Concentration Of Biomolecules Research Articles

Biomolecular condensation programs floral transition to orchestrate flowering time and inflorescence architecture.

Biomolecular condensation involves the concentration of biomolecules (DNA, RNA, proteins) into compartments to form membraneless organelles or condensates with unique properties and functions. This ubiquitous phenomenon has garnered considerable attention in recent years owing to its multifaceted roles in developmental processes and responses to environmental cues in living systems. Recent studies have revealed that biomolecular condensation plays essential roles in regulating the transition of plants from vegetative to reproductive growth, a programmed process known as floral transition that determines flowering time and inflorescence architecture in flowering plants. In this Tansley insight, we review advances in how biomolecular condensation integrates developmental and environmental signals to program and reprogram the floral transition thus diversifies flowering time and inflorescence architecture.

CRISPR-Cas9 target-strand nicking provides phage resistance by inhibiting replication.

Cas endonucleases, like Cas9 and Cas12a, are RNA-guided immune effectors that provide bacterial defense against bacteriophages. Cas endonucleases rely on divalent metal ions for their enzymatic activities and to facilitate conformational changes that are required for specific recognition and cleavage of target DNA. While Cas endonucleases typically produce double-strand breaks (DSBs) in DNA targets, reduced, physiologically relevant Mg2+ concentrations and target mismatches can result in incomplete second-strand cleavage, resulting in the production of a nicked DNA. It remains poorly understood whether nicking by Cas endonucleases is sufficient to provide protection against phage. To address this, we tested phage protection by Cas9 nickases, in which only one of two nuclease domains is catalytically active. By testing a large panel of guide RNAs, we find that target strand nicking can be sufficient to provide immunity, while non-target nicking does not provide any additional protection beyond Cas9 binding. Target-strand nicking inhibits phage replication and can reduce the susceptibility of Cas9 to viral escape when targeting non-essential regions of the genome. Cleavage of the non-target strand by the RuvC domain is strongly impaired at low Mg2+ concentrations. As a result, fluctuations in the concentration of other biomolecules that can compete for binding of free Mg2+ strongly influences the ability of Cas9 to form a DSB at targeted sites. Overall, our results suggest that Cas9 may only nick DNA during CRISPR-mediated immunity, especially under conditions of low Mg2+ availability in cells.

LSPR-susceptible metasurface platform for spectrometer-less and AI-empowered diagnostic biomolecule detection

In response to the growing demand for biomolecular diagnostics, metasurface (MS) platforms based on high-Q resonators have demonstrated their capability to detect analytes with smart data processing and image analysis technologies. However, high-Q resonator meta-atom arrays are highly sensitive to the fabrication process and chemical surface functionalization. Thus, spectrum scanning systems are required to monitor the resonant wavelength changes at every step, from fabrication to practical sensing. In this study, we propose an innovative dielectric resonator-independent MS platform that enables spectrometer-less biomolecule detection using artificial intelligence (AI) at a visible wavelength. Functionalizing the focused vortex MS to capture gold nanoparticle (AuNP)-based sandwich immunoassays causes the resulting vortex beam profiles to be significantly affected by the localized surface plasmon resonance (LSPR) occurring between AuNPs and meta-atoms. The convolutional neural network algorithm was carefully trained to accurately classify the AuNP concentration-dependent focused vortex beam, facilitating the determination of the concentration of the targeted diagnostic biomolecule. Successful in situ identification of various biomolecule concentrations was achieved with over 99 % accuracy, indicating the potential of combining an LSPR-susceptible MS platform and AI for continuously tracking various chemical and biological compounds.

Correlative Effects on Nanoplastic Aggregation in Model Extracellular Biofilm Substances Investigated with Fluorescence Correlation Spectroscopy.

