Influence of the Tissue Collection Procedure on the Adipogenic Differentiation of Human Stem Cells: Ischemic versus Well-Vascularized Adipose Tissue.

Clinical and basic science applications using adipose-derived stem cells (ADSCs) are gaining popularity. The current adipose tissue harvesting procedures introduce nonphysiological conditions, which may affect the overall performance of the isolated ADSCs. In this study, we elucidate the differences between ADSCs isolated from adipose tissues harvested within the first 5 min of the initial surgical incision (well-vascularized, nonpremedicated condition) versus those isolated from adipose tissues subjected to medications and deprived of blood supply during elective free flap procedures (ischemic condition). ADSCs isolated from well-vascularized and ischemic tissues positively immunostained for several standard stem cell markers. Interestingly, the percent change in the CD36 expression for ADSCs isolated from ischemic versus well-vascularized tissue was significantly lower in males than females (p < 0.05). Upon differentiation and maturation to adipocytes, spheroids formed using ADSCs isolated from ischemic adipose tissue had lower triglyceride content compared to those formed using ADSCs isolated from the well-vascularized tissue (p < 0.05). These results indicate that ADSCs isolated from ischemic tissue either fail to uptake fatty acids or fail to efficiently convert those fatty acids into triglycerides. Therefore, more robust ADSCs suitable to establish in vitro adipose tissue models can be obtained by harvesting well-vascularized and nonpremedicated adipose tissues.

Sexual Dimorphism's impact on adipogenesis: A three-dimensional in vitro model treated with 17ß-estradiol and testosterone.

Using a three-dimensional (3-D) in vitro culture model, we report the dose dependent effect of 17ß-estradiol and testosterone on the adipogenic differentiation and maturation of human adipose derived stem cells (hASCs) obtained from female and male patients. Considering sexual dimorphism, we expected male and female adipocytes to respond differently to the sex steroids. Both male and female hASC spheroids were exposed to 100 nM and 500 nM of 17ß-estradiol and testosterone either at the beginning of the adipogenic maturation (Phase I) to discourage intracellular triglyceride accumulation or exposed after adipogenic maturation (Phase II) to reduce the intracellular triglyceride accumulation. The results show that 17ß-estradiol leads to a dose dependent reduction in intracellular triglyceride accumulation in female hASC spheroids compared to the both untreated and testosterone-treated cells. Affirming our hypothesis, 17ß-estradiol prevented intracellular triglyceride accumulation during Phase I, while it stimulated lipolysis during Phase II. PPAR-γ and adiponectin gene expression also reduced upon 17ß-estradiol treatment in female cells. Interestingly, 17ß-estradiol and testosterone had only a modest effect on the male hASC spheroids. Collectively, our findings suggest that 17ß-estradiol can prevent fat accumulation in adipocytes during early and late stages of maturation in females.

Functionalized Collagen/Elastin-like Polypeptide Hydrogels for Craniofacial Bone Regeneration.

Critical-sized cranial bone defects fail to re-ossify and require the surgical intervention of cranioplasty. To achieve superior bone healing in such cases, a hydrogel consisting of an interpenetrating network of collagen and elastin-like polypeptide to encapsulate bone morphogenetic protein-2 (BMP-2), doxycycline, and 45S5 Bioglass is developed. This hydrogel has an appropriate elastic modulus of 39 ± 2.2 kPa to allow proper handling during implantation. The hydrogel promotes human adipose-derived stem attachment, proliferation, and differentiation toward the osteogenic lineage, including the deposition of hydroxyapatite particles embedded within a collagenous fibrillar structure after 21 days of in vitro culture. After eight weeks of implantation of the acellular hydrogel in a critical-sized rat cranial defect model, only a small quantity of various pro-inflammatory (< 20 pg mg-1 ) and anti-inflammatory (< 10 pg mg-1 ) factors in the adjacent cranial tissue is noticed, indicating the overall biocompatibility of the hydrogel. Scanning electron microscopy evidenced the presence of new fibrous extracellular matrix and mineral aggregates at the defect site, with calcium/phosphorus ratio of 0.5 and 2.0 by eight and twelve weeks, respectively. Microcomputed tomography (Micro-CT) and histological analyses showed formation of mature mineralized tissue that bridged with the surrounding bone. Taken together, the acellular composite hydrogel shows great promise for superior bone healing after cranioplasty.

