Sustained release of amoxicillin from hydroxyapatite nanocomposite for bone infections

Vanadium and strontium co-doped hydroxyapatite enriched polycaprolactone matrices for effective bone tissue engineering: A synergistic approach

Scientific research targeted at enhancing scaffold qualities has increased significantly during the last few decades. This emphasis frequently centres on adding different functions to scaffolds in order to increase their usefulness as instruments in the field of regenerative medicine. This study aims to investigate the efficacy of a multifunctional sustainable polymer scaffold, specifically Polycaprolactone (PCL) embedded with hydroxyapatite co-doped with vanadium and strontium (HVS), for bone tissue engineering applications. Polycaprolactone was used to fabricate the scaffold, while hydroxyapatite co-doped with vanadium and strontium (HVS) served as the nanofiller. A thorough investigation of the physicochemical and biological characteristics of the HVS nanofiller was carried out using cutting-edge techniques including Dynamic Light Scattering (DLS), and X-ray Photoelectron Spectroscopy (XPS) and in vitro cell studies. A cell viability rate of more than 70 % demonstrated that the synthesised nanofiller was cytotoxic, but in an acceptable range. The mechanical, biological, and physicochemical properties of the scaffold were extensively evaluated after the nanofiller was integrated. The water absorption characteristics of scaffold were enhanced by the addition of HVS nanofillers, leading to increased swelling, porosity, and hydrophilicity. These improvements speed up the flow of nutrients and the infiltration of cells into the scaffold. The scaffold has been shown to have important properties that stimulate bone cell activity, including better biodegradability and improved mechanical strength, which increased from 5.30 ± 0.37 to 10.58 ± 0.42 MPa. Further, its considerable antimicrobial qualities, blood-compatible nature, and capacity to promote biomineralization strengthen its appropriateness for usage in biomedical applications. Mainly, enhanced Alkaline phosphatase (ALP) activity, Alizarin Red Staining (ARS) activity, and excellent cell adhesive properties, indicating the outstanding osteogenic potential observed in rat bone marrow-derived stromal cells (rBMSC). These combined attributes highlight the pivotal role of these nanocomposite scaffolds in the field of bone tissue engineering.

Synthesis and evaluation of nanosystem containing chondroitinase ABCI based on hydroxyapatite

The bacterial enzyme chondroitinase ABCI (chABCI), which has been isolated from Proteus Vulgaris, is crucial in the treatment of spinal cord injuries. However, due to its short lifespan, the maintenance and clinical application of this enzyme are very constrained. In this study, the immobilization of this enzyme on hydroxyapatite has been carried out and assessed with the aim of enhancing the characteristics and efficiency of chABCI. Hydroxyapatite particles (HAPs) are a potential candidate for drug-delivery carriers because of their excellent biocompatibility, shape controllability, and high adsorption. The use of the nanometer scale allows efficient access to the enzyme's substrate. It demonstrates important biological application capabilities in this way. Field emission gun-scanning electron microscopy (FEG-SEM), X-ray diffraction (XRD), infrared spectroscopy (FT-IR), in vitro release study, and cytotoxicity test were used to characterize the drug nanosystem's properties. According to the findings, electrostatic bindings was formed between charged groups of the enzyme and hydroxyapatite nanoparticles. The results also demonstrated that immobilized chABCI on hydroxyapatite has beneficial properties, such as more manageable drug release, minimal toxicity and side effects, and a high potential to enhance the efficacy of drug delivery and decrease the need for repeated injections.

Synthesis and characterization of pH-responsive conducting polymer/Na-alginate/gelatin based composite hydrogels for sustained release of amoxicillin drug

Composite hydrogels of Na-Alginate (Na-ALG) and Gelatin (GEL) with conducting polymers (CPs) were synthesised using poly(o-phenylenediamine) (POPD), polyaniline (PANI), poly(1-naphthylamine (PNA) and poly(vinylenedine fluoride) (PVDF). The synthesised hydrogels were characterized using FTIR, scanning electron microscopy (SEM) rheology, swelling ability and in-vitro drug release characteristics. The purpose of this investigation was to determine whether these hydrogels could be used to deliver antibiotics for extended drug release. The composite hydrogels were loaded with antibiotic drug: amoxicillin in three different concentrations and the release was studied at intestinal fluid (pH 7.4) and gastric fluid (pH 1.2). Release kinetics was found to show best fit in zero order models at both pH values and showed prolonged release characteristics. The POPD-Na-ALG/GEL showed highest release at intestinal pH of 7.4, while PVDF-Na-ALG/GEL showed highest release at gastric pH at 1.2.

Sodium alginate/Hydroxyapatite/nanocellulose composites: Synthesis and Potentials for bone tissue engineering

Sodium alginate/hydroxyapatite/Nano cellulose (SA/HA/NC) nanocomposite films that possess good biocompatibility for bone tissue engineering are prepared by a simple solution casting. HA is one of the most frequently used bioceramic materials to achieve a high biocompatibility. The bionanocomposite films are analysed by XRD, SEM, EDAX and FTIR studies. XRD confirms the existence of fillers in the polymer. FTIR spectrum shows the different functional modes in the bionanocomposite films. The morphology of fillers and bionanocomposite films are obtained through SEM. The inclusion of NC with different concentrations into the biopolymer film improves the tensile strength. As a result, the loading of 5 wt % of NC and 10 wt% of HA in the SA polymer shows high tensile strength when compared to the pure SA, SA filled with 10 wt% of HA and SA loaded with 10 wt% of HA and inclusion of NC (0.5 and 2.5 wt%). The tensile strength (TS) of bionanocomposite film with 10 wt % of HA is increased by 17%. TS of bionanocomposite film with 0.5 and 2.5 wt% of NC is increased by 177 and 277%, whereas TS of bionanocomposite film loaded 5 wt% of NC is increased by 331%. The swelling, biodegradation and biomineralization tests suggest that this bionanocomposite films are hopeful biomaterials for bone tissue engineering.

