Biology subjects

Konstantinou, G.

Publications and source records attributed to Konstantinou, G..

5 recordsLinked to original sources

bioRxiv2025

VISIBLE: An imaging-driven system for sampling, biofabrication, and manipulation of complex biological models

Complex in vitro models (CIVMs), including organoids, spheroids, and bioprinted constructs, have emerged as powerful platforms for recapitulating human tissue architecture and function. However, their inherent heterogeneity and dynamic nature pose significant challenges for standardization, reproducibility, and real-time manipulation. Here, we present VISIBLE (Versatile Imaging-Based Interactive Sampling and Bioprinting System), a modular, imaging-guided platform that integrates real-time monitoring with automated manipulation and 3D bioprinting that addresses these challenges. VISIBLE employs a dual-axis system comprising independently controlled tool-heads and microscope stages, enabling precise spatiotemporal interventions within live cultures. We demonstrate the system capabilities across a range of applications, including morphology- and function-based sampling of organoids and neurospheres, interactive 3D bioprinting, serial scratch assays, and real-time cell-cell interaction studies. Furthermore, we illustrate the system utility in translational contexts through the selective sampling and implantation of patient-derived xenograft organoids. VISIBLE supports long-term culture within an integrated incubation environment and accommodates interchangeable tool-heads for scalable, high-throughput workflows. By enabling closed-loop, feedback-controlled experimentation, VISIBLE addresses some of the critical limitations in existing CIVM platforms and offers a new versatile solution for a wide range of biomedical research applications. This work represents a significant step toward the development of autonomous experimental systems for complex tissue modelling and preclinical investigation.

bioengineering↗

bioRxiv2025

PhotoNeuro: A compact photodetector for synchronization of visual stimulus presentation during behavioral experiments in neuroscience.

Presenting visual stimuli in neuroscience experiments often requires the combination of analogue signals that carry information about the visual cue presented on the LCD display. Such signals are often sensed by photodetectors and recorded in analogue to digital converter (ADC) acquisition boards. The use of open-source visual programming languages such as Bonsai is becoming more and more popular. They are often used in combination with other open-source hardware such as Arduino development boards. These microcontroller-based boards can be used to automate behavioural experiments: e.g., actuate valves and motors and acquire analogue signals on their ADC channels. LCDs and other modern display allow fast presentation of arbitrary visual stimuli and are widely used for psychophysics and neuroscience experiments. However, most displays do not provide hardware timestamping options and are intrinsically nonlinear. Solving this limitation often requires a direct recording of the light emitted by the display with a photodiode. Such photodetectors are are often amplified at higher voltages and hard to integrate in most common recording systems that use microcontrollers. The other drawback commonly found by neuroscience researchers in commercial devices is the relatively big footprint that the sensor occupies on the screen which, ideally should be minimised so not to interfere with the stimuli presentation. In this paper we present a small footprint photodetector that can be easily replicated and operates at 5V making it suitable to use with common development boards and the visual programming language Bonsai that is commonly used for experiment creation and control. Additionally, we share a version that includes four photodiodes in small area (400 mm2). Specifications table O_TBL View this table: org.highwire.dtl.DTLVardef@7bafcforg.highwire.dtl.DTLVardef@5353ccorg.highwire.dtl.DTLVardef@a29f47org.highwire.dtl.DTLVardef@86f5d2org.highwire.dtl.DTLVardef@74da5f_HPS_FORMAT_FIGEXP M_TBL C_TBL

neuroscience↗

bioRxiv2025

Functional specialisation of multisensory temporal integration in the mouse superior colliculus