Elastin-like Polypeptide Hydrogels for Tunable, Sustained Local Chemotherapy in Malignant Glioma.

Glioblastoma (GBM) is a primary brain tumor that carries a dismal prognosis, which is primarily attributed to tumor recurrence after surgery and resistance to chemotherapy. Since the tumor recurrence appears near the site of surgical resection, a concept of immediate and local application of chemotherapeutic after initial tumor removal could lead to improved treatment outcome. With the ultimate goal of developing a locally-applied, injectable drug delivery vehicle for GBM treatment, we created elastin-like polypeptide (ELP) hydrogels. The ELP hydrogels can be engineered to release anti-cancer drugs over an extended period. The purpose of this study was to evaluate the biomechanical properties of ELP hydrogels, to characterize their ability to release doxorubicin over time, and to investigate, in vitro, the anti-proliferative effect of Dox-laden ELP hydrogels on GBM. Here, we present microstructural differences, swelling ratio measurements, drug release characteristics, and in vitro effects of different ELP hydrogel compositions. We found that manipulation of the ELP-collagen ratio allows for tunable drug release, that the released drug is taken up by cells, and that incubation with a small volume of ELP-Dox hydrogel drastically reduced survival and proliferation of GBM cells in vitro. These results underscore the potential of ELP hydrogels as a local delivery strategy to improve prognosis for GBM patients after tumor resection.

Collagen- and hyaluronic acid-based hydrogels and their biomedical applications.

Hydrogels have been widely investigated in biomedical fields due to their similar physical and biochemical properties to the extracellular matrix (ECM). Collagen and hyaluronic acid (HA) are the main components of the ECM in many tissues. As a result, hydrogels prepared from collagen and HA hold inherent advantages in mimicking the structure and function of the native ECM. Numerous studies have focused on the development of collagen and HA hydrogels and their biomedical applications. In this extensive review, we provide a summary and analysis of the sources, features, and modifications of collagen and HA. Specifically, we highlight the fabrication, properties, and potential biomedical applications as well as promising commercialization of hydrogels based on these two natural polymers.

Direct 3D Printing of Seashell Precursor toward Engineering a Multiphasic Calcium Phosphate Bone Graft.

Multiphasic calcium phosphate (Ca-P) has widely been explored for bone graft replacement. This study represents a simple method of developing osteoinductive scaffolds by direct printing of seashell resources. The process demonstrates a coagulation-assisted extrusion-based three-dimensional (3D) printing process for rapid fabrication of multiphasic calcium phosphate-incorporated 3D scaffolds. These scaffolds demonstrated an interconnected open porous architecture with improved compressive strength and higher surface area. Multiphasic calcium phosphate (Ca-P) and hydroxyapatite present in the multi-scalar naturally resourced scaffold displayed differential protein adsorption, thus facilitating cell adhesion, migration, and differentiation, resulting in enhanced deposition of the extracellular matrix. The microstructural and physicochemical attributes of the scaffolds also lead to enhanced stem cell differentiation as witnessed from gene and protein expression analysis. Furthermore, the histological study of subcutaneous implantation evidently portrays promising biocompatibility without foreign body reaction. Neo-tissue in-growth was manifested with abundant blood vessels, thus indicative of excellent vascularization. Notably, cartilaginous and proteoglycan-rich tissue deposition indicated ectopic bone formation via an endochondral ossification pathway. The hierarchical interconnected porous architectural tribology accompanied with multiphasic calcium phosphate composition manifests its successful implication in enhancing stem cell differentiation and promoting excellent tissue in-growth, thus making it a plausible alternative in bone tissue engineering applications.

Elastin-Collagen Based Hydrogels as Model Scaffolds to Induce Three-Dimensional Adipocyte Culture from Adipose Derived Stem Cells.