Nano-ciprofloxacin/meropenem exhibit bactericidal activity against Gram-negative bacteria and rescue septic rat model

Aim: We hypothesized that simultaneous administration of two antibiotics loaded into a nanopolymer matrix would augment their synergistic bactericidal interaction. Methods: Nanoplatforms of chitosan/Pluronic® loaded with ciprofloxacin/meropenem (CS/Plu-Cip/Mer) were prepared by the ionic gelation method, using Plu at concentrations in the range 0.5-4% w/v. CS/Plu-Cip/Mer was evaluated for antibacterial synergistic activity in vitro and in vivo. Results: CS/Plu-Cip and CS/Plu-Mer with Plu concentrations of 3% w/v and 2% w/v, respectively, exhibited ∼80% encapsulation efficiency. The MICs of pathogens were fourfold to 16-fold lower for CS/Plu-Cip/Mer than for Cip/Mer. Synergy was evidenced for CS/Plu-Cip/Mer with a bactericidal effect (at 1× MIC and sub-MICs), and it significantly decreased bacterial load and rescued infected rats. Conclusion: This study illustrates the ability of CS/Plu nanopolymer to intensify synergy between antibiotics, thereby providing a promising potential to rejuvenate antibiotics considered ineffective against resistant pathogens.

Biodegradable Microneedles Array with Dual-Release Behavior and Parameter Optimization by Finite Element Analysis

Microneedles (MNs) are particularly attractive for transdermal administration because of the improved safety, patient compliance and convenience. Dissolving MNs could provide rapid transdermal delivery, but with relatively low mechanical strength and almost no sustainability. On the other hand, hydrogel MNs are complicated to fabricate and have risk concerns. Herein, we developed a biodegradable MNs array composed of biocompatible silk fibroin and poly(vinyl alcohol) to overcome these limitations. Finite element analysis was employed for parameter optimization. The MNs array fabricated by the optimal parameters and material displayed sufficient mechanical strength to disrupt stratum corneum and formed microchannels for transdermal delivery. Dual-release profile was observed in the MNs array, with rapid release in the beginning, and prolonged release afterward. This release behavior fits Weibull release model and is favorable for topical application. The initial immediate release can quickly deliver active compounds to reach the therapeutic effective concentration and facilitate skin penetration, and the sustained release may supply the skin with active compounds over a prolonged period. This biodegradable MNs array is easy to fabricate, mechanically robust, could eliminate safety concerns, and provide the sustainability and advantage for large-scale production.

Efficacy and Safety of Antibiotic Impregnated Microporous Nanohydroxyapatite Beads for Chronic Osteomyelitis Treatment: A Multicenter, Open-Label, Prospective Cohort Study

Chronic osteomyelitis is still a serious health problem that causes disabling conditions and has an impact on the quality of life. The objective of this study was to determine the clinical efficacy and safety of localized antibiotics delivery via impregnated microporous nanohydroxyapatite (nHA-ATB) beads for chronic osteomyelitis treatment. A total of 62 patients were enrolled in this study. After radical surgical debridement, the bone defect was filled with three types of antibiotics (vancomycin or gentamicin or fosfomycin) impregnated HA beads. The follow-up period was 48 weeks. It was found that the success rate was approximately 98% with a re-infection in only one patient. Quality of life of all patients after treatment improved significantly over time. Systemic exposure to vancomycin and gentamicin after beads implantation was limited and high local antibiotics concentrations were found in wound drainage fluid at 24, 48 and 72 h. Blood biochemistry measurements did not show any nephrotoxic or hepatotoxic effects. 20 adverse events were reported, but 90% of the events were resolved without having to remove the beads and the patients recovered. Satisfactory outcomes were observed in terms of success rate, quality of life and adverse effect. nHA-ATB beads impregnated by vancomycin or gentamicin or fosfomycin could potentially be employed as an alternative product of choice for localized antibiotics delivery in chronic osteomyelitis treatment.

Hydroxyapatite-based carriers for tumor targeting therapy

At present, targeted drug delivery is regarded as the most effective means of tumor treatment, overcoming the lack of conventional chemotherapeutics that are difficult to reach or enter into cancer cells. Hydroxyapatite (HAP) is the main component of biological hard tissue, which can be regarded as a suitable drug carrier due to its biocompatibility, nontoxicity, biodegradation, and absorbability. This review focuses on the cutting edge of HAP as a drug carrier in targeted drug delivery systems. HAP-based carriers can be obtained by doping, modification, and combination, which benefit to improve the loading efficiency of drugs and the response sensitivity of the microenvironment in the synthesis process. The drug adsorbed or in situ loaded on HAP-based carriers can achieve targeted drug delivery and precise treatment through the guidance of the in vivo microenvironment and the stimulation of the in vitro response. In addition, HAP-based drug carriers can improve the cellular uptake rate of drugs to achieve a higher treatment effect. These advantages revealed the promising potential of HAP-based carriers from the perspective of targeted drug delivery for tumor treatment.

