Bisphosphonate-adsorbed ceramic nanoparticles increase bone formation in an injectable carrier for bone tissue engineering

Nano-Hydroxyapatite as a Delivery System for Promoting Bone Regeneration In Vivo: A Systematic Review

Nano-hydroxyapatite (nHA) has been widely used as an orthopedic biomaterial and vehicle for drug delivery owing to its chemical and structural similarity to bone minerals. Several studies have demonstrated that nHA based biomaterials have a potential effect for bone regeneration with very minimal to no toxicity or inflammatory response. This systematic review aims to provide an appraisal of the effectiveness of nHA as a delivery system for bone regeneration and whether the conjugation of proteins, antibiotics, or other bioactive molecules to the nHA further enhances osteogenesis in vivo. Out of 282 articles obtained from the literature search, only 14 articles met the inclusion criteria for this review. These studies showed that nHA was able to induce bone regeneration in various animal models with large or critical-sized bone defects, open fracture, or methicillin-resistant Staphylococcus aureus (MRSA)-induced osteomyelitis. The conjugations of drugs or bioactive molecules such as bone-morphogenetic protein-2 (BMP-2), vancomycin, calcitriol, dexamethasone, and cisplatin were able to enhance the osteogenic property of nHA. Thus, nHA is a promising delivery system for a variety of compounds in promoting bone regeneration in vivo.

Personalized Baghdadite scaffolds: stereolithography, mechanics and in vivo testing

An ongoing challenge in the field of orthopedics is to produce a clinically relevant synthetic ceramic scaffold for the treatment of 'critical-sized' bone defects, which cannot heal without intervention. We had developed a bioactive ceramic (baghdadite, Ca₃ZrSi₂O₉) and demonstrated its outstanding bioactivity using traditional manufacturing techniques. Here, we report on the development of a versatile stereolithography printing technology that enabled fabrication of anatomically-shaped and -sized Baghdadite scaffolds. We assessed the in vivo bioactivity of these scaffolds in co-delivering of bone morphogenetic protein-2 (BMP2) and zoledronic acid (ZA) through bioresorbable coatings to induce bone formation and increase retention in a rat model of heterotopic ossification. Micro-computed tomography, histology, mechanical tests pre- and post-implantation, and mechanical modelling were used to assess bone ingrowth and its effects on the mechanics of the scaffolds. Bone ingrowth and the consequent mechanical properties of the scaffolds improved with increasing BMP2 dose. Co-delivery of ZA with BMP2 further improved this outcome. The significant bone formation within the scaffolds functionalized with 10 µg BMP2 and 2 µg ZA made them 2.3 × stiffer and 2.7 × stronger post-implantation and turned these inherently brittle scaffolds into a tough and deformable material. The effects of bone ingrowth on the mechanical properties of scaffolds were captured in a mechanical model that can be used in future clinical studies for non-destructive evaluation of scaffold's stiffness and strength as new bone forms. These results support the practical utilization of our versatile stereolithographic printing methods and BMP2/ZA functionalization to create fit-for-purpose personalized implants for clinical trials. STATEMENT OF SIGNIFICANCE: In this study, we addressed a long-standing challenge of developing a ceramic printing technology that enables fabrication of customizable anatomically-shaped and -sized bioceramic scaffolds with precise internal architectures using an inexpensive desktop printer. We also addressed another challenge related to delivery of pharmaceuticals. BMP2, currently available as a bone-inducing bioactive protein, is clinically administered in a collagen scaffold that has limited moldability and poor mechanical properties. The comparably stiffer and stronger 3D printed personalized Baghdadite scaffolds developed here can be readily functionalized with bioresorbable coatings containing BMP2 ± ZA. These innovations considerably improve on the prior art and are scalable for use in human surgery.

