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Two-dimensional (2D) boron nitride (BN) and molybdenum disulfide (MoS(2)) materials are increasingly being used for applications due to novel chemical, electronic and optical properties. Although generally considered biocompatible, recent data have shown that BN and MoS(2) could be potentially hazardous under some biological conditions, e.g., during, biodistribution of drug carriers or imaging agents to the liver. However, the effects of these 2D materials on liver cells such as Kupffer cells (KCs), liver sinusoidal endothelial cells (LSECs), and hepatocytes, are unknown. Here, we compared the toxicity of BN and MoS(2), dispersed in Pluronic F87 (designated BN-PF and MoS(2)-PF) with aggregated forms of these materials (BN-Agg and MoS(2)-Agg) in liver cells. MoS(2) induced dose-dependent cytotoxicity in KCs, but not other cell types, while the BN derivatives were non-toxic. The effect of MoS(2) could be ascribed to nanosheet dissolution and the release of hexavalent Mo, capable of inducing mitochondrial ROS generation and caspases 3/7-mediated apoptosis in KUP5 cells. In addition, the phagocytosis of MoS(2)-Agg triggered an independent response pathway involving lysosomal damage, NLRP3 inflammasome activation, caspase-1 activation, IL-1β and IL-18 production. These findings demonstrate the importance of Mo release and the state of dispersion of MoS(2) in impacting Kupffer cell viability.

As a representative two-dimensional (2D) nanomaterial, graphene oxide (GO) has shown high potential in many applications due to its large surface area, high flexibility, and excellent dispersibility in aqueous solutions. These properties make GO an ideal candidate for bio-imaging, drug delivery, and cancer therapy. When delivered to the body, GO has been shown to accumulate in the liver, the primary accumulation site of systemic delivery or secondary spread from other uptake sites, and induce liver toxicity. However, the contribution of the GO physicochemical properties and individual liver cell types to this toxicity is unclear due to property variations and diverse cell types in the liver. Herein, we compare the effects of GOs with small (GO-S) and large (GO-L) lateral sizes in three major cell types in liver, Kupffer cells (KCs), liver sinusoidal endothelial cells (LSECs), and hepatocytes. While GOs induced cytotoxicity in KCs, they induced significantly less toxicity in LSECs and hepatocytes. For KCs, we found that GOs were phagocytosed that triggered NADPH oxidase mediated plasma membrane lipid peroxidation, which leads to PLC activation, calcium flux, mitochondrial ROS generation, and NLRP3 inflammasome activation. The subsequent caspase-1 activation induced IL-1β production and GSDMD-mediated pyroptosis. These effects were lateral size-dependent with GO-L showing stronger effects than GO-S. Amongst the liver cell types, decreased cell association and the absence of lipid peroxidation resulted in low cytotoxicity in LSECs and hepatocytes. Using additional GO samples with different lateral sizes, surface functionalities, or thickness, we further confirmed the differential cytotoxic effects in liver cells and the major role of GO lateral size in KUP5 pyroptosis by correlation studies. These findings delineated the GO effects on cellular uptake and cell death pathways in liver cells, and provide valuable information to further evaluate GO effects on the liver for biomedical applications.

Fouling of surfaces remains one of the largest challenges in the field of water filtration. Electrically conductive surfaces have shown antifouling capabilities under organic foulants. Additionally, two-dimensional nanomaterials—e.g., graphene oxide (GO), reduced graphene oxide (rGO) and molybdenum disulfide (MoS2)—have antifouling properties and can be used to modify conductive polymer surfaces for the mitigation of fouling. Here, the surface attachment of foulants was investigated as a function of the surface charge by applying an external voltage. The release behavior of deposited foulants from polypyrrole surfaces modified with GO (GO-PPy), rGO-2h (rGO-PPy) and MoS2 (MoS2-PPy) was also studied. An electrochemical quartz crystal microbalance with dissipation monitoring (EQCM-D) was used for attachment and release studies of the foulants during external voltage application. Bovine serum albumin (BSA) was used as a model protein foulant in this study. Results show that it was possible to delay the attachment of the BSA foulant (more than 75%) on rGO-PPy and MoS2-PPy surfaces upon the application of −0.5 VAg/AgCl due to the electrostatic repulsion created by the external negative voltage on the surface. Moreover, the BSA attachment rate slows down by 92% and 91% on the rGO-PPy and MoS2-PPy surfaces compared to the bare PPy surface under the no voltage condition. Conversely, applying a voltage of +0.5 VAg/AgCl was not effective in delaying the attachment of BSA due to the presence of positively charged areas on the BSA surface. During the release study, it was found that it is possible to release the deposited BSA from all of the surfaces by NaCl electrolysis upon application of a voltage of +0.74 VAg/AgCl. Continuous generation of free chlorine (HOCl and OCl−) due to the oxidizing current produced on PPy and functionalized surfaces during external voltage application accelerates the degradation of the deposited BSA, resulting in the release of the foulant from the surface.