This study aimed to probe the effect of formulation of scaffolds prepared using collagen and elastin-like polypeptide (ELP) and their resulting physico-chemical and mechanical properties on the adipogenic differentiation of human adipose derived stem cells (hASCs). Six different ELP-collagen scaffolds were prepared by varying the collagen concentration (2 and 6 mg/mL), ELP addition (6 mg/mL), or crosslinking of the scaffolds. FTIR spectroscopy indicated secondary bonding interactions between collagen and ELP, while scanning electron microscopy revealed a porous structure for all scaffolds. Increased collagen concentration, ELP addition, and presence of crosslinking decreased swelling ratio and increased elastic modulus and compressive strength of the scaffolds. The scaffold characteristics influenced cell morphology, wherein the hASCs seeded in the softer, non-crosslinked scaffolds displayed a spread morphology. We determined that stiffer and/or crosslinked elastin-collagen based scaffolds constricted the spreading of hASCs, leading to a spheroid morphology and yielded an enhanced adipogenic differentiation as indicated by Oil Red O staining. Overall, this study underscored the importance of spheroid morphology in adipogenic differentiation, which will allow researchers to create more physiologically-relevant three-dimensional, in vitro culture models.

OPTIMIZATION OF COLLAGEN-ELASTIN-LIKE POLYPEPTIDE-BIOGLASS SCAFFOLD COMPOSITION FOR OSTEOGENIC DIFFERENTIATION OF ADIPOSE-DERIVED STEM CELLS.

We have developed a multicomponent hydrogel scaffold that can mimic the bone extracellular matrix by incorporating collagen, elastin-like polypeptide (ELP), and Bioglass. We examined the effects of Bioglass addition to collagen-ELP scaffolds on mechanical properties, physical characteristics, and in vitro osteogenic differentiation, by varying the Bioglass amount and particle size. Response surface methodology with a central composite design predicted 5 mg (6.6 mg/mL) Bioglass with a particle size of 142 ± 5 µm as the optimal amount and particle size to be mixed with 6 mg/mL collagen and 18 mg/mL ELP to obtain a combination of maximized compressive properties. Swelling ratio and FTIR spectroscopy indicated lower hydrophilicity and the presence of hydrophobic and secondary interactions between collagen, ELP, and Bioglass. Scanning electron microscopy showed a nanofibrous morphology of intermingled collagen-ELP-Bioglass network. In vitro osteogenic characterization using human adipose-derived stem cells revealed increased cell attachment and proliferation with increased ALP activity, osteocalcin content, and mineralized deposit formation during a three-week culture. Numerous mineralized deposits composed of calcium and phosphorous were shown by energy dispersive spectroscopy. Overall, our results show that the collagen-ELP-Bioglass multicomponent composites have enhanced mechanical properties with adequate physical features and cell culture properties for bone tissue engineering.

Collagen-Elastin-Like Polypeptide-Bioglass Scaffolds for Guided Bone Regeneration.

The goals of this study are to evaluate the ability of the multicomponent collagen-elastin-like polypeptide (ELP)-Bioglass scaffolds to support osteogenesis of rat mesenchymal stem cells (rMSCs), demonstrate in vivo biocompatibility by subcutaneous implantation in Sprague-Dawley rats, monitor degradation noninvasively, and finally assess the scaffold's ability in healing critical-sized cranial bone defects. The collagen-ELP-Bioglass scaffold supports the in vitro osteogenic differentiation of rMSCs over a 3 week culture period. The cellular (rMSC-containing) or acellular scaffolds implanted in the subcutaneous pockets of rats do not cause any local or systemic toxic effects or tumors. The real-time monitoring of the fluorescently labeled scaffolds by IVIS reveals that the scaffolds remain at the site of implantation for up to three weeks, during which they degrade gradually. Micro-CT analysis shows that the bilateral cranial critical-sized defects created in rats lead to greater bone regeneration when filled with cellular scaffolds. Bone mineral density and bone microarchitectural parameters are comparable among different scaffold groups, but the histological analysis reveals increased formation of high-quality mature bone in the cellular group, while the acellular group has immature bone and organized connective tissue. These results suggest that the rMSC-seeded collagen-ELP-Bioglass composite scaffolds can aid in better bone healing process.

