FACULTY RESEARCH SPOTLIGHT · 2026

Into the Infrared and Beyond: Zamkov Lab Opens New Frontiers for Quantum Shell Science

Mikhail Zamkov, Ph.D.  ·  Professor  ·  Department of Physics and Astronomy & Center for Photochemical Sciences

The first months of 2026 have already confirmed that the Zamkov Lab's extraordinary output from 2023–2025 was not a peak but a launching point. Three new publications — appearing in ACS Nano, ACS Energy Letters, and Chemistry of Materials — expand the quantum shell research program into new spectral territory, new materials processing strategies, and new cross-laboratory collaborations, while continuing to reveal unexpected and scientifically significant optical phenomena in these remarkable nanostructures.

Note: All three 2026 papers published January–May 2026; research ongoing

PAPER 1: QUANTUM SHELLS ENTER THE NEAR-INFRARED

Published in: ACS Nano, 20(4), 3776–3790 · January 15, 2026

Authors: D. Harankahage, D. Nazar, K. Molkens, M.V. Bondarchuk, C.M. Hicks, A.A. Marder, M. Montemurri, A. Roach, I. Tanghe, L. Sun, R.D. Schaller, B.T. Diroll, A.V. Malko, A.N. Tarnovsky, D. Van Thourhout, Z. Hens, P. Geiregat, M. Zamkov

DOI: 10.1021/acsnano.5c18640

Collaborating Institutions: BGSU, Ghent University, Argonne National Lab, UT Dallas, KAUST

Every version of the quantum shell platform the Zamkov Lab has explored to date — CdS/CdSe/CdS, CdS-CdSe-CdS-ZnS, giant quantum shells — has operated in the visible spectral range. The emitting CdSe shell produces light in the red to near-infrared, but always above approximately 700 nm. Many of the most important applications for colloidal nanocrystal emitters — biological imaging through tissue, fiber-optic telecommunications, night-vision technologies, and thermal sensing — require emission at longer wavelengths, in the 900–1400 nm range that is sometimes called the first and second biological transparency windows.

This landmark ACS Nano paper extends the quantum shell architecture into near-infrared wavelengths for the first time, by replacing the CdSe emitting shell with mercury-containing materials. Two new quantum shell compositions are characterized: CdS/HgS/CdS and CdS/HgCdSe/ZnS. The mercury-containing shells have substantially smaller bandgaps than CdSe, shifting the emission deep into the NIR. The CdS/HgS/CdS shells achieve tunable emission across the NIR with photoluminescence quantum yields reaching approximately 60% below 1000 nm and up to 30% near 1300 nm — performance that is competitive with or superior to existing NIR-emitting colloidal nanocrystal systems.

Optical gain and stimulated emission were observed in the CdS/HgS/CdS system — a critical result for laser applications. In the CdS/HgCdSe/ZnS system, however, the transient absorption measurements (contributed by BGSU's Dr. Tarnovsky) revealed an unexpected phenomenon: instead of optical gain, these shells display a photoinduced absorption — an increase in light absorption rather than gain — despite demonstrating comparably strong Auger suppression. The investigation of this paradox led to a fundamental discovery: the formation of bound multiexciton complexes — correlated clusters of charge carriers — whose collective energies fall below the bandgap of the single-exciton transition.

These bound exciton complexes create long-lived sub-bandgap multiexciton states that persist at room temperature — a rare and scientifically important phenomenon. They open pathways toward a new class of nonlinear NIR photonic phenomena, including biexciton-exciton cascade emission, optical modulation, and single-exciton gain — capabilities that are not achievable in conventional quantum dots or in the visible-range quantum shells previously studied by the group.

Bound multiexciton complexes at room temperature in the near-infrared: a phenomenon that opens entirely new territory for nonlinear nanophotonics.

The paper is a 17-author, four-institution collaboration connecting the Zamkov Lab at BGSU with the Geiregat group at Ghent University (Belgium), the Diroll/Schaller group at Argonne National Laboratory, and the Malko group at UT Dallas — reflecting the global network of collaborators that the quantum shell program has assembled over the past several years. Dr. Liangfeng Sun and Dr. Alexander Tarnovsky of the BGSU CPS both appear as co-authors, contributing spectroscopic expertise central to the characterization.

