A Bifunctional Biomaterial with Photothermal Effect for Tumor Therapy and Bone Regeneration

Malignant bone tumor is one of the major bone diseases. The treatment of such a bone disease typically requires the removal of bone tumor and regeneration of tumor‐initiated bone defects simultaneously. To address this issue, it is required that implanted biomaterials should combine the bifunctions of both therapy and regeneration. In this work, a bifunctional graphene oxide (GO)‐modified β‐tricalcium phosphate (GO‐TCP) composite scaffold combining a high photothermal effect with significantly improved bone‐forming ability is prepared by 3D‐printing and surface‐modification strategies. The prepared GO‐TCP scaffolds exhibit excellent photothermal effects under the irradiation of 808 nm near infrared laser (NIR) even at an ultralow power density of 0.36 W cm^?2, while no photothermal effects are observed for pure β‐TCP scaffolds. The photothermal temperature of GO‐TCP scaffolds can be effectively modulated in the range of 40–90 °C by controlling the used GO concentrations, surface‐modification times, and power densities of NIR. The distinct photothermal effect of GO‐TCP scaffolds induces more than 90% of cell death for osteosarcoma cells (MG‐63) in vitro, and further effectively inhibits tumor growth in mice. Meanwhile, the prepared GO‐TCP scaffolds possess the improved capability to stimulate the osteogenic differentiation of rabbit bone mesenchymal stem cells (rBMSCs) by upregulating bone‐related gene expression, and significantly promote new bone formation in the bone defects of rabbits as compared to pure β‐TCP scaffolds. These results successfully demonstrate that the prepared GO‐TCP scaffolds have bifunctional properties of photothermal therapy and bone regeneration, which is believed to pave the way to design and fabricate novel implanting biomaterials in combination of therapy and regeneration functions.     

An Injectable Supramolecular Polymer Nanocomposite Hydrogel for Prevention of Breast Cancer Recurrence with Theranostic and Mammoplastic Functions

The high locoregional breast cancer recurrence rate poses a significant risk for patients' survival. Injecting theranostic drugs‐laden soft tissue‐like hydrogels into the resected breast cavity is a promising strategy to achieve both precisely local therapy of breast cancer and reconstructive mammoplasty. In this work, a robust injectable thermoresponsive supramolecular poly(N‐acryloyl glycinamide‐co‐acrylamide) (PNAm) hydrogel bearing polydopamine (PDA) coated‐gold nanoparticles (AuNPs) and doxorubicin (DOX) is fabricated. The supramolecular polymer nanocomposite (SPN) hydrogels exhibit an excellent photothermal effect arising from PDA‐AuNPs that are tightly fixed to the hydrogel matrix via PDA and amide moieties in the network, built‐in near infrared (NIR) light‐triggered gel–sol transition as well as tunable drug delivery. The PNAm‐PDAAu‐DOX sol driven by prior heating is injected into the cavity of resected cancerous breasts of rats where gelation occurred rapidly while the temperature decreased to body temperature, thereby finely serving as a breast filler. During 4 week of implantation, interval NIR light irradiation can mediate photothermal effect and concertedly controllable DOX release, thus collectively preventing the recurrence of breast cancer. Remarkably, this stable remoldable SPN hydrogel facilitates the breast reconstruction and can be tracked by computed tomography (CT) imaging owing to the intrinsic X‐ray attenuation property of the loaded AuNPs.     

