potential measurements, viscometry, interfacial composition analysis and fluorescence microscopy. Fresh and aged emulsions differed in terms of droplet size distribution, interfacial protein and pectin concentrations (Γ) depending on the molecular properties of pectin that was used. Specifically, pectins with intermediate length of RG-I branching with molar ratio of (Ara + Gal)/Rha between 2 and 3 exhibit the optimum emulsification capacity whereas samples with the molar ratio outside this range do not favour emulsification. Additionally, low amounts of RG-I segments (HG/RG-I > 2) improve long term stability of emulsions as opposed to the samples that contain high amounts of RG-I (HG/RG-I < 2) which lead to long term instability. Protein was not found to be the controlling factor for the stability of the dispersions. The present results show that rational design of pectin should be sought before application as functional ingredient in food and/or pharmaceutical systems.

Drug-free and non-crosslinked chitosan scaffolds with efficient antibacterial activity against both Gram-negative and Gram-positive bacteria

Treatment of oral pathogens is important for both oral and systemic health. The antimicrobial activity of chitosan (CS)-based scaffolds either loading antibiotics or compositing with other agents are well documented. However, the intrinsic antibacterial activity of CS scaffolds alone has never been reported. Herein, we fabricated the non-crosslinked CS scaffold and investigated its antibacterial activity against typical oral pathogens, Gram-negative Porphyromonas gingivalis and Gram-positive Streptococcus mutans. We found both pathogens were completely killed by 1 mg CS scaffolds at 6 h, due largely to the CS-induced time-dependent bacteria clustering. Interestingly, β-glycerophosphate crosslinked scaffolds showed no antibacterial activity. In conclusion, the bactericidal activity of CS scaffolds alone is reported for the first time. Together with the biodegradability, physical stability, biocompatibility and great antibacterial activity, the non-crosslinked CS scaffolds may have great potentials not only in treating oral diseases but also in wound healing and tissue engineering.

The relationship between GPs and hospital consultants and the implications for patient care: a qualitative study

BACKGROUND

Improving the quality of care of at the medical primary-secondary care interface is both a national and a wider concern. In a qualitative exploration of clinicians' relationship at the interface, we want to study how both GPs and hospital specialists regard and behave towards each other and how this may influence patient care.

METHOD

A qualitative interview study was carried out in primary and secondary care centres in NHS Highland health board area, Scotland. Eligible clinicians (general practitioners and hospital specialists) were invited to take part in a semi-structured interview to explore the implications of interface relationships upon patient care. A standard thematic analysis was used, involving an iterative process based on grounded theory.

RESULTS

Key themes that emerged for clinicians included communication (the importance of accessing and listening to one another, and the transfer of soft intelligence), conduct (referring to perceived inappropriate transfer of workload at the interface, and resistance to this transfer), relationships (between interface clinicians and between clinicians and their patients), and unrealistic expectations (clinicians expressing idealistic hopes of what their colleagues at the other interface could achieve).

CONCLUSION

The relationship between primary and secondary care clinicians, and, in particular, difficulties and misunderstandings can have an influence upon patient care. Addressing key areas identified in the study may help to improve interface relationships and benefit patient care.

Recent NMR developments applied to organic-inorganic materials

In this contribution, the latest developments in solid state NMR are presented in the field of organic-inorganic (O/I) materials (or hybrid materials). Such materials involve mineral and organic (including polymeric and biological) components, and can exhibit complex O/I interfaces. Hybrids are currently a major topic of research in nanoscience, and solid state NMR is obviously a pertinent spectroscopic tool of investigation. Its versatility allows the detailed description of the structure and texture of such complex materials. The article is divided in two main parts: in the first one, recent NMR methodological/instrumental developments are presented in connection with hybrid materials. In the second part, an exhaustive overview of the major classes of O/I materials and their NMR characterization is presented.

Multiscale design and synthesis of biomimetic gradient protein/biosilica composites for interfacial tissue engineering

Continuous gradients present at tissue interfaces such as osteochondral systems, reflect complex tissue functions and involve changes in extracellular matrix compositions, cell types and mechanical properties. New and versatile biomaterial strategies are needed to create suitable biomimetic engineered grafts for interfacial tissue engineering. Silk protein-based composites, coupled with selective peptides with mineralization domains, were utilized to mimic the soft-to-hard transition in osteochondral interfaces. The gradient composites supported tunable mineralization and mechanical properties corresponding to the spatial concentration gradient of the mineralization domains (R5 peptide). The composite system exhibited continuous transitions in terms of composition, structure and mechanical properties, as well as cytocompatibility and biodegradability. The gradient silicified silk/R5 composites promoted and regulated osteogenic differentiation of human mesenchymal stem cells in an osteoinductive environment in vitro. The cells differentiated along the composites in a manner consistent with the R5-gradient profile. This novel biomimetic gradient biomaterial design offers a useful approach to meet a broad range of needs in regenerative medicine.