Green Synthesized Chitosan Nanoparticles for Controlling Multidrug-Resistant mecA- and blaZ-Positive Staphylococcus aureus and aadA1-Positive Escherichia coli.

Antimicrobial resistance has recently been considered an emerging catastrophe globally. The public health and environmental threats were aggravated by the injudicious use of antibiotics in animal farming, aquaculture, and croup fields, etc. Consequently, failure of antibiotic therapies is common because of the emergence of multidrug-resistant (MDR) bacteria in the environment. Thus, the reduction in antibiotic spillage in the environment could be an important step for overcoming this situation. Bear in mind, this research was focused on the green synthesis of chitosan nanoparticles (ChiNPs) using Citrus lemon (Assam lemon) extract as a cross-linker and application in controlling MDR bacteria to reduce the antibiotic spillage in that sector. For evaluating antibacterial activity, Staphylococcus aureus and Escherichia coli were isolated from environmental specimens, and their multidrug-resistant pattern were identified both phenotypically by disk diffusion and genotypically by detecting methicillin- (mecA), penicillin- (blaZ), and streptomycin (aadA1)-resistance encoding genes. The inhibitory zone's diameter was employed as a parameter for determining the antibacterial effect against MDR bacteria revealing 30 ± 0.4 mm, 34 ± 0.2 mm, and 36 ± 0.8 mm zones of inhibition against methicillin- (mecA) and penicillin (blaZ)-resistant S. aureus, and streptomycin (aadA1)-resistant E. coli, respectively. The minimum inhibitory concentration at 0.31 mg/mL and minimum bactericidal concentration at 0.62 mg/mL of yielded ChiNPs were used as the broad-spectrum application against MDR bacteria. Finally, the biocompatibility of ChiNPs was confirmed by showing a negligible decrease in BHK-21 cell viability at doses less than 2 MIC, suggesting their potential for future application in antibiotic-free farming practices.

Magnetic Nanoparticle-Assisted Non-Viral CRISPR-Cas9 for Enhanced Genome Editing to Treat Rett Syndrome.

The CRISPR-Cas9 technology has the potential to revolutionize the treatment of various diseases, including Rett syndrome, by enabling the correction of genes or mutations in human patient cells. However, several challenges need to be addressed before its widespread clinical application. These challenges include the low delivery efficiencies to target cells, the actual efficiency of the genome-editing process, and the precision with which the CRISPR-Cas system operates. Herein, the study presents a Magnetic Nanoparticle-Assisted Genome Editing (MAGE) platform, which significantly improves the transfection efficiency, biocompatibility, and genome-editing accuracy of CRISPR-Cas9 technology. To demonstrate the feasibility of the developed technology, MAGE is applied to correct the mutated MeCP2 gene in induced pluripotent stem cell-derived neural progenitor cells (iPSC-NPCs) from a Rett syndrome patient. By combining magnetofection and magnetic-activated cell sorting, MAGE achieves higher multi-plasmid delivery (99.3%) and repairing efficiencies (42.95%) with significantly shorter incubation times than conventional transfection agents without size limitations on plasmids. The repaired iPSC-NPCs showed similar characteristics as wild-type neurons when they differentiated into neurons, further validating MAGE and its potential for future clinical applications. In short, the developed nanobio-combined CRISPR-Cas9 technology offers the potential for various clinical applications, particularly in stem cell therapies targeting different genetic diseases.

Prefrontal-subthalamic theta signaling mediates delayed responses during conflict processing.

