@article{malhotra2025quantification,

title = {Quantification of Methane in Water at Parts Per Billion Sensitivity Using a Metal–Organic Framework-Functionalized Quartz Crystal Resonator},

author = {Jaskaran Singh Malhotra and Clara Dávila Duarte and Per Reichert and Deepthy Krishnan and Jonas Sundberg},

url = {https://pubs.acs.org/doi/abs/10.1021/acsanm.4c06883},

doi = {https://doi.org/10.1021/acsanm.4c06883},

year  = {2025},

date = {2025-02-26},

urldate = {2025-02-26},

journal = {ACS Applied Nano Materials},

publisher = {ACS Publications},

abstract = {Wetlands and water bodies are essential sources of methane emissions, a greenhouse gas that is roughly 25 times more potent than carbon dioxide. However, the biological production, fluxes, and interplay between methane and carbon dioxide due to microbial activity must be better understood. This is primarily attributed to the lack of sensor technology to provide the required spatial and temporal resolution. Herein, we demonstrate how a porous metal–organic framework material can create a sensor to quantify dissolved methane. The sensor is based on a quartz crystal microbalance, which measures methane adsorption using a quartz resonator functionalized with the material. Combining the quartz crystal microbalance and the nanoporous material yields fast response times and high sensitivity. This is due to a favorable partitioning coefficient between the empty pores of the material and the aqueous phase, promoting rapid migration of dissolved methane into the material. The result is a sensor system that achieves equilibration and response times under 60 s with parts per billion sensitivity. The high sensor performance is based on microporous pore size distribution, surface hydrophobicity, and crystallite size, yielding strong synergy. A fully functioning prototype has been designed, built, and evaluated to demonstrate real-life applicability and obtain a response from methane-spiked lake water. The modular nature of metal–organic frameworks opens possibilities for creating materials for selective sensing of other aqueous species. Thus, our study showcases the importance of materials for methane sensing and environmental monitoring in general.},

keywords = {chemical sensors, greenhouse gas emissions, hydrocarbons, Metal organic frameworks, methane monitoring, openQCM NEXT, QCM, Quartz Crystal Microbalance, Thin films, wetlands},

pubstate = {published},

tppubtype = {article}

}

@article{hunter2024covalent,

title = {Covalent Capture of Nanoparticle-Stabilized Oil Droplets via Acetal Chemistry Using a Hydrophilic Polymer Brush},

author = {Saul J Hunter and Evelin Csányi and Joshua JS Tyler and Mark A Newell and Matthew AH Farmer and Camery Ma and George Sanderson and Graham J Leggett and Edwin C Johnson and Steven P Armes},

url = {https://pubs.acs.org/doi/full/10.1021/acs.langmuir.4c03897},

doi = {https://doi.org/10.1021/acs.langmuir.4c03897},

year  = {2024},

date = {2024-12-06},

urldate = {2024-01-01},

journal = {Langmuir},

publisher = {ACS Publications},

abstract = {We report the capture of nanosized oil droplets using a hydrophilic aldehyde-functional polymer brush. The brush was obtained via aqueous ARGET ATRP of a cis-diol-functional methacrylic monomer from a planar silicon wafer. This precursor was then selectively oxidized using an aqueous solution of NaIO4 to introduce aldehyde groups. The oil droplets were prepared by using excess sterically stabilized diblock copolymer nanoparticles to prepare a relatively coarse squalane-in-water Pickering emulsion (mean droplet diameter = 20 μm). This precursor was then further processed via high-pressure microfluidization to produce ∼200 nm squalane droplets. We demonstrate that adsorption of these nanosized oil droplets involves acetal bond formation between the cis-diol groups located on the steric stabilizer chains and the aldehyde groups on the brush. This interaction occurs under relatively mild conditions and can be tuned by adjusting the solution pH. Hence this is a useful model system for understanding oil droplet interactions with soft surfaces.},

