Monoclonal Antibodies as SARS-CoV-2 Serology Standards: Experimental Validation and Broader Implications for Correlates of Protection.

COVID-19 has highlighted challenges in the measurement quality and comparability of serological binding and neutralization assays. Due to many different assay formats and reagents, these measurements are known to be highly variable with large uncertainties. The development of the WHO international standard (WHO IS) and other pool standards have facilitated assay comparability through normalization to a common material but does not provide assay harmonization nor uncertainty quantification.

Quantitation and integrity evaluation of RNA genome in lentiviral vectors by direct reverse transcription-droplet digital PCR (direct RT-ddPCR).

Lentiviral vectors (LV) have proven to be powerful tools for stable gene delivery in both dividing and non-dividing cells. Approval of these LVs for use in clinical applications has been achieved by improvements in LV design. Critically important characteristics concerning quality control are LV titer quantification and the detection of impurities.

Towards Quantitative and Standardized Serological and Neutralization Assays for COVID-19.

Quantitative and robust serology assays are critical measurements underpinning global COVID-19 response to diagnostic, surveillance, and vaccine development. Here, we report a proof-of-concept approach for the development of quantitative, multiplexed flow cytometry-based serological and neutralization assays. The serology assays test the IgG and IgM against both the full-length spike antigens and the receptor binding domain (RBD) of the spike antigen.

Standards efforts and landscape for rapid microbial testing methodologies in regenerative medicine.

The Standards Coordinating Body for Gene, Cell, and Regenerative Medicines and Cell-Based Drug Discovery (SCB) supports the development and commercialization of regenerative medicine products by identifying and addressing industry-wide challenges through standards. Through extensive stakeholder engagement, the implementation of rapid microbial testing methods (RMTMs) was identified as a high-priority need that must be addressed to facilitate more timely release of products. Since 2017, SCB has coordinated efforts to develop standards for this area through surveys, weekly meetings, workshops, leadership in working groups and participation in standards development organizations.

Reference standards for accurate validation and optimization of assays that determine integrated lentiviral vector copy number in transduced cells.

Lentiviral vectors (LV) have emerged as a robust technology for therapeutic gene delivery into human cells as advanced medicinal products. As these products are increasingly commercialized, there are concomitant demands for their characterization to ensure safety, efficacy and consistency. Standards are essential for accurately measuring parameters for such product characterization.

FDA and NIST collaboration on standards development activities supporting innovation and translation of regenerative medicine products.

The development of standards for the field of regenerative medicine has been noted as a high priority by several road-mapping activities. Additionally, the U.S.

Summary of the National Institute of Standards and Technology and US Food And Drug Administration cell counting workshop: Sharing practices in cell counting measurements.

The emergence of cell-based therapeutics has increased the need for high-quality, robust and validated measurements for cell characterization. Cell count, being one of the most fundamental measures for cell-based therapeutics, now requires increased levels of measurement confidence. The National Institute of Standards and Technology (NIST) and the US Food and Drug Administration (FDA) jointly hosted a workshop focused on cell counting in April 2017 entitled "NIST-FDA Cell Counting Workshop: Sharing Practices in Cell Counting Measurements.

Effect of dental monomers and initiators on Streptococcus mutans oral biofilms.

Objective: Resin-based composites are known to elute leachables that include unincorporated starting materials. The objective of this work was to determine the effect of common dental monomers and initiators on Streptococcus mutans biofilm metabolic activity and biomass.

Methods: S.

Evaluating the quality of a cell counting measurement process via a dilution series experimental design.

Background Aims: Cell counting measurements are critical in the research, development and manufacturing of cell-based products, yet determining cell quantity with accuracy and precision remains a challenge. Validating and evaluating a cell counting measurement process can be difficult because of the lack of appropriate reference material. Here we describe an experimental design and statistical analysis approach to evaluate the quality of a cell counting measurement process in the absence of appropriate reference materials or reference methods.

Polyaspartic Acid Concentration Controls the Rate of Calcium Phosphate Nanorod Formation in High Concentration Systems.

Polyelectrolytes are known to greatly affect calcium phosphate (CaP) mineralization. The reaction kinetics as well as the CaP phase, morphology and aggregation state depend on the relative concentrations of the polyelectrolyte and the inorganic ions in a complex, nonlinear manner. This study examines the structural evolution and kinetics of polyaspartic acid (pAsp) directed CaP mineralization at high concentrations of polyelectrolytes, calcium, and total phosphate (19-30 mg/mL pAsp, 50-100 mM Ca, Ca/P = 2).

Quantifying the sensitivity of the network structure and properties from simultaneous measurements during photopolymerization.

We present a method that combines experimental and computational approaches to assess a comprehensive set of structural and functional evolution during a network formation process via photopolymerization. Our work uses the simultaneous measurement of the degree of conversion, polymerization stress, the change in reaction temperature, and shrinkage strain in situ. These measurements are combined with the theory of viscoelastic materials to deduce the relaxation time and frequency-dependent modulus of the polymerizing network.

Experimental and statistical methods to evaluate antibacterial activity of a quaternary pyridinium salt on planktonic, biofilm-forming, and biofilm states.