Zwitterion Functionalized Graphene Oxide/Polyacrylamide/Polyacrylic Acid Hydrogels with Photothermal Conversion and Antibacterial Properties for Highly Efficient Uranium Extraction from Seawater

In this study, graphene oxide (GO) and polyacrylamide/polyacrylic acid (PAM/PAA) are used to prepare hydrogels with photothermal conversion properties for highly efficient uranium extraction from seawater. Zwitterionic 2-methacryloyloxy ethyl phosphorylcholine (MPC) is introduced in the PAM/PAA/GO hydrogel to obtain PAM/PAA/GO/MPC (PAGM), exhibiting good antibacterial properties. PAGM demonstrates efficient and specific adsorption of uranium (VI) (U(VI)). Under light conditions, the adsorption capacity of PAGM reaches 196.12 mg g⁻¹ (pH = 8, t = 600 min, C₀ = 99.8 mg L⁻¹, m/v = 0.5 g L⁻¹). The adsorption capacity is only 160.29 mg g⁻¹ under dark conditions (pH = 8, t = 600 min, C₀ = 99.8 mg L⁻¹, m/v = 0.5 g L⁻¹). The adsorption capacity of light is 22.5% higher than that of dark. The adsorption process is fitted using the Langmuir and pseudo-second-order models. Furthermore, PAGM exhibits good repeatability and stability after five adsorption–desorption cycles. PAGM exhibits a U(VI) adsorption capacity of 6.1 mg g⁻¹ after storage for one month in natural seawater. The X-ray photoelectron spectroscopy (XPS) results demonstrate that the coordination of the amino, carboxyl, and hydroxyl groups with U(VI) is the primary mechanism of U(VI) adsorption. The mechanism is confirmed through detailed density functional theory calculations. PAGM demonstrates durability, high efficiency, photothermal conversion properties, and antibacterial properties. Thus, it is a promising candidate for uranium extraction from seawater.     

Photothermal Lysis of Engineered Bacteria to Modulate Amino Acid Metabolism against Tumors

Bacterial-mediated synergistic cancer therapy (BMSCT) is used as a promising tumor therapy approach. However, there are some disadvantages of bacterial therapy alone to be resolved, such as low tumor suppression rate in the treatment. In this study, a novel light-controlled engineered bacterial material which synergistically regulates amino acid metabolism to fight tumors is developed. It transcribes l -methionine-γ-lyase (MdeA) into Escherichia coli (E. coli) and loads the approved photothermal agent indocyanine green (ICG), namely E. coli-MdeA@ICG. Using the hypoxic tropism of E. coli, genetically engineered bacteria are first loaded with photothermal agents, then selectively accumulate and replicate in the tumor region. Under laser irradiation, photothermal lysis of E. coli-MdeA is performed to release the MdeA and consume the essential amino acid methionine (Met) in the tumor environment. In vitro cell experiments confirm that the E. coli-MdeA + NIR group can reach 90% of the 4T1 cells killing. In 4T1 tumor-bearing mouse models, E. coli-MdeA@ICG shows enhanced antitumor efficacy, along with 91.8% of the tumor growth inhibited. Apoptosis of tumor cells is induced under the dual action of photothermal therapy (PTT) and amino acid metabolism therapy. This strategy provides new ideas for the combination of synthetic biology and nanotechnology in anti-tumor.     

pH‐Responsive Cyanine‐Grafted Graphene Oxide for Fluorescence Resonance Energy Transfer‐Enhanced Photothermal Therapy

Stimuli‐responsive anticancer agents are of particular interest in the field of cancer therapy. Nevertheless, so far stimuli‐responsive photothermal agents have been explored with limited success for cancer photothermal therapy (PTT). In this work, as a proof‐of‐concept, a pH‐responsive photothermal nanoconjugate for enhanced PTT efficacy, in which graphene oxide (GO) with broad NIR absorbance and effective photothermal conversion efficiency is selected as a typical model receptor of fluorescence resonance energy transfer (FRET), and grafted cyanine dye (e.g., Cypate) acts as the donor of near‐infrared fluorescence (NIRF), is reported for the first time. The conjugate of Cypate‐grafted GO exhibits different conformations in aqueous solutions at various pH, which can trigger pH‐dependent FRET effect between GO and Cypate and thus induce pH‐responsive photothermal effect of GO‐Cypate. GO‐Cypate exhibits severe cell damage owing to the enhanced photothermal effect in lysosomes, and thus generate synergistic PTT efficacy with tumor ablation upon photoirradiation after a single‐dose intravenous injection. The photothermal nanoconjugate with broad NIR absorbance as the effective receptor of FRET can smartly convert emitted NIRF energy from donor cyanine dye into additional photothermal effect for improving PTT. These results suggest that the smart nanoconjugate can act as a promising stimuli‐responsive photothermal nanoplatform for cancer therapy.     