keywords = {Adsorption, lipids, Liquids, Nanoemulsions, nanoparticles, openQCM NEXT, QCM, QCM-D, Quartz Crystal Microbalance},

pubstate = {published},

tppubtype = {article}

}

@article{DATTILO2024114408,

title = {Molecularly Imprinted Polymers (MIPs) for SARS-CoV-2 Omicron variant inhibition: an alternative approach to address the challenge of emerging zoonoses},

author = {Marco Dattilo and Francesco Patitucci and Marisa Francesca Motta and Sabrina Prete and Roberta Galeazzi and Silvia Franzè and Ida Perrotta and Mariangela Cavarelli and Ortensia Ilaria Parisi and Francesco Puoci},

url = {https://www.sciencedirect.com/science/article/pii/S0927776524006672},

doi = {https://doi.org/10.1016/j.colsurfb.2024.114408},

issn = {0927-7765},

year  = {2024},

date = {2024-11-26},

urldate = {2024-01-01},

journal = {Colloids and Surfaces B: Biointerfaces},

pages = {114408},

abstract = {ABSTRACT 

Emerging zoonoses pose significant public health risks and necessitate rapid and effective treatment responses. This study enhances the technology for preparing Molecularly Imprinted Polymers (MIPs), which function as synthetic nanoparticles targeting SARS-CoV-2 receptor-binding domain (RBD), specifically the Omicron variant, thereby inhibiting its function. This study builds on previous findings by introducing precise adjustments in the formulation and process conditions to enhance particle stability and ensure better control over size and distribution, thereby overcoming the issues identified in earlier research. Following docking studies, imprinted nanoparticles were synthesized via inverse microemulsion polymerization and characterized in terms of size, morphology and surface charge. The selective recognition properties and ability of MIPs to obstruct the interaction between ACE2 and the RBD of SARS-CoV-2 were assessed in vitro, using Non-Imprinted Polymers (NIPs) as controls, and rebinding studies were conducted utilizing a Quartz Crystal Microbalance with Dissipation monitoring (QCM-D). The synthesized nanoparticles exhibited uniform dispersion and had a consistent diameter within the nanoscale range. MIPs demonstrated significant recognition properties and exhibited a concentration-dependent ability to reduce RBD binding to ACE2 without cytotoxic or sensitizing effects. MIPs-based platforms offer a promising alternative to natural antibodies for treating SARS-CoV-2 infections, therefore representing a versatile platform for managing emerging zoonoses.},

keywords = {Emulsion Polymerization, Molecular Recognition, Molecularly Imprinted Polymers (MIPs), Omicron Variant, openQCM NEXT, QCM, Quartz Crystal Microbalance, SARS-CoV-2, Spike Protein Receptor-Binding Domain (RBD)},

pubstate = {published},

tppubtype = {article}

}

@article{https://doi.org/10.1002/adfm.202414687,

title = {Acoustic Fingerprinting and Nanoslip Dynamics of Biofilms},

author = {Saikat Jana and Nikhil Bhalla},

url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/adfm.202414687},

doi = {https://doi.org/10.1002/adfm.202414687},

year  = {2024},

date = {2024-11-12},

journal = {Advanced Functional Materials},

volume = {n/a},

number = {n/a},

pages = {2414687},

abstract = {Abstract It is reported that bacteria can generate nanomotion, but understanding the complex dynamics of bacterial colony gliding on solid interfaces has remained unresolved. Here, this work captures the real-time development and gliding of bacterial biofilms on vibrating solids made of piezoelectric quartz. The gliding, characterized by liquid slips, is measured in form of frequency and dissipation changes of the vibrating solid. These vibrations enable the generation of distinct acoustic fingerprints (sound/ music) of the three phases of biofilm development: viscoelastic strengthening, biofilm growth and biofilm stability. In adition, the effect of extracellular matrix secretion on the rigidity of the film and its nanoslip in each of the distinct biofilm developmental phases is quantified. This work provides a real-time, label-free method of quantifying bacteria biofilm dynamics and paves the way for developing libraries of acoustic signatures of bacteria and their metabolic products.},