Recent studies show that biofilm substances in contact with nanoplastics play an important role in the aggregation and sedimentation of nanoplastics. Consequences of these processes are changes in biofilm formation and stability and changes in the transport and fate of pollutants in the environment. Having a deeper understanding of the nanoplastics-biofilm interaction would help to evaluate the risks posed by uncontrolled nanoplastic pollution. These interactions are impacted by environmental changes due to climate change, such as, e.g., the acidification of surface waters. We apply fluorescence correlation spectroscopy (FCS) to investigate the pH-dependent aggregation tendency of non-functionalized polystyrene (PS) nanoparticles (NPs) due to intermolecular forces with model extracellular biofilm substances. Our biofilm model consists of bovine serum albumin (BSA), which serves as a representative for globular proteins, and the polysaccharide alginate, which is a main component in many biofilms, in solutions containing Na+ with an ionic strength being realistic for fresh-water conditions. Biomolecule concentrations ranging from 0.5 g/L up to at maximum 21 g/L are considered. We use non-functionalized PS NPs as representative for mostly negatively charged nanoplastics. BSA promotes NP aggregation through adsorption onto the NPs and BSA-mediated bridging. In BSA-alginate mixtures, the alginate hampers this interaction, most likely due to alginate-BSA complex formation. In most BSA-alginate mixtures as in alginate alone, NP aggregation is predominantly driven by weaker, pH-independent depletion forces. The stabilizing effect of alginate is only weakened at high BSA contents, when the electrostatic BSA-BSA attraction is not sufficiently screened by the alginate. This study clearly shows that it is crucial to consider correlative effects between multiple biofilm components to better understand the NP aggregation in the presence of complex biofilm substances. Single-component biofilm model systems based on comparing the total organic carbon (TOC) content of the extracellular biofilm substances, as usually considered, would have led to a misjudgment of the stability towards aggregation.

Quantitative Proteomics and Metabolomics of Culture Medium from Single Human Embryo Reveal Embryo Quality-Related Multiomics Biomarkers.

An effective tool to assess embryo quality in the assisted reproduction clinical practice will enhance successful implantation rates and mitigate high risks of multiple pregnancies. Potential biomarkers secreted into culture medium (CM) during embryo development enable rapid and noninvasive methods of assessing embryo quality. However, small volumes, low biomolecule concentrations, and impurity interference collectively preclude the identification of quality-related biomarkers in single blastocyst CM. Here, we developed a noninvasive trace multiomics approach to screen for potential markers in individual human blastocyst CM. We collected 84 CM samples and divided them into high-quality (HQ) and low-quality (LQ) groups. We evaluated the differentially expressed proteins (DEPs) and metabolites (DEMs) in HQ and LQ CM. A total of 504 proteins and 189 metabolites were detected in individual blastocyst CM. Moreover, 9 DEPs and 32 DEMs were identified in different quality embryo CM. We also categorized HQ embryos into positive implantation (PI) and negative implantation (NI) groups based on ultrasound findings on day 28. We identified 41 DEPs and 4 DEMs associated with clinical implantation outcomes in morphologically HQ embryos using a multiomics analysis approach. This study provides a noninvasive multiomics analysis technique and identifies potential biomarkers for clinical embryo developmental quality assessment.

High performance Pt-anchored MoS2 based chemiresistive ascorbic acid sensor

Ascorbic acid (AA), known as vitamin C, is a vital bioactive compound that plays a crucial role in several metabolic processes, including the synthesis of collagen and neurotransmitters, the removal of harmful free radicals, and the uptake of iron by cells in the human intestines. As a result, there is an absolute need for a highly selective, sensitive, and economically viable sensing platform for AA detection. Herein, we demonstrate a Pt-decorated MoS2 for efficient detection of an AA biosensor. MoS2 hollow rectangular structures were synthesized using an easy and inexpensive chemical vapor deposition approach to meet the increasing need for a reliable detection platform. The synthesized MoS2 hollow rectangular structures are characterized through field effect scanning electron microscopy (FESEM), energy-dispersive spectroscopy elemental mapping, Raman spectroscopy, and x-ray photoelectron spectroscopy. We fabricate a chemiresistive biosensor based on Pt-decorated MoS2 that measures AA with great precision and high sensitivity. The experiments were designed to evaluate the response of the Pt-decorated MoS2 biosensor in the presence and absence of AA, and selectivity was evaluated for a variety of biomolecules, and it was observed to be very selective towards AA. The Pt-MoS2 device had a higher response of 125% against 1 mM concentration of AA biomolecules, when compared to that of all other devices and 2.2 times higher than that of the pristine MoS2 device. The outcomes of this study demonstrate the efficacy of Pt-decorated MoS2 as a promising material for AA detection. This research contributes to the ongoing efforts to enhance our capabilities in monitoring and detecting AA, fostering advancements in environmental, biomedical, and industrial applications.