Carbon nano dot decorated copper nanowires for SERS-Fluorescence dual-mode imaging/anti-microbial activity and enhanced angiogenic activity.

Copper nanoparticles are explored significantly for their antimicrobial activity, especially for antibiotic-resistant strain infections. However, copper has severe toxic responses and mostly it is due to its generation capability of reactive oxygen species (ROS) molecules while interacting with in vitro or in vivo systems. In the current study, wire shaped copper nanostructures were synthesized via microwave irradiation with single step doping of carbon nanodots (CDs). The synthesized material (CuCs) was characterized by UV-Vis spectroscopy, fluorescence spectroscopy, FTIR, TEM, FESEM, XRD, DLS, and XPS. The fluorescence spectroscopy, microscopy and Raman spectroscopy results suggested CuCs to work well as a bi-modal imaging nanoprobe (fluorescence/SERS). The cell culture studies prove significant cytocompatibility and ROS scavenging property of the samples with respect to control. Further, CuCs-gelatin nanocomposite thin films were prepared and implanted into rodent deep wound model. The histological study has showed enhanced angiogenesis in the subcutaneous region. The results were validated by immuno-histochemistry. The ROS scavenging and enhanced angiogenesis were validated via gene expression studies and a HIF-α induced enhanced angiogenesis mechanism was also proposed for better wound healing.

Drug-Loaded Elastin-Like Polypeptide-Collagen Hydrogels with High Modulus for Bone Tissue Engineering.

Emphasizing the role of hydrogel stiffness and cellular differentiation, this study develops collagen and elastin-like polypeptide (ELP)-based bone regenerative hydrogels loaded with recombinant human bone morphogenetic protein-2 (rhBMP-2) and doxycycline with mechanical properties suitable for osteogenesis. The drug-incorporated collagen-ELP hydrogels has significantly higher modulus of 35 ± 5 kPa compared to collagen-only hydrogels. Doxycycline shows a bi-phasic release with an initial burst release followed by a gradual release, while rhBMP-2 exhibits a nearly linear release profile for all hydrogels. The released doxycycline shows anti-microbial activity against Pseudomonas aeruginosa, Streptococcus sanguinis, and Escherichia coli. Microscopic observation of the hydrogels reveals their interconnected, macroporous, 3D open architecture with pore diameters between 160 and 400 µm. This architecture supports human adipose-derived stem cell attachment and proliferation from initial days of cell seeding, forming a thick cellular sheath by day 21. Interestingly, in collagen and collagen-ELP hydrogels, cell morphology is elongated with stretched slender lamellipodial formation, while cells assemble as spheroidal aggregates in crosslinked as well as drug-loaded hydrogels. Osteogenic markers, alkaline phosphatase and osteocalcin, are expressed maximally for drug-loaded hydrogels compared to those without drugs. The drug-loaded collagen-ELP hydrogels are thus promising for combating bacterial infection and promoting guided bone regeneration.

Manganese oxide-carbon quantum dots nano-composites for fluorescence/magnetic resonance (T1) dual mode bioimaging, long term cell tracking, and ROS scavenging.

Multimodal long-term imaging probes with capability of extracting complementary information are highly important in biomedical engineering for disease diagnosis and monitoring of therapeutics distribution. However, most of the theranostics probes used are transient and have inherent problem of toxicity mostly related to generation of free radicals. In current study, a simple microwave assisted synthesis of multimodal imaging nanoprobe (T1 contrast in MR/fluorescence) is reported via doping carbon quantum dots into manganese oxide nanoparticles. The nanostructures were characterized by US-Vis spectroscopy, fluorescence spectroscopy, FTIR, Raman spectroscopy, TEM, XRD, AFM and XPS. The average particle size was observed to be around 20-40 nm with a height of 7-9 nm and approximate quantum yield of 0.23. The nanostructures were useful for bio imaging and cell tracking via fluorescence microscopy up to 12 generations with nominal cytotoxicity. The material was capable of scavenging free radicals from cellular microenvironment and downregulate gene expression of free radical scavenging enzymes. The material has significant relaxivity (r1) value of 3.98 mM-1.sec-1 at 1.5 T. It was also observed to create significant contrast with high circulation time (30 min) and renal clearance property. The histological analysis of kidney and liver sections were observed to have no significant toxicity from the nanostructure.