Fabrication of Electrospun PLA-nHAp Nanocomposite for Sustained Drug Release in Dental and Orthopedic Applications

This study describes the fabrication of nanocomposites using electrospinning technique from poly lactic acid (PLA) and nano-hydroxyapatite (n-HAp). The prepared electrospun PLA-nHAP nanocomposite is intended to be used for drug delivery application. A hydrogen bond in between nHAp and PLA was confirmed by Fourier transform infrared (FT-IR) spectroscopy. Degradation study of the prepared electrospun PLA-nHAp nanocomposite was conducted for 30 days both in phosphate buffer solution (PBS) of pH 7.4 and deionized water. The degradation of the nanocomposite occurred faster in PBS in comparison to water. Cytotoxicity analysis was conducted on both Vero cells and BHK-21 cells and the survival percentage of both cells was found to be more than 95%, which indicates that the prepared nanocomposite is non-toxic and biocompatible. Gentamicin was loaded in the nanocomposite via an encapsulation process and the in vitro drug delivery process was investigated in phosphate buffer solution at different pHs. An initial burst release of the drug was observed from the nanocomposite after 1 to 2 weeks for all pH media. After that, a sustained drug release behavior was observed for the nanocomposite for 8 weeks with a release of 80%, 70% and 50% at pHs 5.5, 6.0 and 7.4, respectively. It can be suggested that the electrospun PLA-nHAp nanocomposite can be used as a potential antibacterial drug carrier for sustained drug release in dental and orthopedic sector.

Temperature-Responsive Hydrogel for Silver Sulfadiazine Drug Delivery: Optimized Design and In Vitro/In Vivo Evaluation

Response surface methodology (RSM) was applied to optimise a temperature-responsive hydrogel formulation synthesised via the direct incorporation of biocellulose, which was extracted from oil palm empty fruit bunches (OPEFB) using the PF127 method. The optimised temperature-responsive hydrogel formulation was found to contain 3.000 w/v% biocellulose percentage and 19.047 w/v% PF127 percentage. The optimised temperature-responsive hydrogel provided excellent LCST near to the human body surface temperature, with high mechanical strength, drug release duration, and inhibition zone diameter against Staphylococcus aureus. Moreover, in vitro cytotoxicity testing against human epidermal keratinocyte (HaCaT) cells was conducted to evaluate the toxicity of the optimised formula. It was found that silver sulfadiazine (SSD)-loaded temperature-responsive hydrogel can be used as a safe replacement for the commercial SSD cream with no toxic effect on HaCaT cells. Last, but not least, in vivo (animal) dermal testing-both dermal sensitization and animal irritation-were conducted to evaluate the safety and biocompatibility of the optimised formula. No sensitization effects were detected on the skin applied with SSD-loaded temperature-responsive hydrogel indicating no irritant response for topical application. Therefore, the temperature-responsive hydrogel produced from OPEFB is ready for the next stage of commercialisation.

A Novel Hydroxyapatite/Vitamin B12 Nanoformula for Treatment of Bone Damage: Preparation, Characterization, and Anti-Arthritic, Anti-Inflammatory, and Antioxidant Activities in Chemically Induced Arthritic Rats

The usage of nanomaterials for rheumatoid arthritis (RA) treatment can improve bioavailability and enable selective targeting. The current study prepares and evaluates the in vivo biological effects of a novel hydroxyapatite/vitamin B₁₂ nanoformula in Complete Freund's adjuvant-induced arthritis in rats. The synthesized nanoformula was characterized using XRD, FTIR, BET analysis, HERTEM, SEM, particle size, and zeta potential. We synthesized pure HAP NPs with 71.01% loading weight percentages of Vit B12 and 49 mg/g loading capacity. Loading of vitamin B₁₂ on hydroxyapatite was modeled by Monte Carlo simulation. Anti-arthritic, anti-inflammatory, and antioxidant effects of the prepared nanoformula were assessed. Treated arthritic rats showed lower levels of RF and CRP, IL-1β, TNF-α, IL-17, and ADAMTS-5, but higher IL-4 and TIMP-3 levels. In addition, the prepared nanoformula increased GSH content and GST antioxidant activity while decreasing LPO levels. Furthermore, it reduced the expression of TGF-β mRNA. Histopathological examinations revealed an improvement in joint injuries through the reduction of inflammatory cell infiltration, cartilage deterioration, and bone damage caused by Complete Freund's adjuvant. These findings indicate that the anti-arthritic, antioxidant, and anti-inflammatory properties of the prepared nanoformula could be useful for the development of new anti-arthritic treatments.

The Application of Hydroxyapatite NPs for Adsorption Antibiotic from Aqueous Solutions: Kinetic, Thermodynamic, and Isotherm Studies

Antibiotic pollution has become a serious concern due to the extensive use of antibiotics, their resistance to removal, and their detrimental effects on aquatic habitats and humans. Hence, developing an efficient antibiotic removal process for aqueous solutions has become vital. Amoxicillin (Amox) is one of the antibiotics that has been efficiently removed from an aqueous solution using hydroxyapatite nanoparticles (HAP NPs). The current study synthesizes and utilizes hydroxyapatite nanoparticles as a cost-effective adsorbent. Adsorbent dose, pH solution, initial Amox concentration, equilibrium time, and temperature are among the factors that have an evident impact on Amox antibiotic adsorption. The (200) mg dose, pH (5), temperature (25) °C, and time (120) min are shown to be the best-optimized values. The nonlinear Langmuir’s isotherm and pseudo-second-order kinetic models with equilibrium capacities of 4.01 mg/g are highly compatible with the experimental adsorption data. The experimental parameters of the thermodynamic analysis show that the Amox antibiotic adsorption onto HAP NPs powder is spontaneous and exothermic.

