Metal dyshomeostasis, particularly involving Cu2+, is increasingly recognized as a key contributor to amyloid-β (Aβ) aggregation and neurotoxicity in Alzheimer's disease, motivating the development of chelators capable of selectively disrupting pathogenic metal-Aβ interactions without perturbing essential biological metals. Here, we employ steady-state fluorescence anisotropy as a real-time probe of TAMRA-Aβ1-42 rotational mobility to quantify metal-induced aggregation and its reversibility by two chelators with distinct selectivities: EDTA, a broad-spectrum benchmark, and Ni-bme-dach, a sulfur-rich metallodithiolate with high Cu affinity. Cu2+ induces the most significant increases in anisotropy, consistent with rapid formation of large nanoscale aggregates, while Fe3+ produces moderate aggregation and Zn2+ has minimal effect across pH 6.5 and 8.0. EDTA fully reverses Cu2+-induced aggregation but does so nonselectively, accompanied by pronounced fluorescence hyper-recovery indicative of broad metal stripping and fluorophore-environment perturbation. In contrast, Ni-bme-dach selectively extracts Cu2+, restoring monomer-like anisotropy at both pH values without hyper-recovery. UV-vis spectroscopy confirms formation of a discrete [Cu2-(Ni-bme-dach)3] complex, while TEM and AFM corroborate anisotropy trends and reveal a clear hierarchy of chelation responsiveness: Cu (fully reversible) > Fe (partially reversible) ≫ Zn (negligible). Together, these results establish fluorescence anisotropy as a sensitive kinetic platform for benchmarking chelator selectivity and demonstrate that Cu-driven Aβ aggregation is uniquely and selectively reversible. This work highlights metal-specific reversibility as a critical design principle for next-generation, Cu-targeted chelation strategies in Alzheimer's disease.

Redox-active nanomaterials derive important functional properties from surface-mediated electron transfer, yet chemical stabilization is commonly assumed to reduce biological hazards by suppressing oxidation and metal-ion release. Here, we tested this assumption using a chemically matched series of cobalt-gold nanoparticles (Co-AuNPs) with increasing surface complexity: exposed gold nanoflowers (NFLs), citrate-capped Co-Au core-shell nanoparticles, and hybrid lipid membrane (HLM)-coated Co-AuNPs. Increasing surface passivation reduced oxidative dissolution and Co2 + release under both chemical and physiological conditions. However, zebrafish embryo assays revealed a persistence-dominated exposure regime in which the most chemically stabilized nanoparticles produced the strongest toxic response. Citrate-capped NFLs exhibited the highest ICP-MS-measured dissolved cobalt concentrations but showed lower toxicity, whereas HLM-coated Co-AuNPs exhibited substantially lower dissolved cobalt despite producing greater developmental toxicity. These findings show that dissolved cobalt alone does not account for biological effects. Citrate-capped Co-AuNPs further demonstrate that dispersion stability alone is also insufficient to predict toxicity. Instead, the results support a model in which sustained biointerface persistence contributes substantially to toxicity when dissolution is suppressed.

Background and Objectives: We characterised an Ag-Chitosan-NaF product (ClearDefense), marketed for off-label use in caries arrest in children, as an alternative to 38% silver diamine fluoride (SDF). The label lists 0.2% Ag+ and 1.36% F−. No child efficacy or safety studies are reported. Methods: We followed U.S. National Institute of Standards and Technology (NIST) guidelines to describe the composition and stability of the product and assess its safety for children. Results: The product features heterogeneous AgNPs: 86% irregular spherical (32 ± 26 nm), 6% triangular (101 ± 100 nm), and 8% rod-shaped (42 ± 28 nm length, 16 ± 10 nm width). Ag-Chitosan-NaF exhibits agglomeration with Chitosan and NaF, and stability studies reveal an increase in Ag+ ion concentration upon exposure to air, raising concerns about dosage variations. Toxicity assessment reports a Margin of Exposure (MOE) for preschool children of 8-20 mg/kg, based on application amount and a 100X correction factor. Clinical Significance: This Ag-Chitosan-NaF product requires refinement to meet the standards for formulation, purity, and safety for paediatric off-label use. Conclusions: ClearDefense differs from the FDA-approved 38% SDF, raising concerns about consistency and paediatric suitability. A thorough reassessment by the manufacturer is needed to meet paediatric clinical standards.

