Integrating Porous Silicon Nanoneedles within Medical Devices for Nucleic Acid Nanoinjection.

Porous silicon nanoneedles can interface with cells and tissues with minimal perturbation for high-throughput intracellular delivery and biosensing. Typically, nanoneedle devices are rigid, flat, and opaque, which limits their use for topical applications in the clinic. We have developed a robust, rapid, and precise substrate transfer approach to incorporate nanoneedles within diverse substrates of arbitrary composition, flexibility, curvature, transparency, and biodegradability. With this approach, we integrated nanoneedles on medically relevant elastomers, hydrogels, plastics, medical bandages, catheter tubes, and contact lenses. The integration retains the mechanical properties and transfection efficiency of the nanoneedles. Transparent devices enable the live monitoring of cell-nanoneedle interactions. Flexible devices interface with tissues for efficient, uniform, and sustained topical delivery of nucleic acids ex vivo and in vivo. The versatility of this approach highlights the opportunity to integrate nanoneedles within existing medical devices to develop advanced platforms for topical delivery and biosensing.

Lithiated porous silicon nanowires stimulate periodontal regeneration.

Periodontal disease is a significant burden for oral health, causing progressive and irreversible damage to the support structure of the tooth. This complex structure, the periodontium, is composed of interconnected soft and mineralised tissues, posing a challenge for regenerative approaches. Materials combining silicon and lithium are widely studied in periodontal regeneration, as they stimulate bone repair via silicic acid release while providing regenerative stimuli through lithium activation of the Wnt/ß-catenin pathway. Yet, existing materials for combined lithium and silicon release have limited control over ion release amounts and kinetics. Porous silicon can provide controlled silicic acid release, inducing osteogenesis to support bone regeneration. Prelithiation, a strategy developed for battery technology, can introduce large, controllable amounts of lithium within porous silicon, but yields a highly reactive material, unsuitable for biomedicine. This work debuts a strategy to lithiate porous silicon nanowires (LipSiNs) which generates a biocompatible and bioresorbable material. LipSiNs incorporate lithium to between 1% and 40% of silicon content, releasing lithium and silicic acid in a tailorable fashion from days to weeks. LipSiNs combine osteogenic, cementogenic and Wnt/ß-catenin stimuli to regenerate bone, cementum and periodontal ligament fibres in a murine periodontal defect.

Orthopedic Scaffolds: Evaluation of Structural Strength and Permeability of Fluid Flow via an Open Cell Neovius Structure for Bone Tissue Engineering.

The ability of bone to regenerate itself through mechanobiological responses is its dynamic property. Mechanical cues from a neighboring environment produce the structural strain to promote blood flow and bone marrow mobility that in turn aids the bone regeneration process. Occurrences of these phenomena are crucial for the success of metallic scaffolds implanted in the host bone tissue. Thus, permeability and fluid flow-induced wall shear stress (WSS) are two parameters that directly influence cell bioactivities inside a scaffold and are crucial for effective bone tissue regeneration. Given that the scaffolds shall be implanted in the body, permeability assessment was carried out using non-Newtonian fluid. In this work, the triply periodic minimal surface scaffolds with Neovius architectures were fabricated by using selective laser melting technology. The estimation of fluid flow was carried out using computational fluid dynamics (CFD) analysis with a non-Newtonian blood fluid model. Further, the structural strength of various open cell Neovius lattices was evaluated using a static compression test, and in vitro cell culture using Alamar blue assay was evaluated. Results revealed that the values of intrinsic blood flow permeability of the three-dimensional (3D)-printed open cell porous scaffold with Neovius architecture were of the same order of magnitude as those of human bone, ranging from 0.0025 × 10-9 to 0.0152 × 10-9 m2. The structural elastic modulus and compressive strength of NOCL40, NOCL50, and NOCL60 lattices range from 3.27 to 3.71 GPa and 194 to 205 MPa, respectively. All of the values are comparable to the human bone, thus making these lattices a suitable alternative for orthopedic applications.

Physicochemical Properties of UV-Irradiated, Biaxially Oriented PLA Tubular Scaffolds.

