Robert I Maccuspie

• Ph.D. in Nanotechnology
• CEO at MacCuspie Innovations

Fused filament fabrication (FFF) 3D printers are increasingly used in industrial, academic, military, and residential sectors, yet their emissions and associated user exposure scenarios are not fully described. Characterization of potential user exposure and environmental releases requires robust investigation. During operation, common FFF 3D print...

Shortages in the availability of personal protective face masks during the COVID-19 pandemic required many to fabricate masks and filter inserts from available materials. While the base filtration efficiency of a material is of primary importance when a perfect seal is possible, ideal fit is not likely to be achieved by the average person preparing...

Tiered risk as sessment approaches for nanomaterial environmental health and safety (nanoEHS) require a detailed understanding of the size and the size distribution of the material being used. There are many metrological tools to choose from, each with its own strengths and weaknesses that influence the results being reported on the exact same batc...

Both serum protein concentration and ionic strength are important factors in nanoparticle transformation within cell culture environments. However, silver nanoparticles are not routinely tracked at their working concentration in the specific medium used for in vitro toxicology studies. Here we evaluated the transformation of electrostatically stabi...

Cationic polyethylene-imine conjugated gold nanoparticles (AuNP-PEI) are a widely studied vector for drug delivery and an effective probe for interrogating NP-cell interactions. However, an inconsistent body of literature currently exists regarding the reproducibility of physico-chemical properties, colloidal stability and efficacy for these specie...

Provided the rapid emergence of novel technologies containing engineered nanomaterials, there is a need to better understand the potential environmental, health, and safety effects of nanotechnologies before wide-scale deployment. However, the unique properties of nanomaterials and uncertainty regarding applicable test methods have led to a lack of...

FOREWORD: This NIST Special Publication (SP) is one in a series of NIST SPs that address research needs articulated in the National Nanotechnology Initiative (NNI) Environmental, Health, and Safety Research Strategy published in 2011 [1]. This Strategy identified a Nanomaterial Measurement Infrastructure (NMI) as essential for science-based risk as...

While many definitions of what a nanomaterial is exist today, nearly all of these definitions include physical size ranges. Several definitions also mention novel properties different from bulk materials as a requirement to be a nanomaterial. Thus, characterization of a material is required before it can be labeled a nanomaterial. © 2014 Matthew S....

An issue in the application of nano-enabled products is how can we evaluate sustainable solutions to current sys-tem problems based on performance criteria? This work describes the application of an Input–Process–Output (IPO) model as a framework for a life-cycle analysis approach to identify performance metrics and criteria for evaluating the appl...

Little is understood regarding the impact that molecular coatings have on nanoparticle dissolution kinetics and agglomerate formation in a dilute nanoparticle dispersion. Dissolution and agglomeration processes compete in removing isolated nanoparticles from the dispersion, making quantitative time-dependent measurements of the mechanisms of nanopa...

A critical but often overlooked component of silver nanoparticle (AgNP) suspensions involves their behavior following short- and long-term storage. The current study investigates the integrity of citratecapped AgNP suspensions, nominally 20 nm in average diameter, in a series of distinct storage conditions, based on possible combinations of reasona...

We report the development of a novel cationic dendron (TAG1-PCD) and a positively charged gold nanoparticle-dendron conjugate (PCD-AuNP). TAG1-PCD was designed by considering the reactivity, hydrophilicity, and cationic nature that is required to yield a stable gold conjugate in aqueous media. The PCD-AuNPs, nominally 10 nm in size, were synthesize...

Novel physicochemistries of engineered nanomaterials (ENMs) offer considerable commercial potential for new products and processes, but also the possibility of unforeseen and negative consequences upon ENM release into the environment. Investigations of ENM ecotoxicity have revealed that the unique properties of ENMs and a lack of appropriate test...

The increasing application of engineered nanomaterials (ENMs) in consumer and medical products has motivated the development of single particle inductively coupled plasma mass spectrometry (spICP-MS) for characterizing nanoparticles under realistic environmental exposure conditions. Recent studies have established a set of metrological criteria and...