The widespread use of silver nanoparticles (AgNPs) in various applications and industries has brought to light the need for understanding the complex relationship between the physicochemical properties (shape, size, charge, and surface chemistry) of AgNPs that affect their ability to enter cells and cause toxicity. To evaluate their toxicological outcomes, this study systematically analyzed a series of homogeneous hybrid lipid-coated AgNPs spanning sizes from 5 to 100 nm with diverse shapes (spheres, triangles, and cubes). The hybrid lipid membrane comprises hydrogenated phosphatidylcholine (HPC), sodium oleate (SOA), and hexanethiol (HT), which shield the AgNP surface from surface oxidation and toxic Ag+ ion release to minimize its contribution to toxicity. To reduce any significant effects by surface chemistry, the HPC, SOA, and HT membrane composition ratio was kept constant, and the AgNPs were assessed using embryonic zebrafish (Danio rerio). While a direct comparison cannot be drawn due to the lack of complementary sizes below 40 nm for triangular plates and cubes due to synthetic challenges, significant mortality was observed for spherical AgNPs (AgNSs) of 5, 20, 40, and 60 nm at 120 h postfertilization at concentrations ≥6 mg Ag/L. In contrast, the 10, 80, and 100 nm AgNSs, 40, 70, and 100 nm triangular plate AgNPs (AgNPLs), and 55, 75, and 100 nm cubic AgNPs (AgNCs) showed no significant mortality at 5 days postfertilization following exposure to AgNPs at concentrations up to 12 mg Ag/L. With constant surface chemistry on the AgNPs, size is the dominant factor driving toxicological responses, with smaller nanoparticles (5 to 60 nm) being the most toxic. Larger AgNSs, AgNCs, and AgNPLs from 75 to 100 nm do not show any evidence of toxicity. However, when closely examining sizes between 40 and 60 nm for AgNSs, AgNCs, and AgNPLs, there is evidence that discriminates shape as a driver of toxicity since sublethal responses generally were observed to follow a pattern, suggesting toxicity is most significant for AgNSs followed by AgNPLs and then AgNCs, which is the least toxic. Sum frequency generation vibrational spectroscopy showed that irrespective of size or shape, all hybrid lipid-coated AgNPs interact with membrane surfaces and "snorkel" between phases into the lipid monolayer with minimal energetic cost. These findings decisively demonstrate that not only smaller AgNPs but also the shape of the AgNPs influences their biological compatibility.

Producing silver nanoparticles (AgNPs) of homogeneous shapes and sizes that are stable for oxidation remains challenging. Here, a fast and accessible synthesis is presented to tune the homogeneity of triangular plates (AgNPLs) using light. This study showed AgNPs of varying shapes (spheres, rounded triangles, and rods), sizes (10-20, 40, and 33 nm, respectively), and surface chemistry (citrate and PVP capping agents) undergo a light-induced conversion to 75-85% sharp AgNPLs with a narrow-localized surface plasmon resonance (LSPR) band with lambda max at 680 nm and an average edge length of 40 nm +/- 5.6 nm as confirmed by UV-vis spectroscopy and transmission electron microscopy (TEM), respectively. Further exploration into the mechanism confirmed that Ag+ ions, O2, and light are critical parameters for the light-induced transformation of AgNSs to AgNPLs. Under an inert atmosphere, shape transformation is inhibited, reinforcing the essential role of O2 in the process. More remarkably, when AgNPs of any size or shape are coated with a hybrid lipid-coated membrane, the AgNPs had exceptional photostability, showing no change LSPR band, underscoring their resistance to photooxidation and shape transformation even in the presence of excess Ag+ ions, O2, and AgNSs. The results highlight the importance of light in tuning the homogeneity of AgNPs and the superior stabilizing effect of hybrid lipid membranes.

We investigated the impacts of spherical and triangular-plate-shaped lipid-coated silver nanoparticles (AgNPs) designed to prevent surface oxidation and silver ion (Ag+) dissolution in a small-scale microcosm to examine the role of shape and surface functionalization on biological interactions. Exposures were conducted in microcosms consisting of algae, bacteria, crustaceans, and fish embryos. Each microcosm was exposed to one of five surface chemistries within each shape profile (at 0, 0.1, or 0.5 mg Ag/L) to investigate the role of shape and surface composition on organismal uptake and toxicity. The hybrid lipid-coated AgNPs did not result in any significant release of Ag+ and had the most significant toxicity to D. magna, the most sensitive species, although the bacterial population growth rate was reduced in all exposures. Despite AgNPs resulting in increasing algal growth over the experiment, we found no correlation between algal growth and the survival of D. magna, suggesting that the impacts of the AgNPs on bacterial survival influenced algal growth rates. No significant impacts on zebrafish embryos were noted in any exposure. Our results demonstrate that the size, shape, and surface chemistry of AgNPs can be engineered to achieve specific goals while mitigating nanoparticle risks.