PLA and its blends are the most extensively used materials for various biomedical applications such as scaffolds, implants, and other medical devices. The most extensively used method for tubular scaffold fabrication is by using the extrusion process. However, PLA scaffolds show limitations such as low mechanical strength as compared to metallic scaffolds and inferior bioactivities, limiting their clinical application. Thus, in order to improve the mechanical properties of tubular scaffolds, they were biaxially expanded, wherein the bioactivity can be improved by surface modifications using UV treatment. However, detailed studies are needed to study the effect of UV irradiation on the surface properties of biaxially expanded scaffolds. In this work, tubular scaffolds were fabricated using a novel single-step biaxial expansion process, and the surface properties of the tubular scaffolds after different durations of UV irradiation were evaluated. The results show that changes in the surface wettability of scaffolds were observed after 2 min of UV exposure, and wettability increased with the increased duration of UV exposure. FTIR and XPS results were in conjunction and showed the formation of oxygen-rich functional groups with the increased UV irradiation of the surface. AFM showed increased surface roughness with the increase in UV duration. However, it was observed that scaffold crystallinity first increased and then decreased with the UV exposure. This study provides a new and detailed insight into the surface modification of the PLA scaffolds using UV exposure.

Cellular studies and sustained drug delivery via nanostructures fabricated on 3D printed porous Neovius lattices of Ti6Al4V ELI.

Site-specific drug delivery has the potential to reduce drug dosage by 3- to 5-folds. Given the propensity of drugs used in the treatment of tuberculosis and cancers, the increased drug dosages via oral ingestion for several months to a few years of medication is often detrimental to the health of patients. In this study, the sustained delivery of drugs with multiscale structured novel Neovius lattices was achieved. 3D Neovius open cell lattices (NOCL) with porosities of 40%, 45%, and 50% were fabricated layer-by-layer on the laser bed fusion process. Micron-sized Ti6Al4V ELI powder was used for 3D printing. The Young's modulus achieved from the novel Neovius lattices were in the range of 1.2-1.6 GPa, which is comparable to human cortical bone and helps to improve implant failure due to the stress shielding effect. To provide sustained drug delivery, nanotubes (NTs) were fabricated on NOCLs via high-voltage anodization. The osteogenic agent icariin was loaded onto the NOCL-NT samples and their release profiles were studied for 7 d. A significantly steady and slow release rate of 0.05% per hour of the drug was achieved using NOCL-NT. In addition, the initial burst release of NOCL-NT was 4 fold lower than that of the open-cell lattices without NTs. Cellular studies using MG63 human osteoblast-like cells were performed to determine their biocompatibility and osteogenesis which were analyzed using Calcein AM staining and Alamar Blue after 1, 5, and 7 d. 3D printed NOCL samples with NTs and with Icariin loaded NTs demonstrated a significant increase in cell proliferation as compared to as printed NOCL samples.

Multiscale porosity in a 3D printed gellan-gelatin composite for bone tissue engineering.

The aim of this work was to develop a complex-shaped gelatin-gellan composite scaffold with multiscale porosity using a combination of cryogenic 3D printing and lyophilization for bone tissue engineering. Cryogenic 3D printing was used to fabricate a low-concentration composite of complex-shaped macroporous gelatin-gellan structures with a pore size of 919 ± 89 µm. This was followed by lyophilization to introduce micropores of size 20-250 µm and nanometre-level surface functionalities, thus achieving a hierarchical porous structure. These multiscale porous scaffolds (GMu) were compared with two other types of scaffolds having only microporosity (GMi) and macroporosity (GMa) with regard to their physical andin vitrobiological properties. GMu scaffolds were found to be better than GMi and GMa in terms of swelling percentage, degradation rate, uniform pore distribution, cellular infiltration, attachment, proliferation, protein generation and mineralization. In conclusion, we have developed a controlled hierarchical bone-like structure, biomimicking natural bone, together with a reproducible process of manufacture by coupling soft hydrogel 3D printing with lyophilization. This enables the development of complex-shaped patient-specific 3D printed hydrogel scaffolds with enhanced performancein vitroand great potential in the fields of tissue engineering, bioprinting and regenerative medicine.

Biocompatibility analysis of PLA based candidate materials for cardiovascular stents in a rat subcutaneous implant model.

