Radiative and Non-Radiative Decay Pathways in Carbon Nanodots toward Bioimaging and Photodynamic Therapy.

The origin and classification of energy states, as well as the electronic transitions and energy transfers associated with them, have been recognized as critical factors for understanding the optical properties of carbon nanodots (CNDs). Herein, we report the synthesis of CNDs in an optimized process that allows low-temperature carbonization using ethanolamine as the major precursor and citric acid as an additive. The results obtained herein suggest that the energy states in our CNDs can be classified into four different types based on their chemical origin: carbogenic core states, surface defective states, molecular emissive states, and non-radiative trap states. Each energy state is associated with the occurrence of different types of emissions in the visible to near-infrared (NIR) range and the generation of reactive oxygen species (ROS). The potential pathways of radiative/non-radiative transitions in CNDs have been systematically studied using visible-to-NIR emission spectroscopy and fluorescence decay measurements. Furthermore, the bright photoluminescence and ROS generation of these CNDs render them suitable for in vitro imaging and photodynamic therapy applications. We believe that these new insights into the energy states of CNDs will result in significant improvements in other applications, such as photocatalysis and optoelectronics.

Multispectral upconversion nanoparticles for near infrared encoding of wearable devices.

Individual recognition technology such as iris recognition and bar coding has been extensively investigated for non-face-to-face authorization. However, there are still strong unmet needs for facile, rapid, and robust individual recognition. Here, we developed multispectral transparent films of upconversion nanoparticles (UCNPs) for near-infrared (NIR) encoding of wearable devices including contact lenses and patch devices. A multispectral UCNP film in a contact lens showed various luminescence colors of patterns under 980 nm NIR light irradiation and each color could be assigned to a specific code by RGB value analysis. The encoded film of UCNPs in the contact lens was successfully decoded by the RGB value analysis with a charge coupled digital (CCD) camera. Furthermore, the UCNP barcode film could be applied in the form of attachable barcode patches onto various substrates like porcine skin and paper currency. Taken together, we could confirm the feasibility of multispectral UCNP transparent films as a facile individual recognition platform for non-face-to-face authorization.

Hyaluronate-Gold Nanoparticle/Glucose Oxidase Complex for Highly Sensitive Wireless Noninvasive Glucose Sensors.

Noninvasive real-time biosensors to measure glucose levels in the body fluids have been widely investigated for continuous glucose monitoring of diabetic patients. However, they suffered from low sensitivity and reproducibility due to the instability of nanomaterials used for glucose biosensors. Here, we developed a hyaluronate-gold nanoparticle/glucose oxidase (HA-AuNP/GOx) complex and an ultralow-power application-specific integrated circuit chip for noninvasive and robust wireless patch-type glucose sensors. The HA-AuNP/GOx complex was prepared by the facile conjugation of thiolated HA to AuNPs and the following physical binding of GOx. The wireless glucose sensor exhibited slow water evaporation (0.11 µL/min), fast response (5 s), high sensitivity (12.37 µA·dL/mg·cm2) and selectivity, a low detection limit (0.5 mg/dL), and highly stable enzymatic activity (∼14 days). We successfully demonstrated the strong correlation between glucose concentrations measured by a commercially available blood glucometer and the wireless patch-type glucose sensor. Taken together, we could confirm the feasibility of the wireless patch-type robust glucose sensor for noninvasive and continuous diabetic diagnosis.

Hyaluronic Acid Derivatives for Translational Medicines.

The recent progress in various biomaterials with unique physiological and pharmacological properties has expedited the development of translational medicines for the diagnosis, prognosis, and therapy of intractable diseases. Hyaluronic acid (HA) is one of such biomaterials that has attracted great attention due to its unique characteristics for biomedical applications. In this Perspective, we provide an overview of HA-based medicines in a variety of forms such as chemical and biological conjugates, nanoparticles, nanoparticle hybrid systems, hydrogels, and nanogels. We highlight the current-state-of-the-art strategies to design and optimize innovative HA-based medicines for their clinical translations. Finally, we discuss the challenges for technical hurdles and the future directions to expand the feasibility of HA-based translational medicines.

Multimodal Cancer Theranosis Using Hyaluronate-Conjugated Molybdenum Disulfide.