Granular Biomaterials as Bioactive Sponges for the Sequestration and Release of Signaling Molecules.

A major challenge for the regeneration of chronic wounds is an underlying dysregulation of signaling molecules, including inflammatory cytokines and growth factors. To address this, it is proposed to use granular biomaterials composed of jammed microgels, to enable the rapid uptake and delivery of biomolecules, and provide a strategy to locally sequester and release biomolecules. Sequestration assays on model biomolecules of different sizes demonstrate that granular hydrogels exhibit faster transport than comparable bulk hydrogels due to enhanced surface area and decreased diffusion lengths. To demonstrate the potential of modular granular hydrogels to modulate local biomolecule concentrations, microgel scaffolds are engineered that can simultaneously sequester excess pro-inflammatory factors and release pro-healing factors. To target specific biomolecules, microgels are functionalized with affinity ligands that bind either to interleukin 6 (IL-6) or to vascular endothelial growth factor A (VEGF-A). Finally, disparate microgels are combined into a single granular biomaterial for simultaneous sequestration of IL-6 and release of VEGF-A. Overall, the potential of modular granular hydrogels is demonstrated to locally tailor the relative concentrations of pro- and anti-inflammatory factors.

Stable Cd(II)-based coordination polymer as a multifunctional fluorescent sensor for ascorbic acid, acetylacetone and nitrofuran antibiotics

The concentrations of hazardous volatile organic compounds (VOCs), pharmaceutical antibiotics and biomolecules in water systems are closely related with public health and ecological security. Thus, the convenient and accurate detection of these harmful items can not only reflect the state of human health but also evaluate the level of homologous contamination in the environment. To this end, a new Cd(II)-CP ({[Cd3L2(bmoe)]·DMF}n) with excellent luminescence properties was designed by employing the semi-rigid tricarboxylic acid 4-(2′,3′-dicarboxylphenoxy) (H3L) and N-donor ligand 1,1′-bis(1H-benzimidazolyl) oxydiethane (bmoe). The as-prepared Cd-CP features the unique uninodal sql topology. Benefiting from its great stability in the aqueous system, Cd-CP serves as a versatile multifunctional fluorescent sensor for different analytes, ascorbic acid (AA), nitrofuran antibiotics nitrofurantoin (NFT) and nitrofurazone (NFZ) and acetylacetone (ACAC). The established methods are characterized with impressive low detection limits, ultrafast response time, high sensitivity, strong anti-interference ability, as well as reliable reproducibility. Experimental and theoretical calculation reveals that the collaborative effects of Förster resonance energy transfer (FRET), inner-filter effect (IFE) and photoinduced electron transfer (PET) are the most probable causes behind the quenching of the CP's fluorescence signal.

On the accuracy bounds of high-order image correlation spectroscopy

High-order image correlation spectroscopy (HICS) or related image-based cumulant analysis of emitter species are important for identifying properties and concentrations of biomolecules or nanoparticles. However, lack of a thorough parameter space test limits its use in full potential. The current study focused on mapping accuracy bounds of bimodal species concentration space by simulating and analysing more than 2 × 105 images (∼1011 data points). Concentration space maps for four values of quantum yield contrast ratio between two species in a mixture and two sampling spaces (834 and 13357 beam areas in an image) were created, which showed clear accuracy bounds governed by two factors, Poisson fluctuation and quantum yield ratio. Typically, brighter species concentration was 1-3 orders of magnitude lower than that of dimmer species, and higher brightness contrast allowed higher concentration difference. Upper limit of accuracy bounds was governed by resolvable Poisson fluctuation, where this condition was violated for emitter density beyond 10 particles per beam area. The accuracy bounds are shown to be largely invariant under noise correction or the calculation method, and are compared against previous experimental results, showing consistent agreement. This study shows that concentration limit needs to be observed when using HICS or related image moment or cumulant analysis techniques. As a rule of thumb, a large quantum yield contrast and large sampling points allow more concentration difference between two species to be resolved in an analysis.