PAPER 2: EUTECTIC PROCESSING — A NEW PATH TO NANOCRYSTAL INTEGRATION

Published in: ACS Energy Letters · 2026 (Article ASAP)

Authors: D. Harankahage, W. Martin, E. Elce, S. Thennakoon, B. Thennakoon, M.M. Kannen, N. Kholmicheva, B. Kayira, A.D. Waters, D. Nazar, J. Huang, P. Anzenbacher, A.V. Malko, M. Zamkov

DOI: 10.1021/acsenergylett.6c00100

One of the persistent challenges in deploying colloidal nanocrystals in practical devices — solar cells, LEDs, photodetectors, scintillators — is the problem of integration: how do you take nanocrystals synthesized in solution and incorporate them into functional solid-state architectures without degrading their optical properties or disrupting their quantum confinement? The most common approaches — spin-coating, drop-casting, and layer-by-layer deposition — work well for thin films but have limitations for thick, three-dimensional structures or for applications requiring precise control of nanocrystal density and spatial arrangement.

This ACS Energy Letters paper introduces a conceptually different approach: eutectic processing of semiconductor colloidal nanocrystals for energy applications. A eutectic is a mixture of two or more substances that has a lower melting point than any of its pure components — a phenomenon exploited in metallurgy for centuries to control how materials solidify. The Zamkov Lab's innovation is to apply eutectic processing principles to nanocrystal systems, using the eutectic behavior of specific nanocrystal mixtures to achieve controlled, low-temperature solidification into dense, uniform matrices without the ligand exchange, annealing, or sintering steps that typically degrade optical performance.

The result is a materials processing strategy that preserves the quantum confinement and optical properties of the nanocrystals while enabling their integration into three-dimensional solid-state structures. For energy applications — photovoltaics, scintillators, and photodetectors — this opens new design space for devices that require thick, efficient nanocrystal layers that current thin-film deposition methods cannot produce.

The paper also demonstrates the breadth of the Zamkov Lab's collaborative network: Dr. Anzenbacher contributed spectroscopic characterization expertise, and former graduate students Nadia Kholmicheva and Barbra Kayira — now alumni — appear as co-authors alongside current students Dulanjan Harankahage, Amelia Waters, Divesh Nazar, Jiamin Huang, and Maxwell Kannen. The inclusion of Siddhartha and Bolinda Thennakoon as co-authors reflects additional collaborative connections within and beyond the BGSU CPS community.

Eutectic processing brings a metallurgical principle into the nanocrystal lab — and opens a new path to deploying quantum shells in devices that thin-film methods cannot reach.

PAPER 3: PBS NANOPLATELETS WITH LEAD SULFOBROMIDE SHELLS

Published in: Chemistry of Materials, 38(3), 1170–1177 · January 19, 2026

Authors: S. Aryal, Y. Tang, D. Harankahage, M. Zamkov, L. Sun

DOI: 10.1021/acs.chemmater.5c02480

Note: Open Access; cross-group with Liangfeng Sun Lab

This paper, a collaboration between the Zamkov Lab and the adjacent research group of Dr. Liangfeng Sun (also a CPS member), introduces a new class of colloidal semiconductor nanostructure: PbS nanoplatelets — atomically thin, two-dimensional sheets of lead sulfide — with spontaneously formed inorganic lead sulfobromide and lead bromide shells. The work extends the quantum-confined nanocrystal program in a different dimensional direction: from spherical quantum shells to quasi-two-dimensional nanoplatelet architectures in the lead chalcogenide material system, which is of particular interest for near-infrared applications and next-generation solar cells.

PbS nanoplatelets synthesized in bromide-containing media spontaneously develop inorganic shells with type-I band alignment — meaning that both electrons and holes are concentrated within the PbS core, maximizing radiative recombination efficiency. The resulting core-shell structures emit in the near-infrared with a remarkably narrow photoluminescence peak of 78 meV at room temperature — one of the narrowest linewidths reported for any infrared-emitting colloidal nanostructure. The inorganic shells also passivate surface defect states, suppressing the non-radiative recombination that typically limits the quantum yield of unshelled PbS nanostructures.

This paper represents the Zamkov Lab's entry into the nanoplatelet space — a direction that complements the quantum shell (spherical) and quantum dot programs and further expands the range of nanocrystal architectures the group can bring to bear on photonic and energy applications. Published as an Open Access article in Chemistry of Materials, it is freely available to researchers worldwide — reflecting the NSF's expectation that publicly funded research be broadly accessible.

