Carbon nanotubes: An effective platform for biomedical electronics

Enhanced "Electronic Tongue" for Dental Bacterial Discrimination and Elimination Based on a DNA-Encoded Nanozyme Sensor Array

Bacterial infections are the second leading cause of death around the world, especially those caused by delayed treatment and misdiagnosis. Therefore, rapid discrimination and effective elimination of multiple bacteria are of great importance for improving the survival rate in clinic. Herein, a novel colorimetric sensor array for bacterial discrimination and elimination is constructed using programmable DNA-encoded iron oxide nanoparticles (IONPs) as sensing elements. Utilizing differential interactions of bacteria on DNA-encoded IONPs, 11 kinds of dental bacteria and 6 kinds of proteins have been successfully identified by linear discriminant analysis (LDA). Moreover, the developed sensing system also performs well in the quantitative determination of individual bacteria and identification of bacterial mixtures. More importantly, the practicability of this sensing strategy is further verified by precise differentiation of blind and artificial saliva samples. Furthermore, the sensor array is used for efficiently killing multiple bacteria, demonstrating great potential in clinical prophylaxis and therapy.

Soft microfiber-based hollow microneedle array for stretchable microfluidic biosensing patch with negative pressure-driven sampling

Wearable point-of-care testing devices are essential for personalized and decentralized healthcare. They can collect biofluid samples from the human body and use an analyzer to detect biomolecules. However, creating an integrated system is challenging due to the difficulty of achieving conformality to the human body, regulating the collection and transport of biofluids, developing a biosensor patch capable of precise biomolecule detection, and establishing a simple operation protocol that requires minimal wearer attention. In this study, we propose using a hollow microneedle (HMN) based on soft hollow microfibers and a microneedle-integrated microfluidic biosensor patch (MIMBP) capable of integrated blood sampling and electrochemical biosensing of biomolecules. The soft MIMBP includes a stretchable microfluidic device, a flexible electrochemical biosensor, and a HMN array made from flexible hollow microfibers. The HMNs are fabricated by electroplating flexible and mechanically durable hollow microfibers made from a nanocomposite matrix of polyimide, a poly (vinylidene fluoride-co-trifluoroethylene) copolymer, and single-walled carbon nanotubes. The MIMBP uses the negative pressure generated by a single button push to collect blood and deliver it to a flexible electrochemical biosensor modified with a gold nanostructure and Pt nanoparticles. We have demonstrated that glucose can be accurately measured up to the molar range in whole human blood collected through the microneedle. The MIMBP platform with HMNs has great potential as a foundation for the future development of simple, wearable, self-testing systems for minimally invasive biomolecule detection. This platform capable of sequential blood collection and high sensitivity glucose detection, which are ideal for personalized and decentralized healthcare.

Fighting bacterial pathogens with carbon nanotubes: focused review of recent progress

The fast and global spread of bacterial resistance to currently available antibiotics results in a great and urgent need for alternative antibacterial agents and therapeutic strategies. Recent studies on the application of nanomaterials as antimicrobial agents have demonstrated their potential for the management of infectious diseases. Among the diverse palette of nanomaterials currently used in biomedical applications, carbon nanotubes (CNTs) have gained massive interest given their many valuable properties, such as high thermal and electrical conductivity, tensile strength, flexibility convenient aspect ratio, and low fabrication costs. All these features are augmented by facile conjugation with functional groups. CNTs are currently available in many configurations, with two main categories being single-walled and multi-walled CNTs, depending on the number of rolled-up single-layer carbon atoms sheets making up the nanostructure. Both classes have been identified over the past years as promising antibacterial agents but the current level of understanding of their efficiency still harbors many pending questions. This mini-review surveys recent progress on the topic of antibacterial effects of CNTs and examines the proposed mechanisms of action(s) of different CNT typologies, placing the main focus on past studies addressing the antibacterial activity on Staphylococcus aureus and Escherichia coli, two prototypical Gram-positive and Gram-negative pathogens, respectively.