Modification of Polylactic acid (PLA), a biopolymer, is a strategy still to be fully explored for the next generation of bioresorbable vascular stent (BVS) biomaterials. With this focus, inclusions upto 5% of Polycaprolactone (PCL) and Magnesium in PLA were tested in the rat subcutaneous model and their cellular and tissue interactions characterized, specifically with respect to inflammatory response, angiogenesis and capsularization. The cytokines IL6, TNF Alpha and IL-1Beta were estimated in the peri-implant tissue, all of which showed a non-significant difference between the non-implanted animals and those containing PLA by 8 weeks, speaking to the benign nature of PLA as an implant biomaterial. Both modified materials, had increased macrophage counts and cytokine levels, except IL6 at 8 weeks. Vascularization only at 8 weeks in PLA PCL containing tissue was significantly higher than pure PLA, which may be more carefully controlled along with the material hydrophobicity for possible efforts towards therapeutic angiogenesis. Capsule thickness, measured by staining with both Hematoxylin & Eosin and Masson's Trichome did not show any differences between materials, including PLA.

Three Dimensional Quercetin-Functionalized Patterned Scaffold: Development, Characterization, and In Vitro Assessment for Neural Tissue Engineering.

Regeneration of injured neuronal areas is a big challenge owing to the complex structure and function of the nervous system along with the limited regeneration capacity of neural cells. Recent reports show that patterned and functionalized scaffolds could control neural cell directional growth. In this study, aligned nanofibers (ANFs) were fabricated using a versatile and cost-effective approach, electrospinning, and further processed to make a patterned hybrid scaffold (HANF). The patterned scaffold had circular rings of ANFs reinforced in a biocompatible gellan-gelatin hydrogel matrix to provide adequate mechanical strength and contact guidance for adhesion and growth of neural cells in vitro. Quercetin was loaded into the nanofibrous scaffold to provide a functional agent that supported regeneration of neural cells. The reinforced ANFs enhanced the mechanical strength of the scaffold and provided a cylindrical nerve conduit structure to support neuronal cell growth. The influence of scaffold topology on cell behavior was assessed in in vitro cell culture conditions that revealed that the functionalized patterned scaffolds favored directed neurite cell growth/extension with favored cell culture morphology and showed no cytotoxicity toward neural cells. The results ultimately indicated that the fabricated scaffold has potential for guiding nerve tissue growth and can be used as nerve regeneration scaffolds.

Synthesis and characterization of a novel open cellular Mg-based scaffold for tissue engineering application.

Tissue engineering is a field which aims to regenerate damaged tissues by enhancing tissue growth through the porous architecture of the scaffolds which is desired to mimic the human cancellous bone. Mg-based scaffolds are gaining importance in the field of tissue engineering owing to its potential application as a biomaterial. However, fabrication of porous Mg remains a daunting task due to its highly reactive nature. In the present work, a novel Mg-based open cell porous structure with pore interconnectivity and significant strength is successfully fabricated using powder metallurgy approach and Ti-woven wire mesh as a space holding material. Pore morphology and percentage porosity can be easily altered by adjusting the Ti-wire diameter and shape of construct. SEM, EDX and µ-CT analysis were performed to assess the microstructural properties of the fabricated scaffold which revealed a uniform distribution of pores with porosity varying in range 50-60%. The measured values of ultimate compressive strength and elastic modulus using quasi static compression test were found to be 101 MPa and 2 GPa, respectively. Further to improve corrosion resistance of fabricated scaffold, alloying and coating were carried out. Preliminary degradation study as well as cytocompatibility studies using L929 cells was carried out to validate the potential of fabricated scaffold for bone healing/repair applications. Fabricated porous structures showed improved corrosion resistance as well as cell viability of more than 90%, suggesting it as a promising development for bone scaffolding applications in future.

Development of hybrid scaffold with biomimetic 3D architecture for bone regeneration.