A UNIFIED RESEARCH VISION

2026: The Quantum Shell Program Expands in Every Direction

Three papers in the first five months of 2026 — into the near-infrared, into new processing methods, and into a new dimensional architecture — confirm that the Zamkov Lab's quantum shell program is not narrowing toward a single application but expanding across an increasingly broad frontier of nanophotonic science. The bound exciton discovery in NIR quantum shells is the kind of fundamental, unexpected finding that opens new research directions for years to come. The eutectic processing paper is a practical materials innovation that addresses a real bottleneck in device integration. And the PbS nanoplatelet paper demonstrates that the group's nanocrystal synthesis expertise extends well beyond the CdSe/CdS system that has defined the quantum shell platform.

Graduate students Dulanjan Harankahage, Divesh Nazar, Mykhailo Bondarchuk, Christopher Hicks, Amelia Waters, Maxwell Kannen, Adam Roach, Jiamin Huang, and Sabin Aryal continue to be the scientific engine of this output. The international collaborations with Ghent University, Argonne National Laboratory, and UT Dallas that appear across these papers reflect the quantum shell program's standing as a globally recognized research effort — one that attracts collaborators precisely because the science is distinctive and the results are consistently significant.

2026 Publications — Zamkov Laboratory

Harankahage, D., Nazar, D., Molkens, K., Bondarchuk, M.V., Hicks, C.M., Marder, A.A., Montemurri, M., Roach, A., Tanghe, I., Sun, L., Schaller, R.D., Diroll, B.T., Malko, A.V., Tarnovsky, A.N., Van Thourhout, D., Hens, Z., Geiregat, P., & Zamkov, M. (2026). Bound Exciton Complexes in Near-Infrared Emitting Quantum Shells. ACS Nano, 20(4), 3776–3790. https://doi.org/10.1021/acsnano.5c18640

Harankahage, D., Martin, W., Elce, E., Thennakoon, S., Thennakoon, B., Kannen, M.M., Kholmicheva, N., Kayira, B., Waters, A.D., Nazar, D., Huang, J., Anzenbacher, P., Malko, A.V., & Zamkov, M. (2026). Eutectic Processing of Semiconductor Colloidal Nanocrystals for Energy Applications. ACS Energy Letters. https://doi.org/10.1021/acsenergylett.6c00100

Aryal, S., Tang, Y., Harankahage, D., Zamkov, M., & Sun, L. (2026). Bright Infrared Colloidal PbS Nanoplatelets with Lead Sulfobromide Shells. Chemistry of Materials, 38(3), 1170–1177. https://doi.org/10.1021/acs.chemmater.5c02480

FACULTY RESEARCH SPOTLIGHT · 2026

Infrared at the Nanoscale: Sun Lab Achieves Bright, Narrow NIR Emission from PbS Nanoplatelets

Liangfeng Sun, Ph.D.  ·  Professor  ·  Department of Physics and Astronomy & Center for Photochemical Sciences

Among the many families of colloidal semiconductor nanocrystals, lead sulfide — PbS — occupies a special place. Its bulk bandgap of approximately 0.4 eV is so small that, through quantum confinement, PbS nanocrystals can be tuned to emit light across the near-infrared spectrum from roughly 800 nm to beyond 2000 nm. This spectral range is critically important for biomedical imaging (near-infrared light penetrates tissue; visible light does not), for fiber-optic telecommunications (the 1300 nm and 1550 nm windows are the backbone of modern data networks), and for next-generation photovoltaics that can harvest solar energy at wavelengths that conventional silicon cells cannot reach.

Dr. Liangfeng Sun's laboratory at BGSU has focused on lead chalcogenide nanostructures — particularly PbS and PbSe — for much of the past decade, developing expertise in controlling their synthesis, understanding their electronic structure, and exploring their applications in photovoltaics and photonic devices. A 2026 paper in Chemistry of Materials, co-authored with the adjacent Zamkov Lab, represents a significant advance in this program: the development of PbS nanoplatelets with inorganic lead sulfobromide shells that exhibit near-infrared emission with unprecedented linewidth and brightness.

