UMBC Chemistry & Biochemistry Department

Permanent URI for this collectionhttp://hdl.handle.net/11603/55

Browse

Now showing 1 - 20 of 447

Colloidal stabilization of hydrophobic InSe 2D nanosheets in a model environmental aqueous solution and their impact on Shewanella oneidensis MR-1
(The Royal Society of Chemistry, 2024-02-16) Sengupta, Shreyasi; Ambade, Swapnil B.; O'Keefe, Tana L.; Tawakalna, Falak; Orbeck, Jenny K. Hedlund; Hamers, Robert J.; Feng, Z. Vivian; Haynes, Christy L.; Rosenzweig, Zeev
Semiconductor InSe 2D nanomaterials have emerged as potential photoresponsive materials for broadly distributed photodetectors and wearable electronics technologies due to their high photoresponsivity and thermal stability. This paper addresses an environmental concern about the fate of InSe 2D nanosheets when disposed and released into the environment after use. Semiconducting materials are potentially reactive and often form environmentally damaging species, for example reactive oxygen and nitrogen species, when degraded. InSe nanosheets are prepared using a semi bottom-up approach which involves a reaction between indium and selenium precursors at elevated temperature in an oxygen-free environment to prevent oxidation. InSe nanosheets are formed as a stable intermediate with micrometer-sized lateral dimensions and a few monolayer thickness. The InSe 2D nanosheets are obtained when the reaction is stopped after 30 minutes by cooling. Keeping the reaction at elevated temperature for a longer period, for example 60 minutes leads to the formation of InSe 3D nanoparticles of about 5 nm in diameter, a thermodynamically more stable form of InSe. The paper focuses on the colloidal stabilization of InSe nanosheets in an aqueous solution that contains epigallocatechin gallate (EGCG), a natural organic matter (NOM) simulant. We show that EGCG coats the surface of the hydrophobic, water-insoluble InSe nanosheets via physisorption. The formed EGCG-coated InSe nanosheets are colloidally stable in aqueous solution. While unmodified semiconducting InSe nanosheets could produce reactive oxygen species (ROS) when illuminated, our study shows low levels of ROS generation by EGCG-coated InSe nanosheets under ambient light, which might be attributed to ROS quenching by EGCG. Growth-based viability (GBV) assays show that the colloidally stable EGCG-coated InSe nanosheets adversely impact the bacterial growth of Shewanella oneidensis MR-1, an environmentally relevant Gram-negative bacterium in aqueous media. The impact on bacterial growth is driven by the EGCG coating of the nanosheets. In addition, live/dead assays show insignificant membrane damage of the Shewanella oneidensis MR-1 cells by InSe nanosheets, suggesting a weak association of EGCG-coated nanosheets with the cells. It is likely that the adverse impact of EGCG-coated nanosheets on bacterial growth is the result of increasing local concentration of EGCG either when adsorbed on the nanosheets when the nanosheets interact with the cells, or when desorbed from the EGCG-coated nanosheets to interact with the bacterial cells.
Chemical Addition of Octadecane (C18) to 3D-Printed Parts for Surface Activation with Example Applications
(ACS, 2025-04-25) Terrell, John; Jones, Curtis G.; Kabandana, Giraso Keza Monia; Chen, Chengpeng
3D-printing has experienced rapid growth in both research and industry due to its ability to quickly prototype intricate structures, utilize standardized and sharable CAD files, and enable customizable fabrication. While modern 3D printers allow for easy customization of geometry and dimensions, the limited number of options for modifying the surface chemistry of 3D-printed parts restricts the full potential of this technology. In this work, we present an accessible chemical protocol for functionalizing 3D-printed surfaces with octadecane (C18), a commonly used stationary phase in chromatography. This functionalization serves as a versatile platform, enabling strong retention of a wide range of molecules on 3D-printed surfaces via partitioning, thus chemically activating the surface. Thorough quantitative characterizations confirmed the effectiveness of this approach. To demonstrate new opportunities that can be unlocked by the C18-functionalized 3D-printed parts, we showcased applications including protein and enzyme immobilization for sensing, customized solid-phase extraction probes, drug loading and release, and the retention of an antiseptic reagent for effective bacteria elimination in a leaching-free manner. This study substantially enhances the potential of 3D-printing by enabling surface chemistry customization alongside traditional shape customization, thereby promoting future discoveries and innovations.
