Advancing the Shift-of-Strategy approach: Shifting suspects' strategies in extended interviews.

OBJECTIVE: Interviewers often face the challenge of obtaining information from suspects who are willing to speak but are motivated to conceal incriminating information. The Shift-of-Strategy (SoS) approach is an interviewing technique designed to obtain new information from such suspects. This study provides a robust empirical test of the SoS approach using more complex crime events and longer interviews than previously tested as well as testing a new variation of the approach (SoS-Reinforcement) that included a strategic summary of the suspect's statement. We compared this new variation with a standard version of the approach (SoS-Standard) and an interviewing approach that involved no confrontation of discrepancies in the suspects' statements (Direct). HYPOTHESES: We predicted that the two SoS versions would outperform the Direct condition in terms of participants' disclosure of previously unknown information. We also predicted that SoS-Reinforcement would outperform SoS-Standard. Finally, we expected that participants in the SoS conditions would not assess the interview or the interviewer more poorly than participants in Direct. METHOD: A total of 300 participants completed an online mock crime procedure, and they were subsequently interviewed with one of the three interviewing techniques. Following the interview, participants provided assessments of their experiences being interviewed. RESULTS: Participants in both SoS-Standard (d = 0.49, 95% confidence interval [CI: 0.21, 0.78]) and SoS-Reinforcement (d = 0.59, 95% CI [0.30, 0.87]) disclosed more previously unknown information than participants in the Direct condition, but SoS-Reinforcement did not outperform SoS-Standard (d = 0.08, 95% CI [-0.20, 0.36]). Participants in SoS-Reinforcement assessed their experience more negatively than those in Direct. No such differences were observed in the remaining two-way comparisons. CONCLUSIONS: The study provides support for the effectiveness of eliciting new information through the SoS approach and illuminates possible experiential downsides with being subjected to the SoS-Reinforcement approach. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

In Vitro and In Vivo Performance of Pickering Emulsion-Based Powders of Omega-3 Polyunsaturated Fatty Acids.

Omega-3 polyunsaturated fatty acids (n-3 PUFA) are essential nutrients for human health and have been linked to a variety of health benefits, including reducing the risk of cardiovascular diseases. In this paper, a spray-dried powder formulation based on Pickering emulsions stabilized with cellulose nanocrystals (CNC) and hydroxypropyl methylcellulose (HPMC) has been developed. The formulation was compared in vitro and in vivo to reference emulsions (conventional Self-Emulsifying Drug Delivery System, SEDDS) to formulate n-3 PUFA pharmaceutical products, specifically in free fatty acid form. The results of in vivo studies performed in fasted dogs showed that Pickering emulsions reconstituted from powders are freely available (fast absorption) with a similar level of bioavailability as reference emulsions. In the studies performed with dogs in the fed state, the higher bioavailability combined with slower absorption observed for the Pickering emulsion, compared to the reference, was proposed to be the result of the protection of the n-3 PUFAs (in free fatty acid form) against oxidation in the stomach by the solid particles stabilizing the emulsion. This observation was supported by promising results from short-term studies of chemical stability of powders with n-3 PUFA loads as high as 0.8 g oil/g powder that easily regain the original emulsion drop sizes upon reconstitution. The present work has shown that Pickering emulsions may offer a promising strategy for improving the bioavailability and stability as well as providing an opportunity to produce environmentally friendly (surfactant free) and patient-acceptable solid oral dosage forms of n-3 PUFA in the free fatty acid form.

Nanoclay-induced bacterial flocculation for infection confinement.

Effects of size and charge of anionic nanoclays on their interactions with bacteria-mimicking lipid membranes, bacterial lipopolysaccharide (LPS), and Gram-negative bacteria were investigated using ellipsometry, dynamic light scattering, ζ-potential measurements, and confocal microscopy combined with Live/Dead staining. Based on particle size and charge density, three different anionic hectorite nanoclays were employed, and investigated in the presence and absence of the net cationic human antimicrobial peptide LL-37 (LLGDFFRKSKEKIGKEFKRIVQRIKDFLRNLVPRTES). In the absence of this peptide, the nanoclays were found not to bind to similarly anionic bacteria-mimicking model phospholipid membranes, nor to destabilize these. Similarly, while all nanoclays induced aggregation of Escherichia coli bacteria, the flocculated bacteria remained alive after aggregation. In contrast, LL-37 alone, i.e. in the absence of nanoclay particles, displays antimicrobial properties through membrane lysis, but does not cause bacterial aggregation in the concentration range investigated. After loading the nanoclays with LL-37, potent bacterial aggregation combined with bacterial membrane lysis was observed for all nanoclay sizes and charge densities. Demonstrating the potential of these combined systems for confinement of infection, LPS-induced NF-κB activation in human monocytes was found to be strongly suppressed after nanoclay-mediated aggregation, with a wide tolerance for nanoparticle size and charge density.