While medial frontal cortex (MFC) and subthalamic nucleus (STN) have been implicated in conflict monitoring and action inhibition, respectively, an integrated understanding of the spatiotemporal and spectral interaction of these nodes and how they interact with motor cortex (M1) to definitively modify motor behavior during conflict is lacking. We recorded neural signals intracranially across presupplementary motor area (preSMA), M1, STN, and globus pallidus internus (GPi), during a flanker task in 20 patients undergoing deep brain stimulation implantation surgery for Parkinson disease or dystonia. Conflict is associated with sequential and causal increases in local theta power from preSMA to STN to M1 with movement delays directly correlated with increased STN theta power, indicating preSMA is the MFC locus that monitors conflict and signals STN to implement a 'break.' Transmission of theta from STN-to-M1 subsequently results in a transient increase in M1-to-GPi beta flow immediately prior to movement, modulating the motor network to actuate the conflict-related action inhibition (i.e., delayed response). Action regulation during conflict relies on two distinct circuits, the conflict-related theta and movement-related beta networks, that are separated spatially, spectrally, and temporally, but which interact dynamically to mediate motor performance, highlighting complex parallel yet interacting networks regulating movement.

Irregularity of instantaneous gamma frequency in the motor control network characterize visuomotor and proprioceptive information processing.

Objective.The study aims to characterize movements with different sensory goals, by contrasting the neural activity involved in processing proprioceptive and visuo-motor information. To accomplish this, we have developed a new methodology that utilizes the irregularity of the instantaneous gamma frequency parameter for characterization.Approach.In this study, eight essential tremor patients undergoing an awake deep brain stimulation implantation surgery repetitively touched the clinician's finger (forward visually-guided/FV movement) and then one's own chin (backward proprioceptively-guided/BP movement). Neural electrocorticographic recordings from the motor (M1), somatosensory (S1), and posterior parietal cortex (PPC) were obtained and band-pass filtered in the gamma range (30-80 Hz). The irregularity of the inter-event intervals (IEI; inverse of instantaneous gamma frequency) were examined as: (1) auto-information of the IEI time series and (2) correlation between the amplitude and its proceeding IEI. We further explored the network connectivity after segmenting the FV and BP movements by periods of accelerating and decelerating forces, and applying the IEI parameter to transfer entropy methods.Main results.Conceptualizing that the irregularity in IEI reflects active new information processing, we found the highest irregularity in M1 during BP movement, highest in PPC during FV movement, and the lowest during rest at all sites. Also, connectivity was the strongest from S1 to M1 and from S1 to PPC during FV movement with accelerating force and weakest during rest.Significance. We introduce a novel methodology that utilize the instantaneous gamma frequency (i.e. IEI) parameter in characterizing goal-oriented movements with different sensory goals, and demonstrate its use to inform the directional connectivity within the motor cortical network. This method successfully characterizes different movement types, while providing interpretations to the sensory-motor integration processes.

Carbon-based nanocomposites for biomedical applications.

Carbon nanomaterials have attracted significant attention in the biomedical field, including for biosensing, drug delivery, and tissue engineering applications. Based on their inherent properties such as their unique structure and high conductivity, carbon nanomaterials can overcome the current limitations in biomedical research such as poor stability of biomolecules, low sensitivity and selectivity of biosensors, and difficulty in precise drug delivery. In addition, recently, several novel nanomaterials have been integrated with carbon nanomaterials to develop carbon-based nanocomposites for application in biomedical research. In this review, we discuss recent studies on carbon-based nanocomposites and their biomedical applications. First, we discuss the representative carbon nanomaterials and nanocomposites composed of carbon and other novel nanomaterials. Next, applications of carbon nanomaterials and nanocomposites in the biomedical field are discussed according to topics in the biomedical field. We have discussed the recent studies on biosensors, drug delivery, and tissue engineering. In conclusion, we believe that this review provides the potential and applicability of carbon nanomaterials and their nanocomposites and suggests future directions of the application of carbon-based nanocomposites in biomedical applications.

Human Motor System-Based Biohybrid Robot-On-a-Chip for Drug Evaluation of Neurodegenerative Disease.