Organic Small Molecule Based Photothermal Agents with Molecular Rotors for Malignant Breast Cancer Therapy

Organic photothermal nanoagents are promising candidates for treating primary tumors and inhibiting metastasis. However, they often exhibit poor photostability, low absorptivity, or limited photothermal conversion efficiency (PCE). Herein, a facile molecular engineering approach to produce efficient organic photothermal molecules is demonstrated. By integrating donor–acceptor structure and molecular motors, a small molecule ( TA1 ) is synthesized with large absorptivity (22.4 L g^?1 cm^?1), negligible reactive oxygen species generation, high PCE (84.8%), excellent photothermal stability, and good biocompatibility. Furthermore, microfluidics is used to thoroughly study the relationship between the size and process conditions, yielding small uniform nanoparticles (NPs) with a diameter of 44 nm. Importantly, TA1 NPs under near‐infrared laser irradiation significantly suppressed primary breast tumor growth and metastasis, both in vitro and in vivo. This study shows that small organic molecule nanoparticles are promising candidates for future cancer nanomedicine.     

Tumor‐Penetrating Nanotherapeutics Loading a Near‐Infrared Probe Inhibit Growth and Metastasis of Breast Cancer

The tumor growth and metastasis is the leading reason for the high mortality of breast cancer. Herein, it is first reported a deep tumor‐penetrating photothermal nanotherapeutics loading a near‐infrared (NIR) probe for potential photothermal therapy (PTT) of tumor growth and metastasis of breast cancer. The NIR probe of 1,1‐dioctadecyl‐3,3,3,3‐tetramethylindotricarbocyanine iodide (DiR), a lipophilicfluorescent carbocyanine dye with strong light‐absorbing capability, is entrapped into the photothermal nanotherapeutics for PTT application. The DiR‐loaded photothermal nanotherapeutics (DPN) is homogeneous nanometer‐sized particles with the mean diameter of 24.5 ± 4.1 nm. Upon 808 nm laser irradiation, DPN presents superior production of thermal energy than free DiR both in vitro and in vivo. The cell proliferation and migration activities of metastatic 4T1 breast cancer cells are obviously inhibited by DPN in combination with NIR irradiation. Moreover, DPN can induce a higher accumulation in tumor and penetrate into the deep interior of tumor tissues. The in vivo PTT measurements indicate that the growth and metastasis of breast cancer are entirely inhibited by a single treatment of DPN with NIR irradiation. Therefore, the deep tumor‐penetrating DPN can provide a promising strategy for PTT of tumor progression and metastasis of breast cancer.     

Self‐Doped Conjugated Polymeric Nanoassembly by Simplified Process for Optical Cancer Theragnosis

To access smart optical theragnosis for cancer, an easily processable heterocyclic conjugated polymer (poly(sodium3‐((3‐methyl‐3,4‐dihydro‐2H‐thieno[3,4‐b][1,4]dioxepin‐3‐yl)methoxy)propane‐1‐sulfonate), PPDS) nanoassembly is fabricated by a surfactant‐free one‐step process, without the laborious ordinary multicoating process. The conjugated nanoassembly, with a self‐doped structure, provides strong absorbance in the near‐infrared (NIR) range even in a neutral pH medium and exhibits excellent stability (>six months). In addition, the prepared PPDS nanoassembly shows a high photothermal conversion efficiency of 31.4% in organic photothermal nanoparticles. In particular, the PPDS nanoassembly is stably suspended in the biological medium without any additives. Through a simple immobilization with the anti‐CD44 antibody, the prepared biomarker‐targetable PPDS nanoassembly demonstrates specific targeting toward CD44 (expressed in stem‐like cancer cells), allowing NIR absorbance imaging and the efficient targeted photothermal damaging of CD44‐expressing cancer cells, from in vitro 3D mammospheres (similar to the practical structure of tumor in the body) to in vivo xenograft mice tumor models (breast cancer and fibrosarcoma). In this study, the most simplified preparation method is for this organic conjugated polymer‐based nanoassembly by a molecular approach is reported, and demonstrated as a highly promising optical nanoagent for optical cancer theragnosis.     