In the present study, a biomimetic three-dimensional hybrid scaffold has been designed considering the bone natural architecture with favorable interconnected porous structure, nano-microscale features and mechanical strength. The chief components of the hybrid scaffold are core-sheath nanofibers and hydrogel, suitably arranged to create a bone like microenvironment. Specifically, the core-sheath nanofibers were coiled tightly into a ring to mimic the osteon, and reinforced in a hydrogel matrix. Morphological analysis using SEM and 4D-X-ray microscopy revealed that the hybrid scaffold consists of coiled rings of nanofibers in highly porous hydrogel matrix showing structural similarity to osteons. The reinforcement of electrospun nanofibers in hydrogel influenced the mechanical properties of scaffold. The potential application of the biomimetic hybrid scaffold, and the role of its specific architecture, was subsequently investigated in vitro using a human osteosarcoma fibroblast cell line. Furthermore, DNA quantification, alkaline-phosphatase and alizarin assay validated the potential of fabricated scaffold for bone tissue-regeneration.

Synergistic effects of Woodfordia fruticosa gold nanoparticles in preventing microbial adhesion and accelerating wound healing in Wistar albino rats in vivo.

Therapeutic effectiveness of biogenically synthesized Woodfordia fruticosa nano-gold particles (WfAuNPs) has been claimed in this study which prevents microbial adhesion and enhanced wound healing potential on Wistar albino rats. The synthesized WfAuNPs were characterized using several biophysical techniques such as UV-Visible Spectroscopy (UV-vis), X-Ray Diffraction (XRD), Dynamic Light Scattering (DLS), Zeta Potential, Fourier Transform Infrared Spectroscopy (FTIR), Field Emission Scanning Electron Microscopy (FE-SEM), Atomic Force Microscopy (AFM) and High Resolution Transmission Electron Microscopy (HR-TEM) analysis. The synthesized WfAuNPs in the size range of 10-20nm were used to develop 1% Carbopol® 934 based nano gold formulation (WfAuNPs-Carbopol® 934). The WfAuNPs-Carbopol® 934 nanoformulation was evaluated using viscosity and spreadability measurements. The wound healing potential of WfAuNPs-Carbopol® 934 monitored up to 12days was confirmed by performing wound contraction (%), epithelialization, and histopathological studies done in vivo on Wistar albino rats. The hydroxyproline content was also measured in the re-epithelized skin for quantification of collagen content. The effects of WfAuNPs on microbial adhesion leading to biofilm formation were evaluated against Candida albicans and Cryptococcus neoformans fungal strains. The respective Minimum Inhibitory Concentration (MIC80), Biofilm Inhibitory Concentration (BIC80) and Biofilm Eradication Concentration (BEC80) values of C. albicans was found to be 16, 32, 256µg/ml respectively while for C. neoformans it was recorded to be 32, 64, 256µg/ml respectively. Data obtained, confirmed the effectiveness in preventing microbial adhesion and wound healing potential of the WfAuNPs as compared to current marketed formulations.

Novel biogenic synthesis of silver nanoparticles and their therapeutic potential.

Here, we explored the medicinal uses of the novel biogenic silver nanoparticles of Pterospermum acerifolium (PaAgNPs) as a cost effective, eco-friendly, reducing and stabilizing compounds. The formation of PaAgNPs was confirmed by changing its color from colorless to yellowish brown, with maximum absorbance at 417 nm. FTIR spectrum of PaAgNPs suggested the presence of polycyclic compound similar to betulinic acid which plays as a capping agent and provided stability to PaAgNPs. FESEM and HRTEM images depicted the spherical shape of synthesized biogenic silver nanoparticles with an average particle size range of 10-20 nm. The EDX spectrum of the solution confirmed the presence of elemental silver signals. The crystalline nature of PaAgNPs was identified by XRD technique and its stability was recorded using Zeta potential analyzer. The antioxidant potential was assayed using diphenyl-beta-picrylhydrazyl (DPPH). Maximum free radical scavenging action of PaAgNPs was 69.52% as compared to 63.53% for PALE. Using a model of carrageenan-induced paw edema in rats, PaAgNPs showed two-fold enhanced anti-inflammatory activity in vivo.

Ofloxacin loaded gellan/PVA nanofibers - Synthesis, characterization and evaluation of their gastroretentive/mucoadhesive drug delivery potential.

