Chitin and chitosan are biopolymers having immense structural possibilities for chemical and mechanical modifications to generate novel properties, functions and applications especially in biomedical ...area. Chitin and chitosan are effective materials for biomedical applications because of their biocompatibility, biodegradability and non-toxicity, apart from their antimicrobial activity and low immunogenicity, which clearly points to an immense potential for future development. These candidate biopolymers can be easily processed into gels, sponges, membranes, beads and scaffolds forms. This review emphasizes recent research on different aspects of chitin and chitosan based nanomaterials, including the preparation and applications of chitin and chitosan based nanofibers, nanoparticles and nanocomposite scaffolds for tissue engineering, wound dressing, drug delivery and cancer diagnosis.
Prolonged chemodrug delivery to the tumor site is a prerequisite to maintaining its localised therapeutic concentrations for effective treatment of malignant solid tumors.
The current study aims to ...develop implantable polymeric depots through conventional electrospinning for sustained drug delivery, specifically to the peritoneum.
Non-woven electrospun mats were fabricated by simple electrospinning of Polydioxanone solution loaded with the chemodrug, Paclitaxel. The implants were subjected to the analysis of morphology, mechanical properties, degradation and drug release in phosphate buffer and patient-derived peritoneal drain fluid samples. In vivo studies were conducted by surgical knotting of these implants to the peritoneal wall of healthy mice.
Non-woven electrospun mats with a thickness of 0.65±0.07 mm, weighing ~ 20 mg were fabricated by electrospinning 15 w/v% polymer loaded with 10 w/w% drug. These implants possessing good mechanical integrity showed a drug entrapment efficiency of 87.82±2.54 %. In vitro drug release studies in phosphate buffer showed a sustained profile for ~4 weeks with a burst of 10 % of total drug content, whereas this amounted to >60% in patient samples. Mice implanted with these depots remained healthy during the study period. The biphasic drug release profile obtained in vivo showed a slow trend, with peritoneal lavage and tissues retaining good drug concentrations for a sustained period.
The results indicate that non-woven electrospun mats developed from biodegradable Polydioxanone polymer can serve as ideal candidates for easily implantable drug depots to address the challenges of peritoneal metastasis in ovarian cancer.
Single center, noninterventional cohort study to assess 10-year visual and anatomical outcomes following initiation of treatment with antivascular endothelial growth factor (anti-VEGF) agents in ...neovascular age-related macular degeneration (AMD) patients. Neovascular AMD patients initiated on intravitreal anti-VEGF injections in 2008-2009 and continued to be followed up for at least 10 years were included in this study.
The Moorfields OpenEyes database was searched for all patients who were initiated on anti-VEGF therapy for neovascular AMD in 2008-2009 and the visual acuity (VA) in Early Diabetic Retinopathy Study (ETDRS) letters and injection records were analyzed for those who have had at least 10-year follow-up. The spectral-domain optical coherence tomography (SD-OCT) scans, color fundus photos, and fundus fluorescein angiography (FA) were graded by two retinal physicians. The outcomes were also compared between those with good and poor VA outcomes based on pre-defined criteria. The primary end point was change in VA at 10 years; secondary outcomes included percentage with VA of 20/40 or better, 20/70 or better, VA gains and losses, anatomic outcomes and number of injections.
After a mean of 10.04 years after initiation of anti-VEGF therapy, the mean decline in VA from baseline was -2.1 ETDRS letters (SD 19.9, p = 0.65). One hundred eyes (67.1%) achieved a VA threshold of 20/70 or better, 33.5% achieved a VA of 20/40 or better, and 76.5% eyes maintained VA defined as a loss of less than 15 letters. Fourteen percent of study eyes had VA of 20/200 or worse and 23.5% declined by 15 letters or more. 87.5% of eyes were switched from ranibizumab to aflibercept during the course of 10 years and the eyes received a mean of 52.2 (SD 18.1) injections over 10 years. From this cohort, 87 (58.3%) eyes are having on-going treatment. On OCT, 34.9% had persistent fluid at the last visit, 6.7% patients showed new onset atrophy compared to baseline, and 43.7% had increased area of macular atrophy. The mean area of atrophy at the final visit was 4.15 mm
. Comparison between the good and worse visual outcome groups showed lower baseline VA, fovea-involving atrophy and final area of atrophy had a statistically significant negative effect on the final visual outcome (p < 0.05).
Regular monitoring and anti-VEGF treatment over 10 years reduce the risk of visual loss of 15 letters or more in patients with neovascular AMD. The most common cause of substantial visual decline was macular atrophy.