Biodegradable manganese-doped hydroxyapatite antitumor adjuvant as a promising photo-therapeutic for cancer treatment

The efficiency of a cancer therapy agent depends on its ability to eliminate tumors without endangering neighboring healthy tissues. In this present study, a novel multifunctional property enriched nanostructured system was synthesized on manganese-doped hydroxyapatite (Mn-HAp) conjugated with counter folic acid (FA) IR-783 fluorescence dye. The tailored synthesis of nano rod-shaped Mn-HAp nanoparticles with high surface area allows to conjugate FA/IR-783 dye which enhanced retention time during in vivo circulation. The drug-free Photothermal Photodynamic therapy mediated cancer treatment permits the prevention of collateral damages to non-cancerous cells. The safe HAp biomaterial matrix allows a large number of molecules on its surface due to its active different charge moieties (Ca²⁺/PO₄ ^3-) without any recurrence toxicity. The doped Mn allows releasing of Mn²⁺ ions which triggered the production of toxic hydroxyl radicals (•OH) via Fenton or Fenton-like reactions to decompose H₂O₂ in the tumor sites. Herein, IR-783 and FA were selected for targeted fluorescence imaging-guided photothermal therapy. 6The PTT performance of synthesized nanostructured system shows enhanced potential with ∼60°C temperature elevation with 0.75 W∙cm^-2 power irradiated within 7 min of treatment. PDT activity was also observed initially with Methylene Blue (MB) as a targeted material which shows a drastic degradation of MB and further in vitro studies with MDA-MB-231 breast cancer cell line show cytotoxicity due to the generated reactive oxygen species (ROS) effect. FA/IR-783 conjugated Mn-HAp nanoparticles (2.0 mol% Mn-HAp/FA-IR-783) show significant tumor-specific targeting and treatment efficiency while intravenously injected in (tail vain) BALB/c nude mice model without any recurrence. The synthesized nanostructured system had ample scope to be a promising Photo-Therapeutic agent for cancer treatment.

Synthesis and Characterization of Antibiotic–Loaded Biodegradable Citrate Functionalized Mesoporous Hydroxyapatite Nanocarriers as an Alternative Treatment for Bone Infections

The continuing growth of bacterial resistance makes the top challenge for the healthcare system especially in bone-infections treatment. Current estimates reveal that in 2050 the death ratio caused by bacterial infections can be higher than cancer. The aim of this study is to provide an alternative to currently available bone-infection treatments. Here we designed mesoporous hydroxyapatite nanocarriers functionalized with citrate (Ctr–mpHANCs). Amoxicillin (AMX) is used as a model drug to load in Ctr–mpHANCs, and the drug loading was more than 90% due to the porous nature of nanocarriers. Scanning electron microscopy shows the roughly spherical morphology of nanocarriers, and the DLS study showed the approximate size of 92 nm. The Brunauer–Emmett–Teller (BET) specific surface area and pore diameter was found to be about 182.35 m²/g and 4.2 nm, respectively. We noticed that almost 100% of the drug is released from the AMX loaded Ctr–mpHANCs (AMX@Ctr–mpHANCs) in a pH-dependent manner within 3 d and 5 d at pH 2.0 and 4.5, respectively. The sustained drug release behaviour was observed for 15 d at pH 7.4 and no RBCs hemolysis by AMX@Ctr–mpHANCs. The broth dilution and colony forming unit (CFU) assays were used to determine the antimicrobial potential of AMX@Ctr–mpHANCs. It was observed in both studies that AMX@Ctr–mpHANCs showed a significant reduction in the bacterial growth of S. aureus, E. coli, and P. aeruginosa as compared to Ctr–mpHANCs with no bacteria-killing. Thus, we proposed that Ctr–mpHANCs can be used as a drug carrier and a treatment option for bone infections caused by bacteria.

Advances of Hydroxyapatite Hybrid Organic Composite Used as Drug or Protein Carriers for Biomedical Applications: A Review

Hydroxyapatite (HA), especially in the form of HA nanoparticles (HANPs), has excellent bioactivity, biodegradability, and osteoconductivity and therefore has been widely used as a template or additives for drug delivery in clinical applications, such as dentistry and orthopedic repair. Due to the atomically anisotropic distribution on the preferred growth of HA crystals, especially the nanoscale rod-/whisker-like morphology, HA can generally be a good candidate for carrying a variety of substances. HA is biocompatible and suitable for medical applications, but most drugs carried by HANPs have an initial burst release. In the adsorption mechanism of HA as a carrier, specific surface area, pore size, and porosity are important factors that mainly affect the adsorption and release amounts. At present, many studies have developed HA as a drug carrier with targeted effect, porous structure, and high porosity. This review mainly discusses the influence of HA structures as a carrier on the adsorption and release of active molecules. It then focuses on the benefits and effects of different types of polymer-HA composites to re-examine the proteins/drugs carry and release behavior and related potential clinical applications. This literature survey can be divided into three main parts: 1. interaction and adsorption mechanism of HA and drugs; 2. advantages and application fields of HA/organic composites; 3. loading and drug release behavior of multifunctional HA composites in different environments. This work also presents the latest development and future prospects of HA as a drug carrier.

Improvement of mechanical and antibacterial properties of porous nHA scaffolds by fluorinated graphene oxide

Nano-hydroxyapatite (nHA) is widely used as a bio-scaffold material due to its good bioactivity and biocompatibility. In this study, fluorinated graphene oxide (FG) was added to nHA to improve its poor formability, weak mechanical properties, undesirable antimicrobial activity and other disadvantages that affect its clinical application. FG was synthesized by a simple hydrothermal method. Novel porous composite scaffolds were prepared by adding different weight ratios (0.1 wt%, 0.5 wt% and 1 wt%) of FG to nHA using the 3D printing technique. The morphology, phase composition and mechanical properties of the composite scaffolds were characterized. In addition, the degradation performance of the composite scaffolds, antibacterial activity against Staphylococcus aureus and Escherichia coli, and cytocompatibility were also investigated. The results showed that the nHA/FG composite scaffold was successfully prepared with a uniform distribution of FG on the scaffold. The mechanical properties showed that the compression strength of the nHA/FG composite scaffold was significantly higher than that of the nHA scaffold (7.22 ± 1.43 MPa). The porosity of all composite scaffolds was above 70%. The addition of FG significantly improved the mechanical properties of the nHA scaffold without affecting the porosity of the scaffold. In addition, the 0.5 wt% nHA/FG scaffold exhibited satisfactory cytocompatibility and antibacterial properties. Therefore, the constructed nHA/FG composite scaffold can be considered as a novel antimicrobial bone substitute material with good application prospects.