Published in: Chemistry of Materials, 38(3), 1170–1177 · January 19, 2026

Authors: S. Aryal, Y. Tang, D. Harankahage, M. Zamkov, L. Sun

DOI: 10.1021/acs.chemmater.5c02480

Note: Open Access publication; BGSU Physics and CPS

THE NANOPLATELET: A TWO-DIMENSIONAL FRONTIER

Most of the nanocrystal science covered in CPS research highlights has focused on zero-dimensional structures — quantum dots and quantum shells, which are spherical or near-spherical particles in which electrons and holes are confined in all three spatial dimensions. In recent years, two-dimensional semiconductor nanostructures — nanoplatelets, sometimes called colloidal quantum wells — have emerged as a complementary platform with distinctive properties that spherical nanocrystals cannot match.

A nanoplatelet is essentially a crystalline semiconductor sheet that is only a few atomic layers thick. Quantum confinement operates primarily in the thickness direction, making the energy gap and optical properties exquisitely sensitive to the number of atomic layers — even a single additional layer changes the bandgap measurably. In the lateral dimensions, the nanoplatelet can be hundreds of nanometers wide, giving it a very large surface area and enabling strong light-matter interaction. The combination of atomic-scale thickness control with macroscopic lateral extent produces optical properties — narrow emission linewidths, fast radiative rates, and strong absorption cross-sections — that make nanoplatelets attractive for lasers, LEDs, and nonlinear optics.

CdSe nanoplatelets have been intensively studied and show some of the narrowest emission linewidths in the nanocrystal world. But their optical properties fall entirely in the visible range. For near-infrared applications, PbS nanoplatelets are the natural extension — but they have proven much harder to synthesize with the size control and surface passivation needed for high optical performance.

THE INNOVATION: SPONTANEOUS INORGANIC SHELL FORMATION

The central contribution of this paper is the discovery that PbS nanoplatelets synthesized in bromide-containing reaction media spontaneously develop inorganic lead sulfobromide and lead bromide shells around the PbS core. This spontaneous shell formation — which occurs without any post-synthesis shell-growth steps — produces a core/shell heterostructure with a type-I band alignment: both electrons and holes preferentially reside in the PbS core, which is surrounded by the wider-bandgap sulfobromide and bromide shell materials.

This configuration is ideal for bright emission. By confining both charge carriers within the core and away from the surface, the type-I alignment suppresses the surface trap states that would otherwise capture carriers non-radiatively and quench luminescence. The result is a dramatic improvement in photoluminescence performance compared to unshelled PbS nanoplatelets.

The emission from these core/shell PbS nanoplatelets is centered in the near-infrared, with the exact wavelength tunable by controlling nanoplatelet thickness — a direct consequence of quantum confinement in the thickness direction. Most strikingly, the photoluminescence peak at room temperature has a linewidth of only 78 meV — an exceptionally narrow value for any infrared-emitting colloidal nanostructure, and a direct indication that the atomically precise thickness control achievable in nanoplatelet synthesis produces emission from a very narrow distribution of quantum states.

A linewidth of 78 meV at room temperature in the near-infrared: precision that conventional infrared nanocrystals have not been able to reach.

STRUCTURAL CHARACTERIZATION AND OPTICAL PROPERTIES

Cyclic voltammetry measurements confirm the type-I band alignment directly, providing quantitative values for the conduction and valence band offsets between the PbS core and the sulfobromide shell. High-resolution transmission electron microscopy (conducted with technical support from BGSU's own microscopy facilities, with acknowledgment to BGSU's machine shop and TEM specialists) confirms the core/shell structure and the crystallinity of both the PbS core and the inorganic shell.

Transient absorption spectroscopy — contributed in part through collaboration with Argonne National Laboratory's Richard Schaller, a long-standing partner of both the Sun and Zamkov Labs — characterizes the carrier dynamics in these structures, revealing the fast radiative recombination rates that accompany the narrow emission linewidth.

WHY IT MATTERS

This paper establishes a new platform for infrared-emitting colloidal nanostructures. PbS nanoplatelets with inorganic sulfobromide shells combine the spectral tunability and narrow emission of two-dimensional nanostructures with infrared wavelengths that are directly relevant to imaging, communications, and photovoltaics. The spontaneous shell formation mechanism — avoiding the complex post-synthesis shell-growth procedures that other approaches require — makes this synthesis practical and scalable.