Dual actions of osteoclastic-inhibition and osteogenic-stimulation through strontium-releasing bioactive nanoscale cement imply biomaterial-enabled osteoporosis therapy

Repair of defective hard-tissues in osteoporotic patients faces significantly challenges with limited therapeutic options. Although biomedical cements are considered promising materials for healthy bone repair, their uses for healing osteoporotic fracture are clinically limited. Herein, strontium-releasing-nanoscale cement was introduced to provide dual therapeutic-actions (pro-osteogenesis and anti-osteoclastogenesis), eventually for the regeneration of osteoporotic bone defect. The Sr-nanocement hardened from the Sr-doped nanoscale-glass particles was shown to release multiple ions including silicate, calcium and strontium at doses therapeutically relevant over time. When the Sr-nanocement was treated to pre-osteoblastic cells, the osteogenic mRNA level (Runx2, Opn, Bsp, Ocn), alkaline phosphatase activity, calcium deposition, and target luciferase reporter were stimulated with respect to the case with Sr-free-nanocement. When treated to pre-osteoclastic cells, the Sr-nanocement substantially reduced the osteoclastogenesis, such as osteoclastic mRNA level (Casr, Nfatc1, c-fos, Acp, Ctsk, Mmp-9), tartrate-resistant acid trap activity, and bone resorption capacity. In particular, the osteoclastic inhibition resulted in part from the interactive effect of osteoblasts which were activated by the Sr-nanocement, i.e., blockage of RANKL (receptor activator of nuclear factor-κB ligand) binding by enhanced osteoprotegerin and the deactivated Nfatc1. The Sr-nanocement, administered to an ovariectomized tibia defect (osteoporotic model) in rats, exhibited profound bone regenerative potential in cortical and surrounding trabecular area, including increased bone volume and density, enhanced production of osteopromotive proteins, and more populated osteoblasts, together with reduced signs of osteoclastic bone resorption. These results demonstrate that Sr-nanocement, with its dual effects of osteoclastic inhibition and osteogenic-stimulation, can be considered an effective nanotherapeutic implantable biomaterial platform for the treatment of osteoporotic bone defects.

Comparison of the Effect of Oral Versus Intravenous Bisphosphonate Administration on Osteoclastogenesis in Advanced-Stage Medication-Related Osteonecrosis of the Jaw Patients

It is yet unknown whether the intravenous administration route alone can fully account for the exacerbation of medication-related osteonecrosis of the jaw (MRONJ). The purpose of this retrospective study was to identify the potential role of the bisphosphonate (BP) administration route as an independent prognostic factor for non-cancerous, stage III MRONJ patients. Bone samples were retrospectively obtained from two groups of osteoporosis patients who underwent surgery for the treatment of stage III MRONJ. Among the subjects, 10 had a history of only oral BP consumption and 10 of intravenous (IV) BP administration. The samples were assessed for osteoclast morphology and immunohistochemical expression of the receptor activator of NF-κB ligand (RANKL), osteoprotegerin (OPG), and potassium calcium-activated channel subfamily N member 4 (Kcnn4). Although the osteoclasts derived from both groups exhibited no significant differences in the mean quantity, diameter, and nuclearity, significantly attenuated tartrate-resistant acid phosphatase activity was noted among the IV BP-induced MRONJ bones compared to those of the oral BP group. Significant suppression of the RANKL/OPG ratio and Kcnn4 expression among the retrieved bones of IV BP group patients was also noted. Our results indicate the potential of the BP administration route as an independent prognostic factor for advanced-stage MRONJ, regardless of the dosage or indication for which the BP was prescribed.

Long-lasting in situ forming Implant loaded with Bupivacaine: Investigation on the Polymeric and Non-polymeric Carrier and Solvent Effect

INTRODUCTION

Typically, in situ forming implants utilize Poly (lactide-co-glycolide) (PLGA) as a carrier and N-methyl-2-pyrrolidone (NMP) as a solvent. However, it is essential to develop different carriers to release various drugs in a controlled and sustained manner with economic and safety considerations.

OBJECTIVE

The present study aims to evaluate the in-vitro release of Bupivacaine HCl from in situ forming systems as post-operative local anesthesia.

METHODS

We used Sucrose acetate isobutyrate (SAIB), PLGA 50:50, and a mixture of them as carriers to compare the release behavior. Besides, the effect of PLGA molecular weight (RG 502H, RG 503H, and RG 504H), solvent type, and solvent concentration on the drug release profile was evaluated. The formulations were characterized by investigating their in-vitro drug release, rheological properties, solubility, and DSC, in addition to their morphological properties. Furthermore, the Korsmeyer-Peppas and Weibull models were applied to the experimental data. The results revealed that a mixture of SAIB and PLGA compared to using them solely can extend the Bupivacaine HCl release from 3 days to two weeks.