Doping of carbon nanodots for saving cells from silver nanotoxicity: A study on recovering osteogenic differentiation potential.

Silver nanoparticles are explored for many advanced biological applications including the development of antimicrobial surfaces on implants, SERS imaging, nanotherapeutics, biosensing and much more. However, recent research findings suggest silver nanoparticles provide blockade of differentiation of mesenchymal stem cells (MSCs), especially into osteogenic developmental pathway via generation of reactive oxygen species. These studies suggest that the application of silver nanoparticles in medical implants should be prohibited. In the current study, carbon nanodots (CND) supported silver clusters (AgC) is explored as a remedy to this problem. The nanostructure was synthesized in microwave irradiation induced rapid method and characterization was conducted via UV-Vis spectroscopy, fluorescence spectroscopy, HRTEM, XRD, FTIR, Raman spectroscopy, DLS, AFM, and XPS. Fluorescence spectrum showed a quantum yield of 0.25 while Raman spectroscopy showed rapid amplification of CND specific peaks implicating significant SERS property. Further in vitro biocompatibility (MTT) and bio-imaging capability was assessed culturing Wharton's Jelly-derived MSCs. In this study, its efficacy as in-situ cellular oxidative stress scavenger is also studied using NBT and DCFH-DA assay. Via ALP assay, alizarin red staining, cell membrane nanoindentation studies, PCR analysis and immunocytochemistry for osteoblast-like gene expression it was confirmed that AgCs can control silver nanoparticle-induced inhibition of osteogenic differentiation in vitro. Thus, AgCs (Carbon nanodots supported silver clusters) are not only considered to be a dual-mode bio-imaging nanoprobe but also a remedy to the silver-induced ROS generation and osteogenic differentiation blockade of MSCs.

Morphology-induced physico-mechanical and biological characteristics of TPU-PDMS blend scaffolds for skin tissue engineering applications.

Composition and architecture of scaffolds are the most important factors determining the performance of skin substitutes. In this work, morphology induced unique physical and biological characteristics of compatibilized TPU-PDMS blend scaffolds at 90:10, 80:20, and 70:30 blend ratios of TPU and PDMS was studied. The fiber morphology, porosity, surface wettability, and mechanical properties of electrospun scaffolds were distinctly influenced by the presence of PDMS. Interestingly, the scaffold architecture varied from electrospun fibers to porous fibers and finally occurrence of unique porous beads noticed at 30% PDMS in the microstructure which was confirmed using FESEM. Micro-CT analysis revealed that the porosity of electrospun scaffolds was enhanced from 61% to 79% with 30 parts of PDMS addition. Moreover, MTT assay and cell proliferation were studied using human skin fibroblast cells and found to be significantly enhanced with the PDMS percentage. TPU-PDMS blends offer better overall performance at 70:30 blend ratio of TPU and PDMS (T70P30). Only 4% of hemolysis was observed for T70P30 blends, which establishes the hemocompatibility of the material. In comparison, the results reveal the potential of the cytocompatible T70P30 scaffold for the fabrication of skin substitutes for tissue engineering applications. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 1634-1644, 2019.

Carbon Nanodots Doped Super-paramagnetic Iron Oxide Nanoparticles for Multimodal Bioimaging and Osteochondral Tissue Regeneration via External Magnetic Actuation.