Dynamic Monitoring of Biomolecular Hydrodynamic Dimensions by Magnetization Motion on Quartz Crystal Microbalance.

Hydrodynamic dimension (HD) is the primary indicator of the size of bioconjugated particles and biomolecules. It is an important parameter in the study of solid-liquid two-phase dynamics. HD dynamic monitoring is crucial for precise and customized medical research as it enables the investigation of the continuous changes in the physicochemical characteristics of biomolecules in response to external stimuli. However, current HD measurements based on Brownian motion, such as dynamic light scattering (DLS), are inadequate for meeting the polydisperse sample demands of dynamic monitoring. In this paper, we propose MMQCM method samples of various types and HD dynamic monitoring. An alternating magnetic field of frequency ωm excites biomolecule-magnetic bead particles (bioMBs) to generate magnetization motion, and the quartz crystal microbalance (QCM) senses this motion to provide HD dynamic monitoring. Specifically, the magnetization motion is modulated onto the thickness-shear oscillation of the QCM at the frequency ωq. By analysis of the frequency spectrum of the QCM output signal, the ratio of the magnitudes of the real and imaginary parts of the components at frequency ωq ± 2ωm is extracted to characterize the particle size. Using the MMQCM approach, we successfully evaluated the size of bioMBs with different biomolecule concentrations. The 30 min HD dynamic monitoring was implemented. An increase of ∼10 nm in size was observed upon biomolecular structural stretching. Subsequently, the size of bioMBs gradually reduced due to the continuous dissociation of biomolecules, with a total reduction of 20∼40 nm. This HD dynamic monitoring demonstrates that the release of biomolecules can be regulated by controlling the duration of magnetic stimulation, providing valuable insights and guidance for controlled drug release in personalized precision medicine.

Biosynthesis of biomolecules from saffron as an industrial crop and their regulation, with emphasis on the chemistry, extraction methods, identification techniques, and potential applications in human health and food: A critical comprehensive review

The dried stigmas of Crocus sativus, known as “Red Gold,” are highly prized for their nutritional and medicinal qualities. These qualities are due to the presence of apocarotenoids such as crocin, crocetin, safranal, and picrocrocin. The concentrations of biomolecules in saffron play a crucial role in determining its quality and commercial value. Ensuring the purity of saffron biomolecules is crucial for their pharmaceutical and food applications, given their significant potential in these fields. Enhancing cultivation practices and harnessing biosynthesis pathways through genetic engineering are widely used methods to boost the production of saffron biomolecules. Nevertheless, achieving optimal purity and output from the final products necessitates the implementation of efficient extraction methods. Additionally, employing effective identification methods is crucial for attaining accuracy in estimating the quality and quantity of these biomolecules. Hence, understanding the biosynthesis, extraction, and identification methods of saffron biomolecules, along with their significant role in human health and food, holds great importance. There is a need for extensive research to enhance the quality of components used in the food and pharmaceutical industries, surpassing the current studies. Thus, this review provides an overview of saffron biomolecules, including crocin, crocetin, safranal, and picrocrocin, along with their properties, biosynthesis, and regulation. Furthermore, the paper delves into the various aspects of saffron biomolecules, including sample preparation, extraction, identification, and quantification. In addition, the paper highlighted the possible health advantages and food uses of saffron biomolecules, as well as detailed information on the role of artificial intelligence have been discussed as a cutting-edge tool for studying various aspects of saffron biomolecules. Furthermore, the study has emphasized the future potential and opportunities for further research on saffron and its biomolecules, which can pique the interest of researchers, scientists, and industrial people seeking new and innovative opportunities.