Electrochemical deposition multi-walled carbon nanotube coatings on the surface of Ti6Al4V alloy for enhancing its biotribological properties

Ti6Al4V alloys have potential applications as bone implants. However, their poor biotribological performances affected the service life. In this work, carboxylic multi-walled carbon nanotubes (CMWNT) coatings were grafted on the surface of Ti6Al4V alloys by electrochemical deposition for enhancing the biotribological properties. The CMWNT coatings showed lower coefficient of friction and wear rates, with the reduction of wear rates of 6% in dry condition and 90% under simulated body fluid (SBF) lubrication. This result might be ascribed to the transfer of friction behavior from sliding friction to rolling friction. In addition, the tribological regularity of CMWNT coating with the frequency and load were discussed. Under dry friction, with the increase of frequency and the decrease of normal load, the COF of the CMWNT coating decreased. In SBF lubrication, the COF decreased and the wear rate increased with the increase of frequency. Moreover, the excellent anti-wear properties were observed at the below of 10 N. These findings indicate that the CMWNT coating has an excellent protective effect on titanium alloy, and has a certain application potential in the biomedical field.

A Systematic Review of Drug-Carrying Nanosystems Used in the Treatment of Leishmaniasis

Leishmaniasis is an infectious disease responsible for a huge rate of morbidity and mortality in humans. Chemotherapy consists of the use of pentavalent antimonial, amphotericin B, pentamidine, miltefosine, and paromomycin. However, these drugs are associated with some drawbacks such as high toxicity, administration by parenteral route, and most seriously the resistance of some strains of the parasite to them. Several strategies have been used to increase the therapeutic index and reduce the toxic effects of these drugs. Among them, the use of nanosystems that have great potential as a site-specific drug delivery system stands out. This review aims to compile results from studies that were carried out using first- and second-line antileishmanial drug-carrying nanosystems. The articles referred to here were published between 2011 and 2021. This study shows the promise of effective applicability of drug-carrying nanosystems in the field of antileishmanial therapeutics, with the perspective of providing better patient adherence to treatment, increased therapeutic efficacy, reduced toxicity of conventional drugs, as well as the potential to efficiently improve the treatment of leishmaniasis.

Nanoparticles advanced from preclinical studies to clinical trials for lung cancer therapy

Lung cancer is the leading cause of cancer mortality. As a heterogeneous disease, it has different subtypes and various treatment modalities. In addition to conventional surgery, radiotherapy and chemotherapy, targeted therapy and immunotherapy have also been applied in the clinics. However, drug resistance and systemic toxicity still cannot be avoided. Based on the unique properties of nanoparticles, it provides a new idea for lung cancer therapy, especially for targeted immunotherapy. When nanoparticles are used as carriers of drugs with special physical properties, the nanodrug delivery system ensures the accuracy of targeting and the stability of drugs while increasing the permeability and the aggregation of drugs in tumor tissues, showing good anti-tumor effects. This review introduces the properties of various nanoparticles including polymer nanoparticles, liposome nanoparticles, quantum dots, dendrimers, and gold nanoparticles and their applications in tumor tissues. In addition, the specific application of nanoparticle-based drug delivery for lung cancer therapy in preclinical studies and clinical trials is discussed.

Nanoliposome based biosensors for probing mycotoxins and their applications for food: A review

Mycotoxins are the most common feed and food contaminants affecting animals and humans, respectively; continuous exposure causes tremendous health problems such as kidney disorders, infertility, immune suppression, liver inflammation, and cancer. Consequently, their control and quantification in food materials is crucial. Biosensors are potential tools for the rapid detection and quantification of mycotoxins with high sensitivity and selectivity. Nanoliposomes (NLs) are vesicular carriers formed by self-assembling phospholipids that surround the aqueous cores. Utilizing their biocompatibility, biodegradability, and high carrying capacity, researchers have employed NLs in biosensors for monitoring various targets in biological and food samples. The NLs are used for surface modification, signal marker delivery, and detection of toxins, bacteria, pesticides, and diseases. Here, we review marker-entrapped NLs used in the development of NL-based biosensors for mycotoxins. These biosensors are sensitive, selective, portable, and cost-effective analytical tools, and the resulting signal can be produced and/or amplified with or without destroying the NLs. In addition, this review emphasizes the benefits of the immunoliposome method in comparison with traditional detection approaches. We expect this review to serve as a valuable reference for researchers in this rapidly growing field. The insights provided may facilitate the rational design of next-generation NL-based biosensors.