Nano-hydroxyapatite (nHA) is widely used as a bio-scaffold material. In this study, fluorinated graphene oxide (FG) was added to nHA to improve its poor formability, weak mechanical properties and undesirable antimicrobial activity that affect its clinical application.

Effect of Hydroxyapatite Microspheres, Amoxicillin-Hydroxyapatite and Collagen-Hydroxyapatite Composites on Human Dental Pulp-Derived Mesenchymal Stem Cells

In this study, the preparation and characterization of three hydroxyapatite-based bioactive scaffolds, including hydroxyapatite microspheres (HAps), amoxicillin–hydroxyapatite composite (Amx–HAp), and collagen–hydroxyapatite composite (Col–HAp) were performed. In addition, their behavior in human dental pulp mesenchymal stem cell (hDPSC) culture was investigated. HAps were synthesized through the following methods: microwave hydrothermal, hydrothermal reactor, and precipitation, respectively. hDPSCs were obtained from samples of third molars and characterized by immunophenotypic analysis. Cells were cultured on scaffolds with osteogenic differentiation medium and maintained for 21 days. Cytotoxicity analysis and migration assay of hDPSCs were evaluated. After 21 days of induction, no differences in genes expression were observed. hDPSCs highly expressed the collagen IA and the osteonectin at the mRNA. The cytotoxicity assay using hDPSCs demonstrated that the Col–HAp group presented non-viable cells statistically lower than the control group (p = 0.03). In the migration assay, after 24 h HAps revealed the same migration behavior for hDPSCs observed compared to the positive control. Col–HAp also provided a statistically significant higher migration of hDPSCs than HAps (p = 0.02). Migration results after 48 h for HAps was intermediate from those achieved by the control groups. There was no statistical difference between the positive control and Col–HAp. Specifically, this study demonstrated that hydroxyapatite-based bioactive scaffolds, especially Col-Hap, enhanced the dynamic parameters of cell viability and cell migration capacities for hDPSCs, resulting in suitable adhesion, proliferation, and differentiation of this osteogenic lineage. These data presented are of high clinical importance and hold promise for application in therapeutic areas, because Col–HAp can be used in ridge preservation, minor bone augmentation, and periodontal regeneration. The development of novel hydroxyapatite-based bioactive scaffolds with clinical safety for bone formation from hDPSCs is an important yet challenging task both in biomaterials and cell biology.

Hydroxyapatite and Silicon-Modified Hydroxyapatite as Drug Carriers for 4-Aminopyridine

Adsorption and desorption properties of nano-hydroxyapatite (HAP) and silicon-modified hydroxyapatite (Si–HAP) were investigated with 4-aminopyridine (fampridine-4AP). The novelty of this research is the investigation of the suitability of the previously mentioned carriers for drug-delivery of 4AP. UV-VIS spectrophotometric results showed that the presence of silicon in the carrier did not significantly affect its adsorption capacity. The success of the adsorption was confirmed by thermal analysis (TG/DTA), scanning electron microscopy (SEM)/energy dispersive X-ray (EDX), Fourier transform infrared (FTIR) spectroscopy, and X-ray powder diffraction (XRPD). Drug release experiments, performed in simulated body fluid (SBF), revealed a drug release from Si–HAP that was five times slower than HAP, explained by the good chemical bonding between the silanol groups of the carrier and the 4AP functional groups. The electrochemical measurements showed a value of the polarization resistance of the charge transfer (Rct) more than five times smaller in the case of Si–HAP coating loaded with 4AP, so the charge transfer process was hindered. The electrochemical impedance results revealed that electron transfer was inhibited in the presence of 4AP, in concordance with the previously mentioned strong bonds. The silicon substitution in HAP leads to good chemical bonding with the drug and a slow release, respectively.

Fabrication of carbon and silver nanomaterials incorporated hydroxyapatite nanocomposites: Enhanced biological and mechanical performances for biomedical applications

Hydroxyapatite is widely utilized for different biomedical applications because of its outstanding biocompatibility and bioactivity. Cuttlefish bones, which are available aplenty, are both inexpensive and eco-friendly sources for calcium carbonate. In the present study, cuttlefish bones-derived HAp nanorods have been utilized to fabricate HAp nanocomposites incorporating 1, 3 and 5 wt% each of GO, MWCNTs, GONRs and Ag NPs. Characterization using such techniques as XRD, FTIR, HRSEM and EDS was performed to analyze the physicochemical properties of nanocomposites, and MTT assay, hemolysis, bioactivity and drug release to evaluate the biological properties. The XRD and HRSEM results reveal that crystallite and particle size increase with increasing wt% of carbon nanomaterials and Ag NPs. However, the addition of nanomaterials did not modify the shape of HAp. The MTT assay and hemolysis results suggest GONRs possess better biocompatibility than GO and CNTs due to their smooth edge structure. While adding carbon materials up to 3 wt% caused an increase in the hardness, adding up to 5 wt% of them caused a decrease in the hardness due to the agglomeration of the particles. Biocompatibility and Vicker's hardness studies show that adding carbon nanomaterials up to 3 wt% caused significant improvement in biocompatibility and mechanical properties. Antibacterial activity test was performed to analyze the ability to preclude the formation of biofilms. The results showed better activity for silver-incorporated nanocomposites in the presence of E. coli and S. aureus bacteria. Drug release studies were performed using lidocaine drug and the results showed nearly similar drug release profile for all the samples except HAg3. Finally, nanocomposite HRA3 could be a suitable candidate for biomedical applications since it shows better biological and mechanical properties than GO and MWCNTs nanocomposites.