RESULTS

The DSC results demonstrated the compatibility of the mixture by showing a single Tg. The formulation with NMP had a higher burst release and final release in comparison with other solvents by 30% and 96%, respectively. Increasing the solvent concentration from 12% to 32% raised the drug release significantly, which confirmed the larger porosity in the morphology results. From the Korsmeyer-Peppas model, the mechanism of drug release is predicted to be non-Fickian diffusion.

Effect of zoledronic acid and graphene oxide on the physical and in vitro properties of injectable bone substitutes

The aim of this work was to develop injectable bone substitutes (IBS) consisting of zoledronic acid (ZOL) and graphene oxide (GO) for the treatment of osteoporosis and metastasis. The powder phase was consisting of tetra calcium phosphate (TTCP), dicalcium phosphate dihyrate (DCPD) and calcium sulfate dihyrate (CSD), while the liquid phase comprised of methylcellulose (MC), gelatin and sodium citrate dihyrate (SC), ZOL and GO. The structural analysis of IBS samples was performed by Fourier Transform Infrared Spectroscopy (FTIR). Injectability, setting time and mechanical strength were investigated. Additionally, in vitro properties of synthesized IBS were analyzed by means of bioactivity, ZOL release, degradation, pH variation, PO₄^3- ion release and cell studies. Overall, all IBS exhibited excellent injectability results with no phase separation. The setting time of the IBS was prolonged with ZOL incorporation while the prolonging effect decreased with GO incorporation. The mechanical properties decreased with ZOL addition and increased with the incorporation of GO. The maximum compressive strength was found as 25.73 MPa for 1.5GO0ZOL incorporated IBS. In vitro results showed that ZOL and GO loaded IBS also revealed clinically suitable properties with controlled release of ZOL, pH value and PO₄^3- ions. In in vitro cell studies, both the inhibitory effect of ZOL and GO loaded IBS on MCF-7 cells and proliferative effect on osteoblast cells were observed. Moreover, the prepared IBS led to proliferation, differentiation and mineralization of osteoblasts. The results are encouraging and support the conclusion that developed IBS have promising physical and in vitro properties which needs to be further validated by gene expression and in vivo studies.

Magnesium-alloy rods reinforced bioglass bone cement composite scaffolds with cortical bone-matching mechanical properties and excellent osteoconductivity for load-bearing bone in vivo regeneration

Various therapeutic platforms have been developed for repairing bone defects. However, scaffolds possess both cortical bone-matching mechanical properties and excellent osteoconductivity for load-bearing bone defects repair is still challenging in the clinic. In this study, inspired by the structure of the ferroconcrete, a high-strength bifunctional scaffold has been developed by combining surface-modified magnesium alloy as the internal load-bearing skeleton and bioglass-magnesium phosphate bone cement as the osteoconductive matrix. The scaffold combines the high mechanical strength and controllable biodegradability of surface-modified magnesium alloy with the excellent biocompatibility and osteoconductivity of bioglass-magnesium phosphate bone cement, thus providing support for load-bearing bone defects and subsequently bone regeneration. The scaffolds generate hydroxyapatite (HA) during the degrading in simulated body fluid (SBF), with the strength of the scaffold decreasing from 180 to 100 MPa in 6 weeks, which is still sufficient for load-bearing bone. Moreover, the scaffolds showed excellent osteoconductivity in vitro and in vivo. In a New Zealand White Rabbit radius defect model, the scaffolds degrade gradually and are replaced by highly matured new bone tissues, as assessed by image-based analyses (X-ray and Micro-CT) and histological analyses. The bone formation-related proteins such as BMP2, COL1a1 and OCN, all showed increased expression.

