Hyperspectral digital holography realized by using an electro-optical frequency comb via injection locking.

Hyperspectral digital holography (HSDH) is a versatile holographic imaging technique that offers large unambiguous depth range and spectroscopic information. In this Letter, we propose a novel, to the best of our knowledge, HSDH system that is realized by using an electro-optical frequency comb (EOFC) via injection locking. In comparison with conventional dual-comb HSDH, the proposed system only requires one EOFC and few other devices, which not only simplifies the system structure and reduces the cost but also improves the imaging speed. We validated the system using an EOFC with 20 optical frequencies spaced at 18 GHz intervals. In a total measurement time of 0.5 s, we successfully captured images of two targets that were 0.74 mm apart without phase ambiguity and obtained the transmission spectrum of an absorbing gas simultaneously. This work provides valuable insights for HSDH systems relying on an optical frequency comb.

Optical frequency domain reflectometry with broadened frequency sweep range assisted by a dual electro-optic frequency comb.

We propose an optical frequency domain reflectometry (OFDR) with the assistance of a dual electro-optic frequency comb (EOFC), which is intended to improve the system spatial resolution. As the spatial resolution of an OFDR system is inversely proportional to the frequency sweep range, the EOFC acts as a multi-frequency light source for collecting Rayleigh backscattering signals, which are combined to extend the effective frequency sweep range. By utilizing this technique, we have successfully expanded the experimental frequency sweep range to hundreds of gigahertz, achieving a sub-millimeter spatial resolution.

Methacrylated gelatin and platelet-rich plasma based hydrogels promote regeneration of critical-sized bone defects.

Physiological repair of large-sized bone defects requires instructive scaffolds with appropriate mechanical properties, biocompatibility, biodegradability, vasculogenic ability and osteo-inductivity. The objective of this study was to fabricate in situ injectable hydrogels using platelet-rich plasma (PRP)-loaded gelatin methacrylate (GM) and employ them for the regeneration of large-sized bone defects. We performed various biological assays as well as assessed the mechanical properties of GM@PRP hydrogels alongside evaluating the release kinetics of growth factors (GFs) from hydrogels. The GM@PRP hydrogels manifested sufficient mechanical properties to support the filling of the tissue defects. For biofunction assay, the GM@PRP hydrogels significantly improved cell migration and angiogenesis. Especially, transcriptome RNA sequencing of human umbilical vein endothelial cells and bone marrow-derived stem cells were performed to delineate vascularization and biomineralization abilities of GM@PRP hydrogels. The GM@PRP hydrogels were subcutaneously implanted in rats for up to 4 weeks for preliminary biocompatibility followed by their transplantation into a tibial defect model for up to 8 weeks in rats. Tibial defects treated with GM@PRP hydrogels manifested significant bone regeneration as well as angiogenesis, biomineralization, and collagen deposition. Based on the biocompatibility and biological function of GM@PRP hydrogels, a new strategy is provided for the regenerative repair of large-size bone defects.

Composite superplastic aerogel scaffolds containing dopamine and bioactive glass-based fibers for skin and bone tissue regeneration.

Multifunctional bioactive biomaterials with integrated bone and soft tissue regenerability hold great promise for the regeneration of trauma-affected skin and bone defects. The aim of this research was to fabricate aerogel scaffolds (GD-BF) by blending the appropriate proportions of short bioactive glass fiber (BGF), gelatin (Gel), and dopamine (DA). Electrospun polyvinyl pyrrolidone (PVP)-BGF fibers were converted into short BGF through calcination and homogenization. Microporous GD-BF scaffolds displayed good elastic deformation recovery and promoted neo-tissue formation. The DA could enable thermal crosslinking and enhance the mechanical properties and structural stability of the GD-BF scaffolds. The BGF-mediated release of therapeutic ions shorten hemostatic time (<30 s) in a rat tail amputation model and a rabbit artery injury model alongside inducing the regeneration of skin appendages (e.g., blood vessels, glands, etc.) in a full-thickness excisional defect model in rats (percentage wound closure: GD-BF2, 98 % vs. control group, 83 %) at day 14 in vitro. Taken together, these aerogel scaffolds may have significant promise for soft and hard tissue repair, which may also be worthy for the other related disciplines.

Aspirin-Loaded Anti-Inflammatory ZnO-SiO2 Aerogel Scaffolds for Bone Regeneration.