Drug-Releasing Antibacterial Coating Made from Nano-Hydroxyapatite Using the Sonocoating Method

Medical implant use is associated with a risk of infection caused by bacteria on their surface. Implants with a surface that has both bone growth-promoting properties and antibacterial properties are of interest in orthopedics. In the current study, we fabricated a bioactive coating of hydroxyapatite nanoparticles on polyether ether ketone (PEEK) using the sonocoating method. The sonocoating method creates a layer by immersing the object in a suspension of nanoparticles in water and applying a high-power ultrasound. We show that the simple layer fabrication method results in a well-adhering layer with a thickness of 219 nm to 764 nm. Dropping cefuroxime sodium salt (Cef) antibiotic on the coated substrate creates a layer with a drug release effect and antibacterial activity against Staphylococcus aureus. We achieved a concentration of up to 1 mg of drug per cm² of the coated substrate. In drug release tests, an initial burst was observed within 24 h, accompanied by a linear stable release effect. The drug-loaded implants exhibited sufficient activity against S. aureus for 24 and 168 h. Thus, the simple method we present here produces a biocompatible coating that can be soaked with antibiotics for antibacterial properties and can be used for a range of medical implants.

Emerging marine derived nanohydroxyapatite and their composites for implant and biomedical applications

Implant materials must mimic natural human bones with biocompatibility, osteoconductivity and mechanical stability to successfully replace damaged or disease-affected bones. Synthetic hydroxyapatite was incorporated with bioglass to mimic natural bones for replacing conventional implant materials which has led to certain toxicity issues. Hence, hydroxyapatite (HAp) are recently gaining applicational importance as they are resembling the structure and function of natural bones. Further, nanosized HAp is under extensive research to utilize them as a potential replacement for traditional implants with several exclusive properties. However, chemical synthesis of nano-HAp exhibited toxicity towards normal and healthy cells. Recently, biogenic Hap synthesis from marine and animal sources are introduced as a next generation implant materials, due to their mineral ion and significant porous architecture mediated biocompatibility and bone bonding ability, compared to synthetic HAp. Thus, the purpose of the paper is to give a bird's eye view into the conventional approaches for fabricating nano-HAp, its limitations and the significance of using marine organisms and marine food wastes as a precursor for biogenic nano-Hap production. Moreover, in vivo and in vitro analyses of marine source derived nano-HAp and their potential biomedical applications were also discussed.

Biomimetic nanofibrous hybrid hydrogel membranes with sustained growth factor release for guided bone regeneration

A biomimetic nanofibrous membrane can immobilize growth factors or agents to obtain sustained release and prolonged effect in tissue engineering.

Mini-Tablets versus Nanoparticles for Controlling the Release of Amoxicillin: In vitro/In vivo Study

Introduction

Controlling the drug release from the dosage form at a definite rate is the main challenge for a successful oral controlled-release drug delivery system. In this study, mini-tablets (MTs) and lipid/polymer nanoparticles (LPNs) of lipid polymer and chitosan in different ratios were designed to encapsulate and control the release time of Amoxicillin (AMX).

Methods

Physical characteristics and in vitro release profiles of both MT and LPN formulations were studied. Antimicrobial activity and oral pharmacokinetics of the optimum MT and LPN formulations in comparison to market tablet were studied in rats.

Results

All designed formulations of AMX as MTs and LPNs showed accepted characteristics. MT-6 (Compritol/Chitosan 1:1) showed the greatest retardation among all prepared minitablet preparations, releasing about 79.5% of AMX over 8 h. In contrast, LPN-11 (AMX: Cr 1:3/Chitosan 1 mg/mL) had the slowest drug release, revealing the sustained release of 80.9% within 8 h. The MIC of both optimized tablet formula (MT-6) and LPNs formula (LPN-11) was around two-fold lower than the control against H. pylori. The C_max of MT-6 and LPN11 were non significantly different compared with the marketed AMX product. While the bioavailability experiment proved that the relative bioavailability of the AMX was 1.85 and 1.8 after the oral use of LPN11 and MT-6, respectively, compared to the market tablet.

Conclusion

The results verified that both controlled-release mini-tablets and lipid/polymer nanoparticles can be used for sustaining the release and hence improve the bioavailability of amoxicillin.

Inside-outside Ag nanoparticles-loaded polylactic acid electrospun fiber for long-term antibacterial and bone regeneration

Bone infections caused by bacteria during bone graft implantations can impair the ability of bone tissue repair, which is currently a clinical problem. In this study, the electrospinning technique was used to prepare a polylactic acid (PLLA)/silver (Ag) composite fiber, in which the silver nanoparticles (Ag-NPs) were uniformly distributed on the inner surface of PLLA fibers; dopamine (DA) was self-polymerized on the composite fiber surface to construct the adhesive polydopamine (PDA) film and chitosan (CS) was used to regulate Ag⁺ in situ through pulse electrochemical deposition for the construction of a stable Ag-NPs coating (CS/Ag), achieving the steady and slow release of Ag-NPs, therefore accomplishing the construction of a "inside-outside" Ag-NPs-loaded PLLA/Ag@PDA@CS/Ag composite fiber with dual functions of long-lasting antibacterial effect as well as bone regeneration promotion ability. The study results showed that the composite fiber has an excellent antibacterial effect against E. coli and S. aureus, and good osteoinductive and angiogenic properties. In summary, under the dual regulations of the strong adhesion of PDA and CS chelation, the "inside-outside" Ag-NPs-loaded composite fiber was endowed with good physiological stability, long-term antibacterial effect and bone infection inhibition ability, making it a promising bone implant material.