keywords = {acoustics, bacteria-music, biofilms, mutation, openQCM NEXT, QCM-D, Quartz Crystal Microbalance, vibrating-solids},

pubstate = {published},

tppubtype = {article}

}

@article{karchilakis2024capturing,

title = {Capturing Enzyme-Loaded Diblock Copolymer Vesicles Using an Aldehyde-Functionalized Hydrophilic Polymer Brush},

author = {Georgios Karchilakis and Spyridon Varlas and Edwin C Johnson and Oleta Norvilaite and Matthew AH Farmer and George Sanderson and Graham J Leggett and Steven P Armes},

url = {https://pubs.acs.org/doi/full/10.1021/acs.langmuir.4c01561},

doi = {https://doi.org/10.1021/acs.langmuir.4c01561},

year  = {2024},

date = {2024-06-27},

urldate = {2024-06-27},

journal = {Langmuir},

publisher = {ACS Publications},

abstract = {Compared to lipids, block copolymer vesicles are potentially robust nanocontainers for enzymes owing to their enhanced chemical stability, particularly in challenging environments. Herein we report that cis-diol-functional diblock copolymer vesicles can be chemically adsorbed onto a hydrophilic aldehyde-functional polymer brush via acetal bond formation under mild conditions (pH 5.5, 20 °C). Quartz crystal microbalance studies indicated an adsorbed amount, Γ, of 158 mg m–2 for vesicle adsorption onto such brushes, whereas negligible adsorption (Γ = 0.1 mg m–2) was observed for a control experiment conducted using a cis-diol-functionalized brush. Scanning electron microscopy and ellipsometry studies indicated a mean surface coverage of around 30% at the brush surface, which suggests reasonably efficient chemical adsorption. Importantly, such vesicles can be conveniently loaded with a model enzyme (horseradish peroxidase, HRP) using an aqueous polymerization-induced self-assembly formulation. Moreover, the immobilized vesicles remained permeable toward small molecules while retaining their enzyme payload. The enzymatic activity of such HRP-loaded vesicles was demonstrated using a well-established colorimetric assay. In principle, this efficient vesicle-on-brush strategy can be applied to a wide range of enzymes and functional proteins for the design of next-generation immobilized nanoreactors for enzyme-mediated catalysis.},

keywords = {Adsorption, openQCM NEXT, peptides, proteins, QCM-D, Quartz Crystal Microbalance, RAFT polymerization, Thickness, Vesicles},

pubstate = {published},

tppubtype = {article}

}

@article{buksa2024arginine,

title = {Arginine-Functional Methacrylic Block Copolymer Nanoparticles: Synthesis, Characterization, and Adsorption onto a Model Planar Substrate},

author = {Hubert Buksa and Edwin C Johnson and Derek HH Chan and Rory J McBride and George Sanderson and Rebecca M Corrigan and Steven P Armes},

url = {https://pubs.acs.org/doi/10.1021/acs.biomac.4c00128?goto=supporting-info},

doi = {https://pubs.acs.org/doi/10.1021/acs.biomac.4c00128?goto=supporting-info},

year  = {2024},

date = {2024-05-02},

urldate = {2024-05-02},

journal = {Biomacromolecules},

publisher = {ACS Publications},

abstract = {Recently, we reported the synthesis of a hydrophilic aldehyde-functional methacrylic polymer (Angew. Chem., 2021, 60, 12032–12037). Herein we demonstrate that such polymers can be reacted with arginine in aqueous solution to produce arginine-functional methacrylic polymers without recourse to protecting group chemistry. Careful control of the solution pH is essential to ensure regioselective imine bond formation; subsequent reductive amination leads to a hydrolytically stable amide linkage. This new protocol was used to prepare a series of arginine-functionalized diblock copolymer nanoparticles of varying size via polymerization-induced self-assembly in aqueous media. Adsorption of these cationic nanoparticles onto silica was monitored using a quartz crystal microbalance. Strong electrostatic adsorption occurred at pH 7 (Γ = 14.7 mg m–2), whereas much weaker adsorption occurred at pH 3 (Γ = 1.9 mg m–2). These findings were corroborated by electron microscopy, which indicated a surface coverage of 42% at pH 7 but only 5% at pH 3},