For the Sun Lab, this paper represents a significant advance in its PbS nanoplatelet program, building on prior work characterizing the electronic structure, exciton binding energies, and synthesis of unshelled PbS nanosheets. The collaboration with Dulanjan Harankahage from the Zamkov Lab — whose expertise in nanocrystal synthesis and characterization spans both quantum shells and the broader chalcogenide nanocrystal family — reflects the kind of within-CPS collaboration that BGSU's concentration of nanocrystal science enables.

Published as an Open Access article, the paper is freely available to the global research community — an important feature for a field in which researchers at institutions without expensive journal subscriptions often work on closely related problems. The acknowledgment of BGSU's own technical staff — Charles Codding in the machine shop and Dr. Marilyn Cayer for TEM support — reflects the institutional infrastructure that enables this kind of materials characterization.

RESEARCH IN CONTEXT

The Sun Lab in 2026: Pushing the Infrared Frontier

This Chemistry of Materials paper is the Sun Lab's most significant 2026 publication, and it sits within a broader research trajectory focused on advancing the synthesis and understanding of two-dimensional lead chalcogenide nanostructures. Prior papers from the group (in Nano Letters in 2025, and in J. Phys. Chem. Letters in 2022) had established PbS nanoplatelets as a viable material class and characterized their exciton binding energies and amplified spontaneous emission. The 2026 paper advances from bare nanoplatelets to passivated core/shell structures — crossing the threshold from materials of scientific interest to structures with the optical performance needed for device applications.

Graduate students Sabin Aryal and Yiteng Tang, together with Dulanjan Harankahage from the Zamkov Lab, are the lead contributors to this work. Their combined expertise in lead chalcogenide chemistry, optical characterization, and electron microscopy represents the kind of multidisciplinary graduate training that characterizes the best physics and materials science programs — and that the BGSU CPS uniquely enables through the proximity of multiple world-class nanocrystal research groups.

2026 Publication — Sun Laboratory

Aryal, S., Tang, Y., Harankahage, D., Zamkov, M., & Sun, L. (2026). Bright Infrared Colloidal PbS Nanoplatelets with Lead Sulfobromide Shells. Chemistry of Materials, 38(3), 1170–1177. https://doi.org/10.1021/acs.chemmater.5c02480 [Open Access]

FACULTY RESEARCH SPOTLIGHT · 2026

Reading Light in the Dark: Tarnovsky Lab's Ultrafast Spectroscopy Unlocks NIR Quantum Shell Secrets

Alexander N. Tarnovsky, Ph.D.  ·  Associate Professor  ·  Department of Chemistry & Center for Photochemical Sciences

The Tarnovsky Lab at BGSU's Center for Photochemical Sciences operates at the technical frontier of optical measurement: femtosecond transient absorption spectroscopy, capable of capturing molecular and nanocrystal optical events on timescales as short as tens of femtoseconds, across a spectral range spanning the deep ultraviolet through the near-infrared. In a world where quantum shell nanocrystals are producing increasingly surprising and scientifically rich optical behavior, that kind of measurement capability is not just useful — it is irreplaceable.

A 2026 paper in ACS Nano, a 17-author collaboration connecting BGSU with Ghent University, Argonne National Laboratory, UT Dallas, and KAUST, demonstrates exactly why. The paper reports the first characterization of bound exciton complexes in near-infrared emitting quantum shells — a phenomenon that would have gone undetected, or at least unexplained, without the ultrafast spectroscopy measurements that Dr. Tarnovsky's group contributed.

Published in: ACS Nano, 20(4), 3776–3790 · January 15, 2026

Authors: D. Harankahage, D. Nazar, K. Molkens, M.V. Bondarchuk, C.M. Hicks, A.A. Marder, M. Montemurri, A. Roach, I. Tanghe, L. Sun, R.D. Schaller, B.T. Diroll, A.V. Malko, A.N. Tarnovsky, D. Van Thourhout, Z. Hens, P. Geiregat, M. Zamkov

DOI: 10.1021/acsnano.5c18640

THE PUZZLE: ABSORPTION WHERE GAIN WAS EXPECTED

The starting point for this paper was a paradox. The Zamkov Lab had developed two new near-infrared quantum shell compositions — CdS/HgS/CdS and CdS/HgCdSe/ZnS — both featuring mercury-containing emitting shells designed to shift the optical response deep into the NIR. Both demonstrated strong Auger suppression, the hallmark of the quantum shell architecture. And both emitted NIR light with good efficiency.