Conductive fibers for biomedical applications

Bioelectricity has been stated as a key factor in regulating cell activity and tissue function in electroactive tissues. Thus, various biomedical electronic constructs have been developed to interfere with cell behaviors to promote tissue regeneration, or to interface with cells or tissue/organ surfaces to acquire physiological status via electrical signals. Benefiting from the outstanding advantages of flexibility, structural diversity, customizable mechanical properties, and tunable distribution of conductive components, conductive fibers are able to avoid the damage-inducing mechanical mismatch between the construct and the biological environment, in return to ensure stable functioning of such constructs during physiological deformation. Herein, this review starts by presenting current fabrication technologies of conductive fibers including wet spinning, microfluidic spinning, electrospinning and 3D printing as well as surface modification on fibers and fiber assemblies. To provide an update on the biomedical applications of conductive fibers and fiber assemblies, we further elaborate conductive fibrous constructs utilized in tissue engineering and regeneration, implantable healthcare bioelectronics, and wearable healthcare bioelectronics. To conclude, current challenges and future perspectives of biomedical electronic constructs built by conductive fibers are discussed.

AC amplification gain in organic electrochemical transistors for impedance-based single cell sensors

Research on electrolyte-gated and organic electrochemical transistor (OECT) architectures is motivated by the prospect of a highly biocompatible interface capable of amplifying bioelectronic signals at the site of detection. Despite many demonstrations in these directions, a quantitative model for OECTs as impedance biosensors is still lacking. We overcome this issue by introducing a model experiment where we simulate the detection of a single cell by the impedance sensing of a dielectric microparticle. The highly reproducible experiment allows us to study the impact of transistor geometry and operation conditions on device sensitivity. With the data we rationalize a mathematical model that provides clear guidelines for the optimization of OECTs as single cell sensors, and we verify the quantitative predictions in an in-vitro experiment. In the optimized geometry, the OECT-based impedance sensor allows to record single cell adhesion and detachment transients, showing a maximum gain of 20.2±0.9 dB with respect to a single electrode-based impedance sensor.

The authors develop a quantitative description of alternating current amplification gain in organic electrochemical transistors. The findings are applied to achieve detection of single glioblastoma cell adhesion with 20 dB gain compared to microelectrodes.

Eco-friendly synthesis of carbon nanotubes and their cancer theranostic applications

Carbon nanotubes (CNTs) with attractive physicochemical characteristics such as high surface area, mechanical strength, functionality, and electrical/thermal conductivity have been widely studied in different fields of science. However, the preparation of these nanostructures on a large scale is either expensive or sometimes ecologically unfriendly. In this context, plenty of studies have been conducted to discover innovative methods to fabricate CNTs in an eco-friendly and inexpensive manner. CNTs have been synthesized using various natural hydrocarbon precursors, including plant extracts (e.g., tea-tree extract), essential oils (e.g., eucalyptus and sunflower oil), biodiesel, milk, honey, and eggs, among others. Additionally, agricultural bio-wastes have been widely studied for synthesizing CNTs. Researchers should embrace the usage of natural and renewable precursors as well as greener methods to produce various types of CNTs in large quantities with the advantages of cost-effectiveness and environmentally benign features. In addition, multifunctionalized CNTs with improved biocompatibility and targeting features are promising candidates for cancer theranostic applications owing to their attractive optical, chemical, thermal, and electrical properties. This perspective discusses the recent developments in eco-friendly synthesis of CNTs using green chemistry-based techniques, natural renewable resources, and sustainable catalysts, with emphasis on important challenges and future perspectives and highlighting techniques for the functionalization or modification of CNTs. Significant and promising cancer theranostic applications as well as their biocompatibility and cytotoxicity issues are also discussed.

