Fiber-Based Noncontact Sensor with Stretchability for Underwater Wearable Sensing and VR Applications.

The rapid development of artificial intelligent wearable devices has led to an increasing need for seamless information exchange between humans, machines, and virtual spaces, often relying on touch sensors as the primary interaction medium. Additionally, the demand for underwater detection technologies is on the rise owing to the prevalent wet and submerged environment. Here, a fiber-based capacitive sensor with superior stretchability and hydrophobicity is proposed, designed to cater to noncontact and underwater applications. The sensor is constructed using bacterial cellulose (BC)@BC/carbon nanotubes (CNTs) (BBT) helical fiber as the matrix and methyltrimethoxysilane (MTMS) as the hydrophobic modified agent, forming a hydrophobic silylated BC@BC/CNT (SBBT) helical fiber by the chemical vapor deposition (CVD) technique. These fibers exhibit an impressive contact angle of 132.8°. The SBBT helicalfiber-based capacitive sensor presents capabilities for both noncontact and underwater sensing, which exhibits a significant capacitance change of -0.27 (at a distance of 0.5 cm). We have achieved interactive control between real space and virtual space through intelligent data analysis technology with minimal interference from the presence of water. This work has laid a solid foundation of noncontact sensing with attributes such as degradability, stretchability, and hydrophobicity. Moreover, it offers promising solutions for barrier-free communication in virtual reality (VR) and underwater applications, providing avenues for smart human-machine interfaces for submerged use.

[Re-mineralization ability of Galla chinensis extracts on root carious lesions with or without non-collagen proteins].

OBJECTIVE: To evaluate the re-mineralization ability of Galla Chinensis extracts (GCE) on two artificial carious lesions in bovine root de-mineralized in vitro. METHODS: Fourteen bovine root blocks were divided into two parts from buccal to lingual direction. The mesial blocks were treated with a demineralization solution and the distant blocks were treated with another demineralization solution. Two specimens from each group were selected randomly and examined with polarization microscope (PLM). After all blocks were demineralized, half surface of the demineralized zone was covered and the another half was treated with 0.5% NaCl to extract soluble dentin phosphate protein (S-DPP). Then all specimens were submitted to pH-cycling for one week. In the first four days, all specimens were treated with GCE for 21 h and with demineralization solution for 3 h. In the remaining three days, all specimens were treated with GCE. The re-mineralization ability of GCE on the specimens was evaluated by laser scanning confocal microscope (LSCM). RESULTS: There existed intact surface layers on subsurface lesions but no surface layers were produced on erosive lesions. The re-mineralization ability of GCE on erosive lesions improved significantly with the treatment of 0.5% NaCl solution (P < 0.05). But it had no significant effect on subsurface lessions. CONCLUSION: Extraction of S-DPP with 0.5% NaCl can improve the re-mineralization ability of GCE on root caries with erosive lesions. This finding supports the proposition that Galla Chinesis may be a promising anti-caries natural medicine in the future.

Self-Stretchable Fiber Liquid Sensors Made with Bacterial Cellulose/Carbon Nanotubes for Smart Diapers.

Liquid sensors for detecting water and body fluids are crucial in daily water usage and health monitoring, but it is challenging to combine sensing performance with high tensile deformation and multifunctional applications. Here, a substrate-free, self-stretchable bacterial cellulose (BC)/carbon nanotube (CNT) helical fiber liquid sensor was prepared by the solution spinning and coiling process using BC as the water-sensitive matrix and CNTs as the active sensing materials. The BC/CNT (BCT) fiber sensor has a high stretch ratio of more than 1000% and a rapid response for a current change rate of 104% within 1 s, which is almost unaffected under washing and various stretching or knotting deformations. By combination of the BCT fiber, we can design smart diapers or water level detectors, which rapidly monitor the status of smart diapers or water level, and the monitoring result can be transferred on time through an alarm device or smartphone. In short, the scalable and continuous preparation of the self-stretchable BCT helical fiber will provide a capacious platform for the development of a wearable sensor applied in daily life (such as smart diapers, water level detection, etc.).

Anti-Fouling, Adhesive Polyzwitterionic Hydrogel Electrodes Toughened Using a Tannic Acid Nanoflower.