Blood-based cardiometabolic phenotypes in atrial fibrillation and their associated risk: EAST-AFNET 4 biomolecule study.

Atrial fibrillation (AF) and concomitant cardiometabolic disease processes interact and combine to lead to adverse events, such as stroke, heart failure, myocardial infarction, and cardiovascular death. Circulating biomolecules provide quantifiable proxies for cardiometabolic disease processes. The aim of this study was to test whether biomolecule combinations can define phenotypes in patients with AF. This pre-specified analysis of the EAST-AFNET 4 biomolecule study assigned patients to clusters using polytomous variable latent-class analysis based on baseline concentrations of 13 precisely quantified biomolecules potentially reflecting ageing, cardiac fibrosis, metabolic dysfunction, oxidative stress, cardiac load, endothelial dysfunction, and inflammation. In each cluster, rates of cardiovascular death, stroke, or hospitalization for heart failure or acute coronary syndrome, the primary outcome of EAST-AFNET 4, were calculated and compared between clusters over median 5.1 years follow-up. Findings were independently validated in a prospective cohort of 748 patients with AF (BBC-AF; median follow-up 2.9 years).Unsupervised biomolecule analysis assigned 1586 patients (71 years old, 46% women) into four clusters. The highest risk cluster was dominated by elevated bone morphogenetic protein 10, insulin-like growth factor-binding protein 7, N-terminal pro-B-type natriuretic peptide, angiopoietin 2, and growth differentiation factor 15. Patients in the lowest risk cluster showed low concentrations of these biomolecules. Two intermediate-risk clusters differed by high or low concentrations of C-reactive protein, interleukin-6, and D-dimer. Patients in the highest risk cluster had a five-fold higher cardiovascular event rate than patients in the low-risk cluster. Early rhythm control was effective across clusters (Pinteraction = 0.63). Sensitivity analyses and external validation in BBC-AF replicated clusters and risk gradients. Biomolecule concentrations identify cardiometabolic subphenotypes in patients with AF at high and low cardiovascular risk.

Different profiles of soil phosphorous compounds depending on tree species and availability of soil phosphorus in a tropical rainforest in French Guiana

BackgroundThe availability of soil phosphorus (P) often limits the productivities of wet tropical lowland forests. Little is known, however, about the metabolomic profile of different chemical P compounds with potentially different uses and about the cycling of P and their variability across space under different tree species in highly diverse tropical rainforests.ResultsWe hypothesised that the different strategies of the competing tree species to retranslocate, mineralise, mobilise, and take up P from the soil would promote distinct soil 31P profiles. We tested this hypothesis by performing a metabolomic analysis of the soils in two rainforests in French Guiana using 31P nuclear magnetic resonance (NMR). We analysed 31P NMR chemical shifts in soil solutions of model P compounds, including inorganic phosphates, orthophosphate mono- and diesters, phosphonates, and organic polyphosphates. The identity of the tree species (growing above the soil samples) explained > 53% of the total variance of the 31P NMR metabolomic profiles of the soils, suggesting species-specific ecological niches and/or species-specific interactions with the soil microbiome and soil trophic web structure and functionality determining the use and production of P compounds. Differences at regional and topographic levels also explained some part of the the total variance of the 31P NMR profiles, although less than the influence of the tree species. Multivariate analyses of soil 31P NMR metabolomics data indicated higher soil concentrations of P biomolecules involved in the active use of P (nucleic acids and molecules involved with energy and anabolism) in soils with lower concentrations of total soil P and higher concentrations of P-storing biomolecules in soils with higher concentrations of total P.ConclusionsThe results strongly suggest “niches” of soil P profiles associated with physical gradients, mostly topographic position, and with the specific distribution of species along this gradient, which is associated with species-specific strategies of soil P mineralisation, mobilisation, use, and uptake.

Recent Advances in Metallic Nanostructures-Assisted Biosensors for Medical Diagnosis and Therapy.

