Layer‐by‐Layer Coated Gold Nanoparticles: Size‐Dependent Delivery of DNA into Cells

Because nanoparticles are finding uses in myriad biomedical applications, including the delivery of nucleic acids, a detailed knowledge of their interaction with the biological system is of utmost importance. Here the size‐dependent uptake of gold nanoparticles (AuNPs) (20, 30, 50 and 80 nm), coated with a layer‐by‐layer approach with nucleic acid and poly(ethylene imine) (PEI), into a variety of mammalian cell lines is studied. In contrast to other studies, the optimal particle diameter for cellular uptake is determined but also the number of therapeutic cargo molecules per cell. It is found that 20 nm AuNPs, with diameters of about 32 nm after the coating process and about 88 nm including the protein corona after incubation in cell culture medium, yield the highest number of nanoparticles and therapeutic DNA molecules per cell. Interestingly, PEI, which is known for its toxicity, can be applied at significantly higher concentrations than its IC₅₀ value, most likely because it is tightly bound to the AuNP surface and/or covered by a protein corona. These results are important for the future design of nanomaterials for the delivery of nucleic acids in two ways. They demonstrate that changes in the nanoparticle size can lead to significant differences in the number of therapeutic molecules delivered per cell, and they reveal that the toxicity of polyelectrolytes can be modulated by an appropriate binding to the nanoparticle surface.     

Protein oriented ligation on nanoparticles exploiting O6-alkylguanine-DNA transferase (SNAP) genetically encoded fusion

A bimodular genetic fusion comprising a delivery module (scFv) and a capture module (SNAP) is proposed as a novel strategy for the site-specific covalent conjugation of targeting peptides to nanoparticles. An scFv mutant selective for HER2 tumor antigen is chosen as the targeting ligand. SNAP-scFv is immobilized on magnetofluorescent nanoparticles and its targeting efficiency against HER2-positive cells is assessed by flow cytometry and immunofluorescence.     

Kidney Podocytes as Specific Targets for cyclo(RGDfC)‐Modified Nanoparticles

Renal nanoparticle passage opens the door for targeting new cells like podocytes, which constitute the exterior part of the renal filter. When cyclo(RGDfC)‐modified Qdots are tested on isolated primary podocytes for selective binding to the αvβ3 integrin receptor a highly cell‐ and receptor‐specific binding can be observed. In displacement experiments with free cyclo(RGDfC) IC₅₀ values of 150 nM for αvβ3 integrin over‐expressing U87‐MG cells and 60 nM for podocytes are measured. Confocal microscopy shows a cellular Qdot uptake into vesicle‐like structures. Our ex vivo study gives clear evidence that, after renal filtration, nanoparticles can be targeted to podocyte integrin receptors in the future. This could be a highly promising approach for future therapy and diagnostics of podocyte‐associated diseases.     

Ceramic/metal biocidal nanocomposites for bone-related applications

Hydroxyapatite/silver nanocomposites have been designed and synthesized as an engineering material for biomedical applications. The hydroxyapatite matrix was synthesized by a sol-gel method and, subsequently, the Ag nanoparticles were deposited by heterogeneous precipitation followed by two different reduction routes: thermal or chemical. Both sets were studied and compared and, in all cases, the metal nanoparticles appear perfectly isolated and attached to the surface of the hydroxyapatite. The average metal particle size is below 10?nm, allowing an important contact surface between silver and the microorganisms. The antimicrobial behavior against common bacteria showed a high effectiveness, well above the commercial level, as well as against yeast, in the case of the chemically reduced sample. Due to the nanocomposite microstructure, only a negligible portion of metal was released to the lixiviated liquid after the biocide tests, minimizing the risk of toxicity. These nanocomposites offer a solution to the infections on the surface of implants, one of the main problems in reaching a suitable level of osseointegration.     

Gas-phase compaction and unfolding of protein structures

Ion-mobility mass spectrometry is emerging as a powerful tool for studying the structures of less established protein assemblies. The method provides simultaneous measurement of the mass and size of intact protein assemblies, providing information not only on the subunit composition and network of interactions but also on the overall topology and shape of protein complexes. However, how the experimental parameters affect the measured collision cross-sections remains elusive. Here, we present an extensive systematic study on a range of proteins and protein complexes with differing sizes, structures, and oligomerization states. Our results indicate that the experimental parameters, T-wave height and velocity, influence the determined collision cross-section independently and in opposite directions. Increasing the T-wave height leads to compaction of the protein structures, while higher T-wave velocities lead to their expansion. These different effects are attributed to differences in energy transmission and dissipation rates. Moreover, by analyzing proteins in their native and denatured states, we could identify the lower and upper boundaries of the collision cross-section, which reflect the "maximally packed" and "ultimately unfolded" states. Together, our results provide grounds for selecting optimal experimental parameters that will enable preservation of the nativelike conformation, providing structural information on uncharacterized protein assemblies.     

Improving parenting in families referred for child maltreatment: A randomized controlled trial examining effects of Project Support.

Project Support is an intervention designed to decrease coercive patterns of aggressive discipline and increase positive parenting. This research evaluates Project Support in a sample of families reported to Children's Protective Services (CPS) for allegations of physical abuse or neglect; 35 families with a child between 3- and 8-years-old participated. In all families, CPS allowed the children to remain in the family home while the family received services. Families were randomly assigned to receive either Project Support or services as usual, which were provided by CPS or CPS-contracted service providers. To evaluate intervention effects, a multimethod, multi-informant assessment strategy was used that included data from mothers' reports, direct observation of parents' behavior, and review of CPS records for re-referrals for child maltreatment. Families who received Project Support services showed greater decreases than families who received services as usual in the following areas: mothers' perceived inability to manage childrearing responsibilities, mothers' reports of harsh parenting, and observations of ineffective parenting practices. Only 5.9% of families in the Project Support condition had a subsequent referral to CPS for child maltreatment, compared with 27.7% of families in the comparison condition. The results suggest that Project Support may be a promising intervention for reducing child maltreatment among families in which it has occurred. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A SCOR-based model for supply chain performance measurement: application in the footwear industry

Supply Chain Operations Reference (SCOR) is a widely employed model for SC performance assessment, regardless its generic nature. This article presents a SCOR-based model for performance measurement in supply chains (SC) and apply it in the context of Brazilian footwear industry. The model has two dimensions: SCOR processes (source, make, deliver and return) and performance standards adapted from original SCOR (cost, quality, delivery and flexibility). This structure delivers a 4 × 4 matrix, with each component assessed under analytical hierarchy process. Using focus groups, SC’s experts weighted each component of the matrix regarding their relevance. Thereafter, SC’s managers indicated respective results. The SC’s overall performance was obtained by adding the performance of all indicators. The model application embraced one focal footwear manufacturer, four suppliers, three distribution channels and a return channel, with 85 indicators assessed. The achieved performance for the whole SC is 75.29%.The main gaps were found in deliver process (12.78 percentual points of difference between relevance and achieved proportions) and in flexibility performance (9.82). Further application is recommended in order to find consolidated results.