The increasing aging of the population has elevated bone defects to a significant threat to human life and health. Aerogel, a biomimetic material similar to an extracellular matrix (ECM), is considered an effective material for the treatment of bone defects. However, most aerogel scaffolds suffer from immune rejection and poor anti-inflammatory properties and are not well suited for human bone growth. In this study, we used electrospinning to prepare flexible ZnO-SiO2 nanofibers with different zinc concentrations and further assembled them into three-dimensional composite aerogel scaffolds. The prepared scaffolds exhibited an ordered pore structure, and chitosan (CS) was utilized as a cross-linking agent with aspirin (ASA). Interestingly, the 1%ZnO-SiO2/CS@ASA scaffolds not only exhibited good biocompatibility, bioactivity, anti-inflammation, and better mechanical properties but also significantly promoted vascularization and osteoblast differentiation in vitro. In the mouse cranial defect model, the BV/TV data showed a higher osteogenesis rate in the 1%ZnO-SiO2/CS group (10.94 ± 0.68%) and the 1%ZnO-SiO2/CS@ASA group (22.76 ± 1.83%), compared with the control group (5.59 ± 2.08%), and in vivo studies confirmed the ability of 1%ZnO-SiO2/CS@ASA to promote in situ regeneration of new bone. This may be attributed to the fact that Si4+, Zn2+, and ASA released from 1%ZnO-SiO2/CS@ASA scaffolds can promote angiogenesis and bone formation by stimulating the interaction between endothelial cells (ECs) and BMSCs, as well as inducing macrophage differentiation to the M2 type and downregulating the expression of pro-inflammatory factor (TNF-α) to modulate local inflammatory response. These exciting results and evidence suggest that it provides a new and effective strategy for the treatment of bone defects.

Composite Aerogel Scaffolds Containing Flexible Silica Nanofiber and Tricalcium Phosphate Enable Skin Regeneration.

Poor hemostatic ability and less vascularization at the injury site could hinder wound healing as well as adversely affect the quality of life (QOL). An ideal wound dressing should exhibit certain characteristics: (a) good hemostatic ability, (b) rapid wound healing, and (c) skin appendage formation. This necessitates the advent of innovative dressings to facilitate skin regeneration. Therapeutic ions, such as silicon ions (Si4+) and calcium ions (Ca2+), have been shown to assist in wound repair. The Si4+ released from silica (SiO2) can upregulate the expression of proteins, including the vascular endothelial growth factor (VEGF) and alpha smooth muscle actin (α-SMA), which is conducive to vascularization; Ca2+ released from tricalcium phosphate (TCP) can promote the coagulation alongside upregulating the expression of cell migration and cell differentiation related proteins, thereby facilitating the wound repair. The overarching objective of this study was to exploit short SiO2 nanofibers along with the TCP to prepare TCPx@SSF aerogels and assess their wound healing ability. Short SiO2 nanofibers were prepared by electrospinning and blended with varying proportions of TCP to afford TCPx@SSF aerogel scaffolds. The TCPx@SSF aerogels exhibited good cytocompatibility in a subcutaneous implantation model and manifested a rapid hemostatic effect (hemostatic time 75 s) in a liver trauma model in the rabbit. These aerogel scaffolds also promoted skin regeneration and exhibited rapid wound closure, epithelial tissue regeneration, and collagen deposition. Taken together, TCPx@SSF aerogels may be valuable for wound healing.

Shape-Persistent Conductive Nerve Guidance Conduits for Peripheral Nerve Regeneration.

To solve the problems of slow regeneration and mismatch of axon regeneration after peripheral nerve injury, nerve guidance conduits (NGCs) have been widely used to promote nerve regeneration. Multichannel NGCs have been widely studied to mimic the structure of natural nerve bundles. However, multichannel conduits are prone to structural instability. Thermo-responsive shape memory polymers (SMPs) can maintain a persistent initial structure over the body temperature range. Electrical stimulation (ES), utilized within nerve NGCs, serves as a biological signal to expedite damaged nerve regeneration. Here, an electrospun shape-persistent conductive NGC is designed to maintain the persistent tubular structure in the physiological temperature range and improve the conductivity. The physicochemical and biocompatibility of these P, P/G, P/G-GO, and P/G-RGO NGCs are conducted in vitro. Meanwhile, to evaluate biocompatibility and peripheral nerve regeneration, NGCs are implanted in subcutaneous parts of the back of rats and sciatic nerves assessed by histology and immunofluorescence analyses. The conductive NGC displays a stable structure, good biocompatibility, and promoted nerve regeneration. Collectively, the shape-persistent conductive NGC (P/G-RGO) is expected to promote peripheral nerve recovery, especially for long-gap and large-diameter nerves.

Carbon Fiber-Mediated Electrospinning Scaffolds Can Conduct Electricity for Repairing Defective Tendon.