The purpose of this investigation is to formulate a gastroretentive sustained drug release system for ofloxacin to improve its retention time, pharmacological activity, bioavailability and therapeutic efficacy in the stomach. Ofloxacin loaded gellan/poly vinyl alcohol (PVA) nanofibers were fabricated using a simple and versatile electrospinning technique. The fabricated nanofibers were evaluated for percent drug encapsulation efficiency and in vitro drug release in simulated gastric medium (pH1.2). The in vitro release profile and kinetic studies for drug indicated the sustained release of ofloxacin from the nanofibers through Fickian diffusion kinetics. The antimicrobial activity of the ofloxacin loaded nanofibers was assessed in comparison to the pure ofloxacin by means of minimal inhibitory concentrations (MIC) against microbial strains of Enterococcus faecalis, Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa. The optimized ofloxacin loaded gellan/PVA nanofibers displayed biphasic drug release profile with considerable mucoadhesion and gastric retention in the rat's gastric mucosal membrane. Data obtained, suggested that the developed gastroretentive drug delivery can potentially enhance the pharmacological activity of ofloxacin and can also serve as a viable alternative for improving drug bioavailability via oral route.

Kinetics of Synthesis of Gold Nanoparticles by Acinetobacter sp. SW30 Isolated from Environment.

Cell biomass and metal salt concentration have great influence on morphology of biosynthesized nanoparticle. The aim of present study was to evaluate the effect of varying cell density and gold salt concentrations on synthesis of nanoparticles and its morphology, which has not been studied in bacteria till now. When cells of Acinetobacter sp. SW30 were incubated with different cell density and gold chloride concentrations, tremendous variation in color of colloidal solution containing gold nanoparticles (AuNP) was observed indicating variation in their size and shapes. Surprisingly, monodispersed spherical AuNP of size ~19 nm were observed at lowest cell density and HAuCl4 salt concentration while increase in cell number resulted in formation of polyhedral AuNP (~39 nm). Significance of this study lays in the fact that the shape and dispersity of AuNP can be customized depending up on the requirement. FTIR spectrum revealed shift from 3221 to 3196 cm-1 indicating the presence and role of amino acids in Au3+ reduction while possible involvement of amide I and II groups in stabilization of AuNP. The rate constant was calculated for cell suspension of 2.1 × 109 cfu/ml challenged with 1.0 mM HAuCl4, incubated at 30 °C and pH 7 using the slopes of initial part of the plot log (Aα - At) versus time as 1.99 × 10-8 M. Also, this is the first study to report the kinetics of gold nanoparticle synthesis by Acinetobacter sp. SW30.

Synthesis and characterization of crosslinked gellan/PVA nanofibers for tissue engineering application.

Electrospun nanofibers based on gellan are considered as promising biomaterial for tissue engineering and wound healing applications. However, major hurdles in usage of these nanofibers are their poor stability and deprived structural consistency in aqueous medium which is a prerequisite for their application in the biomedical sector. In this investigation, three dimensional nanofibers, consisting of gellan and PVA have been fabricated and then stabilized under various crosslinking conditions in order to improve their physiochemical stability. The impacts of different crosslinking procedures on the gellan/PVA nanofibers were examined in terms of changes in morphological, mechanical, swelling and biological properties. Superior tensile strength and strain was recorded in case of crosslinked nanofibers as compared to non-crosslinked nanofibers. Contact angles and swelling properties of fabricated gellan/PVA nanofibers were found to vary with the crosslinking method. All crosslinking conditions were evaluated with regard to their response towards human dermal fibroblast (3T3L1) cells. Biocompatibility studies suggested that the fabricated crosslinked gellan/PVA nanofibers hold a great prospective in the biomedical engineering arena.

Drug functionalized microbial polysaccharide based nanofibers as transdermal substitute.

In order to promote the natural healing process, drug-functionalized nanofibrous transdermal substitute was fabricated using gellan as chief polymer and polyvinyl alcohol (PVA) as supporting polymer via electrospinning technique. These fabricated nanofibers physiochemically mimic the extracellular matrix (ECM) which supports the cell growth. For neo-tissue regeneration in a sterilized environment, amoxicillin (Amx) was entrapped within these nanofibers. Entrapment of Amx in the nanofibers was confirmed by FESEM, FTIR, XRD and TG analysis. In vitro cell culture studies revealed that the fabricated non-cytotoxic nanofibers promoted enhance cell adherence and proliferation of human keratinocytes. A preliminary in vivo study performed on rat model for full thickness skin excision wound demonstrated the prompt re-epithelialization in early phase and quicker collagen deposition in later phases of wound healing in case of Amx-functionalized gellan/PVA nanofibers. Data collectively confirmed the potential usage of gellan based electrospun nanofibers as transdermal substitute for faster skin restoration.