Local and Sustained Delivery of Rifampicin from a Bioactive Ceramic Carrier Treats Bone Infection in Rat Tibia

Next-generation treatment strategies to treat osteomyelitis with complete eradication of pathogen at the bone nidus and prevention of emergence of drug resistance is a real challenge in orthopedics. Conventional treatment strategies including long-term adherence of patients to systemic antibiotic delivery, local delivery using nondegradable vehicles, and surgical debridement are not completely effective in achieving successful results. In this study, a broad-spectrum antibiotic, rifampicin (RFP), was incorporated into a biphasic nanohydroxyapatite (nHAP)/calcium sulfate ceramic carrier (NC) system. In vivo release and distribution of rifampicin was evaluated for a period of one month by implanting NC and NC + RFP in a subcutaneous pouch in a rat model. We detected the RFP in bone and implanted NC scaffolds even after day 28 and the concentration was still higher than the minimal inhibitory concentration of RFP when it was implanted with NC in an abdominal subcutaneous pouch. Moreover, we also observed the accumulation of RFP in bone and NC when administered orally, showing strong binding between RFP and nHAP. Additionally, we generated an osteomyelitis bone infection model in the rat tibia using Staphylococcus aureus as an infective agent to evaluate the antibacterial and osteogenic efficiency of RFP containing NC as a delivery system. S. aureus mediated implant infection is a major problem in orthopedics. The results suggested that NC loaded with RFP could eradicate the pathogen completely in the bone nidus. Further, defect healing and bone formation were also evaluated by micro-CT and histological analysis demonstrating proper trabecular-type bone formation at the debridement site and complete healing of the defect when NC + RFP was implanted. Our findings provide an insight into the use of an nHAP based ceramic matrix as a carrier of rifampicin to eradicate the bone infection and simultaneously promote bone healing at the bone nidus.

Recent advances in the implant-based drug delivery in otorhinolaryngology

The surgical implant is an interdisciplinary therapeutic modality that offers unique advantages in the daily practice of otorhinolaryngology. Some well-known examples include cochlear implants, bone-anchored hearing aids, sinus stents, and tracheostomy tubes. Neuroprotective, osteogenic, anti-inflammatory, and antimicrobial effects are among their established or pursued functions. Implant-based drug delivery affords an efficient and potent approach to enhancing these therapeutic functions. Recent innovations have infiltrated all four elements of a drug-eluting implant. The purpose of this pre-clinical, biotechnology-oriented review is to discuss these developments in terms of the implant biomaterial, loaded medication, delivery pattern, and system fabrication. Cell-mediated neurotrophin release, fabrication of a hydroxyapatite-supported system, biodegradable polymer-based implants, and multiclass and multidrug delivery are some representative advancements. The ultimate goal here is to bridge the gap between biotechnology advances and clinical needs. The review is concluded with a perspective regarding the future opportunities and challenges in this popular and rapidly developing subject of research. STATEMENT OF SIGNIFICANCE: Surgical implants and local drug delivery are representative modern modalities of surgical treatment and medical treatment, respectively. Their synergy offers unique therapeutic advantages, such as minimal systemic side effects, proximity-related high efficiency, and potential absorbability. The applications of implant-based drug delivery have infiltrated otorhinolaryngology and head & neck surgery, which is well known for its related tissue diversity and surgical complexity. Examples discussed here include cochlear implants, bone-anchored hearing aids, sinus stents, and airway tubes. This timely review focuses primarily on the four fundamental components of an implant-based drug delivery system, namely implant biomaterial, loaded medication, delivery pattern, and system fabrication. A particular emphasis is placed upon the in vitro cellular and in vivo animal studies that demonstrate pre-clinical potentials.

Impact of structural features of Sr/Fe co-doped HAp on the osteoblast proliferation and osteogenic differentiation for its application as a bone substitute

The potential of external ions doped biomaterials has been extensively explored; however, the co-doped biomaterials remain typically unexplored for their biological properties for precise biomedical applications. The current study was aimed to explore the impact of structural features of Sr/Fe co-doped hydroxyapatite (HAp) bionanomaterial on osteoblastic proliferation and osteogenic differentiation for its application as a bone substitute. A 10 mol% isomorphous co-doping of strontium and iron with respect to calcium was carried into HAp in the solid solution. Raman spectroscopy verified the presence of major functional groups of apatite structure together with the carbonate peaks. The Sr/Fe co-doped HAp bionanomaterials showed slightly negative zeta potential (at neutral pH), versatile DLS particle size (140-205 nm), high BET surface area (186 m²/g), and narrow width pore size (13-19 nm). TG/DTA analysis showed low thermal stability of the Sr/Fe co-doped HAp groups. The nanoparticles showed an initial burst release of amoxicillin for 15 h followed by extended-release up to 81 h and demonstrated an excellent antibacterial activity by producing inhibition zones of 17.6 ± 0.3 mm and 19.5 mm ± 0.4 mm for Escherichia coli and Staphylococcus aureus. Live/dead cell staining and MTT assay confirmed the non-toxic nature of Sr/Fe co-doped HAp bionanomaterial towards MC3T3-E1 cells. Further, an improved ALP activity, increased calcium deposition, enhanced RUNX2 expression, and regulated OPN and OCN expression levels suggest in MC3T3-E1 cells demonstrate the maturation of osteoblasts. This study provides the unique advantages of the co-doping approach for the applications Sr/Fe co-doped HAp bionanomaterials as a bone substitute.