Partial or complete rupture of the tendon can damage the collagen structure, resulting in the disruption of the electrical signal pathway. It is a great challenge to reconstruct the original electrical signal pathway of the tendon and promote the regeneration and functional recovery of defective tendon. In this study, carbon fiber-mediated electrospinning scaffolds were fabricated by wrapping conductive, high-strength, loose single-bundle carbon fibers with nanofiber membranes. Due to the presence of nanofiber membranes, the maximum tensile force of the scaffolds was 2.4 times higher than that of carbon fibers, while providing excellent temporal and spatial prerequisites for tenocytes to adapt to electrical stimulation to accelerate proliferation and expression. The diameter of the carbon fiber monofilaments used in this study was 5.07 ± 1.20 µm, which matched the diameter of tendon collagen, allowing for quickly establishing the connection between the tendon tissue and the scaffold, and better promoting the recovery of the electrical signal pathway. In a rabbit Achilles tendon defect repair model, the carbon fiber-mediated electrospinning scaffold was almost filled with collagen fibers compared to a nonconductive polyethylene glycol terephthalate scaffold. Transcriptome sequencing revealed that fibromodulin and tenomodulin expression were upregulated, and their related proteoglycans and glycosaminoglycan binding proteins pathways were enhanced, which could regulate the TGF-ß signaling pathway and optimize the extracellular matrix assembly, thus promoting tendon repair. Therefore, the scaffold in this study makes up for the shortage of conductive scaffolds for repairing tendon defects, revealing the potential impact of conductivity on the signaling pathway of tendon repair and providing a new approach for future clinical studies.

An Injectable Integration of Autologous Bioactive Concentrated Growth Factor and Gelatin Methacrylate Hydrogel with Efficient Growth Factor Release and 3D Spatial Structure for Accelerated Wound Healing.

Growth factors are essential for wound healing owing to their multiple reparative effects. Concentrated growth factor (CGF) is a third-generation platelet extract containing various endogenous growth factors. Herein, a CGF extract solution is combined with gelatin methacrylate (GM) by physical blending to produce GM@CGF hydrogels for wound repair. The GM@CGF hydrogels show no immune rejection during autologous transplantation. Compared to CGF, GM@CGF hydrogels not only exhibit excellent plasticity and adhesivity but also prevent rapid release and degradation of growth factors. The GM@CGF hydrogels display good injectability, self-healing, swelling, and degradability along with outstanding cytocompatibility, angiogenic functions, chemotactic functions, and cell migration-promoting capabilities in vitro. The GM@CGF hydrogel can release various effective molecules to rapidly initiate wound repair, stimulate the expressions of type I collagen, transform growth factor ß1, epidermal growth factor, and vascular endothelial growth factor, promote the production of granulation tissues, vascular regeneration and reconstruction, collagen deposition, and epidermal cell migration, as well as prevent excessive scar formation. In conclusion, the injectable GM@CGF hydrogel can release various growth factors and provide a 3D spatial structure to accelerate wound repair, thereby providing a foundation for the clinical application and translation of CGF.

Injectable nanofiber microspheres modified with metal phenolic networks for effective osteoarthritis treatment.

Osteoarthritis (OA) is one of the most common chronic musculoskeletal diseases, which accounts for a large proportion of physical disabilities worldwide. Herein, we fabricated injectable gelatin/poly(L-lactide)-based nanofibrous microspheres (MS) via electrospraying technology, which were further modified with tannic acid (TA) named as TMS or metal phenolic networks (MPNs) consisting of TA and strontium ions (Sr2+) and named as TSMS to enhance their bioactivity for OA therapy. The TA-modified microspheres exhibited stable porous structure and anti-oxidative activity. Notably, TSMS showed a sustained release of TA as compared to TMS, which exhibited a burst release of TA. While all types of microspheres exhibited good cytocompatibility, TSMS displayed good anti-inflammatory properties with higher cell viability and cartilage-related extracellular matrix (ECM) secretion. The TSMS microspheres also showed less apoptosis of chondrocytes in the hydrogen peroxide (H2O2)-induced inflammatory environment. The TSMS also inhibited the degradation of cartilage along with the considerable repair outcome in the papain-induced OA rabbit model in vivo as well as suppressed the expression level of inflammatory cytokines, such as tumor necrosis factor-alpha (TNF-α) and interleukin-1-beta (IL-1ß). Taken together, TSMS may provide a highly desirable therapeutic option for intra-articular treatment of OA. STATEMENT OF SIGNIFICANCE: Osteoarthritis (OA) is a chronic disease, which is caused by the inflammation of joint. Current treatments for OA achieve pain relief but hardly prevent or slow down the disease progression. Microspheres are at the forefront of drug delivery and tissue engineering applications, which can also be minimal-invasively injected into the joint. Polyphenols and therapeutic ions have been shown to be beneficial for the treatment of diseases related to the joints, including OA. Herein, we prepared gelatin/poly(L-lactide)-based nanofibrous microspheres (MS) via electrospinning incorporated electrospraying technology and functionalized them with the metal phenolic networks (MPNs) consisting of TA and strontium ions (Sr2+), and assessed their potential for OA therapy both in vitro and in vivo.