Conductive polyzwitterionic hydrogels with good adhesion properties show potential prospect in implantable electrodes and electronic devices. Adhesive property of polyzwitterionic hydrogels in humid environments can be improved by the introduction of catechol groups. However, common catechol modifiers can usually quench free radicals, resulting in a contradiction between long-term tissue adhesion and hydrogel toughness. By adding tannic acid (TA) to the dispersion of clay nanosheets and nanofibers, we designed TA-coated nanoflowers and nanofibers as the reinforcing phase to prepare polyzwitterionic hydrogels with adhesion properties. The hydrogel combines the mussel-like and zwitterionic co-adhesive mechanism to maintain long-term adhesion in underwater environments. In particular, the noncovalent cross-linking provided by the nanoflower structure effectively compensates for the defects caused by free-radical quenching so that the hydrogel obtained a high stretchability of over 2900% and a toughness of 1.16 J/m3. The hydrogel also has excellent anti-biofouling property and shows resistance to bacteria and cells. In addition, the hydrogel possesses a low modulus (<10 kPa) and ionic conductivity (0.25 S/m), making it an ideal material for the preparation of implantable electrodes.

TEMPO-Oxidized Bacterial Cellulose Nanofibers/Graphene Oxide Fibers for Osmotic Energy Conversion.

The large osmotic energy between river water and seawater is an inexhaustible blue energy source; however, the complicated manufacturing methods used for ion-exchange devices hinder the development of reverse electrodialysis (RED). Here, we use a wet-spinning method to continuously spin meter-scale 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-oxidized bacterial cellulose (TOBC) nanofiber filaments, which are then used to construct nanochannels for osmotic energy conversion. These are then used to build a nacre-like structure by adding graphene oxide (GO), which provides narrow nanochannels in one-dimensional and two-dimensional nanofluid systems for rapid ion transport. With a 50-fold concentration gradient, the nanochannels in the fibers generate electricity of 0.35 W m-2, with an ionic mobility of 0.94 and an energy conversion efficiency of 38%. The assembly of GO and TOBC results in a high power density of 0.53 W m-2 using artificial seawater and river water. The RED device fabricated from TOBC/GO fibers maintains a stable power density for 15 days. This research proposes a simple method to reduce the size of nanochannels to improve the ionic conductivity, ionic selectivity, and power density of cellulose-based nanofibers to increase the possibility of their application for the conversion of osmotic energy to electrical energy.

Anisotropic bacterial cellulose hydrogels with tunable high mechanical performances, non-swelling and bionic nanofluidic ion transmission behavior.

Water-rich hydrogels with tissue-like softness, especially ion conductive hydrogels with ion signal transfer systems similar to biological areas, are promising soft electrode materials, while too poor or unstable mechanical properties that come from uncontrollable swelling and biocompatibility issues caused by introducing high concentration ions are serious obstacles in practical applications. Herein, a simple method for fabricating strong, stable, ion-conductive, anisotropic bacterial cellulose hydrogels (ABCHs) is first reported. Relying on nanofibers with high aspect ratio in bacterial cellulose (BC), a tailor-made nanofiber-network-reinforced structure is constructed by controlled dissolution, followed by aligning them well via a simple fossilizing process under stretching. Therefore, tunable high mechanical performances can be achieved and the maximum tensile strength can reach 14.3 MPa with 70% water content. It is worth noting that ABCHs will not swell in water for 30 days and maintain 93% tensile strength. Most importantly, the unique nanofluid behaviors from nanochannels in nanofibers allow effective ion transport in ABCHs relying only on low concentrations of ions in body fluids (<300 mM), avoiding sacrificing biocompatibility to achieve useful conductivity. This facile strategy might be very scalable in fabricating high-strength, non-swelling, bio-ion conductive cellulose hydrogels for application in next-generation bio-interfacing and flexible implantable devices.

High-Strength Superstretchable Helical Bacterial Cellulose Fibers with a "Self-Fiber-Reinforced Structure".

As a hydrogel membrane grown on the gas-liquid interface by bacterial culture that can be industrialized, bacterial cellulose (BC) cannot give full play to the advantages of its natural nanofibers. Conversion to the properties of nanofibers from high-performance to macrofibers represents a difficult material engineering challenge. Herein, we construct high-strength BC macrofibers with a "self-fiber-reinforced structure" using a dry-wet spinning method by adjusting the BC dissolution and concentration. The macrofiber with a tensile strength of 649 MPa and a strain of 17.2% can be obtained, which is one of the strongest and toughest cellulose fibers. In addition, the macrofiber can be fabricated to a superstretchable helical fiber without adding other elastomers or auxiliary materials. When the helical diameter is 1.6 mm, the ultimate stretch reaches 1240%. Meanwhile, cyclic tests show that the mechanical properties and morphology of the fiber remained stable after 100 times of 100% cyclic stretching. It is exciting that the helical fiber also owns outstanding knittability, washability, scalability, and dyeability. Furthermore, superstretchable functional helical BC fibers can be fabricated by embedding functional materials (carbon materials, conductive polymers, etc.) on BC or in the spinning dope, which can be made to wearable devices such as fiber solid-state supercapacitors. This work provides a scalable way for high-strength superstretchable and multifunctional fibers applied in wearable devices.