keywords = {aldehyde-functional, nanoparticles, openQCM NEXT, polymers, QCM, QCM-D, Quartz Crystal Microbalance},

pubstate = {published},

tppubtype = {article}

}

@article{astier2024controlling,

title = {Controlling Adsorption of Diblock Copolymer Nanoparticles onto an Aldehyde-Functionalized Hydrophilic Polymer Brush via pH Modulation},

author = {Samuel Astier and Edwin C Johnson and Oleta Norvilaite and Spyridon Varlas and Emma E Brotherton and George Sanderson and Graham J Leggett and Steven P Armes},

url = {https://pubs.acs.org/doi/full/10.1021/acs.langmuir.3c03392},

doi = {https://doi.org/10.1021/acs.langmuir.3c03392},

year  = {2024},

date = {2024-02-06},

urldate = {2024-02-06},

journal = {Langmuir},

publisher = {ACS Publications},

abstract = {Sterically stabilized diblock copolymer nanoparticles with a well-defined spherical morphology and tunable diameter were prepared by RAFT aqueous emulsion polymerization of benzyl methacrylate at 70 °C. The steric stabilizer precursor used for these syntheses contained pendent cis-diol groups, which means that such nanoparticles can react with a suitable aldehyde-functional surface via acetal bond formation. This principle is examined herein by growing an aldehyde-functionalized polymer brush from a planar silicon wafer and studying the extent of nanoparticle adsorption onto this model substrate from aqueous solution at 25 °C using a quartz crystal microbalance (QCM). The adsorbed amount, Γ, depends on both the nanoparticle diameter and the solution pH, with minimal adsorption observed at pH 7 or 10 and substantial adsorption achieved at pH 4. Variable-temperature QCM studies provide strong evidence for chemical adsorption, while scanning electron microscopy images recorded for the nanoparticle-coated brush surface after drying indicate mean surface coverages of up to 62%. This fundamental study extends our understanding of the chemical adsorption of nanoparticles on soft substrates.},

keywords = {Adsorption, Copolymers, nanoparticles, openQCM NEXT, QCM-D, Silicon, Solution chemistry},

pubstate = {published},

tppubtype = {article}

}

@article{wood2023phage,

title = {Phage display against two-dimensional metal-organic nanosheets as a new route to highly selective biomolecular recognition surfaces},

author = {Amelia C Wood and Edwin C Johnson and Ram RR Prasad and Mark V Sullivan and Nicholas W Turner and Steven P Armes and Sarah S Staniland and Jonathan A Foster},

url = {https://chemrxiv.org/engage/chemrxiv/article-details/6570ea7c29a13c4d47ce600d},