But when the researchers examined these two systems for optical gain — the ability to amplify light, which is the prerequisite for lasing — they found a striking difference. The CdS/HgS/CdS shells showed optical gain and stimulated emission, as expected. The CdS/HgCdSe/ZnS shells, despite demonstrating stronger Auger suppression, showed something completely different: instead of optical gain at high excitation densities, they showed photoinduced absorption — an increase in light absorption, not amplification. The material was doing the opposite of what was needed for a laser.

Understanding why required transient absorption measurements with the temporal resolution and spectral breadth that only a femtosecond facility like Dr. Tarnovsky's could provide.

WHAT THE ULTRAFAST MEASUREMENTS REVEALED

The transient absorption spectroscopy performed by the Tarnovsky group revealed the microscopic origin of the photoinduced absorption: the formation of bound multiexciton complexes — correlated clusters of charge carriers — whose collective energies fall below the bandgap of the single-exciton transition. In the conventional picture of a semiconductor nanocrystal, exciton-exciton interactions are repulsive: creating two excitons costs more energy than creating one. But in the CdS/HgCdSe/ZnS quantum shells, the unique band structure created by the HgCdSe alloy shell produces attractive exciton-exciton interactions — the biexciton state is lower in energy than two independent single excitons.

This means that once a single exciton is present in the nanocrystal, adding a second exciton actually lowers the total energy. The system prefers the bound biexciton state. And this preference manifests in the transient absorption spectrum as the photoinduced absorption feature — a new optical transition at lower energy (longer wavelength) than the single-exciton transition, corresponding to absorption into the bound biexciton state.

The temporal dynamics of this feature — how quickly it appears after excitation, how long it persists, and how it depends on pump fluence — are precisely what the Tarnovsky Lab's femtosecond measurements characterize. These dynamics establish that the bound multiexciton complexes are stable on timescales relevant to optical applications (nanoseconds), even at room temperature — which is unusual, since exciton binding effects are typically observable only at cryogenic temperatures in most semiconductor systems.

Femtosecond spectroscopy saw what steady-state measurements could not: the spectroscopic signature of bound exciton clusters forming and persisting at room temperature in the NIR.

WHY TARNOVSKY'S CONTRIBUTION WAS CRITICAL

It is worth being explicit about why the Tarnovsky Lab's contribution was not merely technical but scientifically essential. The photoinduced absorption feature produced by bound multiexciton complexes is spectrally broad, temporally complex, and energetically close to other features in the transient absorption spectrum. Distinguishing it from competing processes — Auger recombination, charge trapping, state filling — requires measurements with sub-100-femtosecond time resolution across a broad spectral window, and the interpretive expertise to separate overlapping contributions.

The Tarnovsky group's femtosecond broadband transient absorption setup — spanning from the deep UV through the near-infrared — and the group's extensive experience in analyzing complex multi-state dynamics in semiconductor nanocrystals (accumulated through years of collaboration with the Zamkov Lab and others) provided exactly this capability. The measurements confirm the bound exciton assignment and rule out alternative explanations, giving the paper the mechanistic rigor that distinguishes a definitive result from a plausible hypothesis.

THE APPLICATIONS HORIZON

Bound multiexciton complexes at room temperature in the near-infrared open a range of photonic applications that are not achievable with conventional nanocrystals. Biexciton-exciton cascade emission — in which a bound biexciton decays in two sequential steps, emitting two photons — is relevant to quantum light sources and entangled photon pair generation. Optical modulation based on biexciton saturation is relevant to ultrafast optical switching. Single-exciton gain, enabled by the negative biexciton binding energy in these materials, could provide a path to NIR lasing at lower excitation thresholds than existing approaches.

For BGSU's CPS, this paper represents the continued deepening of the collaboration between the Zamkov and Tarnovsky labs — a partnership that has now produced co-authored papers across multiple years and multiple scientific discoveries, from the 2024 JACS sub-bandgap stimulated emission paper to the 2026 ACS Nano bound exciton paper. Each discovery has been enabled by the combination of synthetic nanocrystal expertise (Zamkov) and ultrafast optical characterization (Tarnovsky) that no single laboratory could provide alone.

RESEARCH IN CONTEXT

The Tarnovsky Lab: Ultrafast Spectroscopy Across the CPS

Dr. Tarnovsky's contribution to the 2026 ACS Nano paper is the latest in a series of high-impact collaborative contributions from his laboratory to the broader CPS research effort. In 2025, his group's femtosecond measurements were central to both the maleimide ESPT paper (with Sivaguru) and the JACS sub-bandgap stimulated emission paper (with Zamkov). In 2026, the NIR bound exciton paper extends this pattern further.