Engineered nanomaterials (ENMs) have significant commercial potential in a broad range of industries for consumer products as a result of their novel properties. However, these same properties may cause unexpected risks once ENMs are released into the environment either intentionally or unintentionally. Thus, standard methods are needed to accurate...

In this study we use inductively coupled plasma mass spectrometry operated in single particle mode (spICP-MS) to simultaneously characterize the size distribution and dissolved silver fraction of a new silver nanoparticle (AgNP) candidate reference material, RM 8017, composed of polyvinylpyrrolidone (PVP)-stabilized 75 nm AgNPs (nominal size). We s...

Recently, an atomic force microscopy (AFM)-based approach for quantifying the number of biological molecules conjugated to a nanoparticle surface at low number densities was reported. The number of target molecules conjugated to the analyte nanoparticle can be determined with single nanoparticle fidelity using antibody-mediated self-assembly to dec...

Silver nanoparticles (AgNPs) are of inter-est due to their antimicrobial attributes, which are derived from their inherent redox instability and subsequent release of silver ions. At the same time, this instability is a substantial challenge for achieving stable long-term storage for on-demand use of AgNPs. In this study, we describe and validate a...

Exposure to wet aerosols generated during use of spray products containing silver (Ag) has not been evaluated. The goal was to assess the potential for cardiopulmonary toxicity following an acute inhalation of wet silver colloid. Rats were exposed by inhalation to a low concentration (100 μg/m(3) ) using an undiluted commercial antimicrobial produc...

The capping layer stabilizing silver nanoparticles (AgNPs) affects its aggregation, dissolution, and net disinfection action, especially under conditions of varying water composition, such as, pH, ionic strength and organic matter content. Herein, we correlate the silver ion (Ag +) release and reactive oxygen species (ROS) generation rates for AgNP...

Inductively coupled plasma mass spectrometry (ICP-MS) operated in single particle mode is an attractive analytical tool capable of both sizing and counting metal containing nanoparticles in aqueous suspensions. In this study, we have evaluated the performance of single particle-ICP-MS (spICP-MS) for gold nanoparticle (AuNPs) characterization. Instr...

The application of asymmetric-flow field flow fractionation (A4F) for low aspect ratio gold nanorod (GNR) fractionation and characterization was comprehensively investigated. We report on two novel aspects of this application. The first addresses the analytical challenge involved in the fractionation of positively charged nanoparticles by A4F, due...

A riboflavin binding aptamer (RBA) was used in combination with gold nanoparticles (AuNPs) to detect riboflavin in vitro. The RBA–AuNP conjugates (RBA–AuNPs) responded colorimetrically to the presence of riboflavin and this response could be followed by the naked eye. This system was used as a model to study how modifications on the aptamer sequenc...

We report on a systematic investigation of molecular conjugation of tumor necrosis factor-α (TNF) protein onto gold nanoparticles (AuNPs) and the subsequent binding behavior to its antibody (anti-TNF). We employ a combination of physical and spectroscopic characterization methods, including electrospray-differential mobility analysis, dynamic light...

A necessary step in advancing the use of polyethylene glycol (PEG) surface coatings in critical biotechnological applications such as cancer treatments is to provide direct and reliable nanoscale property characterization. Measurements for such characterization are currently provided by scanning probe methods, which are capable of assessing heterog...

Gold nanomaterials (AuNMs) have distinctive electronic and optical properties, making them ideal candidates for biological, medical, and defense applications. Therefore, it is imperative to evaluate the potential biological impact of AuNMs before employing them in any application. This study investigates two AuNMs with different aspect ratios (AR)...

Given the diverse scientific and technological applications of gold nanoparticles (Au NPs), understanding the impact of macromolecular additives on the distribution of size, shape, and composition is crucial to ensure reproducibility and lower production cost. In situ measurement of the evolution of these distributions challenges current techniques...

Due to the increasing use of silver nanoparticles (AgNPs) in consumer products, it is essential to understand how variables, such as light exposure, may change the physical and chemical characteristics of AgNP suspensions. To this end, the effect of 300 nm ultraviolet (UV) light on (20, 40, 60 and 80) nm citrate-capped AgNP suspensions has been inv...