Multifunctional Nanoparticle Loaded Injectable Thermoresponsive Hydrogel as NIR Controlled Release Platform for Local Photothermal Immunotherapy to Prevent Breast Cancer Postoperative Recurrence and Metastases

For breast cancer patients who have undergone breast‐conserving surgery, effective treatments to prevent local recurrences and metastases is very essential. Here, a local injectable therapeutic platform based on a thermosensitive PLEL hydrogel with near‐infrared (NIR)‐stimulated drug release is developed to achieve synergistic photothermal immunotherapy for prevention of breast cancer postoperative relapse. Self‐assembled multifunctional nanoparticles (RIC NPs) are composed of three therapeutic components including indocyanine green, a photothermal agent; resiquimod (R848), a TLR‐7/8 agonist; and CPG ODNs, a TLR‐9 agonist. RIC NPs are physically incorporated into the thermosensitive PLEL hydrogel. The RIC NPs encapsulated PLEL hydrogel (RIC NPs@PLEL) is then locally injected into the tumor resection cavity for local photothermal therapy to ablate residue tumor tissues and produce tumor‐associated antigens. At the same time, NIR also triggers the release of immune components CPG ODNs and R848 from thermoresponsive hydrogels PLEL. The released immune components, together with tumor‐associated antigens, work as an in situ cancer vaccine for postsurgical immunotherapy by inducing effective and sustained antitumor immune effect. Overall, this work suggests that photothermal immunotherapy based on local hydrogel delivery system has great potential as a promising tool for the postsurgical management of breast cancer to prevent recurrences and metastases.     

Bacteria‐Assisted Selective Photothermal Therapy for Precise Tumor Inhibition

Photothermal therapy (PTT) has drawn extensive research attention as a promising approach for tumor treatment. In this study, a bacteria‐assisted strategy relying on the selective reduction of perylene diimide derivative based supramolecular complex (CPPDI) to radical anions (RAs) by Escherichia coli in hypoxic tumors is developed to realize highly precise PTT of tumors. Noninvasive E. coli are first injected intravenously for selectively accumulating and replicating in the tumor due to the hypoxia tropism. Then, CPPDI is loaded in a peptide‐hybrid matrix metalloproteinase‐2 (MMP‐2) responsive liposome (MRL) and injected intravenously. After accumulated and released from MRL in the tumor where MMP‐2 is overexpressed, CPPDI is reduced by E. coli in the hypoxic tumor environment to produce CPPDI RAs (CRAs), which serve as effective photothermal agents for tumor cells thermal ablation under near‐infrared light irradiation. Since E. coli accumulate and grow in tumor sites selectively, this strategy accurately limits the production of CRAs in tumors for highly selective PTT, which will find great potential for precise tumor inhibition.     

Biocompatible D–A Semiconducting Polymer Nanoparticle with Light‐Harvesting Unit for Highly Effective Photoacoustic Imaging Guided Photothermal Therapy

The development of nanotheranostic agents that integrate diagnosis and therapy for effective personalized precision medicine has obtained tremendous attention in the past few decades. In this report, biocompatible electron donor–acceptor conjugated semiconducting polymer nanoparticles (PPor‐PEG NPs) with light‐harvesting unit is prepared and developed for highly effective photoacoustic imaging guided photothermal therapy. To the best of our knowledge, it is the first time that the concept of light‐harvesting unit is exploited for enhancing the photoacoustic signal and photothermal energy conversion in polymer‐based theranostic agent. Combined with additional merits including donor–acceptor pair to favor electron transfer and fluorescence quenching effect after NP formation, the photothermal conversion efficiency of the PPor‐PEG NPs is determined to be 62.3%, which is the highest value among reported polymer NPs. Moreover, the as‐prepared PPor‐PEG NP not only exhibits a remarkable cell‐killing ability but also achieves 100% tumor elimination, demonstrating its excellent photothermal therapeutic efficacy. Finally, the as‐prepared water‐dispersible PPor‐PEG NPs show good biocompatibility and biosafety, making them a promising candidate for future clinical applications in cancer theranostics.     