Biohybrid robots have been developed for biomedical applications and industrial robotics. However, the biohybrid robots have limitations to be applied in neurodegenerative disease research due to the absence of a central nervous system. In addition, the organoids-on-a-chip has not yet been able to replicate the physiological function of muscle movement in the human motor system, which is essential for evaluating the accuracy of the drugs used for treating neurodegenerative diseases. Here, a human motor system-based biohybrid robot-on-a-chip composed of a brain organoid, multi-motor neuron spheroids, and muscle bundle on solid substrateis proposed to evaluate the drug effect on neurodegenerative diseases for the first time. The electrophysiological signals from the cerebral organoid induced the muscle bundle movement through motor neuron spheroids. To evaluate the drug effect on Parkinson's disease (PD), a patient-derived midbrain organoid is generated and incorporated into a biohybrid robot-on-a-chip. The drug effect on PD is successfully evaluated by measuring muscle bundle movement. The muscle bundle movement of PD patient-derived midbrain organoid-based biohybrid robot-on-a-chip is increased from 4.5 ± 0.99 µm to 18.67 ± 2.25 µm in response to levodopa. The proposed human motor system-based biohybrid robot-on-a-chip can serve as a standard biohybrid robot model for drug evaluation.

Recombinant protein embedded liposome on gold nanoparticle based on LSPR method to detect Corona virus.

Antibody sensor to detect viruses has been widely used but has problems such as the difficulty of right direction control of the receptor site on solid substrate, and long time and high cost for design and production of antibodies to new emerging viruses. The virus detection sensor with a recombinant protein embedded liposome (R/Li) was newly developed to solve the above problems, in which R/Li was assembled on AuNPs (Au@R/Li) to increase the sensitivity using localized surface plasmon resonance (LSPR) method. Recombinant angiotensin-converting enzyme-2 (ACE2) was used as host receptors of SARS-CoV and SARS-CoV-2, and the direction of enzyme active site for virus attachment could be controlled by the integration with liposome. The recombinant protein embedded liposomes were assembled on AuNPs, and LSPR method was used for detection. With the sensor platform S1 protein of both viruses was detected with detection limit of 10 pg/ml and SARS-CoV-2 in clinical samples was detected with 10 ~ 35 Ct values. In the selectivity test, MERS-CoV did not show a signal due to no binding with Au@R/Li. The proposed sensor platform can be used as promising detection method with high sensitivity and selectivity for the early and simple diagnosis of new emerging viruses.

Facile synthesis of CuONPs using Citrus limon juice for enhancing antibacterial activity against methicillin-resistant Staphylococcus aureus, beta-lactamase and tetracycline-resistant Escherichia coli.

Antimicrobial resistance (AMR) resulting from indiscriminate use of antibiotics in various fields of agriculture such as livestock farming, aquaculture, and croup fields become an emerging catatroph for the health (human, animal) and environment. Among those, poultry farming has been considered as one of the major contributors of multidrug-resistant (MDR) bacteria. Focusing this, the present research is designed for green synthesis of copper oxide nanoparticles (CuONPs) with the aim of their application in antibiotic-free poultry farming for curving use of antibiotics in that sector. For that, antibacterial CuONPs were nanoformulated to decrease the required doses of bulk CuSO4. We used a CuSO4·5H2O solution as a Cu2+ source and Citrus limon juice as a reducing agent as well as capping agent. Particle yield was initially confirmed by the λmax specific to CuONPs (295 nm) using UV-Vis spectroscopy. The presence of the Cu-O group during particle formation and crystallinity with the purity of yielded NPs was confirmed with Fourier-transform infrared spectroscopy and X-ray diffractometry. The round to spherical CuONPs of 92-155 nm average size was confirmed with atomic force, scanning electron, and transmission electron microscopy. The concentration of yielded NPs was calculated with the dynamic light scattering. The physical characterization tools indicated a maximum CuONPs yield with a 0.001 M ion source with 15% reducing agents after 12 h reduction. Antibacterial effectivity was tested against methicillin-resistant Staphylococcus aureus and tetracycline- and beta-lactamase-resistant Escherichia coli, confirmed by PCR amplicon band at 163 bp, 643 bp, and 577 bp for the mecA, blaTEM-1 and tetA genes, respectively. An antibiogram assay of CuONPs showed a maximum zone of inhibition of 26 ± 0.5 mm for the synthesized particles. The minimum inhibitory and bactericidal concentrations were 1.6 µg ml-1 and 3.1 µg ml-1, respectively, for broad-spectrum application. Finally, the biocompatibility of CuONPs was determined by demonstrating a nonsignificant decrease of BHK-21 cell viability at <2 MIC doses for complying their future in vivo applicability.

