About

Shabnam Akhtari is a professor at the Department of Mathematics in the Eberly College of Science at Pennsylvania State University. Her research interests include Number Theory, Geometry of Numbers, and Diophantine Analysis. Her work focuses on these areas, contributing to the understanding of their fundamental properties and interrelations.

Research topics

• Biochemistry
• Chemistry
• Biophysics
• Biology
• Thermodynamics
• Chromatography
• Organic chemistry
• Chemical engineering

Selected publications

• BPS2026 – Formation and properties of lipid membranes around coacervate droplets

  Biophysical Journal · 2026-02-01

  article1st authorCorresponding
  PublisherDOI

• Residue‐level mapping of crowding effects on protein phase separation

  Protein Science · 2026-03-25

  articleOpen access

  Protein liquid-liquid phase separation has emerged as a key mechanism in cellular organization. While the crowded environment inside cells is expected to influence this process, how crowding shapes the chemical environment and impacts protein phase separation remains largely unknown. Here, we use NMR spectroscopy to map residue-level crowding effects on the intrinsically disordered region of RNA polymerase II under different conditions, including polymer- and protein-based crowders, as well as reconstituted E. coli cytosol. We find a general trend of enhanced protein self-interactions across all conditions, but also distinct chemical environments that depend on crowder identity, reflecting changes in preferential interactions. Given the widespread use of polymer crowders, our results provide a strategy to evaluate their chemical influence and to design more physiologically relevant in vitro crowding models. More broadly, this framework enables systematic probing of residue-level influences in complex, cell-like environments.

  PublisherDOI

• Taming Randomness in Random Lasers: Programmable Disorder for Active Control of Random Lasing via Electric-Field-Directed Assembly of Nanowires

  arXiv (Cornell University) · 2026-04-28

  articleOpen access

  Random lasing exploits multiple scattering to provide optical feedback without conventional resonant cavities, enabling simplified architectures that are readily integrated into compact photonic platforms such as wearable sensors and lab-on-chip devices. However, the same disorder that enables cavity-free lasing also makes it challenging to control and tune the emission properties. Here, an electrically reconfigurable random-lasing platform based on dielectrophoretic assembly of chaining silver nanowires suspended in a dye gain medium is reported. An applied electric field across patterned quadrupole electrodes induces nanowire chaining and programmable alignment, enabling real-time reconfiguration of the disorder landscape. Based on the electrically driven disorder state transitions, tunable random-lasing characteristics, including reduced lasing thresholds, modulation of emission intensity, and control of the polarization state have been demonstrated. Simulations further indicate that chaining enhances scattering relative to absorption, providing more efficient radiative feedback, and the orientation of the nanowire network governs the polarization dependence of the system. These results establish a route to actively modulate random lasing through controllable disorder and point toward adaptive, reconfigurable photonic light sources and sensing systems.

  PublisherOA PDF

• Increasing the compositional heterogeneity of single-chain amphiphile membranes supported by coacervate cores alters stability and properties of the hybrid protocells

  bioRxiv (Cold Spring Harbor Laboratory) · 2026-02-05

  articleOpen accessSenior authorCorresponding

  ABSTRACT Coacervate droplets and lipid vesicles are two classes of self-assembled compartments that have been proposed as protocell models. Hybrid protocells, in which a coacervate core is surrounded by a lipid membrane, can integrate the advantages of both protocell systems while overcoming their limitations. Although hybrid protocell membranes have been produced with a variety of diacyl phospholipids related to modern biology and some single-chain amphiphiles inspired by prebiotic scenarios, little is known about how mixtures of single-chain amphiphiles impact hybrid protocell membrane formation and properties. Given the plausible diversity of amphiphiles in the prebiotic milieu, the resulting membranes would have inherently incorporated multiple lipids of different types, potentially altering the properties and viability of hybrid protocells in their environment. Here, we systematically increased the compositional heterogeneity of hybrid protocell membranes by using different prebiotically relevant single-chain amphiphiles of varying head groups and alkyl chain lengths. These membranes were assembled around model coacervate droplets generated from polyallylamine hydrochloride and adenosine diphosphate, and the effect of heterogeneity on membrane properties and stability was evaluated. Compared to protocells with homogeneous membranes, those with heterogeneous amphiphile membranes exhibited higher yields, smaller sizes, and greater sub-compartment formation. Also, they showed increased membrane order, retained similar lateral lipid diffusion, and showed population-level variability in permeability to small anionic molecules. Notably, heterogeneous membranes showed enhanced structural stability under acidic conditions, retaining key properties like size and sub-compartment heterogeneity, thereby broadening the pH range over which hybrid protocells remain intact. These findings suggest that amphiphile diversity not only would have influenced the structural properties of hybrid protocells but also created diversity within the protocell population and enhanced their robustness, thereby playing a crucial role in protocell evolution on early Earth.