Here, we describe strategies for integrating transferrable professional development (PD) skills into research learning environments for marginalized undergraduate students. The undergraduate research experience evolved to include the competencies students need to be successful and to gain a sense of belonging in the chemistry community they are seeking. These asset-based transferrable PD skills are part of the "hidden curriculum" not taught in traditional classrooms and yet are an integral part of student learning and success. Furthermore, current practices, or lack thereof, tend to promote inequity and fail to amplify key asset-based skills for marginalized students to navigate academic, industrial, and professional settings effectively. Consequently, many students leave STEM communities. The following six PD skills are core competencies that have been implemented in a diverse undergraduate research environment to equip students with the skills needed to navigate various STEM environments. These include: (1) Effective Communication, (2) Negotiation, (3) Leadership, (4) Networking, (5) Interpersonal skills, and (6) Active Listening. Learning topics for each of the PD skills enable mentors to help preprofessional, marginalized students gain a sense of belonging, build a network, connect with mentors, develop self-advocacy, implement interpersonal skills, manage conflict, and navigate spaces that do not fully represent them. The inclusive integration of scientific and PD skills into research experiences serves as a template that can be extended to high school and graduate students. These integrated transferrable skills are one way to increase diversity in STEM professions and bridge the gap in leadership in academia and industry.

Alpha-synuclein (aSyn) is a vertebrate protein, normally found within the presynaptic nerve terminal and nucleus, which is known to form somatic and neuritic aggregates in certain neurodegenerative diseases. Disease-associated aggre-gates of aSyn are heavily phosphorylated at serine-129 (pSyn), while normal aSyn protein is not. Within the nucleus, aSyn can directly bind DNA, but the mechanism of binding and the potential modulatory roles of phosphorylation are poorly un-derstood. Here we demonstrate using a combination of elec-trophoretic mobility shift assay and atomic force microscopy approaches that both aSyn and pSyn can bind DNA within the major groove, in a DNA length-dependent manner and with little specificity for DNA sequence. Our data are consistent with a model in which multiple aSyn molecules bind a single 300 base pair (bp) DNA molecule in such a way that stabilizes the DNA in a bent conformation. We propose that serine-129 phosphorylation decreases the ability of aSyn to both bind and bend DNA, as aSyn binds 304 bp circular DNA forced into a bent shape, but pSyn does not. Two aSyn paralogs, beta-and gamma-synuclein, also interact with DNA differently than aSyn, and do not stabilize similar DNA conformations. Our work suggests that reductions in aSyn's ability to bind and bend DNA induced by serine-129 phosphorylation may be important for modulating aSyn's known roles in DNA metabolism, including the regulation of transcription and DNA repair.

The advancement of safe nanomaterials for use as optical coherence tomography (OCT) imaging and stem cell-labeling agents to longitudinally visually track therapeutic derived retinal stem cells to study their migration, survival rate, and efficacy is challenged by instability, intracellular aggregation, low uptake, and cytotoxicity. Here, we describe a series of hybrid lipid-coated gold nanorods (AuNRs) that could solve these issues. These nanomaterials were made via a layer-by-layer assembly approach, and their stability in biological media, mechanism, efficiency of uptake, and toxicity were compared with a commercially available set of AuNRs with a 5 nm mesoporous silica (mSiO(2))-polymer coating. These nanomaterials can serve as stem cell labeling and OCT imaging agents because they absorb in the near-infrared (NIR) region away from biological tissues. Although both subtypes of AuNRs were taken up by retinal pigment epithelial, neural progenitor, and baby hamster kidney cells, slightly negatively charged hybrid lipid-coated AuNRs had minimal aggregation in biological media and within the cytoplasm of cells (similar to 3000 AuNRs/cell) as well as minimal impact on cell health. Hybrid lipid-coated AuNRs modified with cell-penetrating peptides had the least toxicological impact, with >92% cell viability. In contrast, the more "sticky" AuNRs with a 5 nm mSiO(2)-polymer coating showed significant aggregation in biological media and within the cytoplasm with lower-than-expected uptake of AuNRs (similar to 5400 of AuNRs/cell) given their highly positive surface charge (35+ mV). Collectively, we have demonstrated that hybrid lipid-coated AuNRs, which absorb in the NIR-II region away from biological tissues, with tuned surface chemistry can label therapeutic derived stem cells with minimal aggregation and impact on cell health as well as enhance uptake for OCT imaging applications.