Our perception of the world depends on the brains ability to integrate information from multiple senses, with temporal disparities providing a critical cue for binding or segregating cross-modal signals1,2. The superior colliculus (SC) is a key site for integrating sensory modalities, but how cellular and network mechanisms in distinct anatomical regions within the SC contribute to multisensory integration remains poorly understood. Here, we recorded responses from over 5,000 neurons across the SCs anatomical axes of awake mice during presentations of spatially coincident audiovisual stimuli with varying temporal asynchronies. Our findings revealed that multisensory neurons reliably encoded audiovisual delays and exhibited nonlinear summation of auditory and visual inputs, with nonlinearities being more pronounced when visual stimuli preceded auditory stimuli, consistent with the natural statistics of light and sound propagation. Nonlinear summation was crucial for population-level decoding accuracy and precision of AV delay representation. Moreover, enhanced population decoding of audiovisual delays in the posterior-medial SC, facilitated temporal discriminability in the peripheral visual field. Cross-correlation analysis indicated higher connectivity in the medial SC and functional specific recurrent connectivity, with visual, auditory, and multisensory neurons preferentially connecting to other neurons of the same functional subclass, and multisensory neurons receiving approximately 50 percent of the total local input from other multisensory neurons. Our results highlight the interplay between single-neuron computations, network connectivity, and population coding in the SC, where nonlinear integration, distributed representations and regional functional specialisations enables robust sensory binding and supports the accurate encoding of temporal multisensory information. Our study provides new insights into how the brain leverages both single-neuron and network-level mechanisms to represent sensory features by adapting to the statistics of the natural world.

neuroscience↗

bioRxiv2022

A low-cost device for cryoanesthesia of neonate rodents

Studying the development of neural circuits in rodent models requires surgical access to the neonatal brain. Since commercially available stereotaxic and anesthetic equipment is designed for use in adults, reliable targeting of brain structures in such young animals can be challenging. Hypothermic cooling (cryoanesthesia) has been used as a preferred anesthesia approach in neonates. This commonly involves submerging neonates in ice, an approach that is poorly controllable. We have developed an affordable, simple to construct device - CryoPup - that allows for fast and robust cryoanesthesia of rodent pups. CryoPup consists of a microcontroller controlling a Peltier element and a heat exchanger. It is capable of both cooling and heating, thereby also functioning as a heating pad during recovery. Importantly, it has been designed for size compatibility with common stereotaxic frames. We validate CryoPup in neonatal mice, demonstrating that it allows for rapid, reliable and safe cryoanesthesia and subsequent recovery. This open-source device will facilitate future studies into the development of neural circuits in the postnatal brain. Specifications table O_TBL View this table: org.highwire.dtl.DTLVardef@de1fdorg.highwire.dtl.DTLVardef@16fde69org.highwire.dtl.DTLVardef@172f48corg.highwire.dtl.DTLVardef@15454forg.highwire.dtl.DTLVardef@79676e_HPS_FORMAT_FIGEXP M_TBL C_TBL

neuroscience↗

bioRxiv2022

Combining SLA 3D printing and soft lithography for fast, versatile, and accessible high-resolution fabrication of customised multiscale cell culture devices with complex designs

Cell culture devices, such as microwells and microfluidic chips, are designed to increase the complexity of cell-based models whilst retaining control over culture conditions and have become indispensable platforms for biological systems modelling. From microtopography, microwells, plating devices and microfluidic systems to larger constructs for specific applications such as live imaging chamber slides, a wide variety of culture devices with different geometries have become indispensable in biology laboratories. However, while their application in biological projects is increasing exponentially, due to a combination of the techniques and tools required for their manufacture, and the physical science background sometimes needed, the design and fabrication of such devices directly by biological labs remains a relatively high investment in terms of costs, use of facilities, needed collaborations and time. Whilst commercially available systems are available, these are also often costly, and importantly lack the potential for customisation by each single lab. This combination of factors still limits widespread application of microfabricated custom devices in most biological wet labs. Capitalising on recent important advancements in the fields of bioengineering and microfabrication, and taking advantage of low-cost, high-resolution desktop resin 3D printers combined with PDMS soft lithography, we have developed an optimised low-cost and highly reproducible microfabrication pipeline, capable of generating a wide variety of customisable devices for cell culture and tissue engineering in an easy, fast reproducible way for a fraction of the cost of conventional microfabrication or commercial alternatives. This protocol is designed specifically to be a resource for biological labs with little to none prior exposure to these fields technique and enables the manufacture of complex devices across the {micro}m to cm scale. We provide a ready-to-go pipeline for the efficient treatment of resin-based 3D printed constructs for PDMS curing, using a combination of curing steps, washes and surface treatments. Together with the extensive characterisation of the fabrication pipeline, we show the utilization of this system to a variety of applications and use cases relevant to biological experiments, ranging from micro topographies for cell alignments to complex multi-part hydrogel culturing systems. This methodology can be easily adopted by any wet lab, irrespective of prior expertise or resource availability and will enable the wide adoption of tailored microfabricated devices across many fields of biology.

bioengineering↗