doi = {https://doi.org/10.26434/chemrxiv-2023-6dhn7},

year  = {2023},

date = {2023-12-08},

urldate = {2023-12-08},

abstract = {Peptides are important biomarkers for a range of diseases, however distinguishing different amino-acid sequences using artificial receptors remains a major challenge in biomedical sensing. Here we present a new approach to creating highly selective recognition surfaces using phage display biopanning against metal-organic nanosheets (MONs) and demonstrate their use as the next-generation of biomolecular recognition surfaces. Three MONs (ZIF-7, ZIF-7-NH2 and Hf-BTB-NH2) were chosen as initial targets to demonstrate how simple synthetic modifications can enhance selectivity towards specific amino acid sequences. Each MON system was added to a solution containing every possible combination of 7-residue peptides attached to bacteriophage hosts and the highest affinity binding peptides for each system was identified via successive biopanning rounds. In each case only a single peptide sequence was isolated (YNYRNLL – ZIF-7, NNWWAPA – ZIF-7-NH2 and FTVRDLS – Hf-BTB-NH2). This indicates that these MONs are highly selective, which is attributed to their 2D nanosheet structure. Zeta potential and contact angle measurements were conducted on each MON and combined with calculated properties for the peptide sequences and binding studies to provide insights into the relative importance of electrostatic, hydrophobic and co-ordination bonding interactions. A quartz crystal microbalance (QCM) was used to model phage binding and the Hf-BTB-NH2 MON coated QCM produced a 5-fold higher signal for FTVRDLS functionalised phage compared to phage with generic peptide sequences. Further studies focusing on Hf-BTB-NH2 confirmed that the VRDL sequence was highly conserved, and on-target binding exhibited equilibrium dissociation constants that are comparable to natural recognition materials. Surface plasmon resonance (SPR) studies indicated a 4600-fold higher equilibrium dissociation constant (KD) for FTVRDLS compared to those obtained for off-target sequences, comparable to those of antibodies (KD = 4 x10-10). We anticipate that the highly tunable nature of MONs will enhance our understanding of binding interactions and enable molecular recognition of biomedically important peptides.},

keywords = {Biopanning, Metal-organic framwork nanosheets (MONs), openQCM NEXT, peptide, Phage display, Sensing, two-dimensional materials},

pubstate = {published},

tppubtype = {article}

}

@article{milsom2023situ,

title = {In-situ measurements and modelling of the oxidation kinetics in films of a cooking aerosol proxy using a Quartz Crystal Microbalance with Dissipation monitoring (QCM-D)},

author = {Adam Milsom and Shaojun Qi and Ashmi Mishra and Thomas Berkemeier and Zhenyu Zhang and Christian Pfrang},

url = {https://acp.copernicus.org/articles/23/10835/2023/},

doi = {https://doi.org/10.5194/acp-23-10835-2023},

year  = {2023},

date = {2023-10-04},

urldate = {2023-10-04},

journal = {EGUsphere},

volume = {23},

issue = {19},

pages = {10835–10843},

publisher = {Copernicus Publications Göttingen, Germany},

abstract = {Aerosols and films are found in indoor and outdoor environments. How they interact with pollutants, such as ozone, has a direct impact on our environment via cloud droplet formation and the chemical persistence of toxic aerosol constituents. The chemical reactivity of aerosol emissions is typically measured spectroscopically or by techniques such as mass spectrometry, directly monitoring the amount of material during a chemical reaction. We present a study which indirectly measures oxidation kinetics in a common cooking aerosol proxy using a low-cost quartz crystal microbalance with dissipation monitoring (QCM-D). We validated this approach by comparison with kinetics measured both spectroscopically and with high-intensity synchrotron radiation. Using microscopy, we found that the film morphology changed and film rigidity increased during oxidation. There was evidence of surface crust formation on oxidised particles, though this was not consistent for all experiments. Crucially, our kinetic modelling of these experimental data confirmed that the oleic acid decay rate is in line with previous literature determinations, which demonstrates that performing such experiments on a QCM-D does not alter the underlying mechanism. There is clear potential to take this robust and low-cost but sensitive method to the field for in situ monitoring of reactions outdoors and indoors.},

keywords = {aerosol, Dissipation Monitoring, films, openQCM NEXT, Ozone, pollutants, pollution, QCM, QCM-D, Quartz Crystal Microbalance},

pubstate = {published},

tppubtype = {article}

}

@article{zholdassov2023kinetics,

title = {Kinetics of Photochemical and Mechanochemical Organic Reactions on Surface},