Among various 2D nanomaterials, molybdenum disulfide (MoS2 ) exhibits unique visible photoluminescence with high absorption at the near-infrared (NIR) range. Despite these optical properties, the efforts to use MoS2 nanomaterials for optical imaging and photothermal therapy are hampered by their instability and low intracellular delivery efficiency. Multifunctional MoS2 conjugated with hyaluronate (HA) for cancer theranosis is reported herein. HA facilitates the delivery of MoS2 to tumor cells by the HA-receptor mediated endocytosis. In BALB/c nude mice inoculated with a colorectal cancer cell line of HCT116, HA-MoS2 conjugates appear to be accumulated in the primary tumor at a content more than that in the liver and kidney. The disulfide bonding between MoS2 and thiolated HA seems to degrade in the cytoplasm, releasing MoS2 sheets in stacks and enhancing luminescence efficiency. The HA-MoS2 conjugates are readily detected via photoacoustic imaging as well as upconversion and downconversion fluorescence imaging. With NIR light illumination, HA-MoS2 conjugates enable highly effective photothermal tumor ablation. All these results confirm the promising potential of HA-MoS2 conjugates for cancer theranosis.

Comparison of temporomandibular joint shape and size in patients with facial asymmetry.

OBJECTIVE: To examine the morphologic similarities and differences in mandibular condyle and glenoid fossa between the deviated and non-deviated sides in patients with facial asymmetry using statistical analysis. METHODS: One hundred eighty-four patients (95 men, 89 women; mean age, 22.30 ± 3.87 years) with facial asymmetry were examined with cone-beam computed tomography (CBCT). Shape analysis was performed to compare the shapes and sizes of the condyle and fossa between the deviated and non-deviated sides in the frontal and lateral aspects. Ordinary Procrustes analysis (OPA) was used to determine shape variations of the fossa and condyle. RESULTS: Shape variations derived from ordinary sum of squares (OSS) suggested that, in the frontal aspect, there was a difference between the two sides in both the fossa and condyle (P < 0.05). In the lateral aspect, there was no difference in fossa shape between the two sides (P > 0.05); however, the shape of condyle was different between the non-deviated and deviated sides (P < 0.05). Size comparison in OPA matching and centroid size (CS) in the frontal aspect demonstrated that the non-deviated side was larger than the deviated side. In the lateral aspect, fossa showed no difference in CS between the two sides (P > 0.05); however, the non-deviated side was larger than the deviated side for condyle (P < 0.05). CONCLUSIONS: Morphometric differences in condyle and fossa between the deviated and non-deviated sides were observed. Structures of the non-deviated side were relatively larger than those of the deviated side, except for fossa in the lateral aspect.

Defect-Induced Fluorescence of Silica Nanoparticles for Bioimaging Applications.

With biocompatibility, biodegradability, and high functionality, silica nanoparticles (SNPs) have been widely investigated for various biomedical applications. However, lack of optical fluorescence has limited the application of SNPs as a degradable imaging agent. Here, we hydrothermally synthesized fluorescent SNPs by artificially generating optically active defect centers using tetraethyl orthosilicate and (3-aminopropyl)trimethoxysilane. The synthesized SNPs demonstrated strong blue photoluminescence originating from the dioxasilyrane (=Si(O2)) and silylene (=Si:) defect centers with the aid of aminopropyl groups. Furthermore, phosphorescence was observed at 459 nm, indicating the presence of silylene in SNPs. Finally, these SNPs have been successfully utilized as a fluorescent probe for bioimaging of normal, cancer, and macrophage cells.

Morphometric analysis for evaluating the relation between incisal guidance angle, occlusal plane angle, and functional temporomandibular joint shape variation.