Understanding the effects of amine and morpholine adsorption on unglazed earthenware using density functional theory
(Elsevier, 2023-05-01) Heimann, Jessica; Rosenzweig, Zeev; Bennett, Joseph
Recent efforts within the field of conservation science have focused on understanding how chemicals off-gassed from common storage materials impact museum objects. One source of particular concern is the identification of amines and morpholines as chemicals volatilized from polyester polyurethane foam, which is used extensively as crate padding for artwork storage and transport. Although a white-colored efflorescence on the surface of objects has been linked with amines off-gassed from these foams, little is known about the surface interactions that lead to these deposits. In the present work, periodic density functional theory (DFT) is used to investigate the molecular-level interactions that occur when clay mineral surfaces (such as those encountered in unglazed earthenware objects) are exposed to amines and alkylmorpholines. The data obtained here show that energetically favorable interactions are observed when kaolinite, partially dehydrated kaolinite, and metakaolin surfaces are exposed to different categories of amines including neutral amines, amine salts, morpholines, and morpholinium salts. Furthermore, it is demonstrated that surface dehydration is a key factor in how reactive a structure is toward these amine adsorbates. Special precautions are therefore recommended when storing unglazed earthenware in the presence of polyester polyurethane foam.
Teaching chemists to code with diversity in mind: a pedagogy of belonging for end-user conditions
(2025-04-04) Staveren, Marie van
While teaching students to code is a valuable skill, we need to consider the equity implications of such instruction. Computer programming is a highly stereotyped activity, and as such can negatively impact a student’s sense of chemistry identity. This is likely to be especially acute for students from historically excluded groups. Recommendations for coding instruction that will support a student’s sense of chemistry identity are given. These include pedagogies that encourage student interaction (Live Coding, spending class time for introductory instruction), differentiating by prior knowledge, and knowing how computer scientists talk about coding. By using pedagogies that increase student’s chemistry identity during programming instruction, we can send the message that all students belong in our field.
Active Learning, New Occupancy Models, and Collaborative Research Enhance Interdisciplinary Science
(Tradeline, 2013-02-01) Carbasho, Tracy; Cuddy, Dennis P.; LaCourse, William
The University of Maryland in Baltimore County (UMBC) is surpassing expectations for student retention, faculty recruitment, and productivity by using active learning, pioneering research models, and new building occupancy criteria in its Interdisciplinary Life Sciences Building (ILSB). The 130,000-gsf building, which opened in 2019, provides 70,000 nasf of flexible research and education space to accommodate current and future students and faculty in the life sciences and biotechnology programs.
Simultaneous Multicolor Imaging of Lymph Node Chains Using Hydroporphyrin-Doped Near-Infrared-Emitting Polymer Dots
(Taylor & Francis, 2023-04-01) Kato, Takuya; Riahin, Connor; Furusawa, Aki; Fukushima, Hiroshi; Wakiyama, Hiroaki; Okuyama, Shuhei; Takao, Seiichiro; Choyke, Peter L.; Ptaszek, Marcin; Rosenzweig, Zeev; Kobayashi, Hisataka
Aim: Evaluation of lymphatic drainage can be challenging to differentiate between separate drainage basins because only one ‘color’ is typically employed in sentinel node studies. This study aimed to test the feasibility of multicolor in vivo lymphangiography using newly developed organic polymer dots. Materials & methods: Biocompatible, purely organic, hydroporphyrin-doped near-infrared-emitting polymer dots were developed and evaluated for in vivo multicolor imaging in mouse lymph nodes. Results & conclusion: The authors demonstrated successful multicolor in vivo fluorescence lymphangiography using polymer dots, each tuned to a different emission spectrum. This allows minimally invasive visualization of at least four separate lymphatic drainage basins using fluorescent nanoparticles, which have the potential for clinical translation.