  PublisherOA PDFDOI

• Increasing the Compositional Heterogeneity of Single-Chain Amphiphile Membranes Supported by Coacervate Cores Alters Stability and Properties of the Hybrid Protocells

  Langmuir · 2026-05-01

  articleOpen accessSenior author

  Coacervate droplets and lipid vesicles are two classes of self-assembled compartments that have been proposed as protocell models. Hybrid protocells, in which a coacervate core is surrounded by a lipid membrane, can integrate the advantages of both protocell systems while overcoming their limitations. Although hybrid protocell membranes have been produced with a variety of diacyl phospholipids related to modern biology and some single-chain amphiphiles inspired by prebiotic scenarios, little is known about how mixtures of single-chain amphiphiles impact hybrid protocell membrane formation and properties. Given the plausible diversity of amphiphiles in the prebiotic milieu, the resulting membranes would have inherently incorporated multiple lipids of different types, potentially altering the properties and viability of hybrid protocells in their environment. Here, we systematically increased the compositional heterogeneity of hybrid protocell membranes by using different prebiotically relevant single-chain amphiphiles of varying head groups and alkyl chain lengths. These membranes were assembled around model coacervate droplets generated from poly(allylamine hydrochloride) and adenosine diphosphate, and the effect of heterogeneity on membrane properties and stability was evaluated. Compared to protocells with homogeneous membranes, those with heterogeneous amphiphile membranes exhibited higher yields, smaller sizes, and greater subcompartment formation. Also, they showed increased membrane order, retained similar lateral lipid diffusion, and showed population-level variability in permeability to small anionic molecules. Notably, heterogeneous membranes showed enhanced structural stability under acidic conditions, retaining key properties like size and subcompartment heterogeneity, thereby broadening the pH range over which hybrid protocells remain intact. These findings suggest that amphiphile diversity not only would have influenced the structural properties of hybrid protocells but also created diversity within the protocell population and enhanced their robustness, thereby playing a crucial role in protocell evolution on early Earth.

  PublisherDOI

• Methodological Gate-Opening

  2026-03-16

  book-chapter1st authorCorresponding

  Abstract This chapter calls for the democratization and decolonization of the practice of political theorizing. It argues that normative theorizing—understood as the practice of critiquing, visioning, and strategizing for change—is a vital activity, critical to community and collective living. It further contends that epistemic hierarchies and Eurocentered colonial logics and legacies alienate people from collective meaning-making processes and from communities as sites of knowledge. Drawing on the work of women of color, transnational, Indigenous, and decolonial theorists, the chapter foregrounds a practice of participatory and pluriversal theorizing that can, in the words of the Zapatistas, help create “a world where many worlds fit.”

  PublisherDOI

• Taming Randomness in Random Lasers: Programmable Disorder for Active Control of Random Lasing via Electric-Field-Directed Assembly of Nanowires

  arXiv (Cornell University) · 2026-04-28

  preprintOpen access

  Random lasing exploits multiple scattering to provide optical feedback without conventional resonant cavities, enabling simplified architectures that are readily integrated into compact photonic platforms such as wearable sensors and lab-on-chip devices. However, the same disorder that enables cavity-free lasing also makes it challenging to control and tune the emission properties. Here, an electrically reconfigurable random-lasing platform based on dielectrophoretic assembly of chaining silver nanowires suspended in a dye gain medium is reported. An applied electric field across patterned quadrupole electrodes induces nanowire chaining and programmable alignment, enabling real-time reconfiguration of the disorder landscape. Based on the electrically driven disorder state transitions, tunable random-lasing characteristics, including reduced lasing thresholds, modulation of emission intensity, and control of the polarization state have been demonstrated. Simulations further indicate that chaining enhances scattering relative to absorption, providing more efficient radiative feedback, and the orientation of the nanowire network governs the polarization dependence of the system. These results establish a route to actively modulate random lasing through controllable disorder and point toward adaptive, reconfigurable photonic light sources and sensing systems.