Interaction of Laponite with Membrane Components-Consequences for Bacterial Aggregation and Infection Confinement.

The antimicrobial effects of Laponite nanoparticles with or without loading of the antimicrobial peptide LL-37 was investigated along with their membrane interactions. The study combines data from ellipsometry, circular dichroism, fluorescence spectroscopy, particle size/ζ potential measurements, and confocal microscopy. As a result of the net negative charge of Laponite, loading of net positively charged LL-37 increases with increasing pH. The peptide was found to bind primarily to the outer surface of the Laponite nanoparticles in a predominantly helical conformation, leading to charge reversal. Despite their net positive charge, peptide-loaded Laponite nanoparticles did not kill Gram-negative Escherichia coli bacteria or disrupt anionic model liposomes. They did however cause bacteria flocculation, originating from the interaction of Laponite and bacterial lipopolysaccharide (LPS). Free LL-37, in contrast, is potently antimicrobial through membrane disruption but does not induce bacterial aggregation in the concentration range investigated. Through LL-37 loading of Laponite nanoparticles, the combined effects of bacterial flocculation and membrane lysis are observed. However, bacteria aggregation seems to be limited to Gram-negative bacteria as Laponite did not cause flocculation of Gram-positive Bacillus subtilis bacteria nor did it bind to lipoteichoic acid from bacterial envelopes. Taken together, the present investigation reports several novel phenomena by demonstrating that nanoparticle charge does not invariably control membrane destabilization and by identifying the ability of anionic Laponite nanoparticles to effectively flocculate Gram-negative bacteria through LPS binding. As demonstrated in cell experiments, such aggregation results in diminished LPS-induced cell activation, thus outlining a promising approach for confinement of infection and inflammation caused by such pathogens.

Avidin-Biotin Cross-Linked Microgel Multilayers as Carriers for Antimicrobial Peptides.

Herein, we report on the formation of cross-linked antimicrobial peptide-loaded microgel multilayers. Poly(ethyl acrylate- co-methacrylic acid) microgels were synthesized and functionalized with biotin to enable the formation of microgel multilayers cross-linked with avidin. Microgel functionalization and avidin cross-linking were verified with infrared spectroscopy, dynamic light scattering, and z-potential measurements, while multilayer formation (up to four layers) was studied with null ellipsometry and quartz crystal microbalance with dissipation (QCM-D). Incorporation of the antimicrobial peptide KYE28 (KYEITTIHNLFRKLTHRLFRRNFGYTLR) into the microgel multilayers was achieved either in one shot after multilayer formation or through addition after each microgel layer deposition. The latter was found to strongly promote peptide incorporation. Further, antimicrobial properties of the peptide-loaded microgel multilayers against Escherichia coli were investigated and compared to those of a peptide-loaded microgel monolayer. Results showed a more pronounced suppression in bacterial viability in suspension for the microgel multilayers. Correspondingly, LIVE/DEAD staining showed promoted disruption of adhered bacteria for the KYE28-loaded multilayers. Taken together, cross-linked microgel multilayers thus show promise as high load surface coatings for antimicrobial peptides.

Peptide-Loaded Microgels as Antimicrobial and Anti-Inflammatory Surface Coatings.

Here we report on covalently immobilized poly(ethyl acrylate- co-methacrylic acid) microgels loaded with the host defense peptide KYE28 (KYEITTIHNLFRKLTHRLFRRNFGYTLR), which is derived from human heparin cofactor II, as well as its poly(ethylene glycol)-conjugated (PEGylated) version, KYE28PEG. Peptide loading and release, as well as the consequences of these processes on the microgel and peptide properties, were studied by in situ ellipsometry, confocal microscopy, zeta potential measurements, and circular dichroism spectroscopy. The results show that the microgel-peptide interactions are electrostatically dominated, thus promoted at higher microgel charge density, while PEGylation suppresses peptide binding. PEGylation also enhances the α-helix induction observed for KYE28 upon microgel incorporation. Additionally, peptide release is facilitated at physiological salt concentration, particularly so for KYE28PEG, which illustrates the importance of electrostatic interactions. In vitro studies on Escherichia coli show that the microgel-modified surfaces display potent antifouling properties in both the absence and presence of the incorporated peptide. While contact killing dominates at low ionic strength for the peptide-loaded microgels, released peptides also provide antimicrobial activity in bulk at a high ionic strength. Additionally, KYE28- and KYE28PEG-loaded microgels display anti-inflammatory effects on human monocytes. Taken together, these results not only show that surface-bound microgels offer an interesting approach for local drug delivery of host defense peptides but also illustrate the need to achieve high surface loads of peptides for efficient biological effects.