A systematic comparison of ACE-FTS δD retrievals with airborne in situ sampling
(2025-04-04) Clouser, Benjamin Wade; KleinStern, Carly Cyd; Desmoulin, Adrien; Singer, Clare E.; St. Clair, Jason; Hanisco, Thomas F.; Sayres, David S.; Moyer, Elisabeth J.
The isotopic composition of water vapor in the upper troposphere and lower stratosphere (UTLS) can be used to understand and constrain the budget and pathways of water transport into that region of the atmosphere. Measurements of the water isotopic composition help further understanding of the region's chemistry, radiative budget, and the sublimation and growth of polar stratospheric clouds and high-altitude cirrus, both of which are also important to stratospheric chemistry and Earth's radiation budget. Here we present the first intercomparison of water isotopic composition δD using in situ measurements from the ChiWIS, Harvard ICOS, and Hoxotope instruments and satellite retrievals from ACE-FTS. The in situ data comes from the AVE-WIIF, TC4, CR-AVE, StratoClim, and ACCLIP field campaigns, and satellite retrievals of isotopic composition are derived from the ACE-FTS v5.2 data set. We find that in all campaign intervals, the satellite retrievals above about 14 km altitude are depleted by up to 150 ‰ with respect to in situ measurements. We also use in situ measurements from the ChiWIS instrument, which has flown in both the Asian Summer Monsoon (AM) and the North American Monsoon (NAM), to confirm the isotopic enhancement in δD observed in satellite retrievals above the NAM.
Meeting report: Seventh summer school on innovative approaches for identification of antiviral agents (IAAASS)
(Elsevier, 2025-06-01) Corona, Angela; Cagno, Valeria; Grandi, Nicole; Fanunza, Elisa; Esposito, Francesca; Seley-Radtke, Katherine; Tramontano, Enzo
The 7th Summer School on Innovative Approaches for the Identification of Antiviral Agents (IAAASS) was held at the Sardegna Ricerche Research Park in Santa Margherita di Pula, Sardinia, Italy from September 23–27, 2024, organized by the Co.S.Me.Se, the Department of Life and Environmental Sciences of the University of Cagliari and Sardegna Ricerche in the frame of Next Generation Virology initiative and the Antiviral DiscoVery Initiatives: Educating Next-Gen Scientists (ADVISE Project) 2024. The Summer School is proposed as an informal high-level event comprehensive of the different scientific souls involved in the design and development of new antiviral drug-candidates and their validation and progression up-to the clinic, and it offers, to a limited number of early career scientists, high-level lectures, networking and mentoring opportunities by internationally recognized scientists in a highly interactive environment. The meeting was a very successful event that convened 21 senior speakers with internationally recognized experience in the field of antiviral research and 60 Early Career Scientists (graduated master students, PhD students and early post doctoral researchers) from 13 different countries (Belarus, Belgium, Brazil, Bulgaria, Chile, Denmark, Germany, Italy, Russian Federation, Spain, Switzerland, The Netherlands, and the USA).