Insights on functionalized carbon nanotubes for cancer theranostics

Despite the exciting breakthroughs in medical technology, cancer still accounts for one of the principle triggers of death and conventional therapeutic modalities often fail to attain an effective cure. Recently, nanobiotechnology has made huge advancement in cancer therapy with gigantic application potential because of their ability in achieving precise and controlled drug release, elevating drug solubility and reducing adverse effects. Carbon nanotubes (CNTs), one of the most promising carbon-related nanomaterials, have already achieved much success in biomedical field. Due to their excellent optical property, thermal and electronic conductivity, easy functionalization ability and high drug loading capacity, CNTs can be applied in a multifunctional way for cancer treatment and diagnosis. In this review, we will give an overview of the recent progress of CNT-based drug delivery systems in cancer theranostics, which emphasizes their targetability to intracellular components of tumor cells and extracellular elements in tumor microenvironment. Moreover, a detailed introduction on how CNTs penetrate inside the tumor cells to reach their sites of action and achieve the therapeutic effects, as well as their diagnostic applications will be highlighted.

NIR Light-Triggered Chemo-Phototherapy by ICG Functionalized MWNTs for Synergistic Tumor-Targeted Delivery

The combinational application of photothermal therapy (PTT), chemotherapy, and nanotechnology is a booming therapeutic strategy for cancer treatment. Multi-walled carbon nanotube (MWNT) is often utilized as drug carrier in biomedical fields with excellent photothermal properties, and indocyanine green (ICG) is a near-infrared (NIR) dye approved by FDA. In addition, ICG is also a photothermal agent that can strongly absorb light energy for tumor ablation. Herein, we explored a synergistic strategy by connecting MWNT and a kind of ICG derivate ICG-NH₂ through hyaluronic acid (HA) that possesses CD44 receptor targeting ability, which largely enhanced the PTT effect of both MWNT and ICG-NH₂. To realize the synergistic therapeutic effect of chemotherapy and phototherapy, doxorubicin (DOX) was attached on the wall of MWNT via π-π interaction to obtain the final MWNT-HA-ICG/DOX nanocomplexes. Both in vitro and in vivo experiments verified the great therapeutic efficacy of MWNT-HA-ICG/DOX nanocomplexes, which was characterized by improved photothermal performance, strengthened cytotoxicity, and elevated tumor growth inhibition based on MCF-7 tumor models. Therefore, this synergistic strategy we report here might offer a new idea with promising application prospect for cancer treatment.

A dual-quenched ECL immunosensor for ultrasensitive detection of retinol binding protein 4 based on luminol@AuPt/ZIF-67 and MnO2@CNTs

Background

Retinol binding protein 4 (RBP4) has been regarded as an important serological biomarker for type 2 diabetes mellitus (T2DM). Hence, the construction of a highly sensitive detection method for RBP4 is the key to early prevention and multidisciplinary intervention of T2DM. In this work, a dual-quenched electrochemiluminescence (ECL) immunosensor has been fabricated for ultrasensitive detection of RBP4 by combining zeolitic imidazolate framework-67/AuPt-supported luminol (luminol@AuPt/ZIF-67) with MnO₂ nanosheets-grown on carbon nanotubes (MnO₂@CNTs).

Results

AuPt/ZIF-67 hybrids with high-efficiency peroxidase-like activity could provide multipoint binding sites for luminol and antibodies and significantly boost the amplified initial signal of the ECL immunosensor. Upon glutathione/H₂O₂ coreactants system, MnO₂@CNTs composites could quench the initial signal by inhibiting mimic peroxidase activity of luminol@AuPt/ZIF-67. Moreover, the absorption spectrum of the MnO₂@CNTs composites completely overlaps with the emission spectrum of luminol, which can further reduce initial signal by ECL resonance energy transfer (ECL-RET).

Conclusions

Benefiting from the above-mentioned properties, the designed immunoassay sensitivity exhibited excellent sensitivity and relative stability for RBP4 detection range from 0.0001 to 100 ng mL⁻¹ with a low detection limit of 43 fg mL⁻¹. Therefore, our ECL immunosensor provides an alternative assaying strategy for early diagnosis of T2DM.

Graphic abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s12951-021-01020-1.