OBJECTIVE: The correlations between morphology of the temporomandibular joint structure, the anterior guidance angle, and occlusal plane were investigated. MATERIALS AND METHODS: A cone beam computed tomography analysis was performed in 158 patients (86 women and 72 men). 3D software was employed to obtain the coordinates of the shape of the incisal guidance angle, occlusal guidance angle, articular fossa, and mandibular condyle. Generalized Procrustes analysis including principal components analysis (PCA) were performed and produced principal components (PCs) scores of each shape and their centroid size (CS). RESULTS: A significant Pearson correlation coefficient of 0.3451 (p < .001) was observed between the incisal guidance angle and occlusal plane. The CS also showed a correlation with the incisal guidance angle, but not with the occlusal plane angle. The PCA results revealed that there were no significant correlations between the temporomandibular joint structure (TMJ) shape (fossa and condyle) and the incisal guidance angle. CONCLUSIONS: Incisor guidance angle and occlusal plane angle were correlated. In addition, there was a correlation between CS and incisal guidance angle. In the PCA, It can be concluded that the size is more related to the incisor guidance angle than the morphological factors of the constituent components of the TMJ.

Multifunctional Photonic Nanomaterials for Diagnostic, Therapeutic, and Theranostic Applications.

The last decade has seen dramatic progress in the principle, design, and fabrication of photonic nanomaterials with various optical properties and functionalities. Light-emitting and light-responsive nanomaterials, such as semiconductor quantum dots, plasmonic metal nanoparticles, organic carbon, and polymeric nanomaterials, offer promising approaches to low-cost and effective diagnostic, therapeutic, and theranostic applications. Reasonable endeavors have begun to translate some of the promising photonic nanomaterials to the clinic. Here, current research on the state-of-the-art and emerging photonic nanomaterials for diverse biomedical applications is reviewed, and the remaining challenges and future perspectives are discussed.

Supramolecular hydrogels encapsulating bioengineered mesenchymal stem cells for ischemic therapy.

We developed supramolecular hyaluronate (HA) hydrogels to encapsulate genetically engineered mesenchymal stem cells (MSCs) for the treatment of limb ischemia. In vivo angiogenic factors could be produced stably by the bioengineered MSCs (BMSCs) within the supramolecular hydrogels showing effective vascular repair and enhanced blood perfusion.

Hyaluronate - parathyroid hormone peptide conjugate for transdermal treatment of osteoporosis.

Human parathyroid hormone 1-34 fragment (PTH1-34) has been used as a FDA-approved therapeutics to treat osteoporosis by daily subcutaneous injection. In this work, we successfully developed PTH1-34 conjugated hyaluronic acid (HA) for the transdermal treatment of osteoporosis with improved patient compliance. HA-PTH1-34 conjugate was synthesized by the coupling reaction between aldehyde group introduced to HA and amine group of PTH1-34. After characterization by gel permeation chromatography (GPC) and ELISA, the biological effect of HA-PTH1-34 conjugate on the proliferation of human osteoblast cells was confirmed by in vitro calcium colorimetric assay and cAMP assay. Two-photon microscopy clearly visualized the effective skin penetration of FITC modified HA-PTH1-34 conjugate. The transdermally delivered HA-PTH1-34 conjugates elevated the blood calcium concentration for more than 2 days, reflecting the feasibility for the treatment of osteoporosis.

Dual-Color-Emitting Carbon Nanodots for Multicolor Bioimaging and Optogenetic Control of Ion Channels.

The development of intrinsically multicolor-emitting carbon nanodots (CNDs) has been one of the great challenges for their various fields of applications. Here, the controlled electronic structure engineering of CNDs is performed to emit two distinct colors via the facile surface modification with 4-octyloxyaniline. The so-called dual-color-emitting CNDs (DC-CNDs) can be stably encapsulated within poly(styrene-co-maleic anhydride) (PSMA). The prepared water-soluble DC-CNDs@PSMA can be successfully applied to in vitro and in vivo dual-color bioimaging and optogenetics. In vivo optical imaging can visualize the biodistribution of intravenously injected DC-CNDs@PSMA. In addition, the light-triggered activation of ion channel, channelrhodopsin-2, for optogenetic applications is demonstrated. As a new type of fluorophore, DC-CNDs offer a big insight into the design of charge-transfer complexes for various optical and biomedical applications.

Upconversion Nanoparticles/Hyaluronate-Rose Bengal Conjugate Complex for Noninvasive Photochemical Tissue Bonding.