Modulation of bone formation and resorption using a novel zoledronic acid loaded gelatin nanoparticles integrated porous titanium scaffold: an in vitro and in vivo study

Osteoporotic bone defects are a major challenge in clinics for bone regeneration. With the condition of osteoporosis, excessive bone absorption and impaired osteogenesis result in unexpectedly long healing procedures for defects. In order to simultaneously enhance bone formation and reduce bone resorption, a polydopamine-coated porous titanium scaffold was designed, to be integrated with anti-catabolic drug zoledronic acid nanoparticles (ZOL loaded gelatin NPs), which was able to achieve a local sustained release of ZOL as expected. The in vitro study demonstrated that extracts of the composite scaffolds would stimulate osteoblast differentiation; they also inhibited osteoclastogenesis at a ZOL loading concentration of 50 μmol l^-1. In the subsequent in vivo study, the composite scaffolds were implanted into ovariectomy-induced osteoporotic rabbits suffering from femoral condyles defects. The results indicated that the composite scaffolds without ZOL loaded gelatin NPs only induced callus formation, mainly at the interface margin between the implant and bone, whereas the composite scaffolds with ZOL loaded gelatin NPs were capable of further enhancing osteogenesis and bone growth into the scaffolds. Moreover, the research proved that the promoting effect was optimal at a ZOL loading concentration of 50 μmol l^-1. In summary, the present research indicated that a new type of porous titanium scaffold integrated with ZOL loaded gelatin NPs inherited a superior biocompatibility and bone regeneration capability. It would be an optimal alternative for the reconstruction of osteoporosis-related defects compared to a traditional porous titanium implant; in other words, the new type of scaffold offers a new effective and practical procedure option for patients suffering from osteoporotic bone defects.

Synthesis and Characterization of a Biocomposite Bone Bandage for Controlled Delivery of Bone-Active Drugs in Fracture Nonunions

Fracture nonunions are common in orthopedics and their treatment often involves multiple surgical interventions. The aim of this study was to fabricate and characterize a gelatin-nano-hydroxyapatite membrane (GM)-based bone bandage for controlled delivery of bio-active molecules; recombinant human bone morphogenic protein-2 (rhBMP-2) and zoledronic acid (ZA) to promote osteoinduction and prevent callus resorption, respectively. In vitro cell-material interaction experiments using MC3T3 cells seeded on the GM indicated good biocompatibility. rhBMP-2-functionalized GM promoted osteogenic differentiation of MC3T3 cells and the rhBMP-2 bio-activity thus remained, as indicated by increased levels of alkaline phosphatase compared to only GM. The GM released a small amount (1.1%) of rhBMP-2 in vitro over a period of 5 weeks, demonstrating a strong interaction of rhBMP-2 with the GM. In the first animal study, the GM specimens loaded with rhBMP-2 or with the combination of rhBMP-2 + ZA were placed in the abdominal muscle pouch of rats. In the GM + rhBMP-2 + ZA group, significantly higher bone volume (21.5 ± 5.9 vs 2.7 ± 1.0 mm³) and area (3.3 ± 2.3 vs 1.0 ± 0.4 mm²) of bone were observed compared to GM + rhBMP-2 after 4 weeks, as indicated by micro-computed tomography and histomorphometry, respectively. Finally, a nonunion model in rats was used to evaluate the efficacy of the GM bandage and bio-active molecules in healing of fracture nonunions. The GM functionalized with rhBMP-2 + ZA led to higher bone formation around the fracture (63.9 ± 19.0 vs 31.8 ± 3.7 mm³) and stronger fracture callus (110.8 ± 46.8 vs 45.6 ± 17.8 N) compared to the empty controls. However, the overall union rate was only marginally improved. The GM alone or combined with ZA did not aid in bone healing in this model. Thus, this study shows that controlled delivery of rhBMP-2 + ZA via the developed GM is a promising approach that could aid in earlier full load bearing in patients with nonunion.