This collaborative role reflects a model for how specialized, technically demanding research infrastructure can serve the entire center. Dr. Tarnovsky's femtosecond facility is not merely a service resource — it is an active scientific partner in the research it supports, with the interpretive depth and physical understanding to make new discoveries from the data it generates. The Sivaguru-Tarnovsky and Zamkov-Tarnovsky collaborations both exemplify what the CPS's model of co-located, complementary expertise is designed to produce: science that is more than the sum of its parts.

2026 Publication — Tarnovsky Laboratory (collaborative)

Harankahage, D., Nazar, D., Molkens, K., Bondarchuk, M.V., Hicks, C.M., Marder, A.A., Montemurri, M., Roach, A., Tanghe, I., Sun, L., Schaller, R.D., Diroll, B.T., Malko, A.V., Tarnovsky, A.N., Van Thourhout, D., Hens, Z., Geiregat, P., & Zamkov, M. (2026). Bound Exciton Complexes in Near-Infrared Emitting Quantum Shells. ACS Nano, 20(4), 3776–3790. https://doi.org/10.1021/acsnano.5c18640

FACULTY RESEARCH SPOTLIGHT · 2026

Inside the Lipid Bilayer: How Stimulant Drugs Disrupt the Neuronal Membrane at the Molecular Level

H. Peter Lu, Ph.D.  ·  Ohio Eminent Scholar and Professor  ·  Department of Chemistry & Center for Photochemical Sciences

The plasma membrane of a neuron is not simply a passive wrapper. It is a dynamic, selectively permeable barrier whose biophysical properties — fluidity, thickness, local charge distribution, and dielectric environment — directly influence the electrical signaling that underlies every thought, sensation, and movement. When drugs, toxins, or disease processes alter these properties, the consequences can range from subtle changes in firing threshold to catastrophic loss of membrane integrity.

For Dr. H. Peter Lu, Ohio Eminent Scholar and Professor at BGSU's Center for Photochemical Sciences, the biophysics of the neuronal membrane has become an increasingly important research frontier — one that builds directly on his laboratory's long-standing expertise in single-molecule force manipulation and spectroscopy. A 2026 paper in the Journal of Physical Chemistry B, published as a cover article, advances this frontier with a detailed investigation of how methamphetamine — a neuronal stimulant and one of the most widely abused drugs in the United States — disrupts the structural and dielectric environment of lipid bilayers at the molecular level.

Published in: Journal of Physical Chemistry B, 130, 345–361 · 2026  [COVER ARTICLE]

Authors: H.R. Eheliyagoda, S.M. Katugampalage, H.P. Lu

DOI: 10.1021/acs.jpcb.5c

Note: Cover page article — selected by J. Phys. Chem. B editors for featured cover image

FROM PATCH-CLAMP TO MOLECULAR DYNAMICS — AND BEYOND

This 2026 paper is a direct extension of the research published in Dr. Lu's 2025 ACS Chemical Neuroscience paper, which used whole-cell patch-clamp electrophysiology and molecular dynamics simulation to characterize how methamphetamine disrupts lipid bilayer structure and increases membrane permeability in HT22 neuronal cells. That study established the macroscopic picture: the drug inserts into the bilayer, clusters near the lipid headgroup layer, and creates measurable "electric leaking states" that increase in severity with drug concentration.

The 2026 paper takes the analysis to a new level of molecular detail, focusing on a phenomenon that the 2025 paper identified but did not fully characterize: the solvation fluctuations of the methamphetamine molecule itself within the nanostructured, confined environment of the lipid bilayer. Solvation — the process by which solvent molecules (in this case, water and lipid head groups) organize around a solute — is not a static phenomenon. It fluctuates dynamically, and those fluctuations carry information about how the drug interacts with its environment at the molecular level.

DIPOLAR MOLECULE SOLVATION IN A CONFINED ENVIRONMENT

Methamphetamine is a dipolar molecule — it carries a permanent electric dipole moment that makes it interact differently with different parts of the lipid bilayer. At the water-lipid interface, where polar headgroups meet the hydrophobic core, the dielectric environment changes dramatically over nanometer distances. A drug molecule embedded in this environment experiences a highly inhomogeneous electrical landscape that fluctuates as the surrounding lipid and water molecules move.