The influence of functional groups on the degradation of graphene oxide nanomaterials under direct sunlight was investigated by systematically varying the surface chemistry. Using a solvothermal reduction process, graphene nanomaterials with varying oxidation levels, including graphene oxide, partially reduced graphene oxide and fully reduced graphene oxide, were prepared. The physical and chemical properties of the nanomaterials were extensively characterized before and after exposure to simulated sunlight. The degradation of the nanomaterials was determined to be directly related to the functional groups present on the basal plane of the graphene nanomaterials. Specifically, the hydroxyl and epoxy functional groups are the most susceptible to photodegradation. Upon sunlight exposure, the amount of oxygen-containing functional groups on all graphene nanomaterials decreases over time, with fully reduced graphene oxide showing the lowest degradation rate due to the presence of fewer reactive functional groups on the surface. Overall, these results suggest that the oxygen-containing functional groups on the basal plane are the major initiators of the photodegradation of graphene nanomaterials.

Hexagonal boron nitride (hBN) is a thermally conductive yet electrically insulating two-dimensional layered nanomaterial that has attracted significant attention as a dielectric for high-performance electronics in addition to playing a central role in thermal management applications. Here, we report a high-content hBN-polymer nanocomposite ink, which can be 3D printed to form mechanically robust, self-supporting constructs. In particular, hBN is dispersed in poly(lactic-co-glycolic acid) and 3D printed at room temperature through an extrusion process to form complex architectures. These constructs can be 3D printed with a composition of up to 60% vol hBN (solids content) while maintaining high mechanical flexibility and stretchability. The presence of hBN within the matrix results in enhanced thermal conductivity (up to 2.1 W K–1 m–1) directly after 3D printing with minimal postprocessing steps, suggesting utility in thermal management applications. Furthermore, the constructs show high levels of cytocomp...

Fouling remains one of the biggest challenges in a myriad of applications such as water filtration, ship hulls, biomedical devices, coating, and painting. Fouling severely hampers the performance and increases the operation and maintenance costs in industries. There is a critical need to develop antifouling surfaces, and two-dimensional (2D) materials, such as graphene oxide (GO) and molybdenum disulfide (MoS2), have shown potential for antifouling surface preparation due to some unique properties. Here, the antifouling properties of these two materials were investigated by observing the deposition kinetics of bacteria and natural organic matter (NOM) using a quartz crystal microbalance with dissipation monitoring (QCM-D). Suwannee River humic acid (SRHA) and E. coli K-12 were used as model NOM and bacteria, respectively. Overall, MoS2 showed slightly better antifouling properties compared to GO. In most cases, the deposition of NOM and E. coli was significantly lower on MoS2 than GO due to the presence of functional groups on GO that bind more easily with the foulants. Deposition of NOM was at least 1.5 times lower on the MoS2 surface than on the GO surface in the presence of both monovalent (Na+) and divalent (Mg2+) cations. However, the presence of 0.5 mM divalent cations (Ca2+, Mg2+) with NOM reduced the antifouling properties of both MoS2 and GO by a factor of ≥1.5 due to a salt bridging effect and reduced energy barrier.