Gold nanorods (AuNRs) hold tremendous potential to improve the diagnosis and therapeutic options across the blood-retinal barrier to treat retinal diseases. For clinical ophthalmological translation, a fundamental understanding of how their physicochemical properties such as size, shape, charge, surface chemistry, and concentration, impact their stability biological environments, mechanism and efficiency of uptake, and toxicity is a necessity. Here we interrogated the uptake efficiency, biocompatibility, and stability of two subtypes of AuNRs with different types of surface coatings and varying charges, including a commercially available set of AuNRs with a 5 nm mSiO2-polymer coating and hybrid lipid-coated AuNRs developed in-house. Confocal and bright field microscopy images showed uptake of both subtypes of AuNRs in retinal pigment epithelium (RPE), neural progenitor (NP), and baby hamster kidney (BHK) cells. Transmission electron microscopy (TEM) confirms both types of AuNRs are taken up into the cytoplasm of the cells; however, larger aggregates of AuNRs are observed with the more positive and “sticky” AuNRs with a 5 nm mSiO2-polymer coating than the slightly negative hybrid lipid-coated AuNRs. Inductively Coupled Mass Spectroscopy (ICP-MS) confirm that ~3,000 of the slightly negative hybrid lipid-coated AuNRs cells and ~5,400 of the positively charged AuNRs with a 5 nm mSiO2-polymer coating (+35 mV) are taken up into RPE and BHK cell lines. Stability studies in a variety of cellular media showed that hybrid lipid-coated AuNRs are stable and disaggregated in water, 10 mM PBS buffer pH 7, and BHK media except for NP media. In contrast, the positively charged AuNRs with a 5 nm mSiO2-zeta polymer coating aggregated in all media, indicating more interactions with each other and components of the media. Bright-field and TEM confirm the presence of large aggregates of AuNRs on the surface and within the cytoplasm. Cytotoxicity studies both subtypes of AuNRs have an 80 ± 8 % cell viability, indicating mild toxicity. The hybrid lipid-coated AuNR with the cell-penetrating peptide had the least toxicological impact with a > 92 ± 7 % cell viability. Our study highlights the importance of evaluating the impact of the physicochemical features of each new nanoparticle design on their stability in biologically relevant environments and their impact on cellular uptake and toxicity in stem cell-derived therapeutic cells. Here we also provide a simple design strategy for tuning the surface chemistry of robust hybrid lipid-coated AuNRs to enhance cellular uptake to label stem cells with minimal aggregation and toxicity.

Research experience provides critical training for new biomedical research scientists. Students from underrepresented populations studying science, technology, engineering, and mathematics (STEM) are increasingly recruited into research pathways to diversify STEM fields. However, support structures outside of research settings designed to help these students navigate biomedical research pathways are not always available; nor are program support components outside the context of laboratory technical skills training and formal mentorship well understood. This study leveraged a multi-institutional research training program, Enhancing Cross-Disciplinary Infrastructure and Training at Oregon (EXITO), to explore how nine institutions designed a new curricular structure (Enrichment) to meet a common goal of enhancing undergraduate research training and student success. EXITO undergraduates participated in a comprehensive, 3-year research training program with the Enrichment component offered across nine sites: three universities and six community colleges, highly diverse in size, demographics, and location. Sites’ approaches to supporting students in the training program were studied over a 30-month period. All sites independently created their own nonformal curricular structures, implemented interprofessionally via facilitated peer groups. Site data describing design and implementation were thematically coded to identify essential programmatic components across sites, with student feedback used to triangulate findings. Enrichment offered students time to critically reflect on their interests, experiences, and identities in research; network with peers and professionals; and support negotiation of hidden and implicit curricula. Students reported the low-pressure setting and student-centered curriculum balanced the high demands associated with academics and research. Core curricular themes described Enrichment as fostering a sense of community among students, exposing students to career paths and skills, and supporting development of students’ professional identities. The non-formal, interprofessional curricula enabled students to model diverse biomedical identities and pathways for each other while informing institutional structures to improve diverse undergraduate students’ success in academia and research.