The paper characterizes these solvation dynamics using a theoretical framework called "dynamic disordered rate process" — an approach developed in Dr. Lu's group for analyzing fluctuation processes that are heterogeneous, non-stationary, and occur across multiple timescales simultaneously. Applied to the methamphetamine-bilayer system, this framework reveals that the drug's solvation fluctuations in the lipid bilayer are fundamentally different from those in bulk water: they are slower, more heterogeneous, and coupled to the structural dynamics of the surrounding lipid molecules in ways that depend on the drug's position within the bilayer.

The key finding — that methamphetamine's dynamic disordered solvation within the nanostructured bilayer environment disrupts the membrane's function as a dielectric barrier — connects molecular-level physics to the macroscopic membrane permeability changes observed in the 2025 electrophysiology work. Together, the two papers provide a complete multi-scale picture: from atomic-level solvation fluctuations to measurable changes in membrane conductance.

A drug molecule in a lipid bilayer is not simply dissolved — it is confined, oriented, and dynamically coupled to its environment in ways that drive membrane disruption from the inside out.

THE COVER RECOGNITION

Selection as the cover article of Journal of Physical Chemistry B reflects the editors' assessment that the paper's approach and findings represent a notable contribution to the field. Cover selection is competitive and is reserved for papers that the editorial board considers to be among the most significant and visually compelling in a given issue. For Dr. Lu's group, the cover recognition is also an opportunity to communicate the visual richness of their research — the nanoscale world of membrane-drug interactions — to the broader physical chemistry community.

Graduate student Hashini R. Eheliyagoda, whose prior work in the Lu Lab produced the 2025 ACS Chemical Neuroscience paper on methamphetamine and membrane electrophysiology, and new graduate student Shermi M. Katugampalage are the co-first authors on this 2026 paper. Their combined expertise in experimental membrane biophysics and computational modeling is what makes this kind of mechanistically complete, multi-scale study possible.

WHY IT MATTERS

Methamphetamine addiction is a significant and growing public health crisis in the United States, with particular impact in rural and Midwest communities. Understanding how the drug affects neurons at the molecular level — not just through receptor binding, but through direct physical disruption of the membrane itself — is essential for developing a complete picture of its neurotoxicity and for identifying potential therapeutic targets.

More broadly, the solvation fluctuation framework developed and applied in this paper is generalizable beyond methamphetamine to any dipolar drug or toxin that partitions into lipid bilayers. Given the large number of pharmacologically active molecules that interact with cell membranes — including anesthetics, antidepressants, antipsychotics, and many others — this methodological contribution has implications well beyond the specific case of methamphetamine neurotoxicity.

For the Lu Lab, this paper is also a milestone in a sustained research program that is increasingly bridging single-molecule biophysics and neuropharmacology — using the tools of physical chemistry to ask questions that matter for human health.

RESEARCH IN CONTEXT

The Lu Lab in 2026: Deepening the Membrane Story

The 2026 J. Phys. Chem. B cover paper sits within a broader 2025–2026 research arc from the Lu Lab that is systematically building a molecular-level understanding of how physical forces and chemical agents disrupt neuronal cell membranes and membrane-associated proteins. The 2025 papers explored EGFR under compressive force, nucleosome rupture, nitric oxide synthase force-activation, and methamphetamine's membrane effects through patch-clamp. The 2026 paper goes deeper into the solvation physics underlying the methamphetamine-membrane interaction.

Together, these papers define a research identity that is genuinely distinctive within the CPS: single-molecule biophysics applied to problems of neurological significance, using a toolkit of AFM, patch-clamp, fluorescence spectroscopy, and theory that few laboratories in the world can bring to bear simultaneously. As the CPS continues to develop its research profile in the post-40th-anniversary era, the Lu Lab's sustained productivity across this frontier is a defining contribution.

2026 Publication — Lu Laboratory

Eheliyagoda, H.R., Katugampalage, S.M., & Lu, H.P. (2026). Neuronal Stimulant Dipolar Molecule Solvation Fluctuation in a Nano-Structured and Confined Environment of Lipid Bilayer: A Dynamic Disordered Rate Process Disrupts the Cell Membrane. Journal of Physical Chemistry B, 130, 345–361. [Cover Article]