Robust evaluation and comparison of antimicrobial technologies are critical to improving biofilm prevention and treatment. Herein, a multi-pronged experimental framework and statistical models were applied to determine the effects of quaternary pyridinium salt, 4-acetyl-1-hexadecylpyridin-1-ium iodide (QPS-1), on Streptococcus mutans in the planktonic, biofilm-forming and biofilm cell states. Minimum inhibitory and bactericidal concentrations (MIC and MBC, respectively) were determined via common methods with novel application of statistical approaches combining random effects models and interval censored data to estimate uncertainties.

Primer containing dimethylaminododecyl methacrylate kills bacteria impregnated in human dentin blocks.

Antibacterial dimethylaminododecyl methacrylate (DMADDM) was recently synthesized. The objectives of this study were to: (1) investigate antibacterial activity of DMADDM-containing primer on Streptococcus mutans impregnated into dentin blocks for the first time, and (2) compare the antibacterial efficacy of DMADDM with a previous quaternary ammonium dimethacrylate (QADM). Scotchbond Multi-Purpose (SBMP) bonding agent was used.

Strategies for Achieving Measurement Assurance for Cell Therapy Products.

Unlabelled: The cell therapy industry has identified the inability to reliably characterize cells as possibly its greatest challenge and has called for standards and reference materials to provide assurance for measurements of cell properties. The challenges in characterization of cell therapy products can be largely addressed with systematic approaches for assessing sources of uncertainty and improving confidence in key measurements. This article presents the many strategies that can be used to ensure measurement confidence and discusses them in terms of how they can be applied to characterization of cell therapy products.

Novel Dental Cement to Combat Biofilms and Reduce Acids for Orthodontic Applications to Avoid Enamel Demineralization.

Orthodontic treatments often lead to biofilm buildup and white spot lesions due to enamel demineralization. The objectives of this study were to develop a novel bioactive orthodontic cement to prevent white spot lesions, and to determine the effects of cement compositions on biofilm growth and acid production. 2-methacryloyloxyethyl phosphorylcholine (MPC), nanoparticles of silver (NAg), and dimethylaminohexadecyl methacrylate (DMAHDM) were incorporated into a resin-modified glass ionomer cement (RMGI).

Kinetics of aggregation and crystallization of polyaspartic Acid stabilized calcium phosphate particles at high concentrations.

Bone is an important material to study due to its exceptional mechanical properties and relevance with respect to hard tissue regeneration and repair. A significant effort has been directed toward understanding the bone formation process and the production of synthetic bone mimicking materials. Here, the formation and structural evolution of calcium phosphate (CaP) was investigated in the presence of relatively high concentrations of calcium, phosphate, and polyaspartic acid (pAsp) using dynamic light scattering (DLS) and cryo-transmission electron microscopy (cryo-TEM).

Simultaneous measurement of polymerization stress and curing kinetics for photo-polymerized composites with high filler contents.

Objectives: Photopolymerized composites are used in a broad range of applications with their performance largely directed by reaction kinetics and contraction accompanying polymerization. The present study was to demonstrate an instrument capable of simultaneously collecting multiple kinetics parameters for a wide range of photopolymerizable systems: degree of conversion (DC), reaction exotherm, and polymerization stress (PS).

Methods: Our system consisted of a cantilever beam-based instrument (tensometer) that has been optimized to capture a large range of stress generated by lightly-filled to highly-filled composites.

Antibacterial activity and ion release of bonding agent containing amorphous calcium phosphate nanoparticles.

Objective: Recurrent caries at the margins is a primary reason for restoration failure. The objectives of this study were to develop bonding agent with the double benefits of antibacterial and remineralizing capabilities, to investigate the effects of NACP filler level and solution pH on Ca and P ion release from adhesive, and to examine the antibacterial and dentin bond properties.

Methods: Nanoparticles of amorphous calcium phosphate (NACP) and a quaternary ammonium monomer (dimethylaminododecyl methacrylate, DMADDM) were synthesized.

Effects of nanoparticle size and charge on interactions with self-assembled collagen.

Hypothesis: Insights into bone formation have suggested that the critical first step in the biomineralization process is the integration of small (nanometer dimension) mineral clusters into collagen fibers. Not only is such behavior of interest for understanding biomineralization but also should be important to nanotoxicology because collagen is a major component of structural tissues in the human body and accounts for more than 25% of the whole body protein content. Here, utilizing the current insights from biomineralization, we hypothesize that the binding affinity of nanoparticles to self-assembled collagen fibers is size and surface charge dependent.

Microstructure and mechanical properties of in situ Streptococcus mutans biofilms.

Insight into live microbial biofilm microstructure and mechanical properties and their interactions with the underlying substrate can lead to the development of new remedial strategies and/or materials. Here we report mechanical properties of dental pathogenic Streptococcus mutans biofilms, grown on a polystyrene-coated plate of a shear rheometer in physiologically relevant conditions, precisely controlled in a custom built bioreactor. In situ measurements demonstrated the importance of microstructure and composition of extracellular polymeric substances on the biofilm modulus.

Different kinetic pathways of early stage calcium-phosphate cluster aggregation induced by carboxylate-containing polymers.

Acidic proteins are critical to biomineral formation, although their precise mechanistic function remains poorly understood. A number of recent studies have suggested a nonclassical mineralization model that emphasizes the importance of the formation of polymer-stabilized mineral clusters or particles; however, it has been difficult to characterize the precursors experimentally due to their transient nature. Here, we successfully captured stepwise evolution of transient CaP clusters in mineralizing solutions and studied the roles of functional polymers with laser light scattering (LLS) to determine how these polymers influence the stability of nanoclusters.