A Bioactive Coating Enhances Bone Allografts in Rat Models of Bone Formation and Critical Defect Repair

Bone allografts are inferior to autografts for the repair of critical-sized defects. Prior studies have suggested that bone morphogenetic protein-2 (BMP-2) can be combined with allografts to produce superior healing. We created a bioactive coating on bone allografts using polycondensed deoxyribose isobutyrate ester (PDIB) polymer to deliver BMP-2 ± the bisphosphonate zoledronic acid (ZA) and tested its ability to enhance the functional utility of allografts in preclinical Wistar rat models. One ex vivo and two in vivo proof-of-concept studies were performed. First, PDIB was shown to be able to coat bone grafts (BGs). Second, PDIB was used to coat structural allogenic corticocancellous BG with BMP-2 ± ZA ± hydroxyapatite (HA) microparticles and compared with PDIB-coated grafts in a rat muscle pouch model. Next, a rat critical defect model was performed with treatment groups including (i) empty defect, (ii) BG, (iii) collagen sponge + BMP-2, (iv) BG + PDIB/BMP-2, and (v) BG + PDIB/BMP-2/ZA. Key outcome measures included detection of fluorescent bone labels, microcomputed tomography (CT) quantification of bone, and radiographic healing. In the muscle pouch study, BMP-2 did not increase net bone volume measured by microCT, however, fluorescent labeling showed large amounts of new bone. Addition of ZA increased BV by sevenfold (p < 0.01). In the critical defect model, allografts were insufficient to promote reliable union, however, union was achieved in collagen/BMP-2 and all BG/BMP-2 groups. Statement of clinical significance: These data support the concept that PDIB is a viable delivery method for BMP-2 and ZA delivery to enhance the bone forming potential of allografts. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 37:2278-2286, 2019.

Sucrose Acetate Isobutyrate as an In situ Forming Implant for Sustained Release of Local Anesthetics

OBJECTIVE

In this study, an injectable Sucrose Acetate Isobutyrate (SAIB) drug delivery system (SADS) was designed and fabricated for the sustained release of Ropivacaine (RP) to prolong the duration of local anesthesia.

METHODS

By mixing SAIB, RP, and N-methyl-2-pyrrolidone, the SADS was prepared in a sol state with low viscosity before injection. After subcutaneous injection, the pre-gel solution underwent gelation in situ to form a drug-released depot.

RESULT

The in vitro release profiles and in vivo pharmacokinetic analysis indicated that RP-SADS had suitable controlled release properties. Particularly, the RP-SADS significantly reduced the initial burst release after subcutaneous injection in rats.

CONCLUSION

In a pharmacodynamic analysis of rats, the duration of nerve blockade was prolonged by over 3-fold for the RP-SADS formulation compared to RP solution. Additionally, RP-SADS showed good biocompatibility in vitro and in vivo. Thus, the SADS-based depot technology is a safe drug delivery strategy for the sustained release of local anesthetics with long-term analgesia effects.

Dual modulation of bone formation and resorption with zoledronic acid-loaded biodegradable magnesium alloy implants improves osteoporotic fracture healing: An in vitro and in vivo study

Osteoporotic fracture (OPF) remains a major clinical challenge for skeletal regeneration. Impaired osteogenesis and excessive remodeling result in prolonged and poor quality of fracture healing. To augment bone formation and inhibit excessive resorption simultaneously, we constructed a biodegradable magnesium-based implant integrated with the anti-catabolic drug zoledronic acid (ZA); this implant exhibits controllable, sustained release of magnesium degradation products and ZA in vitro. The extracts greatly stimulate the osteogenic differentiation of rat-bone marrow-derived mesenchymal stem cells (rBMSCs), while osteoclastogenesis is inhibited by ZA. Implantation of intramedullary nails to fix femur fracture in ovariectomy-induced osteoporotic rats for up to 12 weeks demonstrates magnesium implants alone can enhance OPF repair through promoting callus formation compared to conventional stainless steel, while the combinatory treatment with local ZA release from implant coating further increases bone regeneration rate and callus size, remarkably improves bone quality and mechanical strength and suppresses osteoclasts and bone remodeling, due to the synergistic effect of both agents. The slow and uniform degradation of the implant ensures a steady decrease in bending force, which meets clinical requirements. In summary, biodegradable magnesium-based implants can locally co-deliver magnesium degradation products and zoledronic acid in a controlled manner, and can be superior alternatives for the reconstruction of osteoporosis-related fracture.