Nano-Enabled Antivirals for Overcoming Antibody Escaped Mutations Based SARS-CoV-2 Waves.

This review discusses receptor-binding domain (RBD) mutations related to the emergence of various SARS-CoV-2 variants, which have been highlighted as a major cause of repetitive clinical waves of COVID-19. Our perusal of the literature reveals that most variants were able to escape neutralizing antibodies developed after immunization or natural exposure, pointing to the need for a sustainable technological solution to overcome this crisis. This review, therefore, focuses on nanotechnology and the development of antiviral nanomaterials with physical antagonistic features of viral replication checkpoints as such a solution. Our detailed discussion of SARS-CoV-2 replication and pathogenesis highlights four distinct checkpoints, the S protein (ACE2 receptor coupling), the RBD motif (ACE2 receptor coupling), ACE2 coupling, and the S protein cleavage site, as targets for the development of nano-enabled solutions that, for example, prevent viral attachment and fusion with the host cell by either blocking viral RBD/spike proteins or cellular ACE2 receptors. As proof of this concept, we highlight applications of several nanomaterials, such as metal and metal oxide nanoparticles, carbon-based nanoparticles, carbon nanotubes, fullerene, carbon dots, quantum dots, polymeric nanoparticles, lipid-based, polymer-based, lipid-polymer hybrid-based, surface-modified nanoparticles that have already been employed to control viral infections. These nanoparticles were developed to inhibit receptor-mediated host-virus attachments and cell fusion, the uncoating of the virus, viral gene expression, protein synthesis, the assembly of progeny viral particles, and the release of the virion. Moreover, nanomaterials have been used as antiviral drug carriers and vaccines, and nano-enabled sensors have already been shown to enable fast, sensitive, and label-free real-time diagnosis of viral infections. Nano-biosensors could, therefore, also be useful in the remote testing and tracking of patients, while nanocarriers probed with target tissue could facilitate the targeted delivery of antiviral drugs to infected cells, tissues, organs, or systems while avoiding unwanted exposure of non-target tissues. Antiviral nanoparticles can also be applied to sanitizers, clothing, facemasks, and other personal protective equipment to minimize horizontal spread. We believe that the nanotechnology-enabled solutions described in this review will enable us to control repeated SAR-CoV-2 waves caused by antibody escape mutations.

A Nano-Biohybrid-Based Bio-Solar Cell to Regulate the Electrical Signal Transmission to Living Cells for Biomedical Application.

Bio-solar cells are studied as sustainable and biocompatible energy sources with significant potential for biomedical applications. However, they are composed of light-harvesting biomolecules with narrow absorption wavelengths and weak transient photocurrent generation. In this study, a nano-biohybrid-based bio-solar cell composed of bacteriorhodopsin, chlorophyllin, and Ni/TiO2 nanoparticles is developed to overcome the current limitations and verify the possibility of biomedical applications. Bacteriorhodopsin and chlorophyllin are introduced as light-harvesting biomolecules to broaden the absorption wavelength. As a photocatalyst, Ni/TiO2 nanoparticles are introduced to generate a photocurrent and amplify the photocurrent generated by the biomolecules. The developed bio-solar cell absorbs a broad range of visible wavelengths and generates an amplified stationary photocurrent density (152.6 nA cm-2 ) with a long lifetime (up to 1 month). Besides, the electrophysiological signals of muscle cells at neuromuscular junctions are precisely regulated by motor neurons excited by the photocurrent of the bio-solar cell, indicating that the bio-solar cell can control living cells by signal transmission through other types of living cells. The proposed nano-biohybrid-based bio-solar cell can be used as a sustainable and biocompatible energy source for the development of wearable and implantable biodevices and bioelectronic medicines for humans.