The field of nanotechnology has witnessed remarkable progress in recent years, particularly in its application to medical diagnosis and therapy. Metallic nanostructures-assisted biosensors have emerged as a powerful and versatile platform, offering unprecedented opportunities for sensitive, specific, and minimally invasive diagnostic techniques, as well as innovative therapeutic interventions. These biosensors exploit the molecular interactions occurring between biomolecules, such as antibodies, enzymes, aptamers, or nucleic acids, and metallic surfaces to induce observable alterations in multiple physical attributes, encompassing electrical, optical, colorimetric, and electrochemical signals. These interactions yield measurable data concerning the existence and concentration of particular biomolecules. The inherent characteristics of metal nanostructures, such as conductivity, plasmon resonance, and catalytic activity, serve to amplify both sensitivity and specificity in these biosensors. This review provides an in-depth exploration of the latest advancements in metallic nanostructures-assisted biosensors, highlighting their transformative impact on medical science and envisioning their potential in shaping the future of personalized healthcare.

Gas Evolution as a Tool to Study Reaction Kinetics Under Biomimetic Conditions.

The field of bioorthogonal chemistry is rapidly growing, presenting successful applications of organic and transition metal-catalysed reactions in cells and living systems (in vivo). The development of such reactions typically proceeds through many iterative steps focused on biocompatibility and fast reaction kinetics to ensure product formation. However, obtaining kinetic data, even under simulated biological (biomimetic) conditions, remains a challenge due to substantial concentrations of salts and biomolecules hampering the use of typically employed solution-phase analytical techniques. In this study, we explored the suitability of gas evolution as a probe to study kinetics under biomimetic conditions. As proof of concept, we show that the progress of two transition metal-catalysed bioorthogonal chemical reactions can be accurately monitored, regardless of the complexity of the medium. As such, we introduce a protocol to gain more insight into the performance of a catalytic system under biomimetic conditions to further progress iterative catalyst development for in vivo applications.

Toward Prebiotic Chemistry on Titan: Impact Experiments on Organic Haze Particles

Impacts are critical to producing the aqueous environments necessary to stimulate prebiotic chemistry on Titan’s surface. Furthermore, organic hazes resting on the surface are a likely feedstock of biomolecules. In this work, we conduct impact experiments on laboratory-produced organic haze particles and haze/sand mixtures and analyze these samples for life’s building blocks. Samples of unshocked haze and sand particles are also analyzed to determine the change in biomolecule concentrations and distributions from shocking. Across all samples, we detect seven nucleobases, nine proteinogenic amino acids, and five other biomolecules (e.g., urea) using a blank subtraction procedure to eliminate signals due to contamination. We find that shock pressures of 13 GPa variably degrade nucleobases, amino acids, and a few other organics in haze particles and haze/sand mixtures; however, certain individual biomolecules become enriched or are even produced from these events. Xanthine, threonine, and aspartic acid are enriched or produced in impact experiments containing sand, suggesting these minerals may catalyze the production of these biomolecules. On the other hand, thymine and isoleucine/norleucine are enriched or produced in haze samples containing no sand, suggesting catalytic grains are not necessary for all impact shock syntheses. Uracil, glycine, proline, cysteine, and tyrosine are the most unstable to impact-related processing. These experiments suggest that impacts alter biomolecule distributions on Titan’s surface, and that organic hazes co-occurring with fine-grained material on the surface may provide an initial source for further prebiotic chemistry on Titan.

Multicompartmental coacervate-based protocell by spontaneous droplet evaporation

Hierarchical compartmentalization, a hallmark of both primitive and modern cells, enables the concentration and isolation of biomolecules, and facilitates spatial organization of biochemical reactions. Coacervate-based compartments can sequester and recruit a large variety of molecules, making it an attractive protocell model. In this work, we report the spontaneous formation of core-shell cell-sized coacervate-based compartments driven by spontaneous evaporation of a sessile droplet on a thin-oil-coated substrate. Our analysis reveals that such far-from-equilibrium architectures arise from multiple, coupled segregative and associative liquid-liquid phase separation, and are stabilized by stagnation points within the evaporating droplet. The formation of stagnation points results from convective capillary flows induced by the maximum evaporation rate at the liquid-liquid-air contact line. This work provides valuable insights into the spontaneous formation and maintenance of hierarchical compartments under non-equilibrium conditions, offering a glimpse into the real-life scenario.