Rhein-PEG-nHA conjugate as a bone targeted drug delivery vehicle for enhanced cancer chemoradiotherapy

Bone-targeted therapies have been the choice of treatments for cancer metastases in bone to minimize skeletal morbidity and preserve patients' quality of life. Rhein is of particular interest due to its high bone affinity. Here we reported a novel Rhein- polyethylene glycol (PEG)-nano hydroxyapatite (nHA) conjugate to deliver doxorubicin (DOX) and Phosphorus-32 (³²P) simultaneously for enhanced cancer chemo-radiotherapy. The synthetic Rhein-PEG-nHA conjugates were sphere in shape with an average diameter of ~120 nm. Their morphology, drug release and bone affinity were confirmed in vitro. The release profiles of DOX depend on pH condition, but ³²P exhibited good stability. Rhein-PEG-nHA also showed high bone affinity in vivo, and the tumor volume decreased after the DOX@Rhein-PEG-nHA and ³²P@Rhein-PEG-nHA treatments. Most importantly, the DOX/³²P@Rhein-PEG-nHA showed the strongest inhibition on the growth of bone metastases of breast cancer. We revealed the potential of Rhein-PEG-nHA in combined chemo-radiation treatment for bone metastases of breast cancer.

Synthesis and Characterization of Sintered Sr/Fe-Modified Hydroxyapatite Bioceramics for Bone Tissue Engineering Applications

In the current study, Sr/Fe co-substituted hydroxyapatite (HAp) bioceramics were prepared by the sonication-assisted aqueous chemical precipitation method followed by sintering at 1100 °C for bone tissue regeneration applications. The sintered bioceramics were analyzed for various structural and chemical properties through X-ray diffraction, scanning electron microscopy, and Fourier transform infrared spectroscopy, which confirmed the phase purity of HAp and Sr/Fe co-substitution into its lattice. The Vickers hardness measurement, high blood compatibility (less than 5% hemolysis), and ability to support the adhesion, proliferation, and osteogenic differentiation of human mesenchymal stem cells suggest the suitability of Sr/Fe:HAp bioceramics for bone implant applications. The physicochemical analysis revealed that the developed Sr/Fe:HAp bioceramics exhibited a polyphasic nature (HAp and βTCP) with almost identical structural morphology having a particle size less than 0.8 μm. The dielectric constant (ε') and dielectric loss (ε″) were potentially affected by the incorporated foreign ions together with the polyphasic nature of the material. The Sr/Fe co-substituted samples demonstrated extended drug (5-fluorouracil and amoxicillin) release profiles at the pH of physiological medium. The multifunctional properties of the developed HAp bioceramics enabled them to be an auspicious candidate for potential biomedical applications, including targeted drug-delivery applications, heating mediator in hyperthermia, and bone tissue repair implants.

Recent developments in the use of organic-inorganic nanohybrids for drug delivery

Organic-inorganic nanohybrid (OINH) structures providing a versatile platform for drug delivery with improved characteristics are an area which has gained recent attention. Much effort has been taken to develop these structures to provide a viable treatment options for much alarming diseases such as cancer, bone destruction, neurological disorders, and so on. This review focuses on current work carried out in producing different types of hybrid drug carriers identifying their properties, fabrication techniques, and areas where they have been applied. A brief introduction on understating the requirement for blending organic-inorganic components into a nanohybrid drug carrier is followed with an elaboration given about the different types of OINHs developed currently highlighting their properties and applications. Then, different fabrication techniques are discussed given attention to surface functionalization, one-pot synthesis, wrapping, and electrospinning methods. Finally, it is concluded by briefing the challenges that are remaining to be addressed to obtain multipurpose nanohybrid drug carriers with wider applicability. This article is categorized under: Therapeutic Approaches and Drug Discovery > Emerging Technologies.

Hydroxyapatite/silver electrospun fibers for anti-infection and osteoinduction

Bone implant materials cause the most common complication of bone infections in orthopedic surgery, resulting in implant failure. Antibiotic treatment of bone infections leads to problems such as bacterial resistance and reduced osteogenic capacity. In this study, dopamine (DA) was self-polymerized on the surface of Polylactic acid (PLLA)/Hydroxyapatite (HA) nanowire composite fibers to form an adhesive polydopamine (PDA) membrane, and a stable silver-nanoparticles (Ag-NPs) coating layer was constructed on it by electrochemically driven Ag⁺ coordination and chelation through Polypyrrole (PPy) mediation, achieving steady and slow release of Ag-NPs. With optimized DA soaking time of 24 h and soaking concentration of 0.5 g·L^-1, nanoparticles were uniformly distributed on PLLA/HA/PDA/PPy/Ag composite fibers and the hydrophilicity of the composite fibers was well-behaved. Besides, the composite fibers possessed good physiological stability and 100% antibacterial rate against Escherichia coli (E. coli) as well as Staphylococcus aureus (S. aureus). In addition, the composite fibers had promoted apatite nucleation and growth on surface and good cytocompatibility with osteoblasts, indicating ability of inducing osteogenic differentiation. In summary, a multi-functional PLLA/HA/PDA/PPy/Ag composite fiber with long-term antibacterial property, bioactivity and osteoinductivity was successfully constructed by electrospinning and electrochemical deposition.