Nanomaterial-based biohybrid hydrogel in bioelectronics.

Despite the broadly applicable potential in the bioelectronics, organic/inorganic material-based bioelectronics have some limitations such as hard stiffness and low biocompatibility. To overcome these limitations, hydrogels capable of bridging the interface and connecting biological materials and electronics have been investigated for development of hydrogel bioelectronics. Although hydrogel bioelectronics have shown unique properties including flexibility and biocompatibility, there are still limitations in developing novel hydrogel bioelectronics using only hydrogels such as their low electrical conductivity and structural stability. As an alternative solution to address these issues, studies on the development of biohybrid hydrogels that incorporating nanomaterials into the hydrogels have been conducted for bioelectronic applications. Nanomaterials complement the shortcomings of hydrogels for bioelectronic applications, and provide new functionality in biohybrid hydrogel bioelectronics. In this review, we provide the recent studies on biohybrid hydrogels and their bioelectronic applications. Firstly, representative nanomaterials and hydrogels constituting biohybrid hydrogels are provided, and next, applications of biohybrid hydrogels in bioelectronics categorized in flexible/wearable bioelectronic devices, tissue engineering, and biorobotics are discussed with recent studies. In conclusion, we strongly believe that this review provides the latest knowledge and strategies on hydrogel bioelectronics through the combination of nanomaterials and hydrogels, and direction of future hydrogel bioelectronics.

A photoluminescence sensor for in-situ monitoring of the dopamine neurotransmitters released from PC12 cells.

Constructing simple, stable, fast, and sensitive neurotransmitter-based sensors is a promising tool to diagnose neurological diseases. Dopamine (DA), "a catecholamine neurotransmitter" is important in transmitting nerve impulses. Therefore, great attention is taken to monitor DA concentrations received. The challenge in developing a DA-based sensor is to enhance its stability and sensitivity. Thus, we have used o-phthalaldehyde (OPA)/2-mercapto ethanol (2ME)/mesoporous silica instated of 2ME in solution. Here we have successfully developed a fluorescence DA neurotransmitters sensor. The sensor was used for detecting a wide range of concentrations of DA (5 nM to 5 µM). Effects of pH (4.3-11.4) and temperatures (25-70 °C) on the sensor efficiency were investigated. The detection limit was 1.35 × 10-11 mol/dm3, which is lower than the normal DA level in the central nervous system. The results indicated that using OPA/2ME/MSNPs has long-time stability over a year of its preparation. Moreover, the developed sensor showed high specificity towards DA in the presence of different interferences such as ascorbic acid or another catecholamine neurotransmitter such as γ-aminobutyric acid. Finally, the fabricated biosensor was used to monitor the DA neurotransmitter released from PC12 cells. Hence, it was successfully developed a simple and stable probe for accurate photoluminescence detection of DA neurotransmitters.

A neurocomputational theory of action regulation predicts motor behavior in neurotypical individuals and patients with Parkinson's disease.

Surviving in an uncertain environment requires not only the ability to select the best action, but also the flexibility to withhold inappropriate actions when the environmental conditions change. Although selecting and withholding actions have been extensively studied in both human and animals, there is still lack of consensus on the mechanism underlying these action regulation functions, and more importantly, how they inter-relate. A critical gap impeding progress is the lack of a computational theory that will integrate the mechanisms of action regulation into a unified framework. The current study aims to advance our understanding by developing a neurodynamical computational theory that models the mechanism of action regulation that involves suppressing responses, and predicts how disruption of this mechanism can lead to motor deficits in Parkinson's disease (PD) patients. We tested the model predictions in neurotypical individuals and PD patients in three behavioral tasks that involve free action selection between two opposed directions, action selection in the presence of conflicting information and abandoning an ongoing action when a stop signal is presented. Our results and theory suggest an integrated mechanism of action regulation that affects both action initiation and inhibition. When this mechanism is disrupted, motor behavior is affected, leading to longer reaction times and higher error rates in action inhibition.

