arXiv subjects

Vikas

Publications and source records attributed to Vikas.

4 recordsLinked to original sources

arXiv2026

Single-cell-level distributions and relationships can differentiate cell-division and growth models

Complex interactions among regulatory molecules determine the rules underlying cell growth and division in microbial cells. While the governing molecular network may not always be obvious, it is well known that correlations among certain physiological quantities measured in experiments, such as birth-size, division-size, division-time, and division-added-size, can differentiate among various cell-division models, such as Timer, Sizer, and Adder. Here we show that, apart from these correlations, which we extend for the case of stochastic single-cell growth and stochastic asymmetric partitioning, probability distributions of these quantities and statistical relationships between them can also be used to differentiate between these division models. Interestingly, we show that these quantities can not only differentiate the division models, but also distinguish among the single-cell growth paradigms, such as linear and exponential growth. We then demonstrate this differentiability among various division and growth models by comparing our analytical results with published experimental data. We further show that these results remain valid even when the growth rate of a cell is correlated with the growth rate of cells from previous generations in the lineage.

cond-mat.stat-mech↗

arXiv2025

On distinguishability among cell-division models based on population and single-cell-level distributions

It is well known that the different cell-division models, such as Timer, Sizer, and Adder, can be distinguished based on the correlations between different single-cell-level quantities such as birth-size, division-time, division-size, and division-added-size. Here, we show that other statistical properties of these quantities can also be used to distinguish between them. Additionally, the statistical relationships and different correlation patterns can also differentiate between the different types of single-cell growth, such as linear and exponential. Further, we demonstrate that various population-level distributions, such as age, size, and added-size distributions, are indistinguishable across different models of cell division despite them having different division rules and correlation patterns. Moreover, this indistinguishability is robust to stochasticity in growth rate and holds for both exponential and linear growth. Finally, we show that our theoretical predictions are corroborated by simulations and supported by existing single-cell experimental data.

cond-mat.stat-mech↗

arXiv2023

Plasmonic photothermal response of a phantom embedded with gold nanorod aggregates on broadband near-infrared irradiation

Longer near-infrared wavelengths provide better penetration depth in biological tissues, so these are useful for plasmonic photothermal cancer therapeutics. In the context of nanoparticles for such applications, the absorption can be tuned for longer NIR wavelengths. However, on increasing the size of the nanoparticle, the scattering is enhanced and thus is not suitable for plasmonic therapeutics. Therefore, to overcome this issue, different types of small gold nanorods were synthesized and converted into stable aggregates to red-shift the plasmonic resonance wavelength to longer near-infrared wavelengths. The gold nanorod aggregates were embedded into the agarose gel phantoms mimicking the tumor-tissue-like structure. The photothermal response was measured through the prepared phantoms using a broadband near-infrared light source. It was shown that even in an extremely dilute concentration of gold nanorods, the photothermal heat generation could increase after the aggregation and also give gives deeper penetration of thermal energy. The observed photothermal response was also verified through numerical simulation. The current study shows better performance by increasing the plasmonic coupling, reducing the mismatch issue of plasmonic resonance shift in the second biological therapeutic window for the aggregates without increasing the size of individual nanoparticles. The aggregates provide better light penetration at deeper tissue by red-shifting the absorbance resonance wavelength which is useful for plasmonic photothermal cancer therapy.

physics.optics↗

arXiv2021

Photothermal properties of stable aggregates of gold nanorods

Aggregation of the nanoparticles is a natural phenomena due to various biological and physical parameters but these aggregates are highly unstable. If aggregates would have been stable then it might be useful for some biomedical applications. To study the optical properties and photothermal heat generation of stable aggregates of the metal nanopartilces, we present a forced synthesis of aggregates of small gold nanorods in a mixture of Dulbecco's Modified Eagle's medium (DMEM) and Bovine Serum Albumin (BSA). We synthesised hexadecyltrimethylammonium bromide (CTAB) coated gold nanorods and then prepared the stable aggregates to study the optical characteristics of these aggregates. Absorption spectra of aggregates show the redshift compared to the monodispersive gold nanorods and confirm that the shape and size of aggregate depend on the amount of BSA in DMEM as well as on the concentration of CTAB in the stock solution of the gold nanorods suspension. The higher concentration of the BSA in DMEM and lower concentration of CTAB of monodispersive gold nanorod suspension causes greater redshift. We tuned the well defined plasmonic absorption resonance peaks of the aggregates of gold nanorods up to the second biological therapeutic window. We studied the stability of the synthesised aggregates of gold nanorods for up to one week and found that the aggregates were stable for atleast one week. A photothermal study of these aggregates was also carried out using high power broadband near-infrared light source. Aggregates were also photothermally stable which warrants their repeated use for such applications. The photothermal conversion efficiency of the these stable gold nanorod aggregates were higher than its monodispersive form of the nanorods.

physics.optics↗