Super-paramagnetic iron oxide nanoparticles (SPIONs) have multiple theranostics applications such as T2 contrast agent in magnetic resonance imaging (MRI) and electromagnetic manipulations in biomedical devices, sensors, and regenerative medicines. However, SPIONs suffer from the limitation of free radical generation, and this has a certain limitation in its applicability in tissue imaging and regeneration applications. In the current study, we developed a simple hydrothermal method to prepare carbon quantum dots (CD) doped SPIONs (FeCD) from easily available precursors. The nanoparticles are observed to be cytocompatible, hemocompatible, and capable of scavenging free radicals in vitro. They also have been observed to be useful for bimodal imaging (fluorescence and MRI). Further, 3D printed gelatin-FeCD nanocomposite nanoparticles were prepared and used for tissue engineering using static magnetic actuation. Wharton's jelly derived mesenchymal stem cells (MSCs) were cultured on them with magnetic actuation and implanted at the subcutaneous region. The tissues obtained have shown features of both osteogenic and chondrogenic differentiation of the stem cells in vivo. In vitro, PCR studies show MSCs express gene expression of both bone and cartilage-specific markers, suggesting FeCDs under magnetic actuation can lead MSCs to go through differentiating into an endochondral ossification route.

In Vivo Cell Tracking, Reactive Oxygen Species Scavenging, and Antioxidative Gene Down Regulation by Long-Term Exposure of Biomass-Derived Carbon Dots.

Biomass derived carbon dots (CD) have been observed to be excellent bioimaging probes due to their nontoxic, stable fluorescence, lesser bleachability, and excellent bioconjugation properties. In the current study, green chili extract derived CD synthesis via microwave irradiation is reported. The time dependent top down degradation of carbonaceous materials to CD are monitored via electron microscopy and correlated with fluorescence intensity. Further, the CD were explored for long-term cell tracking and cell therapy monitoring in a rodent model to study wound healing kinetics. The cells were monitorable up to 21 days (until the entire wound healed). CD were observed to scavenge reactive oxygen species (ROS) in vitro and in vivo and provided control over ROS scavenging enzyme gene expressions via down regulation. Further, it was observed to remodel the wound healing kinetics via altering granulation tissue distribution and formation of microvessels to establish the capability of CD to enhance wound healing.

Surface Modification of Eggshell Membrane with Electrospun Chitosan/Polycaprolactone Nanofibers for Enhanced Dermal Wound Healing.

Eggshell membrane (ESM), a naturally occurring microfibrous biopolymer network comprising collagen I, V, and X, GAGs, and other significant proteins, is responsible for guided tissue regeneration. The extraction methodology of ESM and surface topography of the microfibers impede its extensive usage in skin tissue engineering. Herein we deploy a unique route of ESM surface modification utilizing chitosan/polycaprolactone (CS/PCL) nanofibers to fabricate a bilayered scaffold for wound healing application. Microstructural and surface topographic analysis of the construct confirms the bilayered structure of the composite with smooth nanofibers of CS/PCL decorated on ESM. The two layers were cross-linked by carbodiimide chemistry as confirmed by XPS and FTIR analysis. Cytocompatibility of the scaffolds was evaluated with human dermal fibroblast (HDF) cells culture study. The biomimetic architecture and composition of modified ESM facilitated extensive cell adhesion, migration, and proliferation while an impeded cell adhesion was observed on the natural tissue. Moreover, owing to the presence of ESM, the scaffolds adhered naturally to the wound bed while implanted on a full-thickness wound in a rat model. Further, the nanofiber modified ESM group showed extensive host cell migration and proliferation thus leading to faster re-epithelization and dermal regeneration with high collagen deposition in comparison to natural ESM. The above in vitro and in vivo results substantiate the effect of nanofiber functionalization on the ESM surface thus making the bilayered construct a potential dermal substitute.

Bilayered nanofibrous 3D hierarchy as skin rudiment by emulsion electrospinning for burn wound management.