author = {Yerzhan Zholdassov},

url = {https://academicworks.cuny.edu/gc_etds/5476/},

year  = {2023},

date = {2023-09-01},

urldate = {2023-09-01},

abstract = {Solvents used in traditional chemical processes account for a large percentage of reaction mass and waste and can pose significant environmental and health risks. The environmentally friendly nature of mechanochemistry, in addition to other benefits, makes it a promising approach for sustainable chemistry over traditional solvent-based methods. However, it is still not a widely adopted method for performing chemical reactions on an industrial scale. This is partially due to the significant challenge associated with understanding the reaction kinetics under mechanochemical conditions. Many variations of scanning probe lithography (SPL) techniques are able to manipulate the organic molecules with precise control over force and position on surfaces, which offer unique opportunity to investigate the mechanochemical reactions at molecular level. Chapter 1 gives a review on recent advances in the application of SPL techniques in studying fundamental questions in mechanochemistry.



Polymer brushes, defined as thin polymer coatings in which individual polymer chains are tethered by one chain end to a solid interface. They are considered as the most powerful tools to interface properties. Potential applications of polymer brush patterns span a wide range from organic light emitting diodes (OLEDs) to membranes for desalination and gas separation, from tissue engineering to protein adsorption, controlled surface wettability and the study of fundamentals of cell biology. A number of controlled/“living” polymerization techniques, in particular those based on radical chemistry have been applied to generate such coatings on various types of substrates. It enables the grafting density, the thickness, and the chemistry of the coating to be manipulated very readily without altering the bulk mechanical properties of biomaterials. Responsive polymer brushes are a category of polymer brushes that are capable of conformational and chemical changes in response to external stimuli. They offer unique opportunities for the control of surface properties due to the precise control of chemical and structural parameters such as the brush thickness, density, chemistry, and architecture. In Chapter 2 we will discuss multiplexed stimuli responsive polymer brushes patterns that contain hidden information within the same area.



In Chapter 3 we apply novel printing platform to investigate the mechanosusceptibility of molecules to the applied mechanical energy. Mechanochemical solvent-free reactions by milling, grinding or other types of mechanical action have emerged as a viable alternative to solution chemistry. Mechanochemistry offers not only a possibility to eliminate the need for bulk solvent use, and reduce the generation of waste, but it also unlocks the door to a different reaction environment in which synthetic strategies, reactions and molecules previously not accessible in solution, can be achieved. We have used elastomeric tip arrays to precisely control the time and force applied between dienes and dienophiles on a surface to determine rate constants, activation energies and activation volumes for four reaction systems.},

key = {surface chemistry, mechanochemistry, photochemistry, openQCM, openQCM NEXT, QCM-D},

keywords = {mechanochemistry, openQCM, openQCM NEXT, photochemistry, QCM-D, surface chemistry},

pubstate = {published},

tppubtype = {article}

}

@article{hunter2023mucoadhesive,

title = {Mucoadhesive Pickering Nanoemulsions via Dynamic Covalent Chemistry},

author = {Saul J Hunter and Mahmoud H Abu Elella and Edwin C Johnson and Laura Taramova and Emma E Brotherton and Steven P Armes and Vitaliy V Khutoryanskiy and Mark J Smallridge},