A new method for Monitoring seafood quality and spoilage using a novel dye Reagent, alizarin red S activated Si-HOBt
(Elsevier, 2024-08-01) Seh Noel Guei, Jules; Kalivretenos, Aristotle; LaCourse, William
Ensuring adequate food quality is essential for the health and safety of consumers and populations worldwide. Monitoring seafood and fish quality indicators during processing, storage, and on store shelves is critical to anticipate spoilage and quality deterioration, consequently preventing fish poisoning and fish-borne illnesses. Common chemical indicators of fish quality deterioration and spoilage are biogenic amines (BAs). BAs are endogenous amines found at low levels in microorganisms, plants, and animals, where they play contributing roles in the biosynthesis of nucleic acids, proteins, alkaloids, and hormones. They are the result of biochemical reactions between amines and carbonyl-containing compounds (i.e., ketones or aldehydes) but also the products of the bacterial-induced decarboxylation of unbound amino acids in cells. As fish quality degrades due to several factors, including spoilage induced by increased bacterial and enzymatic activities, handling, and temperature, the concentrations of biogenic amines increase to unhealthy levels for humans. Consumption of fish and fish products containing high concentrations of biogenic amines has been attributed to fish-related toxicity and illnesses. A common fish-borne illness in humans is scombroid poisoning (histamine poisoning), which occurs as a result of consumption of fish from Scombridae and Scomberesocidae families (i.e., mackerel, tuna, mahi-mahi, etc.). Government health officials worldwide have established safe levels or concentration limits for biogenic amines to ensure and maintain fish quality and safety. In the United States, the United States Food and Drug Administration (USFDA) has set histamine concentrations not to equal or exceed 50 mg/kg for a whole fish, while the European Union establishes the maximum dose of histamine at 100–––200 mg/kg for fish and 400 mg/kg for fish products. In Brazil, the maximum concentration of histamine in whole and gutted fish is set at 10 mg/100 g. Many qualitative and quantitative methods to analyze biogenic amines have been developed and used to monitor the quality of fish and fish products . A common method for biogenic amines analyses in fish is reversed-phase HPLC with pre or post-column derivatization. One of the common derivatizing reagents for BAs in fish is ophthalaldehyde (OPA). However, OPA only derivatized primary amines and the derivatized products are unstable. Herein, we are reporting a novel sensitive and versatile reagent, a red dye, alizarin red S activated silica-bound 1-hydroxybenzotriazole (alizarin red S activated Si-HOBt), for off-line pre-column derivatization of biogenic amines, including histamine, tyramine, putrescine, diethylamine, pyrrolidine, phenylethylamine, and isopropylamine followed by their qualitative and quantitative analysis using HPLC-UV. Mackerel, a fish from the Scombridae family, was used in the application. The chromatographic run time was less than 1 h, BAs were extracted in acetonitrile/triethylamine, and the derivatized biogenic amines were stable at room temperature and in the chromatographic conditions.
Front Cover: Geometry-Independent Ultrafast Energy Transfer in Bioinspired Arrays Containing Electronically Coupled BODIPY Dimers as Energy Donors (Chem. Eur. J. 58/2023)
(Wiley, 2023) Ansteatt, Sara; Gelfand, Rachel; Pelton, Matthew; Ptaszek, Marcin
Arrays composed of a electronically coupled BODIPY dimer as energy donor and chlorins as energy acceptors show broad absorption profiles and ultrafast ( 10 ps) energy transfer, regardless of the array architecture, and may serve as bioinspired light-harvesting antennas for solar energy conversion. More information can be found in the Research Article by M. Pelton, M. Ptaszek and co-workers (DOI: 10.1002/chem.202301571).
Optimized Preparation of Segmentally Labeled RNAs for NMR Structure Determination
(Elsevier, 2025-03-05) Grossman, Brian D.; Beyene, Bethel G.; Tekle, Bersabel; Sakowicz, William; Ji, Xinjie; Camacho, Joshua Miguele; Vaishnav, Nandini; Ahmed, Amina; Bhandari, Naman; Desai, Kush; Hardy, Josiah; Hollman, Nele M.; Marchant, Jan; Summers, Michael F.
RNA structures are significantly underrepresented in public repositories (∼ 100-fold compared to proteins) despite their importance for mechanistic understanding and for development of structure prediction/validation tools. A substantial portion of deposited RNA structures have been determined by NMR (∼30%), but most comprise fewer than 60 nucleotides due to complications associated with NMR signal overlap. A promising approach for applying NMR to larger RNAs involves use of a mutated DNA polymerase (TGK) that can extend “primer” RNA strands generated independently by synthetic or enzymatic methods [Haslecker et al., Nature Commun. 2023]. In attempts to employ this technology, we uncovered sequence- and enzyme-dependent complications for most constructs examined that prohibited preparation of homogeneous samples. By using TGK extension efficiency and NMR as guides, we identified non-templated run-on by wild-type T7-RNA polymerase (RNAPWT) as the primary source of product heterogeneity. Use of 2′-O-methylated DNA templates did not prevent RNAPWT run-on for most constructs examined. However, primer RNAs with appropriate 3′ end homogeneity were obtained in high yield using a recently described T7 RNAP mutant designed for improved immunogenic behavior. Minor spectral heterogeneity sometimes observed for 3′ residues, caused by partial premature TGK termination, could be moved to sites downstream of the RNA region of interest by employing extended template DNAs that encode additional non-interacting 3′ nucleotides. We additionally present an approach for large-scale synthesis of homogeneous template DNA required for TGK extension. With these modifications, segmentally labeled RNAs appropriate for high resolution structural studies are now routinely obtainable.