STATEMENT OF SIGNIFICANCE

Management of osteoporotic fracture has posed a major challenge in orthopedics, as the imbalance between diminished osteogenesis and excessive bone remodeling often leads to delayed and compromised fracture repair. Among various efforts expended on augmenting osteoporotic fracture healing, herein we reported a new strategy by engineering and utilizing a biodegradable magnesium-based implant integrated with local drug delivery, specifically, zoledronic acid (ZA)-loaded polylactic acid/brushite bilayer coating on a biodegradable Mg-Nd-Zn-Zr alloy (denoted as Mg/ZA/CaP), aiming to combine the favorable properties of Mg and zoledronic acid for simultaneous modulation of bone formation and bone resorption. In vitro and in vivo studies demonstrated its superior treatment efficacy along with adequate degradation. It stimulated new bone formation while suppressing remodeling, ascribed to the local release of magnesium degradation products and zoledronic acid. To our knowledge, the enhanced fracture repair capability of Mg-based implants was for the first time demonstrated in an osteoporotic fracture animal model. This innovative biodegradable Mg-based orthopedic implant presents great potential as a superior alternative to current internal fixation devices for treating osteoporotic fracture.

Intracellular co-delivery of Sr ion and phenamil drug through mesoporous bioglass nanocarriers synergizes BMP signaling and tissue mineralization

Inducing differentiation and maturation of resident multipotent stem cells (MSCs) is an important strategy to regenerate hard tissues in mal-calcification conditions. Here we explore a co-delivery approach of therapeutic molecules comprised of ion and drug through a mesoporous bioglass nanoparticle (MBN) for this purpose. Recently, MBN has offered unique potential as a nanocarrier for hard tissues, in terms of high mesoporosity, bone bioactivity (and possibly degradability), tunable delivery of biomolecules, and ionic modification. Herein Sr ion is structurally doped to MBN while drug Phenamil is externally loaded as a small molecule activator of BMP signaling, for the stimulation of osteo/odontogenesis and mineralization of human MSCs derived from dental pulp. The Sr-doped MBN (85Si:10Ca:5Sr) sol-gel processed presents a high mesoporosity with a pore size of ∼6nm. In particular, Sr ion is released slowly at a daily rate of ∼3ppm per mg nanoparticles for up to 7days, a level therapeutically effective for cellular stimulation. The Sr-MBN is internalized to most MSCs via an ATP dependent macropinocytosis within hours, increasing the intracellular levels of Sr, Ca and Si ions. Phenamil is loaded maximally ∼30% into Sr-MBN and then released slowly for up to 7days. The co-delivered molecules (Sr ion and Phenamil drug) have profound effects on the differentiation and maturation of cells, i.e., significantly enhancing expression of osteo/odontogenic genes, alkaline phosphatase activity, and mineralization of cells. Of note, the stimulation is a result of a synergism of Sr and Phenamil, through a Trb3-dependent BMP signaling pathway. This biological synergism is further evidenced in vivo in a mal-calcification condition involving an extracted tooth implantation in dorsal subcutaneous tissues of rats. Six weeks post operation evidences the osseous-dentinal hard tissue formation, which is significantly stimulated by the Sr/Phenamil delivery, based on histomorphometric and micro-computed tomographic analyses. The bioactive nanoparticles releasing both Sr ion and Phenamil drug are considered to be a promising therapeutic nanocarrier platform for hard tissue regeneration. Furthermore, this novel ion/drug co-delivery concept through nanoparticles can be extensively used for other tissues that require different therapeutic treatment.

STATEMENT OF SIGNIFICANCE

This study reports a novel design concept in inorganic nanoparticle delivery system for hard tissues - the co-delivery of therapeutic molecules comprised of ion (Sr) and drug (Phenamil) through a unique nanoparticle of mesoporous bioactive glass (MBN). The physico-chemical and biological properties of MBN enabled an effective loading of both therapeutic molecules and a subsequently sustained/controlled release. The co-delivered Sr and Phenamil demonstrated significant stimulation of adult stem cell differentiation in vitro and osseous/dentinal regeneration in vivo, through BMP signaling pathways. We consider the current combination of Sr ion with Phenamil is suited for the osteo/odontogenesis of stem cells for hard tissue regeneration, and further, this ion/drug co-delivery concept can extend the applications to other areas that require specific cellular and tissue functions.