Two‐Stage Size Decrease and Enhanced Photoacoustic Performance of Stimuli‐Responsive Polymer‐Gold Nanorod Assembly for Increased Tumor Penetration

A promising theranostic platform for solid tumors would deliver and release anticancer nanomedicine effectively in tumor cells. However, diverse biological barriers, especially related to the tumor microenvironment, impede these theranostic agents from reaching the tumor cell. Herein, a sequential pH and reduction‐responsive polymer and gold nanorod (AuNR) core–shell assembly to overcome these barriers via a two‐stage size decrease and disassembly of the nanoplatform responding to the specified tumor microenvironment are reported. The tumor uptake of the hybrid nanoparticle (NP) is 14.2% ID g^?1, which is two and four times higher than the noneresponsive hybrid NPs and small AuNR@PEG, respectively. After tumor uptake of the hybrid NPs, the disassembled ultrasmall AuNRs coated with a polymer of polymerized reduction‐responsive doxorubicin (DOX) prodrug monomers penetrate into the solid tumor and lead to localized DOX release in the tumor cell. A linear increase in photoacustic (PA) effects from the PA activating polymer on an AuNR cluster surface indicates a critical role of electromagnetic fields in the AuNR assembly, which is consistent with the theoretical calculation results. Furthermore, the hybrid NP can serve as a promising deep‐tissue PA and surface‐enhanced Raman scattering imaging agent for real‐time in vivo investigation of physiological behaviors and deep tumor penetrating nanotherapy effects.     

Near-Infrared Light Triggered Silk Fibroin Scaffold for Photothermal Therapy and Tissue Repair of Bone Tumors

Silk fibroin (SF) has attracted great interest in bone tissue engineering due to its extraordinary characteristics in terms of mechanical properties, biocompatibility, and biodegradability. SF scaffolds are assembled by biocompatible polydopamine nanoparticles at mesoscopic scale, which endows the scaffolds with a near-infrared (NIR) light response for the treatment of bone tumors. The functionalized SF scaffold not only enhances the significant structure and performance of native SF scaffold for bone treatment and reconstruction, such as primary and mesoscopic structure, multi-level pores, and biodegradation, as well as biocompatibility but also have excellent photothermal effect leading a significant cytotoxicity to MG63 cancer cells after NIR laser irradiation. Moreover, the penetration of NIR light in tissue is improved using an optical fiber, which demonstrates the obtained scaffolds’ great potential in the application of photothermal therapy.     

Injectable 3D-Printed Porous Scaffolds for Adipose Stem Cell Delivery and Endometrial Regeneration

Stem-cell-based therapeutic strategies are promising in the clinical treatment of intrauterine adhesions (IUAs), while endometrial regeneration still hardly restores the structure and function of the endometrium because of the inadequate microenvironment for the grafted stem cells and subsequent limited therapeutic efficiency. Herein, an injectable porous hydrogel scaffold (PH scaffold) with customizable shapes is presented by using a microfluidic-based 3D printing technique for adipose-derived stem cells (ADSCs) delivery to enhance endometrial regeneration. These scaffolds display a controllable interconnected porous structure, which not only facilitates the encapsulation of ADSCs within the scaffold but also supports the recovery to their original shapes after injection. Furthermore, the cell viability of the laden ADSCs is well-maintained post-injection, exhibiting promotive effects on cell migration, proliferation, and tube formation. Based on these features, an ADSCs-laden PH scaffold with a hollow endometrium-mimicking morphology is designed and in situ injected into the damaged endometrium in rats of IUAs. These results show that the ADSCs-laden PH scaffolds can enhance functional endometrial regeneration by suppressing the inflammatory response, promoting cell proliferation, and improving vascularization. Thus, it is believed that such unique 3D-printed porous scaffolds are promising candidates for cell delivery, which also provides a minimally-invasive and effective strategy for endometrial regeneration.     