A 3D Hepatocyte Model with Composite Nanofibers that Reproduced Human in vivo Drug Clearance Profiles
(2025-03-04) Park, Rudolph; Chen, Chengpeng
This study presents a novel in vitro 3D hepatocyte model that contains a nanofibrous scaffold designed to mimic the extracellular matrix (ECM) of the human liver, both structurally and biochemically. A modular 3D-printed device housing the ECM scaffold was also developed, readily fitting in well plates. HepaRG hepatocytes cultured on the scaffold exhibited enhanced metabolic activity compared to traditional 2D cultures, indicating improved hepatocyte functionality. Drug clearance studies with lidocaine, clozapine, and fluoxetine demonstrated significantly faster clearance rates on the scaffold, closely aligning with in vivo results from literature, while 2D cultures showed limited metabolic capacity. This model offers a physiologically relevant platform for hepatocyte studies. The findings underscore the model’s potential to advance preclinical drug development by replicating liver-specific functions in vitro.
3D-Printed Microfluidic-Based Cell Culture System With Analysis to Investigate Macrophage Activation
(Wiley, 2025-2-18) Selemani, Major A.; Kabandana, Giraso Keza Monia; Chen, Chengpeng; Martin, R. Scott
In this paper, we describe the development of 3D-printed microfluidic cell culture devices that can be coupled with a circulation system to study the dynamics of both intracellular and extracellular (release) processes. Key to this approach is the ability to quantitate key analytes on a minutes timescale with either on-line (in this study, quantitating nitric oxide production using an amperometric flow cell) or off-line (in this work, quantitating intracellular itaconate production with LC/MS) analytical measurements. To demonstrate the usefulness of this approach, we chose to study macrophage polarization as a function of the extracellular matrix (silk) fiber size, a major area of research in tissue engineering. It was found that the use of larger fibers (1280 nm vs. smaller 512 nm fibers) led to increases in the production of both nitric oxide and itaconate. These findings set the foundation for future research for the creation of finely tuned microfluidic 3D cell culture approaches in areas where flow and the extracellular matrix play a significant role in barrier transport and where integrated analysis of key markers is needed.
Application of the Rd/w framework to assess Donnan dialysis performance
(Elsevier, 2023-12-01) Chen, Hui; Souizi, Sahar; Stewart, Kaylyn; Blaney, Lee
Donnan dialysis exploits electrochemical potential gradients across ion-exchange membranes to separate ions between feed and draw solutions. This technique has been applied for treatment and recovery of chemicals in water and wastewater. Previous studies have arbitrarily selected the draw solution chemistry, making it difficult to fairly compare experimental outcomes. A universal framework is needed to standardize design and interpretation of Donnan dialysis systems. We calculated the Rd/w parameter, which is related to the draw ion concentrations in the feed and draw solutions at Donnan equilibrium, for previous studies. Rd/w values were used to determine theoretical recoveries and compare them to experimental outcomes. Of the literature data, 57% matched the theoretical recovery, 37% underperformed due to operating time constraints or transport limitations, and 6% outperformed Donnan equilibrium due to use of integrated processes. Ultimately, this work highlights the benefits of the Rd/w framework for standardizing interpretation of Donnan dialysis systems.
Recent Advances in Wearable Sweat Sensor Development
(Wiley, 2025) Zhang, Tao; Kabandana, Giraso Keza Monia; Terrell, John A.; Chen, Hui; Chen, Chengpeng
Wearable sweat sensors for detecting biochemical markers have emerged as a transformative research area, with the potential to revolutionize disease diagnosis and human health monitoring. Since 2016, a substantial body of pioneering and translational work on sweat biochemical sensors has been reported. This review aims to provide a comprehensive summary of the current state-of-the-art in the field, offering insights and perspectives on future developments. The focus is on wearable microfluidic platforms for sweat collection and delivery and the analytical chemistry applicable to wearable devices. Various microfluidic technologies, including those based on synthetic polymers, paper, textiles, and hydrogels, are discussed alongside diverse detection methods such as electrochemistry and colorimetry. Both the advantages and current limitations of these technologies are critically examined. The review concludes with our perspectives on the future of wearable sweat sensors, with the goal of inspiring new ideas, innovations, and technical advancements to further the development and practical application of these devices in promoting human health.