url = {https://www.sciencedirect.com/science/article/pii/S0021979723014200},

doi = {https://doi.org/10.1016/j.jcis.2023.07.162},

year  = {2023},

date = {2023-07-27},

urldate = {2023-07-27},

journal = {Journal of Colloid and Interface Science},

publisher = {Elsevier},

abstract = {Hypothesis. Submicron oil droplets stabilized using aldehyde-functionalized nanoparticles should adhere to the primary amine groups present at the surface of sheep nasal mucosal tissue via Schiff base chemistry. Experiments. Well-defined sterically-stabilized diblock copolymer nanoparticles of 20 nm diameter were prepared in the form of concentrated aqueous dispersions via reversible addition-fragmentation chain transfer (RAFT) aqueous emulsion polymerization of 2,2,2-trifluoroethyl methacrylate (TFEMA) using a water-soluble methacrylic precursor bearing cis-diol groups. Some of these hydroxyl-functional nanoparticles were then selectively oxidized using an aqueous solution of sodium periodate to form a second batch of nanoparticles bearing pendent aldehyde groups within the steric stabilizer chains. Subjecting either hydroxyl- or aldehyde-functional nanoparticles to high-shear homogenization with a model oil (squalane) produced oil-in-water Pickering macroemulsions of 20-30 µm diameter. High-pressure microfluidization of such macroemulsions led to formation of the corresponding Pickering nanoemulsions with a mean droplet diameter of around 200 nm. Quartz crystal microbalance (QCM) experiments were used to examine adsorption of both nanoparticles and oil droplets onto a model planar substrate bearing primary amine groups, while a fluorescence microscopy-based mucoadhesion assay was developed to assess adsorption of the oil droplets onto sheep nasal mucosal tissue. Findings. Squalane droplets coated with aldehyde-functional nanoparticles adhered significantly more strongly to sheep nasal mucosal tissue than those coated with the corresponding hydroxyl-functional nanoparticles. This difference was attributed to the formation of surface imine bonds via Schiff base chemistry and was also observed for the two types of nanoparticles alone in QCM studies. Preliminary biocompatibility studies using planaria indicated only mild toxicity for these new mucoadhesive Pickering nanoemulsions, suggesting potential applications for the localized delivery of hydrophobic drugs.},

keywords = {Aldehyde-Functionalized Nanoparticles, Mucoadhesive Drug, Nanoemulsions, openQCM NEXT, QCM-D, Quartz Crystal Microbalance},

pubstate = {published},

tppubtype = {article}

}

@article{malhotra2023room,

title = {Room-temperature monitoring of CH4 and CO2 using a metal-organic framework-based QCM sensor showing inherent analyte discrimination},

author = {Jaskaran Singh Malhotra and Mariusz Kubus and Kasper Steen Pedersen and Simon Ivar Andersen and Jonas Sundberg},

url = {https://chemrxiv.org/engage/chemrxiv/article-details/646b938eccabde9f6e2fd280},

doi = {https://doi.org/10.26434/chemrxiv-2023-djhp2},

year  = {2023},

date = {2023-05-24},

urldate = {2023-05-24},

abstract = {The detection of methane and carbon dioxide is of growing importance due to their negative impact on global warming. This is true both for environmental monitoring, as well as leak detection in industrial processes. Although solid-state sensors are technologically mature, they have limitations that prohibit their use in certain situations, e.g., explosive atmospheres. Thus, there is a need to develop new types of sensor materials. Herein, we demonstrate a simple, low-cost metal-organic framework-based gas leak detection sensor. The system is based on gravimetric sensing using a quartz crystal microbalance. The quartz crystal is functionalized by layer-by-layer growth of a thin metal-organic framework film. This film shows selective uptake of methane or carbon dioxide under atmospheric conditions. The hardware has low cost, simple operation, and theoretically high sensitivity. Overall, the sensor is characterized by simplicity and high robustness. Furthermore, by exploiting the different adsorption kinetics as measured by multiple harmonics analyses, it is possible to discriminate whether the response is due to methane or carbon dioxide. In summary, we demonstrate data relevant towards new applications of metal-organic frameworks and microporous hybrid materials in sensing applications.},

keywords = {carbon dioxide, CH4, CO2, Dissipation, metal-organic frameworks, methane, openQCM NEXT, QCM, QCM-D, Quartz Crystal Microbalance, sensors},

pubstate = {published},

tppubtype = {article}

}

@article{maity2023chemically,

title = {Chemically routed interpore molecular diffusion in metal-organic framework thin films},

author = {Tanmoy Maity and Pratibha Malik and Sumit Bawari and Soumya Ghosh and Jagannath Mondal and Ritesh Haldar},