Membrane interactions of microgels as carriers of antimicrobial peptides.

Microgels are interesting as potential delivery systems for antimicrobial peptides. In order to elucidate membrane interactions of such systems, we here investigate effects of microgel charge density on antimicrobial peptide loading and release, as well as consequences of this for membrane interactions and antimicrobial effects, using ellipsometry, circular dichroism spectroscopy, nanoparticle tracking analysis, dynamic light scattering and z-potential measurements. Anionic poly(ethyl acrylate-co-methacrylic acid) microgels were found to incorporate considerable amounts of the cationic antimicrobial peptides LL-37 (LLGDFFRKSKEKIGKEFKRIVQRIKDFLRNLVPRTES) and DPK-060 (GKHKNKGKKNGKHNGWKWWW) and to protect incorporated peptides from degradation by infection-related proteases at high microgel charge density. As a result of their net negative z-potential also at high peptide loading, neither empty nor peptide-loaded microgels adsorb at supported bacteria-mimicking membranes. Instead, membrane disruption is mediated almost exclusively by peptide release. Mirroring this, antimicrobial effects against several clinically relevant bacteria (methicillin-resistant Staphylococcus aureus (MRSA), Escherichia coli, and Pseudomonas aeruginosa) were found to be promoted by factors facilitating peptide release, such as decreasing peptide length and decreasing microgel charge density. Microgels were further demonstrated to display low toxicity towards erythrocytes. Taken together, the results demonstrate some interesting opportunities for the use of microgels as delivery systems for antimicrobial peptides, but also highlight several key factors which need to be controlled for their successful use.

Surface-bound microgels - From physicochemical properties to biomedical applications.

Microgels offer robust and facile approaches for surface modification, as well as opportunities to introduce biological functionality by loading such structures with bioactive agents, e.g., in the context of drug delivery, functional biomaterials, and biosensors. As such, they provide a versatile approach for the design of surfaces with pre-determined characteristics compared to more elaborate bottom-up approaches, such as layer-by-layer deposition and surface-initiated polymerization. In the present overview, properties of surface-bound microgels are discussed, ranging from physical adsorption and covalent grafting in dilute systems, to directed self-assembly, multilayer structures, and composites, as well as loading an release of drugs and other cargo molecules into/from such systems, and biomedical applications of these.

Electrostatic Swelling Transitions in Surface-Bound Microgels.

Herein, electrostatic swelling transitions of poly(ethyl acrylate-co-methacrylic acid) microgels covalently bound to silica surfaces are investigated. Confined at a solid surface, microgel swelling is anisotropically hindered and the structure is flattened to an extent dictated by pH and microgel composition. Microgel deformation under applied load is also shown to depend on microgel charge density, with the highest deformation observed at intermediate charge densities. Two modes of microgel deformation under load were observed, one elastic and one viscoelastic, related to polymer strand deformation and displacement of trapped water, respectively. Results on polymer strand dynamics reveal that the microgels are highly dynamic, as the number of strand-tip interaction points increases 4-fold during a 10 s contact time. Furthermore, finite element modeling captures these effects qualitatively and shows that stress propagation in the microgel network decays locally at the rim of contact with a solid interface or close to the tip probe. Taken together, the results demonstrate a delicate interplay between the surface and microgel which determines the structure and nanomechanical properties of the latter and needs to be controlled in applications of systems such as pH-responsive surface coatings in biomaterials.

Factors Affecting Peptide Interactions with Surface-Bound Microgels.

Effects of electrostatics and peptide size on peptide interactions with surface-bound microgels were investigated with ellipsometry, confocal microscopy, and atomic force microscopy (AFM). Results show that binding of cationic poly-L-lysine (pLys) to anionic, covalently immobilized, poly(ethyl acrylate-co-methacrylic acid) microgels increased with increasing peptide net charge and microgel charge density. Furthermore, peptide release was facilitated by decreasing either microgel or peptide charge density. Analogously, increasing ionic strength facilitated peptide release for short peptides. As a result of peptide binding, the surface-bound microgels displayed pronounced deswelling and increased mechanical rigidity, the latter quantified by quantitative nanomechanical mapping. While short pLys was found to penetrate the entire microgel network and to result in almost complete charge neutralization, larger peptides were partially excluded from the microgel network, forming an outer peptide layer on the microgels. As a result of this difference, microgel flattening was more influenced by the lower Mw peptide than the higher. Peptide-induced deswelling was found to be lower for higher Mw pLys, the latter effect not observed for the corresponding microgels in the dispersed state. While the effects of electrostatics on peptide loading and release were similar to those observed for dispersed microgels, there were thus considerable effects of the underlying surface on peptide-induced microgel deswelling, which need to be considered in the design of surface-bound microgels as carriers of peptide loads, for example, in drug delivery or in functionalized biomaterials.