Identification of a macrocyclic compound targeting the lassa virus polymerase
(Elsevier, 2024-08-01) Aida-Ficken, Virginia; Kelly, Jamie A.; Chatterjee, Payel; Jenks, M. Harley; McMullan, Laura K.; Albariño, César G.; Montgomery, Joel M.; Seley-Radtke, Katherine L.; Spiropoulou, Christina F.; Flint, Mike
There are no approved vaccines or therapeutics for Lassa virus (LASV) infections. To identify compounds with anti-LASV activity, we conducted a cell-based screening campaign at biosafety level 4 and tested almost 60,000 compounds for activity against an infectious reporter LASV. Hits from this screen included several structurally related macrocycles. The most potent, Mac128, had a sub-micromolar EC50 against the reporter virus, inhibited wild-type clade IV LASV, and reduced viral titers by 4 orders of magnitude. Mechanistic studies suggested that Mac128 inhibited viral replication at the level of the polymerase.
Meeting report of the 37th International Conference on Antiviral Research in Gold Coast, Australia, May 20?24, 2024, organized by the International Society for Antiviral Research
(Elsevier, 2024-12-01) Welch, Stephen R.; Bilello, John P.; Carter, Kara; Delang, Leen; Dirr, Larissa; Durantel, David; Feng, Joy Y.; Gowen, Brian B.; Herrero, Lara J.; Janeba, Zlatko; Kleymann, Gerald; Lee, Alpha A.; Meier, Chris; Moffat, Jennifer; Schang, Luis M.; Schiffer, Joshua T.; Seley-Radtke, Katherine L.; Sheahan, Timothy P.; Spengler, Jessica R.
The 37th International Conference on Antiviral Research (ICAR) was held in Gold Coast, Australia, May 20–24, 2024. ICAR 2024 featured over 75 presentations along with two poster sessions and special events, including those specifically tailored for trainees and early-career scientists. The meeting served as a platform for the exchange of cutting-edge research, with presentations and discussions covering novel antiviral compounds, vaccine development, clinical trials, and therapeutic advancements. A comprehensive array of topics in antiviral science was covered, from the latest breakthroughs in antiviral drug development to innovative strategies for combating emerging viral threats. The keynote presentations provided fascinating insight into two diverse areas fundamental to medical countermeasure development and use, including virus emergence at the human-animal interface and practical considerations for bringing antivirals to the clinic. Additional sessions addressed a variety of timely post-pandemic topics, such as the hunt for broad spectrum antivirals, combination therapy, pandemic preparedness, application of in silico tools and AI in drug discovery, the virosphere, and more. Here, we summarize all the presentations and special sessions of ICAR 2024 and introduce the 38th ICAR, which will be held in Las Vegas, USA, March 17–21, 2025.
Recent advances in microalgae-driven carbon capture, utilization, and storage: Strain engineering through adaptive laboratory evolution and microbiome optimization
(Elsevier, 2024-11-09) He, Zhongshi; Wang, Jing; Li, Yantao
The potential of microalgae as a biological resource for carbon capture, utilization, and storage (CCUS) has been extensively discussed. Although genetic engineering methods have been employed to improve microalgal phenotypes, they often face challenges related to public concerns regarding genetically modified organisms. By contrast, adaptive laboratory evolution (ALE) and microbiome optimization have emerged as promising non-genetic modification strategies, with notable success in bacterial models. In microalgae, ALE has been employed to improve resilience against varying environmental and stress factors and increase carbon capture efficiency, and for the production of valuable bioproducts through gradual accumulation of beneficial mutations following manual or automated selection. Furthermore, advancements in the understanding of microbial symbiotic relationships in the phycosphere have facilitated microbiome optimization in microalgal cultivation systems, significantly improving their functionality and productivity. In this study, we provide a comprehensive overview of the latest advancements in ALE and microbiome optimization of microalgae for CCUS across different carbon emission scenarios, including flue gas, biogas, wastewater, and landfill leachate. We further discuss the current challenges and future directions for the integration of ALE with microbiome optimization, focusing on the potential synergies of these methodologies. Overall, ALE and microbiome optimization are promising approaches to direct microalgae for environmental and industrial CCUS applications, thereby reducing global carbon emissions and addressing climate change challenges.