Recent progress in nanomaterial-based bioelectronic devices for biocomputing system.

Bioelectronic devices have received the massive attention because of their huge potential to develop the core electronic components for biocomputing system. Up to now, numerous bioelectronic devices have been reported such as biomemory and biologic gate by employment of biomolecules including metalloproteins and nucleic acids. However, the intrinsic limitations of biomolecules such as instability and low signal production hinder the development of novel bioelectronic devices capable of performing various novel computing functions. As a way to overcome these limitations, nanomaterials have the great potential and wide applicability to grant and extend the electronic functions, and improve the inherent properties from biomolecules. Accordingly, lots of nanomaterials including the conductive metal, graphene, and transition metal dichalcogenide nanomaterials are being used to develop the remarkable functional bioelectronic devices like the multi-bit biomemory and resistive random-access biomemory. This review discusses the nanomaterial-based superb bioelectronic devices including the biomemory, biologic gates, and bioprocessors. In conclusion, this review will provide the interdisciplinary information about utilization of various novel nanomaterials applicable for biocomputing system.

Electroactive nano-Biohybrid actuator composed of gold nanoparticle-embedded muscle bundle on molybdenum disulfide nanosheet-modified electrode for motion enhancement of biohybrid robot.

There have been several trials to develop the bioactuator using skeletal muscle cells for controllable biobybird robot. However, due to the weak contraction force of muscle cells, the muscle cells could not be used for practical applications such as biorobotic hand for carrying objects, and actuator of biohybrid robot for toxicity test and drug screening. Based on reported hyaluronic acid-modified gold nanoparticles (HA@GNPs)-embedded muscle bundle on PDMS substrate, in this study for augmented actuation, we developed the electroactive nano-biohybrid actuator composed of the HA@GNP-embedded muscle bundle and molybdenum disulfide nanosheet (MoS2 NS)-modified electrode to enhance the motion performance. The MoS2 NS-modified Au-coated polyimide (PI) electrode to be worked in mild pH condition for viable muscle cell was utilized as supporting- and motion enhancing- substrate since it was electrochemically active, which caused the movement of flexible PI electrode. The motion performance of this electroactive nano-biohybrid actuator by electrical stimulation was increased about 3.18 times compared with that of only HA@GNPs embedded-muscle bundle on bare PI substrate. The proposed electroactive nano-biohybrid actuator can be applied to the biorobotic hand and biohybrid robot.

3D Neural Network Composed of Neurospheroid and Bionanohybrid on Microelectrode Array to Realize the Spatial Input Signal Recognition in Neurospheroid.

There have been several studies for demonstration of 2D neural network using living cells or organic/inorganic molecules, but to date, there is no report of development of a 3D neural network in vitro. Based on developed bionanohybrid composed of protein, DNA, molybdenum disulfide nanoparticles, and peptides for controlling electrophysiological states of living cells, here, the in vitro 3D neural network composed of the bionanohybrid, 3D neurospheroid and the microelectrode array (MEA) is developed. After production of the 3D neurospheroid derived from human neural stem cells, the bionanohybrid developed on the MEA successfully semi-penetrates the neurites of the 3D neurospheroid and forms the 3D neural network. The developed 3D neural network successfully exhibited the electrophysiological output signals of the 3D neurospheroid by transmitting the input signal applied by the bionanohybrid. Moreover, by using the selectively immobilized bionanohybrid on the MEA, the spatial input signal recognition in the neurospheroid of 3D neural network is realized for the first time. This newly developed in vitro 3D neural network provides a promising strategy to be applied in brain-on-a-chip, brain disease-related drug efficacy evaluation, bioelectronics, and bioelectronic medicine.

Ultrasensitive Electrochemical Detection of Mutated Viral RNAs with Single-Nucleotide Resolution Using a Nanoporous Electrode Array (NPEA).