The electronic properties of single-walled carbon nanotubes (SWCNTs) are potentially useful for electronics, optics, and sensing applications. Depending on the chirality and diameter, individual SWCNTs can be classified as semiconducting (S-SWCNT) or metallic (M-SWCNT). From a biological perspective, the hazard profiling of purified metallic versus semiconducting SWCNTs has been pursued only in bacteria, with the conclusion that aggregated M-SWCNTs are more damaging to bacterial membranes than S-SWCNTs. However, no comparative studies have been performed in a mammalian system, where most toxicity studies have been undertaken using relatively crude SWCNTs that include a M:S mix at 1:2 ratio. In order to compare the toxicological impact of SWCNTs sorted to enrich them for each of the chirality on pulmonary cells and the intact lung, we used density gradient ultracentrifugation and extensive rinsing to prepare S- and M-SWCNTs that are >98% purified. In vitro screening showed that both tube variants trigger similar amounts of interleukin 1β (IL-1β) and transforming growth factor (TGF-β1) production in THP-1 and BEAS-2B cells, without cytotoxicity. Oropharyngeal aspiration confirmed that both SWCNT variants induce comparable fibrotic effects in the lung and abundance of IL-1β and TGF-β1 release in the bronchoalveolar lavage fluid. There was also no change in the morphology, membrane integrity, and viability of E. coli, in contradistinction to the previously published effects of aggregated tubes on the bacterial membrane. Collectively, these data indicate that the electronic properties and chirality do not independently impact SWCNT toxicological impact in the lung, which is of significance to the safety assessment and incremental use of purified tubes by industry.

Indium monoselenide (InSe) is an emerging two-dimensional semiconductor with superlative electrical and optical properties whose full potential for high-performance electronics and optoelectronics has been limited by the lack of reliable large-area thin-film synthesis methods. The difficulty in InSe synthesis lies in the complexity of the indium-selenium phase diagram and inadequate understanding of how this complexity is manifested in the growth of thin films. Herein, we present a systematic method for synthesizing InSe thin films by pulsed laser deposition followed by vacuum thermal annealing. The controlled phase evolution of the annealed InSe thin films is elucidated using a comprehensive set of in situ and ex situ characterization techniques. The annealing temperature is identified as the key parameter in controlling phase evolution with pure thin films of InSe developed within a window of 325 °C to 425 °C. To exert finer stoichiometric control over the as-deposited InSe thin film, a co-deposition scheme utilizing InSe and In2Se3 pulsed laser deposition targets is employed to mitigate the effects of mass loss during annealing, ultimately resulting in the synthesis of centimeter-scale, thickness-tunable e-InSe thin films with high crystallinity. The optimized InSe thin films possess a strong optoelectronic response, exhibited by phototransistors with high responsivities up to 103 A/W. Additionally, enhancement-mode InSe field-effect transistors are fabricated over large areas with device yields exceeding 90% and high on/off current modulation greater than 104, realizing a degree of electronic uniformity previously unattained in InSe thin-film synthesis.

Fouling remains a major challenge for the longevity of filtration membranes and their application in membrane-based treatment facilities. Polymers, such as polysulfone (Psf) and polyamide (PA) that are used as commercial and laboratory ultrafiltration and nanofiltration membranes, are prone to severe fouling over the course of their lifetime. In this study, polyethersulfone (PES) membranes were coated with two-dimensional nanomaterials, including graphene oxide (GO), reduced graphene oxide (rGO), and molybdenum disulfide (MoS2). The effect of the nanosheets on the pressure-driven water transport and antifouling performance of the modified membranes was investigated in terms of water permeability, initial flux decline under simulated fouling condition, and flux recovery ratio (FRR). The GO functionalized membrane significantly impedes water transport due to the side-pinning effect of functional groups. 32% reduction in C–O and 35% reduction in overall oxygen content of GO by reducing thermally it to rGO, restored the permeability by 300%. However, despite the higher initial water flux, the rGO functionalized membranes were still more prone to fouling than GO due to the increase in hydrophobicity. Conversely, MoS2 nanosheets with no functional groups offer a frictionless water flow through nanochannels. The smooth MoS2/PES membrane showed better antifouling performance than both the GO and rGO functionalized membranes while providing 3.7 times faster water transport.

The family of two-dimensional (2D) materials is comprised of a continually expanding palette of unique compositions and properties with potential applications in electronics, optoelectronics, energy capture and storage, catalysis, and nanomedicine. To accelerate the implementation of 2D materials in widely disseminated technologies, human health and environmental implications need to be addressed. While extensive research has focused on assessing the toxicity and environmental fate of graphene and related carbon nanomaterials, the potential hazards of other 2D materials have only recently begun to be explored. Herein, the toxicity and environmental fate of post-carbon 2D materials, such as transition metal dichalcogenides, hexagonal boron nitride, and black phosphorus, are reviewed as a function of their preparation methods and surface functionalization. Specifically, we delineate how the hazard potential of 2D materials is directly related to structural parameters and physicochemical properties, and how experimental design is critical to the accurate elucidation of the underlying toxicological mechanisms. Finally, a multidisciplinary approach for streamlining the hazard assessment of emerging 2D materials is outlined, thereby providing a pathway for accelerating their safe use in a range of technologically relevant contexts.