Recombinant silk protein condensates show widely different properties depending on the sample background.

There is an increasing understanding that condensation is a crucial intermediate step in the assembly of biological materials and for a multitude of cellular processes. To apply and to understand these mechanisms, in vitro biophysical characterisation techniques are central. The formation and biophysical properties of protein condensates depend on a multitude of factors, such as protein concentration, pH, temperature, salt concentration, and presence of other biomolecules as well as protein purification and storage conditions. Here we show how critical the procedures for preparing protein samples for in vitro studies are. We compare two purification methods of the recombinant spider silk protein CBM-AQ12-CBM and study the effect of background molecules, such as DNA, on the formation and properties of the condensates. We characterize the condensates using aggregation induced emitters (AIEs), coalescence studies, and micropipette aspiration. The condensated sample containing background molecules exhibit a lower threshold concentration for condensate formation accompanied by a lower surface tension and longer coalescence time when compared to the pure protein condensates. Furthermore, the partitioning of small AIEs is enhanced in the presence of background molecules. Our results highlight that the purification method and remaining background molecules strongly affect the biophysical properties of spider silk condensates. Using the acquired knowledge about spider silk protein purification we derive guidelines for reproducible condensate formation that will foster the use of spider silk proteins as adhesives or carriers for biomedical applications.

Physics-based analytical model for trap assisted biosensing in dual cavity negative capacitance junctionless accumulation mode FET

The design of a ferroelectric-based biosensor for detecting various biomolecules like proteins and DNA has captivated the interest of researchers in early disease diagnostics and treatment monitoring. Doomed by this interest, an analytical model for trap-assisted biosensing in Dual Cavity Negative Capacitance Junctionless Accumulation Mode FET is proposed for detecting various biomolecules. The biomolecules are treated as traps that tunnel through the biosensor's ferroelectric layer. The analytical model is validated through extensive numerical device simulations. The device incorporates the detection of charged and uncharged biomolecules in terms of dielectric constants and biomolecule concentration. The nano-cavities are created inside the gate dielectric stack to collect biomolecules like proteins and DNA. As the biomolecules are infused as traps in cavity areas, electrical properties of the biosensor, like input characteristics, transconductance, threshold voltage, on-state current, and subthreshold swing change. The sensitivity obtained for the proposed biosensor is compared with the existing biosensor and found that it is best suited for susceptible biosensing applications.

A direct MIP-interfaced FET sensor for sensitive, selective, and real time biomolecule detection in unamplified samples: Toward POC bioelectronic transduction

Diverse efforts undertaken to mitigate the Debye screening effect of field-effect transistor (FET) biosensors have achieved higher sensitivity. However, the charge transfer or induction mechanism between the captured biomolecules and the sensing surface, resulting in shift of surface potential and, hence, the drain current magnitude, shows poor selectivity for real time detection of ultra-low biomolecule concentration in unamplified samples. Herein, enabling direct interaction of the target molecule with edge passivated thermally reduced graphene oxide, through the template of molecularly imprinted polymer (MIP), specific trap induced characteristic bulges in the noise spectrum has been observed only in the presence of target molecule. Such a phenomenon has not been observed either with antibodies or aptamers as receptors. Hence, the direct interface of MIP with a graphene FET (GFET) results in the generation of an additional electronic label in FET transduction. As a proof of concept, this principle has been validated for serotonin detection in serum in the presence of other neurotransmitters, resulting in detection limit of 0.05 fM in real time, which is more than two orders of magnitude lower than existing reports and, hence, is expected to pave the way for advancing GFET based sensors toward ultrasensitive point-of-care applications without requiring complex machine learning algorithms.