A novel gellan-PVA nanofibrous scaffold for skin tissue regeneration: Fabrication and characterization.

In this investigation, we have introduced novel electrospun gellan based nanofibers as a hydrophilic scaffolding material for skin tissue regeneration. These nanofibers were fabricated using a blend mixture of gellan with polyvinyl alcohol (PVA). PVA reduced the repulsive force of resulting solution and lead to formation of uniform fibers with improved nanostructure. Field emission scanning electron microscopy (FESEM) confirmed the average diameter of nanofibers down to 50 nm. The infrared spectra (IR), differential scanning calorimetry (DSC) and X-ray diffraction (XRD) analysis evaluated the crosslinking, thermal stability and highly crystalline nature of gellan-PVA nanofibers, respectively. Furthermore, the cell culture studies using human dermal fibroblast (3T3L1) cells established that these gellan based nanofibrous scaffold could induce improved cell adhesion and enhanced cell growth than conventionally proposed gellan based hydrogels and dry films. Importantly, the nanofibrous scaffold are biodegradable and could be potentially used as a temporary substrate/or biomedical graft to induce skin tissue regeneration.

Antiproliferative activity of ferulic acid-encapsulated electrospun PLGA/PEO nanofibers against MCF-7 human breast carcinoma cells.

Ferulic acid (FA) is a polyphenolic phytonutrient which possesses strong antiproliferative effect; however, it has limited therapeutic applications due to its physiochemical instability and low bioavailability at the tumor site. In present study, these shortcomings associated with FA were overcome by fabricating FA-encapsulated poly(D,L-lactide-co-glycolide)/polyethylene oxide (PLGA/PEO) blend nanofibers using electrospinning technique. FESEM and fluorescence microscopic analysis imitates the smooth morphology and even distribution of FA within the polymeric nanofibers at optimum 2 wt% concentration of FA. The average diameters were recorded to be 150 ± 47.4 and 200 ± 79 nm for PLGA/PEO and FA-encapsulated PLGA/PEO nanofibers, respectively. The encapsulation, compatibility, and physical state of FA within the nanofibers were further confirmed by FTIR, TGA and XRD analysis. In vitro drug delivery studies demonstrated initial burst liberation of FA within 24 h followed by a sustained release for the subsequent time. MTT assay revealed the effectiveness of FA-encapsulated nanofibers against human breast carcinoma cells (MCF-7) cells as compared to control. FESEM and fluorescence microscopic analysis further confirmed the apoptotic effect of FA-encapsulated PLGA/PEO nanofibers against MCF-7. These fabricated nanofibers hold enormous potential to be used as a therapeutic agent for various biomedical applications.

Biomedical applications of ferulic acid encapsulated electrospun nanofibers.

Ferulic acid is a ubiquitous phytochemical that holds enormous therapeutic potential but has not gained much consideration in biomedical sector due to its less bioavailability, poor aqueous solubility and physiochemical instability. In present investigation, the shortcomings associated with agro-waste derived ferulic acid were addressed by encapsulating it in electrospun nanofibrous matrix of poly (d,l-lactide-co-glycolide)/polyethylene oxide. Fluorescent microscopic analysis revealed that ferulic acid predominantly resides in the core of PLGA/PEO nanofibers. The average diameters of the PLGA/PEO and ferulic acid encapsulated PLGA/PEO nanofibers were recorded as 125 ± 65.5 nm and 150 ± 79.0 nm, respectively. The physiochemical properties of fabricated nanofibers are elucidated by IR, DSC and NMR studies. Free radical scavenging activity of fabricated nanofibers were estimated using di(phenyl)-(2,4,6-trinitrophenyl)iminoazanium (DPPH) assay. 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay confirmed the cytotoxicity of ferulic acid encapsulated nanofibers against hepatocellular carcinoma (HepG2) cells. These ferulic acid encapsulated nanofibers could be potentially explored for therapeutic usage in biomedical sector.