While 2-dimensional graphene oxide (GO) is used increasingly in biomedical applications, there is uncertainty on how specific physicochemical properties relate to biocompatibility in mammalian systems. Although properties such as lateral size and the colloidal properties of the nanosheets are important, the specific material properties that we address here is the oxidation state and reactive surface groups on the planar surface. In this study, we used a GO library, comprised of pristine, reduced (rGO), and hydrated GO (hGO), in which quantitative assessment of the hydroxyl, carboxyl, epoxy and carbon radical contents were used to study the impact on epithelial cells and macrophages, as well as in the murine lung. Strikingly, we observed that hGO, which exhibits the highest carbon radical density, was responsible for the generation of cell death in THP-1 and BEAS-2B cells as a consequence of lipid peroxidation of the surface membrane, membrane lysis, and cell death. In contrast, pristine GO had lesser effects while rGO showed extensive cellular uptake with minimal effects on viability. In order to see how these in vitro effects relate to adverse outcomes in the lung, mice were exposed to GOs by oropharyngeal aspiration. Animal sacrifice after 40h demonstrated that hGO was more prone than other materials in generating acute lung inflammation, accompanied by the highest lipid peroxidation in alveolar macrophages, cytokine production (LIX, MCP-1) and LDH release in bronchoalveolar lavage fluid. Pristine GO showed less toxicity while rGO had minimal effects. In summary, we demonstrate that the surface oxidation state and carbon radical content play major roles in the induction of toxicity by GO in mammalian cells and the lung.

Conditions for the dispersion of molybdenum disulfide (MoS2) in aqueous solution at concentrations up to 0.12 mg mL(-1) using a range of nonionic, biocompatible block copolymers (i.e., Pluronics and Tetronics) are identified. Furthermore, the optimal Pluronic dispersant for MoS2 is found to be effective for a range of other 2D materials such as molybdenum diselenide, tungsten diselenide, tungsten disulfide, tin selenide, and boron nitride.

The aggregation and stability of graphene oxide (GO) and three successively reduced GO (rGO) nanomaterials were investigated. Reduced GO species were partially reduced GO (rGO-1h), intermediately reduced GO (rGO-2h), and fully reduced GO (rGO-5h). Specifically, influence of pH, ionic strength, ion valence, and presence of natural organic matter (NOM) were studied. Results show that stability of GO in water decreases with successive reduction of functional groups, with pH having the greatest influence on rGO stability. Stability is also dependent on ion valence and the concentration of surface functional groups. While pH did not noticeably affect stability of GO in the presence of 10 mM NaCl, adding 0.1 mM CaCl2 reduced stability of GO with increased pH. This is due to adsorption of Ca(2+) ions on the surface functional groups of GO which reduces the surface charge of GO. As the concentration of rGO functional groups decreased, so did the influence of Ca(2+) ions on rGO stability. Critical coagulation concentrations (CCC) of GO, rGO-1h, and rGO-2h were determined to be ∼ 200 mM, 35 mM, and 30 mM NaCl, respectively. In the presence of CaCl2, CCC values of GO and rGO are quite similar, however. Long-term studies show that a significant amount of rGO-1h and rGO-2h remain stable in Call's Creek surface water, while effluent wastewater readily destabilizes rGO. In the presence NOM and divalent cations (Ca(2+), Mg(2+)), GO aggregates settle from suspension due to GO functional group bridging with NOM and divalent ions. However, rGO-1h and rGO-2h remain suspended due to their lower functional group concentration and resultant reduced NOM-divalent cation bridging. Overall, pH, divalent cations, and NOM can play complex roles in the fate of rGO and GO.