Silver nanoparticles (AgNPs) are widely used in commerce, however, the effect of their physicochemical properties on toxicity remains debatable because of the confounding presence of Ag+ ions. Thus, we designed a series of AgNPs that are stable to surface oxidation and Ag+ ion release. AgNPs were coated with a hybrid lipid membrane comprised of L-phosphatidylcholine (PC), sodium oleate (SOA), and a stoichiometric amount of hexanethiol (HT) to produce oxidant-resistant AgNPs, Ag–SOA–PC–HT. The stability of 7-month aged, 20–100 nm Ag–SOA–PC–HT NPs were assessed using UV–Vis, dynamic light scattering (DLS), and inductively coupled plasma mass spectrometry (ICP-MS), while the toxicity of the nanomaterials was assessed using a well-established, 5-day embryonic zebrafish assay at concentrations ranging from 0–12 mg/L. There was no change in the size of the AgNPs from freshly made samples or 7-month aged samples and minimal Ag+ ion release (<0.2%) in fishwater (FW) up to seven days. Toxicity studies revealed AgNP size- and concentration-dependent effects. Increased mortality and sublethal morphological abnormalities were observed at higher concentrations with smaller nanoparticle sizes. This study, for the first time, determined the effect of AgNP size on toxicity in the absence of Ag+ ions as a confounding variable.

Introduction: Humans are intentionally exposed to gold nanoparticles (AuNPs) where they are used in variety of biomedical applications as imaging and drug delivery agents as well as diagnostic and therapeutic agents currently in clinic and in a variety of upcoming clinical trials. Consequently, it is critical that we gain a better understanding of how physiochemical properties such as size, shape, and surface chemistry drive cellular uptake and AuNP toxicity in vivo. Understanding and being able to manipulate these physiochemical properties will allow for the production of safer and more efficacious use of AuNPs in biomedical applications. Methods and Materials: Here, AuNPs of three sizes, 5 nm, 10 nm, and 20 nm, were coated with a lipid bilayer composed of sodium oleate, hydrogenated phosphatidylcholine, and hexanethiol. To understand how the physical features of AuNPs influence uptake through cellular membranes, sum frequency generation (SFG) was utilized to assess the interactions of the AuNPs with a biomimetic lipid monolayer composed of a deuterated phospholipid 1.2-dipalmitoyl-d62-sn-glycero-3-phosphocholine (dDPPC). Results and Discussion: SFG measurements showed that 5 nm and 10 nm AuNPs are able to phase into the lipid monolayer with very little energetic cost, whereas, the 20 nm AuNPs warped the membrane conforming it to the curvature of hybrid lipid-coated AuNPs. Toxicity of the AuNPs were assessed in vivo to determine how AuNP curvature and uptake influence cell health. In contrast, in vivo toxicity tested in embryonic zebrafish showed rapid toxicity of the 5 nm AuNPs, with significant 24 hpf mortality occurring at concentrations >= 20 mg/L, whereas the 10 nm and 20 nm AuNPs showed no significant mortality throughout the five-day experiment. Conclusion: By combining information from membrane models using SFG spectroscopy with in vivo toxicity studies, a better mechanistic understanding of how nanoparticles (NPs) interact with membranes is developed to understand how the physiochemical features of AuNPs drive nanoparticle-membrane interactions, cellular uptake, and toxicity.

Hybrid lipid membranes shields and protects silver nanoparticles (AgNPs) from surface oxidation, Ag+ ion release, aging, and shape conversion.

Porphyrin-based molecules are actively studied as dual function theranostics: fluorescence-based imaging for diagnostics and fluorescence-guided therapeutic treatment of cancers. The intrinsic fluorescent and photodynamic properties of the bimodal molecules allows for these theranostic approaches. Several porphyrinoids bearing both hydrophilic and/or hydrophobic units at their periphery have been developed for the aforementioned applications, but better tumor selectivity and high efficacy to destroy tumor cells is always a key setback for their use. Another issue related to their effective clinical use is that, most of these chromophores form aggregates under physiological conditions. Nanomaterials that are known to possess incredible properties that cannot be achieved from their bulk systems can serve as carriers for these chromophores. Porphyrinoids, when conjugated with nanomaterials, can be enabled to perform as multifunctional nanomedicine devices. The integrated properties of these porphyrinoid-nanomaterial conjugated systems make them useful for selective drug delivery, theranostic capabilities, and multimodal bioimaging. This review highlights the use of porphyrins, chlorins, bacteriochlorins, phthalocyanines and naphthalocyanines as well as their multifunctional nanodevices in various biomedical theranostic platforms.