Agglomeration of nanoparticles during measurements in relevant biological and environmental media is a frequent problem in nanomaterial property characterization. The primary problem is typically that any changes to the size distribution can dramatically affect the potential nanotoxicity or other size-determined properties, such as the absorbance s...

Distinguishing the toxic effects of nanoparticles (NPs) themselves from the well-studied toxic effects of their ions is a critical but challenging measurement for nanotoxicity studies and regulation. This measurement is especially difficult for silver NPs (AgNPs) because in many relevant biological and environmental solutions, dissolved silver form...

The dispersion stabilization of silver nanoparticles (AgNPs) in synthetic lung fluid was studied to interrogate the effects on colloidal stability due to the principal constituents of the fluid. The colloidal stability of 20 nm citrate-AgNPs dispersed in the presence of each constituent of the synthetic lung fluid (individually, the complete fluid,...

We report the synthesis and evaluation of four Newkome-type dendrons, G1-COOH, G2-COOH, SH-G1-COOH, and TA-G1-COOH, and their respective gold-dendron conjugates, where GX represents the generation number. G1- and G2-COOH are 2-directional symmetric dendrons that have cystamine cores containing a disulfide group. SH-G1-COOH was prepared by treatment...

This investigation focuses on predicting the persistence of citrate-capped 20 nm AgNPs by measuring their colloidal stability in natural freshwaters and synthetic aquatic media. Ultraviolet-visible absorbance spectroscopy, dynamic light scattering, and atomic force microscopy were used to evaluate the colloidal stability of AgNPs in locally-obtaine...

The formation of silver nanoparticles (AgNPs) via reduction of silver ions (Ag(+)) in the presence of humic acids (HAs) under various environmentally relevant conditions is described. HAs tested originated from the Suwannee River (SUW), and included samples of three sedimentary HAs (SHAs), and five soils obtained across the state of Florida. The ti...

Quantification of very low density molecular coatings on large (60 nm) gold nanoparticles (AuNPs) is demonstrated via the use of antibody-mediated self-limiting self-assembly of small and large AuNPs into raspberry-like structures subsequently imaged by atomic force microscopy (AFM). AFM imaging is proposed as an automated, lower-cost, higher-throu...

The reported size distribution of silver nanoparticles (AgNPs) is strongly affected by the underlying measurement method, agglomeration state, and dispersion conditions. A selection of AgNP materials with vendor-reported diameters ranging from 1 nm to 100 nm, various size distributions, and biocompatible capping agents including citrate, starch and...

The adsorption and conformation of bovine serum albumin (BSA) on gold nanoparticles (AuNPs) were interrogated both qualitatively and quantitatively via complementary physicochemical characterization methods. Dynamic light scattering (DLS), asymmetric-flow field flow fractionation (AFFF), fluorescence spectrometry, and attenuated total reflectance-F...

To study the toxicity of nanoparticles under relevant conditions, it is critical to disperse nanoparticles reproducibly in different agglomeration states in aqueous solutions compatible with cell-based assays. Here, we disperse gold, silver, cerium oxide, and positively-charged polystyrene nanoparticles in cell culture media, using the timing betwe...

Macroscopic assemblies of nanoparticles with fluid like characteristics, i.e. nanoparticle liquids (NPLs), are a new class of materials that exhibit unique properties compared with dispersions of nanoparticles in a molecularly distinct matrix phase. By focusing on reaction ratios, techniques to maximize concentration of reactants and quantification...

Understanding the colloidal stability of nanoparticles (NPs) plays a key role in phenomenological interpretation of toxicological experiments, particularly if single NPs or their aggregates or agglomerates determine the dominant experimental result. This report examines a variety of instrumental techniques for surveying the colloidal stability of a...

Competitive adsorption kinetics between thiolated polyethylene glycol (SH-PEG) and mercaptopropionic acid (MPA) on gold nanoparticles (Au-NPs) were studied using a prototype physical characterization approach that combines dynamic light scattering (DLS) and electrospray differential mobility analysis (ES-DMA). The change in hydrodynamic particle si...

