Biology subjects

Martensson, G.

Publications and source records attributed to Martensson, G..

5 recordsLinked to original sources

bioRxiv2025

Sheathless elasto-inertial focusing of sub-25 nm particles in straight microchannels

Nanoscale biological particles, such as lipoproteins (10-80 nm) or extracellular vesicles (30-200 nm), play pivotal roles in health and disease, including conditions like cardiovascular disorders and cancer. Their effective analysis is crucial for applications in diagnostics, quality control, and nanomedicine development. While elasto-inertial focusing offers a powerful method to manipulate particles without external fields, achieving consistent focusing of nanoparticles (<500 nm) has remained a challenge. In this study, we experimentally demonstrate elasto-inertial focusing of nanoparticles as small as 25 nm using straight high-aspect-ratio microchannels in a sheathless flow. Systematic investigations reveal the influence of channel width, particle size, viscoelastic concentration, and flow rate on focusing behavior. Additionally, through numerical simulations and experimental validation, we provide insights into particle migration dynamics and viscoelastic forces governing nanoparticle focusing. Finally, we successfully focus biological particles, including liposomes (90-140 nm), extracellular vesicles (100 nm), and lipoproteins (10-25 nm), under optimized conditions, showcasing potential applications in medical diagnostics and targeted drug delivery. These findings mark a significant advancement toward size-based high-resolution particle separation, with implications for biomedicine and environmental sciences.

bioengineering↗

bioRxiv2023

Lifelong olfactory deprivation-dependent cortical reorganization restricted to orbitofrontal cortex

Prolonged sensory deprivation has repeatedly been linked to cortical reorganization. We recently demonstrated that individuals with congenital anosmia (CA, complete olfactory deprivation since birth) have seemingly normal morphology in piriform (olfactory) cortex despite profound morphological deviations in the orbitofrontal cortex (OFC), a finding contradictory to both the known effects of blindness on visual cortex and to the sparse literature on brain morphology in anosmia. To establish whether these unexpected findings reflect the true brain morphology in CA, we first performed a direct replication of our previous study. Individuals with CA (n=30) were compared to age and sex matched controls (n=30) using voxel- and surface-based morphometry. The replication results were near identical to the original study: bilateral clusters of group differences in the OFC, including CA atrophy around the olfactory sulci and volume increases in the medial orbital gyri. Importantly, no group differences in piriform cortex were detected. Subsequently, to assess any subtle patterns of group differences not detectable by our mass-univariate analysis, we explored the data from a multivariate perspective. Combining the newly collected data with data from the replicated study (CA=49, Control=49) we performed support vector machine classification based on gray matter volume. In line with the mass-univariate analyses, the multivariate analysis could accurately differentiate between the groups in bilateral OFC (75-96% accuracy), whereas the classification accuracy in piriform cortex was at chance level. Our results suggest that despite lifelong olfactory deprivation, piriform (olfactory) cortex is morphologically unaltered and the morphological deviations in CA are confined to the OFC.

neuroscience↗

bioRxiv2020

High resolution and high throughput bacteria separation from blood using elasto-inertial microfluidics

Improved sample preparation has the potential to address a huge unmet need for fast turnaround sepsis tests that enable early administration of appropriate antimicrobial therapy. In recent years, inertial and elasto-inertial microfluidics-based sample preparation has gained substantial interest for bioparticle separation applications. However, for applications in blood stream infections the throughput and bacteria separation efficiency has thus far been limited. In this work, for the first time we report elasto-inertial microfluidics-based bacteria isolation from blood at throughputs and efficiencies unparalleled with current microfluidics-based state of the art. In the method, bacteria-spiked blood sample is prepositioned close to the outer wall of a spiral microchannel using a viscoelastic sheath buffer. The blood cells will remain fully focused throughout the length of the channel while bacteria migrate to the inner wall for effective separation. Initially, particles of different sizes were used to investigate particle focusing and the separation performance of the spiral device. A separation efficiency of 96% for the 1 {micro}m particles was achieved, while 100% of 3 {micro}m particles were recovered at the desired outlet at a high throughput of 1 mL/min. Following, processing blood samples revealed a minimum of 1:2 dilution was necessary to keep the blood cells fully focus at the outer wall. In experiments involving bacteria spiked in diluted blood, viable E.coli were continuously separated at a total flow rate of 1 mL/min, with an efficiency between 82 to 90% depending on the blood dilution. Using a single spiral, it takes 40 minutes to process 1 mL of blood at a separation efficiency of 82% and 3 hours at 90% efficiency. To the best of our knowledge, this is the highest blood sample throughput per single microfluidic chip reported for the corresponding separation efficiency. As such, the label-free, passive and high throughput bacteria isolation method has a great potential for speeding up downstream phenotypic and molecular analysis of bacteria.

biophysics↗

bioRxiv2020

Normal Olfactory Functional Connectivity Despite Life-Long Absence of Olfactory Experiences

Congenital blindness is associated with atypical morphology, and functional connectivity within and from, visual cortical regions; changes that are hypothesized to originate from a life-long absence of visual input and could be regarded as a general (re)organization principle of sensory cortices. Challenging this is the fact that individuals with congenital anosmia (life-long olfactory sensory loss) display little to no morphological changes in primary olfactory cortex. To determine whether olfactory input from birth is essential to establish and maintain normal functional connectivity in olfactory processing regions, akin to the visual system, we assessed differences in functional connectivity within olfactory cortex between individuals with congenital anosmia (n=33) and matched controls (n=34). Specifically, we assessed differences in connectivity between core olfactory processing regions as well as differences in regional homogeneity and homotopic connectivity within primary olfactory cortex. In contrast to congenital blindness, none of the analyses indicated atypical connectivity in individuals with congenital anosmia. In fact, post-hoc Bayesian analysis provided support for an absence of group differences. These results suggest that a lifelong absence of olfactory experience has limited impact on the functional connectivity in olfactory cortex, a finding that indicates a clear difference between sensory modalities in how sensory cortical regions develop.

neuroscience↗

bioRxiv2019

Divergent morphological changes within the orbitofrontal cortex in individuals with congenital olfactory sensory loss

Individuals with congenital sensory loss usually demonstrate altered brain morphology in areas associated with early processing of the lost sense. Here, we aimed to establish whether this also applies to individuals born without a sense of smell (congenital anosmia) by comparing cortical morphology between 33 individuals with isolated congenital anosmia and matched controls. We detected no structural alterations in the primary olfactory (piriform) cortex. However, individuals with anosmia demonstrated gray matter volume atrophy in bilateral olfactory sulci, explained by decreased cortical area, curvature, and sulcus depth. They further demonstrated increased gray matter volume and cortical thickness in the medial orbital gyri; regions closely associated with olfactory processing, sensory integration, and value-coding. Our results suggest that a lifelong absence of sensory input does not necessarily lead to morphological alterations in primary sensory cortex and extend previous findings with divergent morphological alterations in bilateral orbitofrontal cortex, indicating influences of different plastic processes.

neuroscience↗