Temperature‐Induced Hydrogels Through Self‐Assembly of Cholesterol‐Substituted Star PEG‐b‐PLLA Copolymers: An Injectable Scaffold for Tissue Engineering

Partially cholesterol‐substituted 8‐arm poly(ethylene glycol)‐block‐poly(L ‐lactide) (8‐arm PEG‐b‐PLLA‐cholesterol) has been prepared as a novel star‐shaped, biodegradable copolymer derivative. The amphiphilic 8‐arm PEG‐b‐PLLA‐cholesterol aqueous solution (polymer concentration, above 3 wt%) exhibits instantaneous temperature‐induced gelation at 34 °C, but the virgin 8‐arm PEG‐b‐PLLA does not, irrespective of concentration. Moreover, an extracellular matrix (ECM)‐like micrometer‐scale network structure has been created with favorable porosity for three‐dimensional proliferation of cells inside the hydrogel. This network structure is mainly attributed to specific self‐assembly between cholesterol groups. The 10 and 20 wt% hydrogels are eroded gradually in phosphate buffered saline at 37 °C over the course of a month, and after that the gel becomes completely dissociated. Moreover, L929 cells encapsulated into the hydrogel are viable and proliferate three‐dimensionally inside the hydrogels. Thus, in‐vitro cell culture studies demonstrate that 8‐arm PEG‐b‐PLLA‐cholesterol is a promising candidate as a novel injectable cellular scaffold.     

The Implications of Polymer Selection in Regenerative Medicine: A Comparison of Amorphous and Semi‐Crystalline Polymer for Tissue Regeneration

Biodegradable polymeric scaffolds are being investigated as scaffolding materials for use in regenerative medicine. While the in vivo evaluation of various three‐dimensional (3D), porous, biodegradable polymeric scaffolds has been reported, most studies are ≤3 months in duration, which is typically prior to bulk polymer degradation, a critical event that may initiate an inflammatory response and inhibit tissue formation. Here, a 6 month in vitro degradation and corresponding in vivo studies that characterized scaffold changes during complete degradation of an amorphous, 3D poly(lactide‐co‐glycolide)(3D‐PLAGA) scaffold and near‐complete degradation of a semi‐crystalline3D‐PLAGA scaffold are reported. Using sintered microsphere matrix technology, constructs were fabricated in a tubular shape, with the longitudinal axis void and a median pore size that mimicked the architecture of native bone. Long‐term quantitative measurements of molecular weight, mechanical properties, and porosity provided a basis for theorization of the scaffold degradation process. Following implantation in a critical size ulnar defect model, histological analysis and quantitative microCT indicated early solubilization of the semi‐crystalline polymer created an acidic microenvironment that inhibited mineralized tissue formation. Thus, the use of amorphous over semi‐crystalline PLAGA materials is advocated for applications in regenerative medicine.     

A Non‐Mulberry Silk Fibroin Protein Based 3D In Vitro Tumor Model for Evaluation of Anticancer Drug Activity

The limitations of clinical chemotherapy are credited primarily to drug resistance. Effective development and screening of new drugs require appropriate in vitro tumor models that resemble the in vivo situation to evaluate drug efficiency and to decrease the use of experimental animals. 3D in vitro model systems that are able to mimic in vivo microenvironments are now highly sought after in cancer research. Here, the characteristics of breast cancer cell line MDA‐MB‐231 cells on 3D, and 2D Antheraea mylitta silk matrices and tissue culture plates are compared. After long term culture of breast cancer cells in the silk scaffold, the engineered tumor construct shows different zones of cell proliferation, such as an avascular tumor. Silk fibroin matrix 3D tumor models are studied for the evaluation of various anticancer drugs. The cytotoxic effects of three different drugs (Paclitaxel, Celecoxib, and ZD6474) at different concentrations are evaluated for MDA‐MB‐231 grown on 2D films as well as on a 3D fibroin scaffold. Higher drug concentrations are required to achieve a comparable reduction in cell viability and invasive potential in 3D culture. Combinatorial treatment of drugs at IC₅₀ concentrations result in up to 84% death of cancer cells. The results indicate that 3D in vitro tumor models may be better systems to evaluate cancer treatment strategies.     