Development and Application of 3D Bioprinted Scaffolds Supporting Induced Pluripotent Stem Cells.

Three-dimensional (3D) bioprinting is a revolutionary technology that replicates 3D functional living tissue scaffolds in vitro by controlling the layer-by-layer deposition of biomaterials and enables highly precise positioning of cells. With the development of this technology, more advanced research on the mechanisms of tissue morphogenesis, clinical drug screening, and organ regeneration may be pursued. Because of their self-renewal characteristics and multidirectional differentiation potential, induced pluripotent stem cells (iPSCs) have outstanding advantages in stem cell research and applications. In this review, we discuss the advantages of different bioinks containing human iPSCs that are fabricated by using 3D bioprinting. In particular, we focus on the ability of these bioinks to support iPSCs and promote their proliferation and differentiation. In addition, we summarize the applications of 3D bioprinting with iPSC-containing bioinks and put forward new views on the current research status.

A 3D-printable TEMPO-oxidized bacterial cellulose/alginate hydrogel with enhanced stability via nanoclay incorporation.

Three-dimensional (3D) printing offers a novel approach to manufacture repeatable personalized structures for mass customization in medical fields. Considering the resemblance of materials in composition and microstructure to biological tissues, polysaccharide-based hydrogel is a promising printing material. However, its long-term stability of structure has always been a problem. In this work, we showed a green nanocomposite printing ink based on 2,2,6,6-tetramethylpiperidinyl-1-oxyl (TEMPO)-oxidized bacterial cellulose (TOBC), sodium alginate (SA) and laponite nanoclay (Xls). The TOBC/SA/Xls hydrogel prepared by the 3D printing ink not only exhibited structural stability, but also performed a long-term release behavior of protein which could be attractive in medical application of drug release, biomedical devices and tissue engineering.

[Effect of Er:YAG laser on the dynamic changes in subgingival flora in type 2 diabetic patients with periodontitis].

OBJECTIVE: To observe the changes in subgingival microflora before and after Er:YAG laser treatment on diabetic patients with periodontitis, and to compare with the subgingival microflora of chronic periodontitis. METHODS: Subgingival plaque of 13 pairs of teeth (26 sites) was selected from type 2 diabetic patients at pretreatment, one month post-treatment, and three months post-treatment. Subgingival plaque was also obtained from 11 cases of moderate to severe chronic periodontitis with similar severity of periodontitis. The DNA of the subgingival plaque samples was extracted. Whole bacterial 16S rDNA gene fragments separated by denaturing gradient gel electrophoresis. Specific DNA bands were then chosen for retrieval and sequencing. RESULTS: The gene sequencing results of the special DNA bands of subgingival plaque samples show that the pathogenic bacteria of both diabetic periodontitis and simple chronic periodontitis were Prevotella intermedia and Tannerella forsythia, respectively. The composition of the subgingival microflora before and after laser treatment changed. Some DNA bands, including that of Tannerella forsythia, disappeared or weakened one month after treatment. A new strip appeared, which belonged to Actinomyces sp. CONCLUSION: The profiles of the subgingival microflora changed after treatment, and one month was indicated as an important stage. Er:YAG laser may have an important function in delaying microflora recolonization.

Effect of Galla chinensis on the remineralization of two bovine root lesions morphous in vitro.

The present study aims to evaluate the effect of Galla chinensis compounds on the remineralization of two artificial root lesions morphous in vitro. Sixty bovine dentine blocks were divided into two groups and individually treated with two levels of demineralization solutions to form erosive and subsurface artificial carious lesions in vitro. Each group was then divided into three subgroups, each of which were treated with a remineralization solution (positive control), deionized water (negative control), or 4 000 mg⋅L(-1) aqueous solutions of Galla chinensis extract. The dentine blocks were then subjected to a pH-cycling regime for 7 days. During the first 4 days, the daily cycle included 21-h deal and 3-h demineralization applications. The dentine blocks were dealt with the entire day during the remaining 3 days. Two specimens from each of the treatment groups were selected and observed under a polarized light microscope. Data collected using a laser scanning confocal microscope were computerized and analyzed. Galla chinensis extract clearly enhanced the remineralization of both erosive lesion and subsurface lesion patterns in the specimens (P<0.05). The level of remineralization of the erosive lesion by Galla chinensis extract was lower than that of the subsurface lesion (P<0.05). In addition, the remineralization of the subsurface lesion by Galla chinensis extract was higher than that of the remineralization solution (P<0.05). No significant difference between the remineralization of erosive lesions by Galla chinensis extract and the remineralization solution was observed (P>0.05). So Galla chinensis extract has the potential to improve the remineralization of artificial root lesions under dynamic pH-cyclic conditions, indicating its potential use as a natural remineralization medicine.