Direct Detection and Quantification of Aqueous Proteins via a Fluorescent Probe Through the Use of Fluorophore-Induced Plasmonic Current
(MDPI, 2025-02-27) Pierce, Daniel; Geddes, Chris
We report on the recent advancements in the sensing of proteins, both directly and with the use of a fluorescent probe, through the use of Fluorophore-Induced Plasmonic Current (FIPC). FIPC are a phenomenon where a fluorophore or excited state species is in close proximity to a plasmonically active metal nanoparticle film (MNF), and the excited state is able to couple to the particle, ultimately leading to enhanced spectroscopic properties. This phenomenon is similar to the well-reported metal-enhanced fluorescence (MEF) phenomenon, wherein the coupled complex produces an enhanced fluorescence emission and a shorter lifetime. However, if the particles themselves are sufficiently spaced and oriented, an induced current can transfer from each discreet particle to the next, creating a detectable current across the film. This detectable current has a magnitude that is proportional to the fluorescent properties of the species that produced it, and can be affected by the polarization of the excitation source; the spacing and size of the particles on the film; the overlap between the spectral properties of the film and the species; as well as externally applied voltages and currents. In this study, we examined whether it is possible to detect protein species, directly due to both their intrinsic fluorescent and absorptive properties, and how that compares to commercially available protein detection probes, in a similar manner to prior work by our group addressing analyte detection via turn-on fluorescent probes. This FIPC-based detection technique is a novel method that has not been used for the detection of proteins, and the use of this method could expand the dynamic sensing range of first-pass testing, while overcoming some of the physical limitations on the upper limit of detection of both absorption spectroscopy and fluorescence emission spectroscopy. Our experiments sought to highlight the selectivity of FIPC-based detection relative to both fluorescence and absorption spectroscopy, as well as its sensitivity when working with protein analytes. We examined the effects of protein concentration, intrinsic fluorescent properties, and turn-on probes, as well as how these techniques compare to traditional analytical techniques used today.
Enhanced Line Narrowing of Selectively Labeled [9-15N] Guanosine Enables Probing of Large RNAs
(2025-02-04) Attionu, Solomon; Dill, Rita; Summers, Michael; Case, David; Marchant, Jan; Dayie, T. Kwaku
RNA regulates various cellular processes using malleable 3D structures and characterizing their structural dynamics is critical to shedding light on their mechanism of action. To mitigate continuing limitations on studies of large RNA by solution NMR spectroscopy, we have extended a recently described 2H-enhanced, 1H-15N correlation approach by developing a chemoenzymatic labeling technology that grafts selectively labeled [9-15N]-Guanine on to any available labeled ribose to make [9-15N]-GTP. The low CSA of the N9 nucleus (~112 ppm) in combination with extensive ribose deuteration leads to long-lived NMR signals that enable chemical shift assignment, analyze the structure of three biologically relevant large RNA constructs pivotal to viral life cycles [human hepatitis B virus ? RNA (61nt), the HIV-1 primer binding site segment RNA (103 nt), and the HIV-1 Rev response element (232 nt)], observe N9-H8 and N9-H1? correlations, and measure longitudinal and transverse relaxation rates for RNAs as large as 78 kDa. We show CSA dominates both N7 (>99%) and N9 (>90%) relaxation and enables straightforward analysis of dynamics. Taken together, application of these selective labels in conjunction with optimized NMR pulse sequences could help us push the limits of size restrictions in RNA NMR structural biology beyond 100 nt.

Browse

Recent Submissions