  PublisherDOI

• Primitive Molecular Buffering by Low-Multivalency Coacervates

  bioRxiv (Cold Spring Harbor Laboratory) · 2025-05-27

  preprintOpen accessSenior authorCorresponding

  Abstract Coacervate droplets formed by liquid-liquid phase separation serve as models for intracellular biomolecular condensates and as potential protocellular compartments during the emergence of life. Changes in availability of molecular components can be anticipated for intracellular and prebiotic milieu, and protocells may have also faced fluctuations in salinity and pH. Compartments able to maintain their molecular composition, i.e. homeostasis, under such conditions would be better able to preserve internal functions. Phase separation could in principle provide resistance to local changes in molecular composition. To evaluate this possibility, we investigated the impact of non-stoichiometric charge ratios of coacervate molecules on coacervate formation and RNA compartmentalization in oligoarginine (R10)/ATP coacervates across salinity and pH conditions relatable to plausible prebiotic environments. These R10/ATP coacervate systems resisted changes in oligoarginine concentration in both phases under freshwater and ocean-relevant salt conditions, providing a primitive molecular buffering function. Moreover, RNA accumulation was observed in the coacervates over a range of pH, salinity, and R10/ATP stoichiometry. We also observed salt-dependent differences in molecular buffering and compartmentalization that can be understood in terms of how salinity impacts the relative strengths of intermolecular binding modes that drive coacervation and RNA uptake. By varying relative phase volumes and altering which intermolecular binding modes dominate, LLPS provides general mechanisms for resisting changes in molecular availability and environmental conditions, even without the active homeostasis of living cells. Such primitive molecular buffering could have aided the emergence of life and may find utility in biotechnological or commercial applications based on molecular compartmentalization.

  PublisherOA PDFDOI

• BPS2025 - Implications of arginine methylation on bioinspired complex coacervation as a model of membraneless organelles

  Biophysical Journal · 2025-02-01

  articleSenior author
  PublisherDOI

• BPS2025 - Phase-separated aqueous polyelectrolyte solutions as “proto-cytoplasm” and their response to guest molecules and environmental perturbations

  Biophysical Journal · 2025-02-01

  articleSenior author
  PublisherDOI

Recent grants

• NIH Grant R01EB000268

  NIH · $1.5M · 2010

• Dynamic formation/disassembly of membraneless organelle model systems by post-translational modification: Mechanisms and consequences

  NSF · $900k · 2017–2022

• RoL: RAISE: DESYN-C3: Engineering multi-compartmentalised synthetic minimal cells

  NSF · $1.0M · 2018–2024

• Model Cytoplasm: From Fundamentals to Asymmetric Division of Cytomimetic Vesicles

  NSF · $595k · 2008–2012

• NIH Grant R01HG002228

  NIH · $477k · 2004

Frequent coauthors

• Theresa S. Mayer

  Purdue University West Lafayette

  83 shared

• Antoine Thill

  Université Paris-Saclay

  63 shared

• Jeffrey S. Mayer

  Villanova University

  63 shared

• Wafa Achouak

  Centre National de la Recherche Scientifique

  62 shared

• Catherine Santaella

  62 shared

• Armand Masion

  62 shared

• Jean‐Yves Bottero

  62 shared

• Alain Thiéry

  62 shared

Education

• Postdoctoral Researcher, Chemistry

  Pennsylvania State University

  1999

• Ph.D., Chemistry

  Penn State University

  1997

• B.S., Biology and Chemistry

  Saint Francis College

  1991

Awards & honors

• Whitman Fellowship Award, University of Chicago Marine Biolo…
• Langmuir Lectureship Award, 2024
• Shapiro Professor of Chemistry, 2021-present
• Distinguished Professor of Chemistry, 2020-2021
• Penn State Faculty Scholar Medal in Life and Health Sciences…