Research and development of two-dimensional transition metal dichalcogenides (TMDC) (e.g., molybdenum disulfide [MoS2]) in electronic, optical, and catalytic applications has been growing rapidly. However, there is little known regarding the behavior of these particles once released into aquatic environments. Therefore, an in-depth study regarding the fate and transport of two popular types of MoS2 nanomaterials, lithiated (MoS2-Li) and Pluronic PF-87 dispersed (MoS2-PL), was conducted in saturated porous media (quartz sand) to identify which form would be least mobile in aquatic environments. The electrokinetic properties and hydrodynamic diameters of MoS2 as a function of ionic strength and pH were determined using a zeta potential analyzer and dynamic light scattering techniques. Results suggest that the stability is significantly decreased beginning at 10 and 31.6 mM KCl, for MoS2-PL and MoS2-Li, respectively. Transport study results from breakthrough curves, column dissections, and release experiments suggest that MoS2-PL exhibits a greater affinity to be irreversibly bound to quartz surfaces as compared with the MoS2-Li at a similar ionic strength. Derjaguin–Landau–Verwey–Overbeek theory was used to help explain the unique interactions between the MoS2-PL and MoS2-Li surfaces between particles and with the quartz collectors. Overall, the results suggest that the fate and transport of MoS2 is dependent on the type of MoS2 that enters the environment, where MoS2-PL will be least mobile and more likely be deposited in porous media from pluronic–quartz interactions, whereas MoS2-Li will travel greater distances and have a greater tendency to be remobilized in sand columns.

Efficient energy storage systems based on lithium-ion batteries represent a critical technology across many sectors including consumer electronics, electrified transportation, and a smart grid accommodating intermittent renewable energy sources. Nanostructured electrode materials present compelling opportunities for high-performance lithium-ion batteries, but inherent problems related to the high surface area to volume ratios at the nanometer-scale have impeded their adoption for commercial applications. Here, we demonstrate a materials and processing platform that realizes high-performance nanostructured lithium manganese oxide (nano-LMO) spinel cathodes with conformal graphene coatings as a conductive additive. The resulting nanostructured composite cathodes concurrently resolve multiple problems that have plagued nanoparticle-based lithium-ion battery electrodes including low packing density, high additive content, and poor cycling stability. Moreover, this strategy enhances the intrinsic advantages of nano-LMO, resulting in extraordinary rate capability and low temperature performance. With 75% capacity retention at a 20C cycling rate at room temperature and nearly full capacity retention at -20 °C, this work advances lithium-ion battery technology into unprecedented regimes of operation.

© 2016 American Chemical Society. While the antibacterial properties of graphene oxide (GO) have been demonstrated across a spectrum of bacteria, the critical role of functional groups is unclear. To address this important issue, we utilized reduction and hydration methods to establish a GO library with different oxidation, hydroxyl, and carbon radical (•C) levels that can be used to study the impact on antibacterial activity. Using antibiotic-resistant bacteria as a test platform, we found that the •C density is most proximately associated with bacterial killing. Accordingly, hydrated GO (hGO), with the highest •C density, had the strongest antibacterial effects through membrane binding and induction of lipid peroxidation. To explore its potential applications, we demonstrated that coating of catheter and glass surfaces with hGO is capable of killing drug-resistant bacteria. In summary, •C is the principle surface moiety that can be utilized for clinical applications of GO-based antibacterial coatings.

Carbon nanotubes (CNTs) exhibit a number of physicochemical properties that contribute to adverse biological outcomes. However, it is difficult to define the independent contribution of individual properties without purified materials. A library of highly purified single-walled carbon nanotubes (SWCNTs) of different lengths is prepared from the same base material by density gradient ultracentrifugation, designated as short (318 nm), medium (789 nm), and long (1215 nm) SWCNTs. In vitro screening shows length-dependent interleukin-1β (IL-1β) production, in order of long > medium > short. However, there are no differences in transforming growth factor-β1 production in BEAS-2B cells. Oropharyngeal aspiration shows that all the SWCNTs induce profibrogenic effects in mouse lung at 21 d postexposure, but there are no differences between tube lengths. In contrast, these SWCNTs demonstrate length-dependent antibacterial effects on Escherichia coli, with the long SWCNT exerting stronger effects than the medium or short tubes. These effects are reduced by Pluronic F108 coating or supplementing with glucose. The data show length-dependent effects on proinflammatory response in macrophage cell line and antibacterial effects, but not on collagen deposition in the lung. These data demonstrate that over the length scale tested, the biological response to highly purified SWCNTs is dependent on the complexity of the nano/bio interface.

© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. 2D molybdenum disulfide (MoS2) has distinct optical and electronic properties compared to aggregated MoS2, enabling wide use of these materials for electronic and biomedical applications. However, the hazard potential of MoS2 has not been studied extensively. Here, a comprehensive analysis of the pulmonary hazard potential of three aqueous suspended forms of MoS2 - aggregated MoS2 (Agg-MoS2), MoS2 exfoliated by lithiation (Lit-MoS2), and MoS2 dispersed by Pluronic F87 (PF87-MoS2) - is presented. No cytotoxicity is detected in THP-1 and BEAS-2B cell lines. However, Agg-MoS2 induces strong proinflammatory and profibrogenic responses in vitro. In contrast, Lit- and PF87-MoS2 have little or no effect. In an acute toxicity study in mice, Agg-MoS2 induces acute lung inflammation, while Lit-MoS2 and PF87-MoS2 have little or no effect. In a subchronic study, there is no evidence of pulmonary fibrosis in response to all forms of MoS2. These data suggest that exfoliation attenuates the toxicity of Agg-MoS2, which is an important consideration toward the safety evaluation and use of nanoscale MoS2 materials for industrial and biological applications. The pulmonary hazard potential of three forms of MoS2 - aggregated (Agg-MoS2), lithiation-exfoliated (Lit-MoS2), and Pluronic F87 dispersed MoS2 (PF87-MoS2) - is studied. Although Agg-MoS2 induces profibrogenic responses in vitro and acute lung inflammation in vivo, Lit- and PF87-MoS2 have no such effect. These data suggest that exfoliation attenuates Agg-MoS2's toxicity, which is important toward its industrial and biological applications.

Supramolecular hydrogels (SMHs) are three-dimensional constructs wherein the majority of the volume is occupied by water. Since the bonding forces between the components of SMHs are noncovalent, SMH properties are often tunable, stimuli responsive, and reversible, which enables a range of applications including triggered drug release, sensing, and tissue engineering. Meanwhile, single-walled carbon nanotubes (SWCNTs) possess high aspect ratios, superlative electrical and thermal conductivities, high mechanical strength and resilience, and strong optical absorption at near-infrared wavelengths that have the potential to add unique functionality to SMHs. However, SWCNT-based SMHs have thus far not fully realized this potential, particularly not yet utilizing the optical properties of SWCNTs to enable reversible response to near-infrared irradiation. Here, we present a novel SMH architecture comprised solely of DNA and SWCNTs, wherein noncovalent interactions between DNA and SWCNTs provide structural integrity to the SMH without compromising the intrinsic properties of SWCNTs. The mechanical properties of these SWCNT-DNA SMHs are readily tuned by varying the relative concentrations of DNA and SWNCNTs, which varies the density of cross-linking as shown by molecular dynamics simulations. Moreover, the SWCNT-DNA SMH gelation transition is fully reversible and can be triggered by a change in temperature or near-infrared irradiation. This work explores a new regime for SWCNT-DNA SMHs with potential utility for a range of applications including sensors, actuators, responsive substrates, and 3D printing.

Assembled polydimethylsiloxane microfluidic devices were modified with a sulfobetaine polymer through continuous “tip-to-tip” modification, significantly reducing blood clotting and extending device patency under blood flow. This technology can be designed to enable the development of devices that can continuously work in whole blood, especially in an extracorporeal or in vivo environment.

We have developed a rapid, nondestructive analytical method that estimates the thickness of a surface polymer layer with high precision but unknown accuracy using a single attenuated total reflection Fourier transform infrared (ATR FT-IR) measurement. Because the method is rapid, nondestructive, and requires no sample preparation, it is ideal as a process analytical technique. Prior to implementation, the ATR FT-IR spectrum of the substrate layer pure component and the ATR FT-IR and real refractive index spectra of the surface layer pure component must be known. From these three input spectra a synthetic mid-infrared spectral matrix of surface layers 0 nm to 10 000 nm thick on substrate is created de novo. A minimum statistical distance match between a process sample's ATR FT-IR spectrum and the synthetic spectral matrix provides the thickness of that sample. We show that this method can be used to successfully estimate the thickness of polysulfobetaine surface modification, a hydrated polymeric surface layer covalently bonded onto a polyetherurethane substrate. A database of 1850 sample spectra was examined. Spectrochemical matrix-effect unknowns, such as the nonuniform and molecularly novel polysulfobetaine-polyetherurethane interface, were found to be minimal. A partial least squares regression analysis of the database spectra versus their thicknesses as calculated by the method described yielded an estimate of precision of ±52 nm.