The detection of nucleic acids and their mutation derivatives is vital for biomedical science and applications. Although many nucleic acid biosensors have been developed, they often require pretreatment processes, such as target amplification and tagging probes to nucleic acids. Moreover, current biosensors typically cannot detect sequence-specific mutations in the targeted nucleic acids. To address the above problems, herein, we developed an electrochemical nanobiosensing system using a phenomenon comprising metal ion intercalation into the targeted mismatched double-stranded nucleic acids and a homogeneous Au nanoporous electrode array (Au NPEA) to obtain (i) sensitive detection of viral RNA without conventional tagging and amplifying processes, (ii) determination of viral mutation occurrence in a simple detection manner, and (iii) multiplexed detection of several RNA targets simultaneously. As a proof-of-concept demonstration, a SARS-CoV-2 viral RNA and its mutation derivative were used in this study. Our developed nanobiosensor exhibited highly sensitive detection of SARS-CoV-2 RNA (∼1 fM detection limit) without tagging and amplifying steps. In addition, a single point mutation of SARS-CoV-2 RNA was detected in a one-step analysis. Furthermore, multiplexed detection of several SARS-CoV-2 RNAs was successfully demonstrated using a single chip with four combinatorial NPEAs generated by a 3D printing technique. Collectively, our developed nanobiosensor provides a promising platform technology capable of detecting various nucleic acids and their mutation derivatives in highly sensitive, simple, and time-effective manners for point-of-care biosensing.

Biomolecular Electron Controller Composed of Nanobiohybrid with Electrically Released Complex for Spatiotemporal Control of Neuronal Differentiation.

In vitro spatiotemporal control of cell differentiation is a critical issue in several biomedical fields such as stem cell therapy and regenerative medicine, as it enables the generation of heterogeneous tissue structures similar to those of their native counterparts. However, the simultaneous control of both spatial and temporal cell differentiation poses important challenges, and therefore no previous studies have achieved this goal. Here, the authors develop a cell differentiation biomolecular electron controller ("Biomoletron") composed of recombinant proteins, DNA, Au nanoparticles, peptides, and an electrically released complex with retinoic acid (RA) to spatiotemporally control SH-SY5Y cell differentiation. RA is only released from the Biomoletron when the complex is electrically stimulated, thus demonstrating the temporal control of SH-SY5Y cell differentiation. Furthermore, by introducing a patterned Au substrate that allows controlling the area where the Biomoletron is immobilized, spatiotemporal differentiation of the SH-SY5Y cell is successfully achieved. Therefore, the proposed Biomoletron-mediated differentiation method provides a promising strategy for spatiotemporal cell differentiation control with applications in regenerative medicine and cell therapy.

Actuation-Augmented Biohybrid Robot by Hyaluronic Acid-Modified Au Nanoparticles in Muscle Bundles to Evaluate Drug Effects.

Biohybrid robots, which comprise soft materials with biological components, have the potential to sense, respond, and adapt to changing environmental loads dynamically. Instead of humans and other living things, biohybrid robots can be used in various fields such as drug screening and toxicity assessment. In the actuation part, however, since a muscle cell-based biohybrid robot is limited in that the driving force is weak, it is difficult to evaluate drug and toxicological effects by distinguishing changes in the biohybrid robot's motion. To overcome this limitation, we introduced hyaluronic acid-modified gold nanoparticles (HA-AuNPs) into a muscle bundle-based biohybrid robot that moves forward in response to electrical stimulation. To enhance the actuation of muscle bundles, HA-AuNPs were embedded into the muscle bundles. The motion of the fabricated biohybrid robot was improved due to the enhanced differentiation and the improved electrical conductivity of muscle bundles by HA-AuNPs. In addition, the fabricated biohybrid robot exhibited huge changes in motion with respect to the addition of positive and negative inotropic drugs. The proposed biohybrid robot has the potential for neuromuscular disease drug screening by incorporating nervous tissues such as motor neuron organoids and brain organoids.