Molecular-receptor-targeted imaging of folate receptor positive oral carcinoma cells using folic-acid-conjugated fluorescent Au(25) nanoclusters (Au NCs) is reported. Highly fluorescent Au(25) ...clusters were synthesized by controlled reduction of Au(+) ions, stabilized in bovine serum albumin (BSA), using a green-chemical reducing agent, ascorbic acid (vitamin-C). For targeted-imaging-based detection of cancer cells, the clusters were conjugated with folic acid (FA) through amide linkage with the BSA shell. The bioconjugated clusters show excellent stability over a wide range of pH from 4 to 14 and fluorescence efficiency of approximately 5.7% at pH 7.4 in phosphate buffer saline (PBS), indicating effective protection of nanoclusters by serum albumin during the bioconjugation reaction and cell-cluster interaction. The nanoclusters were characterized for their physico-chemical properties, toxicity and cancer targeting efficacy in vitro. X-ray photoelectron spectroscopy (XPS) suggests binding energies correlating to metal Au 4f(7/2) approximately 83.97 eV and Au 4f(5/2) approximately 87.768 eV. Transmission electron microscopy and atomic force microscopy revealed the formation of individual nanoclusters of size approximately 1 nm and protein cluster aggregates of size approximately 8 nm. Photoluminescence studies show bright fluorescence with peak maximum at approximately 674 nm with the spectral profile covering the near-infrared (NIR) region, making it possible to image clusters at the 700-800 nm emission window where the tissue absorption of light is minimum. The cell viability and reactive oxygen toxicity studies indicate the non-toxic nature of the Au clusters up to relatively higher concentrations of 500 microg ml(-1). Receptor-targeted cancer detection using Au clusters is demonstrated on FR(+ve) oral squamous cell carcinoma (KB) and breast adenocarcinoma cell MCF-7, where the FA-conjugated Au(25) clusters were found internalized in significantly higher concentrations compared to the negative control cell lines. This study demonstrates the potential of using non-toxic fluorescent Au nanoclusters for the targeted imaging of cancer.
Magnetite/gold (Fe(3)O(4)/Au) hybrid nanoparticles were synthesized from a single iron precursor (ferric chloride) through a green chemistry route using grape seed proanthocyanidin as the reducing ...agent. Structural and physicochemical characterization proved the nanohybrid to be crystalline, with spherical morphology and size ~35 nm. Magnetic resonance imaging and magnetization studies revealed that the Fe(3)O(4) component of the hybrid provided superparamagnetism, with dark T(2) contrast and high relaxivity (124.2 ± 3.02 mM(-1) s(-1)). Phantom computed tomographic imaging demonstrated good X-ray contrast, which can be attributed to the presence of the nanogold component in the hybrid. Considering the potential application of this bimodal nanoconstruct for stem cell tracking and imaging, we have conducted compatibility studies on human Mesenchymal Stem Cells (hMSCs), wherein cell viability, apoptosis, and intracellular reactive oxygen species (ROS) generation due to the particle-cell interaction were asessed. It was noted that the material showed good biocompatibility even for high concentrations of 500 μg/mL and up to 48 h incubation, with no apoptotic signals or ROS generation. Cellular uptake of the nanomaterial was visualized using confocal microscopy and prussian blue staining. The presence of the nanohybrids were clearly visualized in the intracytoplasmic region of the cell, which is desirable for efficient imaging of stem cells in addition to the cytocompatible nature of the hybrids. Our work is a good demonstrative example of the use of green aqueous chemistry through the employment of phytochemicals for the room temperature synthesis of complex hybrid nanomaterials with multimodal functionalities.
To evaluate the inter-rater reliability for identification of complete retinal pigment epithelium and outer retinal atrophy (cRORA) on SD-OCT images as defined by the Classification of Atrophy ...Meetings (CAM) group.
Fifty images of anonymized SD-OCT line scans of eyes with cRORA due to AMD were selected. Each .tiff image was saved in both black-on-white (BW) and white-on-black (WB) format. Five retina-trained clinicians graded both sets of images twice for the diagnosis of cRORA based on the CAM group definition. Fleiss kappa statistic was calculated for inter-rater reliability and Cohen's kappa statistic for intra-grader and inter-grader reliability between any two graders.
The inter-grader reliability varied from as low as 0.28 to 0.92 for WB images and 0.34 to 0.86 for BW images. However, the inter-grader and intra-grader agreement was ĸ WB 0.92; ĸ BW 0.86 and ĸ 0.92 respectively, for graders accustomed to the CAM criteria. Fleiss kappa was ĸ 0.49 (p value < 0.0001) for WB images and ĸ 0.34 (p value < 0.0001 for BW images. Overall, the agreement was better using WB images for all parameters except RPE attenuation/loss.
There is significant variability in diagnosis of cRORA on SD-OCT by retina-trained ophthalmologists in the real world. The study highlights the need for training to recognise the different features of cRORA prior to its implementation in clinical practice.
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A promising strategy for augmenting bone formation involves the local delivery of multiple osteoinductive and vasculogenic growth factors. However, success depends on sustained growth ...factor release and its appropriate combination to induce stem cells and osteogenic cells at the bony site. Herein, we have developed a nanocomposite fibrous scaffold loaded with fibroblast growth factor 2 (FGF2), vascular endothelial growth factor (VEGF) and bone morphogenetic protein 2 (BMP2) and its ability to promote vascularisation and bone regeneration in critical sized calvarial defect was compared to the scaffold with VEGF + BMP2 and FGF2 + BMP2. Simple loading of growth factors on the scaffold could provide a differential release pattern, both in vitro and in vivo (VEGF release for 1 week where as BMP2 and FGF2 release for 3 weeks). Among all the groups, dual growth factor loaded scaffold (VEGF + BMP2 & FGF2 + BMP2) enhanced vascularisation and new bone formation, but there was no difference between FGF2 and VEGF loaded scaffolds although its release pattern was different. FGF2 mainly promoted stem cell migration, whereas VEGF augmented new blood vessel formation at the defect site. This study suggests that biomimetic nanocomposite scaffold is a promising growth factor delivery vehicle to improve bone regeneration in critical sized bone defects.