url = {https://pubmed.ncbi.nlm.nih.gov/37072404/},

doi = {https://doi.org/10.1038/s41467-023-37739-8},

year  = {2023},

date = {2023-04-18},

urldate = {2023-04-18},

journal = {Nature Communications},

volume = {14},

number = {1},

pages = {2212},

publisher = {Nature Publishing Group UK London},

abstract = {Transport diffusivity of molecules in a porous solid is constricted by the rate at which molecules move from one pore to the other, along the concentration gradient, i.e. by following Fickian diffusion. In heterogeneous porous materials, i.e. in the presence of pores of different sizes and chemical environments, diffusion rate and directionality remain tricky to estimate and adjust. In such a porous system, we have realized that molecular diffusion direction can be orthogonal to the concentration gradient. To experimentally determine this complex diffusion rate dependency and get insight of the microscopic diffusion pathway, we have designed a model nanoporous structure, metal-organic framework (MOF). In this model two chemically and geometrically distinct pore windows are spatially oriented by an epitaxial, layer-by-layer growth method. The specific design of the nanoporous channels and quantitative mass uptake rate measurements have indicated that the mass uptake is governed by the interpore diffusion along the direction orthogonal to the concentration gradient. This revelation allows chemically carving the nanopores, and accelerating the interpore diffusion and kinetic diffusion selectivity.},

keywords = {molecular diffusion, Nanoporous channels, openQCM NEXT, QCM, QCM-D, Quartz Crystal Microbalance},

pubstate = {published},

tppubtype = {article}

}

@article{qi2023porous,

title = {Porous Cellulose Thin Films as Sustainable and Effective Antimicrobial Surface Coatings},

author = {Shaojun Qi and Ioannis Kiratzis and Pavan Adoni and Aekkachai Tuekprakhon and Harriet James Hill and Zania Stamataki and Aneesa Nabi and David Waugh and Javier Rodriguez Rodriguez and Stuart Matthew Clarke and others},

url = {https://pubs.acs.org/doi/full/10.1021/acsami.2c23251},

doi = {https://doi.org/10.1021/acsami.2c23251},

year  = {2023},

date = {2023-03-29},

urldate = {2023-01-01},

journal = {ACS Applied Materials & Interfaces},

publisher = {ACS Publications},

abstract = {In the present work, we developed an effective antimicrobial surface film based on sustainable microfibrillated cellulose. The resulting porous cellulose thin film is barely noticeable to human eyes due to its submicrometer thickness, of which the surface coverage, porosity, and microstructure can be modulated by the formulations and the coating process. Using goniometers and a quartz crystal microbalance, we observed a threefold reduction in water contact angles and accelerated water evaporation kinetics on the cellulose film (more than 50% faster than that on a flat glass surface). The porous cellulose film exhibits a rapid inactivation effect against SARS-CoV-2 in 5 min, following deposition of virus-loaded droplets, and an exceptional ability to reduce contact transfer of liquid, e.g., respiratory droplets, to surfaces such as an artificial skin by 90% less than that from a planar glass substrate. It also shows excellent antimicrobial performance in inhibiting the growth of both Gram-negative and Gram-positive bacteria (Escherichia coli and Staphylococcus epidermidis) due to the intrinsic porosity and hydrophilicity. Additionally, the cellulose film shows nearly 100% resistance to scraping in dry conditions due to its strong affinity to the supporting substrate but with good removability once wetted with water, suggesting its practical suitability for daily use. Importantly, the coating can be formed on solid substrates readily by spraying, which requires solely a simple formulation of a plant-based cellulose material with no chemical additives, rendering it a scalable, affordable, and green solution as antimicrobial surface coating. Implementing such cellulose films could thus play a significant role in controlling future pan- and epidemics, particularly during the initial phase when suitable medical intervention needs to be developed and deployed.},

key = {cellulose, film, antimicrobial, evaporation, SARS-CoV-2, robustness},

keywords = {antimicrobial, cellulose, evaporation, film, openQCM NEXT, QCM, QCM-D, Quartz Crystal Microbalance, robustness, SARS-CoV-2},

pubstate = {published},

tppubtype = {article}

}