The recent progress in photonic nanomaterials has contributed greatly to the development of photomedicines. However, the finite depth of light penetration is still a serious limitation, constraining their clinical applications. Here, we developed a poly(allylamine) (PAAm)-modified upconversion nanoparticle/hyaluronate-rose bengal (UCNP/PAAm/HA-RB) conjugate complex for photochemical bonding of deep tissue with near-infrared (NIR) light illumination. Compared to the conventional invasive treatment via suturing and stapling, the UCNP/PAAm/HA-RB conjugate complex could be noninvasively delivered into the deep tissue and accelerate the tissue bonding upon NIR light illumination. HA in the outer layer of the complex facilitated the penetration of RB into the collagen layer of the dermis. The NIR light triggered UCNP of NaYF4: Yb/Er (Y:Yb:Er = 78:20:2) in the complex to illuminate visible green light under the skin tissue. The activated RB in the HA-RB conjugate by the green light induced radical formation for the cross-linking of incised collagen matrix. An in vitro light propagation test and collagen fibrillogenesis analysis, an in vivo animal tissue bonding test, and an ex vivo tensile strength test of dissected skin tissues confirmed the successful photochemical tissue bonding effect of the UCNP/PAAm/HA-RB conjugate complex.

Hyaluronate and its derivatives for customized biomedical applications.

Since hyaluronate (HA) was firstly isolated from the vitreous of bovine eyes in 1934, HA has been widely investigated for various biomedical applications. As a naturally-occurring polysaccharide, HA has been used for joint lubrication and ocular treatment in its intact form due to the excellent biocompatibility, viscoelasticity, biodegradability, and hygroscopic properties. HA can be easily functionalized via the chemical modification of its carboxyl and hydroxyl groups. Recently, a variety of biological functions of HA have been explored and a number of customized applications have been investigated taking advantages of the interaction between HA and biological tissues. HA has been used for drug delivery to enhance the blood circulation time of drugs with target-specificity to HA receptors in the body. HA has been also used to prepare tissue engineering hydrogel scaffolds for the spatiotemporal control of encapsulated cells. In this review, we describe the key biological functions of HA in the body in terms of its structure, physical properties, biodistribution and interaction with HA receptors. After that, we describe unique advantages that allow HA to be applied in various biomedical fields. Finally, we report the conventional and newly emerging applications of HA and its derivatives under commercial development stages.

Photodynamic therapy of melanoma skin cancer using carbon dot - chlorin e6 - hyaluronate conjugate.

Despite wide application of photodynamic therapy (PDT) for the treatment of melanoma skin cancers, there are strong biomedical unmet needs for the effective generation of singlet oxygen after targeted delivery of photosensitizers. Here, we investigated a facile PDT of melanoma skin cancer using transdermal carbon dot - chlorine e6 - hyaluronate (Cdot-Ce6-HA) conjugates. The Cdot-Ce6-HA conjugate was synthesized by the coupling reaction of diaminohexane modified HA (DAH-HA) with the carboxylic group of Ce6. The singlet oxygen generation of Cdot-Ce6-HA conjugates in aqueous solution was more significant than that of free Ce6. The enhanced transdermal and intracellular delivery of Cdot-Ce6-HA conjugates to B16F10 melanoma cells in tumor model mice were corroborated by confocal microscopy and two-photon microscopy. The laser irradiation after topical treatment with Cdot-Ce6-HA conjugates resulted in complete suppression of melanoma skin cancers. The antitumor effect was confirmed by histological analysis with H&E staining and TUNEL assay for tumor apoptosis. Taken together, we could confirm the feasibility of Cdot-Ce6-HA conjugate for transdermal PDT of melanoma skin cancers. STATEMENT OF SIGNIFICANCE: To our knowledge, this is the first report on a facile transdermal photodynamic therapy (PDT) of melanoma skin cancer using carbon dot - chlorine e6 - hyaluronate (Cdot-Ce6-HA) conjugates. We found that the singlet oxygen generation of Cdot-Ce6-HA conjugates in aqueous solution was more significant than that of free Ce6. Confocal microscopy and two-photon microscopy clearly confirmed the enhanced transdermal and intracellular delivery of Cdot-Ce6-HA conjugates to B16F10 melanoma cells in tumor model mice. Taken together, we could confirm the feasibility of Cdot-Ce6-HA conjugate for transdermal PDT of melanoma skin cancers.