Many studies have shown the effect of growth factors like VEGF-BMP2 or FGF2-BMP2 in enhancing bone formation in critical sized defects, but there are no reports that demonstrate the direct comparison of VEGF-BMP2 and FGF2-BMP2. In this study, we have developed a nanocomposite fibrous scaffold that could differentially release growth factors like VEGF, BMP2 and FGF2 (VEGF release for 1 week where as BMP2 and FGF2 release for 3 weeks), which in turn promoted neovascularisation and new bone formation in critical sized defects. There was no difference in vascularisation and bone formation induced by VEGF + BMP2 or FGF2 + BMP2. The growth factor was loaded in a simple manner, which would ensure ease of use for the end-user, especially for the surgeons treating a patient in an operating room.
We report the effect of carboxyl functionalization of graphene in pacifying its strong hydrophobic interaction with cells and associated toxic effects. Pristine graphene was found to accumulate on ...the cell membrane causing high oxidative stress leading to apoptosis, whereas carboxyl functionalized hydrophilic graphene was internalized by the cells without causing any toxicity.
Graphene and its derivatives are being proposed for several important biomedical applications including drug delivery, gene delivery, contrast imaging, and anticancer therapy. Most of these ...applications demand intravenous injection of graphene and hence evaluation of its hemocompatibility is an essential prerequisite. Herein, both pristine and functionalized graphene are extensively characterized for their interactions with murine macrophage RAW 264.7 cells and human primary blood components. Detailed analyses of the potential uptake by macrophages, effects on its metabolic activity, membrane integrity, induction of reactive oxygen stress, hemolysis, platelet activation, platelet aggregation, coagulation cascade, cytokine induction, immune cell activation, and immune cell suppression are performed using optimized protocols for nanotoxicity evaluation. Electron microscopy, confocal Raman spectral mapping, and confocal fluorescence imaging studies show active interaction of both the graphene systems with macrophage cells, and the reactive oxygen species mediated toxicity effects of hydrophobic pristine samples are significantly reduced by surface functionalization. In the case of hemocompatibility, both types of graphene show excellent compatibility with red blood cells, platelets, and plasma coagulation pathways, and minimal alteration in the cytokine expression by human peripheral blood mononuclear cells. Further, both samples do not cause any premature immune cell activation or suppression up to a relatively high concentration of 75 μg mL−1 after 72 h of incubation under in vitro conditions. This study clearly suggests that the observed toxicity effects of pristine graphene towards macrophage cells can be easily averted by surface functionalization and both the systems show excellent hemocompatibility.
Surface functionalization reduces the toxicity of pristine graphene towards macrophage cells in vitro. Macrophages show relatively high intracellular uptake of functionalized, hydrophilic graphene compared to hydrophobic pristine graphene. The excellent compatibility of both types of graphene with human blood components is demonstrated.
Abstract Targeted cancer imaging using rare-earth oxide nanocrystals, free from heavy metals (Cd, Se, Te, Hg and Pb), showing bright red-fluorescence and magnetic resonance imaging (MRI) is ...presented. Y2 O3 nanocrystals (YO NC) doped in situ with fluorescent (Eu3+ ) and paramagnetic (Gd3+ ) impurities and conjugated with a potential cancer targeting ligand, folic acid (FA), were prepared using an all-aqueous wet-chemical process. Structural, optical and magnetic properties of these multifunctional nanocrystals were investigated by X-ray diffraction, electron microscopy, photoluminescence and magnetization studies. Highly monodisperse nanocrystals of size ∼20 nm with cubic bixbyite crystal structure showed bright red-fluorescence when doped with Eu3+ . Co-doping with Gd3+ and mild air drying resulted significantly enhanced fluorescence quantum efficiency of ∼60% together with paramagnetic functionality, enabling T1 -weighted MR contrast with ∼5 times higher spin-lattice relaxivity compared to the clinically used Gd3+ contrast agent. Cytotoxicity and reactive oxygen stress studies show no toxicity by YO NC in both normal and cancer cells up to higher doses of 500 μ m and longer incubation time, 48 h. Cancer targeting capability of FA conjugated NCs was demonstrated on folate receptor positive (FR+) human nasopharyngeal carcinoma cells (KB) with FR depressed KB (FRd) and FR negative (FR-) lung cancer cells A549 as controls. Fluorescence microscopy and flow-cytometry data show highly specific binding and cellular uptake of large concentration of FA conjugated NCs on FR+ve cells compared to the controls. Thus, the present study reveals, unique bi-modal contrast imaging capability, non-toxicity and cancer targeting capability of multiple impurities doped rare-earth oxide nanocrystals that can find promising application in molecular imaging.
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