In this work, we combined synthesis of Au nanorods (AuNRs) and Au−Ag core−shell nanorod-like structures, of narrow size distribution in all dimensions and for a broad range of aspect ratios, with computational prediction of the localized surface plasmon resonance (LSPRs), in order to gain a better understanding of the optical response. Self-assembl...

Robust trace-level detection of viruses is crucial to meet urgent needs in fighting the spread of disease or detecting bioterrorism events. We report a new method for rapid and highly sensitive detection of viruses utilizing fluorescent antibodynanotubes. When viral pathogens were mixed with these antibodynanotubes, the nanotubes rapidly aggregated...

Gold (Au) nanoparticles (NPs) are a mainstay of current nanoscience and technology. With such a diversity of applications, developing a better understanding of the impact of macromolecular additives on single-phase fabrication routes, and ultimately on the resultant interfacial composition and structure (size, shape and dispersity), is critical to...

Capacitances of five types of viruses, adenovirus type 5 (AV5), herpes simplex virus type 1 (HSV1), simian virus 40 (SV40), vaccinia (MVA), and cowpea mosaic virus (CPMV), were compared by AC capacitance scanning probe microscopy. This technique, using a Pt-coated AFM tip as an electrode to probe capacitance of materials between the tip and a botto...

Submonolayer coatings of noble-metal nanoparticle liquids (NPLs) are shown to provide replenishable surfaces with robust asperities and metallic conductivity that extends the durability of electrical relays by 10 to 100 times (depending on the current driven through the contact) as compared to alternative approaches. NPLs are single-component mater...

High inorganic volume fraction, solventless nanoparticle liquids have many potential applications, including reconfigurable electronic materials. Materials such as conductive lubricants could find applications in MEMS devices to increase relay switch performance as one example. The ability of the conductive nanoparticles to reconfigure themselves a...

By minimizing the volume fraction of the organic corona necessary to generate a net long-range repulsive pair-potential (and thus maximizing inorganic volume fraction), neat nanoparticle assembles may exhibit liquid-like behavior, which affords intriguing possibilities for numerous applications including solvent-less inks for micro-fabrication and...

The peptide nano-rings containing Au nanoparticles inside their cavities were self-assembled on dithiol SAMs patterned as an array by AFM-based nanolithography. The peptide nano-rings were aligned as a line on these SAMs, and Au formed lines with the spacing between these nanoparticles as the peptide nano-rings functioned as spacers. This type of a...

Pathogen identification at highly sensitive levels is crucial to meet urgent needs in fighting the spread of disease or detecting bioterrorism events. Toward that end, a new method for biosensing utilizing fluorescent antibody nanotubes is proposed. Fundamental studies on the self-assembly of these peptide nanotubes are performed, as are applicatio...

The integration of multiple nanoparticles (NPs) with different physical properties into a multifunctional hybrid NP is a challenge. Here, a new wet chemical synthesis is used to generate hybrid NPs by the heterogeneous growth of one NP onto another equivalent-sized NP (see Figure). The hybrid NPs consist of Ag-NPs and Se-NPs in controlled nanoparti...

A variety of nanotubes were addressed to particular directions by using external forces such as microfluidics, magnetic fields, electric fields, and the Langmuir−Blodgett technique. Recently in another approach, nanotubes were assembled by chemical interactions. For example, nanotubes coated by proteins were assembled onto the complimentary ligand-...

Application of biotechnology in nanofabrication has an advantage to produce functional building-block materials that may not have synthetic counterparts. Here we introduced a new type of building block, antibody nanotubes, and demonstrated anchoring them on complementary antigen arrays via antibody-antigen recognition. Biological recognition betwee...

Protoporphyrin IX Zn(II) has been demonstrated to form metalloporphyrin coatings on peptide nanotubes via hydrogen bonds and produce metalloporphyrin nanotubes. This diacid metalloporphyrin was stabilized on the peptide nanotube surfaces with two types of hydrogen bonds, intermolecular hydrogen bond between the carboxylic acid of metalloporphyrins...

Attomolar detection of viruses utilizing a multifunctional peptide nanotube-based assay has been developed. Details of the mechanism of detection have been elucidated by TEM. Proof of principle experiments have demonstrated the multiplex ability of this assay, and its limit of detection for several viruses is reported.