Mimicking skin extracellular matrix hierarchy, the present work aims to develop a bilayer skin graft comprising a porous cotton-wool-like 3D layer with membranous structure of PCL-chitosan nanofibers. Emulsion electrospinning with differential stirring periods of PCL-chitosan emulsion results in development of a bilayer 3D structure with varied morphology. The electrospun membrane has fiber diameter ∼274 nm and pore size ∼1.16 µm while fluffy 3D layer has fiber diameter ∼1.62 µm and pore size ∼62 µm. The 3D layer was further coated with collagen I isolated from Cirrhinus cirrhosus fish scales to improve biofunctionality. Surface coating with collagen I resulted in bundling the fibers together, thereby increasing their average diameter to 2.80 µm and decreasing pore size to ∼45 µm. The architecture and composition of the scaffold promotes efficient cellular activity where interconnected porosity with ECM resembling collagen I coating assists cellular adhesion, infiltration, and proliferation from initial days of fibroblast seeding, while keratinocytes migrate on the surface only without infiltrating in the membranous nanofiber layer. Anatomy of the scaffold arising due to variation in pore size distribution at different layers thereby facilitates compartmentalization and prevents initial cellular transmigration. The scaffold also assists in extracellular matrix protein synthesis and keratinocyte stratification in vitro. Further, the scaffold effectively integrates and attaches with third-degree burn wound margins created in rat models and accelerates healing in comparison to standard Tegaderm dressing™. The bilayer scaffold is thus a promising, readily available, cost-effective, off-the-shelf matrix as a skin substitute.

Effect of Vitamin E and a Long-Chain Alcohol n-Octanol on the Carbohydrate-Based Nonionic Amphiphile Sucrose Monolaurate-Formulation of Newly Developed Niosomes and Application in Cell Imaging.

We have introduced new niosome formulations using sucrose monolaurate, vitamin E and n-octanol as independent additives. Detailed characterization techniques including turbidity, dynamic light scattering, transmission electron microscopy, ξ potential, and proton nuclear magnetic resonance measurements have been introduced to monitor the morphological transition of the carbohydrate-based micellar assembly into niosomal aggregates. Moreover, microheterogeneity of these niosomal aggregates has been investigated through different fluorescence spectroscopic techniques using a hydrophobic probe molecule coumarin 153 (C153). Further, it has been observed that vitamin E and octanol have an opposing effect on the rotational motion of C153 in the respective niosome assemblies. The time-resolved anisotropy studies suggest that incorporation of vitamin E and octanol into the surfactant aggregates results in slower and faster rotational motion of C153, respectively, compared to the micellar assemblies. Moreover, the ability to entrap a probe molecule by these niosomes is utilized to encapsulate and deliver the anticancer drug doxorubicin inside the mammalian cells which is monitored through fluorescence microscopic images. Interestingly, the niosome composed of vitamin E demonstrated better cytocompatibility toward primary chondrocyte cell lines compared to the octanol-forming niosome.

Carbon nanodot impregnated fluorescent nanofibers for in vivo monitoring and accelerating full-thickness wound healing.

Semiconductor quantum dots are overwhelmingly used for in situ monitoring and imaging of cell-scaffold interactions. However, quantum dots suffer from oxidative biodegradation in biological systems, besides being toxic due to the presence of heavy metals. In this study, we report the development of an intrinsically fluorescent nanofibrous scaffold of polycaprolactone-gelatin for skin tissue regeneration and noninvasive monitoring of scaffold activity in vivo. The presence of the incorporated carbon nanodots played a critical role in imparting the scaffold with these novel characteristics. The developed scaffold was uniform and bead free with fiber diameter of 698 ± 420 nm and pore diameter of 2.93 ± 1.13 µm. Inclusion of carbon nanodots not only bestowed uniform fluorescence of the scaffold but also promoted fibroblast cell adhesion, migration and proliferation. Co-culture of fibroblast and keratinocyte cells on the scaffold surface also enabled the development of a stratified epithelial layer. The scaffold exhibited antioxidant properties by scavenging free radicals and reducing the expression of antioxidative enzymes. Upon implantation in a full-thickness excision wound, the scaffold accelerated the progression of healing and the regenerated skin exhibited a stratified epithelial layer with mature dermal tissue. The scaffold enabled noninvasive monitoring of the wound healing kinetics in vivo through two-photon microscopy. With excellent photoluminescence, biocompatibility, and photo stability, the scaffold can suitably be used for prolonged monitoring of cell-scaffold interactions and further efficiently reduce the oxidative stress during continuous imaging. Additionally, being synthesized from inexpensive precursors employing a simple procedure, carbon nanodot production is cost-effective and the developed scaffold would be an off-the-shelf, readily available economical product.