A facile, inexpensive and green electrochemical sensor for sensitive detection of imidacloprid residue in rice using activated electrodes

The development of sensitive, facile, cost-effective and eco-friendly sensors is essential for monitoring imidacloprid (IDP) residue on a large scale. Compared with popular modification of electrodes with advanced materials, electrochemical activation is promising at this point. In this paper, we found that strongly basic electrolytes (e.g. KOH and K₃PO₄) and applying cyclic potential during the activating process are beneficial to greatly amplify the electro-reduction response of IDP by nearly 16 times. Combining the characterization of activated electrodes with electrochemical behavior analysis of IDP, it is speculated that specific oxygen-contained functional groups were formed to bond with IDP molecules, leading to fast electron transfer kinetics. Then a sensitive IDP sensor has been developed with a low limit of detection (LOD) of 0.03 μM in the range of 0.1-100 μM. The methodological evaluation including reproducibility, stability and recovery has been also carefully studied, verifying the potential of proposed activated electrodes for application in rice samples.

Carbon nanotubes as an emerging nanocarrier for the delivery of doxorubicin for improved chemotherapy

Carbon nanotubes (CNTs), a versatile nanocarrier for doxorubicin (DOX) delivery had attracted significant attention in drug delivery of pharmaceuticals. Several properties such as high surface area, high drug loading capacity, stability, ease of functionalization, ultrahigh length to diameter ratio and good cellular uptake make them preferred nanocarrier as multipurpose drug delivery system. Several surface properties of CNTs can be easily modified by covalent/noncovalent functionalization, which can make CNTs a profound nanomaterial. Hydrophobic surface of CNTs facilitated π-π stacking interactions, with several drugs and therapeutic agents having aromatic ring in their structure, for example anthracyclines. In case some drug molecules, electrostatic interaction between drug and CNTs comes into the picture. DOX, an anthracycline anticancer drug, can easily adsorb on the surface of CNTs by π-π stacking interactions. In present article, we have reviewed various CNTs based drug delivery systems for the delivery of DOX alone or in combination with genetic materials and other drug molecules. In addition, we described recent updates in CNTs based drug delivery system for the delivery of DOX, we covered adsorption and desorption, different types of functionalization, to alter the properties of CNTs in vitro and in vivo. CNT attached many targeting ligands for the targeted delivery of DOX have also been discussed.

Green Approaches to Carbon Nanostructure-Based Biomaterials

The family of carbon nanostructures comprises several members, such as fullerenes, nano-onions, nanodots, nanodiamonds, nanohorns, nanotubes, and graphene-based materials. Their unique electronic properties have attracted great interest for their highly innovative potential in nanomedicine. However, their hydrophobic nature often requires organic solvents for their dispersibility and processing. In this review, we describe the green approaches that have been developed to produce and functionalize carbon nanomaterials for biomedical applications, with a special focus on the very latest reports.

Recent Trends, Construction and Applications of Smart Textiles and Clothing for Monitoring of Health Activity: A Comprehensive Multidisciplinary Review

In the area of biomedical signal monitoring, wearable electronics represents a dynamically growing field with a significant impact on the market of commercial products of biomedical signal monitoring and acquisition, as well as consumer electronic for vital functions monitoring. Since the electrodes are perceived as one of the most important part of the biomedical signal monitoring, they have been one of the most frequent subjects in the research community. Electronic textile (e-textile), also called smart textile represents a modern trend in the wearable electronics, integrating of functional materials with common clothing with the goal to realize the devices, which include sensors, antennas, energy harvesters and advanced textiles for self-cooling and heating. The area of textile electrodes and e-textile is perceived as a multidisciplinary field, integrating material engineering, chemistry, and biomedical engineering. In this review, we provide a comprehensive view on this area. This multidisciplinary review integrates the e-textile characteristics, materials and manufacturing of the textile electrodes, noise influence on the e-textiles performance, and mainly applications of the textile electrodes for biomedical signal monitoring and acquisition, including pressure sensors, electrocardiography, electromyography, electroencephalography and electrooculography monitoring.

Review of Research into the Determination of Acrylamide in Foods

Acrylamide (AA) is produced by high-temperature processing of high carbohydrate foods, such as frying and baking, and has been proved to be carcinogenic. Because of its potential carcinogenicity, it is very important to detect the content of AA in foods. In this paper, the conventional instrumental analysis methods of AA in food and the new rapid immunoassay and sensor detection are reviewed, and the advantages and disadvantages of various analysis technologies are compared, in order to provide new ideas for the development of more efficient and practical analysis methods and detection equipment.