Design of polyaspartic acid peptide-poly (ethylene glycol)-poly (ε-caprolactone) nanoparticles as a carrier of hydrophobic drugs targeting cancer metastasized to bone

Treatment of cancer metastasized to bone is still a challenge due to hydrophobicity, instability, and lack of target specificity of anticancer drugs. Poly (ethylene glycol)-poly (ε-caprolactone) polymer (PEG-PCL) is an effective, biodegradable, and biocompatible hydrophobic drug carrier, but lacks bone specificity. Polyaspartic acid with eight peptide sequences, that is, (Asp)₈, has a strong affinity to bone surface. The aim of this study was to synthesize (Asp)₈-PEG-PCL nanoparticles as a bone-specific carrier of hydrophobic drugs to treat cancer metastasized to bone. ¹H nuclear magnetic resonance, Fourier transform infrared spectroscopy, and transmission electron microscopy data showed that (Asp)₈-PEG-PCL nanoparticles (size 100 nm) were synthesized successfully. (Asp)₈-PEG-PCL nanoparticles did not promote erythrocyte aggregation. Fluorescence microscopy showed clear uptake of Nile red-loaded (Asp)₈-PEG-PCL nanoparticles by cancer cells. (Asp)₈-PEG-PCL nanoparticles did not show cytotoxic effect on MG63 and human umbilical vein endothelial cells at the concentration of 10-800 μg/mL. (Asp)₈-PEG-PCL nanoparticles bound with hydroxyapatite 2-fold more than PEG-PCL. Intravenously injected (Asp)₈-PEG-PCL nanoparticles accumulated 2.7-fold more on mice tibial bone, in comparison to PEG-PCL. Curcumin is a hydrophobic anticancer drug with bone anabolic properties. Curcumin was loaded in the (Asp)₈-PEG-PCL. (Asp)₈-PEG-PCL showed 11.07% loading capacity and 95.91% encapsulation efficiency of curcumin. The curcumin-loaded (Asp)₈-PEG-PCL nanoparticles gave sustained release of curcumin in high dose for >8 days. The curcumin-loaded (Asp)₈-PEG-PCL nanoparticles showed strong antitumorigenic effect on MG63, MCF7, and HeLa cancer cells. In conclusion, (Asp)₈-PEG-PCL nanoparticles were biocompatible, permeable in cells, a potent carrier, and an efficient releaser of hydrophobic anticancer drug and were bone specific. The curcumin-loaded (Asp)₈-PEG-PCL nanoparticles showed strong antitumorigenic ability in vitro. Therefore, (Asp)₈-PEG-PCL nanoparticles could be a potent carrier of hydrophobic anticancer drugs to treat the cancer metastasized to bone.

C-Dot Generated Bioactive Organosilica Nanospheres in Theranostics: Multicolor Luminescent and Photothermal Properties Combined with Drug Delivery Capacity

Biocompatible nanomaterials that allow for labeling cells and tissues with the capacity to load and deliver drug molecules hold great promise for the therapeutic-diagnostic purposes in tissue repair and disease cure. Here a novel nanoplatform, called C-dot bioactive organosilica nanosphere (C-BON), is introduced to have excellent theranostic potential, such as controlled drug delivery, visible-light imaging, and NIR photothermal activity. C-dots with a few nanometers were in situ generated in the Ca-containing organosilica mesoporous nanospheres through the sol-gel and thermal-treatment processes. The C-BON exhibited multicolor luminescence over a wide visible-light range with strong emissions and high photostability over time and against acidity and the possible in vivo optical imaging capacity when injected in rat subcutaneous tissues. Moreover, the C-BON showed a photothermal heating effect upon the irradiation of near-infrared. The C-BON, thanks to the high mesoporosity and existence of Ca(2+) ions, demonstrated excellent loading capacity of anticancer drug doxorubicin (as high as 90% of carrier weight) and long-term (over a couple of weeks) and pH/NIR-dependent release ability. The C-BON preserved the compositional merit of Ca-Si glass, having excellent bioactivity and cell compatibility in vitro. Taken all, the multifunctional properties of C-BON-multicolor luminescence, photothermal activity, and high drug loading and controlled release-together with its excellent bioactivity and cell compatibility potentiate the future applications in theranostics (chemotherapy and photothermal therapy with optical imaging).