Using Plasma Deposits to Promote Cell Population of the Porous Interior of Three‐Dimensional Poly(D,L‐Lactic Acid) Tissue‐Engineering Scaffolds

Cell adhesion and proliferation on poly(D,L ‐lactic acid) (P_DLLA) tissue‐engineering scaffolds is low. This is generally regarded to be due to the surface chemistry of the P_DLLA polymer, although topographic features often worsen the situation. This study reports for the first time successful deposition of a plasma polymer throughout the porous network of a three‐dimensional scaffold. This allylamine plasma deposit was used to improve cell adhesion on the P_DLLA surface. X‐ray photoelectron spectroscopy (XPS) analysis of sectioned scaffolds was used to demonstrate the penetration of nitrogen species to the inner surfaces and to compare the virgin P_DLLA scaffold and the plasma polymer coated P_DLLA scaffold with plasma‐grafted allylamine. The nitrogen concentration at the exterior and interior scaffold surfaces was greater for the plasma deposits than for the grafted surfaces, and the chemical state of the incorporated surface nitrogen using the two methods was found to be different. Evaluation in vitro was carried out by studying 3T3 fibroblast attachment, morphology, and metabolic activity on the scaffolds. Cell activity and attachment was found to be greater for the plasma deposits than the plasma‐grafted P_DLLA scaffolds, and both were greater than for the virgin P_DLLA scaffolds. It is concluded that plasma deposition is a viable method of increasing cell attachment throughout porous P_DLLA scaffolds without changing the bulk characteristics of the polymer.     

Solid Free‐Form Fabrication of Tissue‐Engineering Scaffolds with a Poly(lactic‐co‐glycolic acid) Grafted Hyaluronic Acid Conjugate Encapsulating an Intact Bone Morphogenetic Protein–2/Poly(ethylene glycol) Complex

Despite wide applications of bone morphogenetic protein–2 (BMP‐2), there are few methods to incorporate BPM‐2 within polymeric scaffolds while maintaining biological activity. Solid free‐form fabrication (SFF) of tissue‐engineering scaffold is successfully carried out with poly(lactic‐co‐glycolic acid) grafted hyaluronic acid (HA‐PLGA) encapsulating intact BMP‐2/poly(ethylene glycol) (PEG) complex. HA‐PLGA conjugate is synthesized in dimethyl sulfoxide (DMSO) by the conjugation reaction of adipic acid dihydrazide modified HA (HA‐ADH) and PLGA activated with N,N′‐dicyclohexylcarbodiimide (DCC) and N‐hydroxysuccinimide (NHS). BMP‐2 is complexed with PEG, which is encapsulated within the PLGA domain of the HA‐PLGA conjugate by SFF to prepare tissue‐engineering scaffolds. In vitro release tests confirm the sustained release of intact BMP‐2 from the scaffolds for up to a month. After confirmation of the enhanced osteoblast cell growth, and high gene‐expression levels of alkaline phosphatase (ALP), osteocalcin (OC), and osterix (OSX) in the cells, the HA‐PLGA/PEG/BMP‐2 scaffolds are implanted into calvarial bone defects of Sprague Dawley (SD) rats. Microcomputed tomography (μCT) and histological analyses with Masson's trichrome, and hematoxylin and eosin (H&E) staining reveal effective bone regeneration on the scaffolds of HA‐PLGA/PEG/BMP‐2 blends.