We report the biological evaluation of bis-MPA dendrimers terminated with either cysteamine (CYS) or 2-(dimethylamino)ethanethiol (DA) groups for siRNA transfection. The results show that aggregation phenomena are critical to the biological performance of these constructs. Confocal and 2D microscopy demonstrated that only the G3-CYS dendrimer transported siRNA into cells. Accordingly, G3-CYS-mediated siRNA transfection reduced intracellular levels of the target proteins─p42-MAPK, Rheb, and MGMT─to 15–25% of control levels in a human glioblastoma cell line and mouse astrocytes. G3-CYS transfection efficiency was similar to that of commercial transfectants. However, its self-degradable bis-MPA backbone and tunable peripheral groups render it markedly superior, making it a promising transfection agent and emphasize the critical balance between structural design, biological efficacy, and safety. Despite its efficacy, G3-CYS displayed a narrow therapeutic window with pronounced cytotoxicity above 1 μM. In vivo studies further confirmed dose-dependent systemic toxicity, likely associated with enhanced blood coagulation.

Cancer drug development faces escalating costs and limited success, driving interest toward drug repurposing strategies. Diclofenac, a widely used nonsteroidal anti-inflammatory drug (NSAID) with emerging anticancer potential, exhibits poor aqueous solubility and rapid systemic clearance, limiting its chemotherapeutic suitability. Here, we engineered PEGylated heterofunctional polyester dendrimers (HFDs) as modular nanocarriers that enable controlled multivalent presentation of diclofenac through orthogonal chemistry. Diclofenac was conjugated within the dendritic interior using copper(I)-catalyzed azide–alkyne cycloaddition (CuAAC) while peripheral PEGylation was introduced through anhydride esterification. First- and second-generation constructs, G1-(Dicl)₃-(mPEG)₆ and G2-(Dicl)₉-(mPEG)₁₂, assembled into amphiphilic core–shell nanostructures with hydrodynamic diameters of 170–330 nm and well-defined drug loading. G1-(Dicl)₃-(mPEG)₆ demonstrated the strongest therapeutic performance, reducing viability by 50–70% in MCF-7, U-87 MG, and PANC-1 cancer cells at 1–10 μM while maintaining >95% viability in noncancerous fibroblasts. This represents a >20-fold improvement in therapeutic index compared to free diclofenac. G2-(Dicl)₉-(mPEG)₁₂ displayed potent but cell-line-dependent activity, with highest efficacy in MCF-7 cells. Both dendrimers required 10–100× lower concentrations than free diclofenac to induce comparable reactive oxygen species (ROS) levels, with G1 producing 3–4-fold ROS elevation at 10 μM and G2 achieving similar induction at 0.1 μM. Mechanistic analysis confirmed ROS-mediated cytotoxicity as a key contributing pathway and correlated directly with cytotoxicity across various cancer models. These findings establish HFDs as an adaptable nanomedicine platform for repurposing clinically approved drugs, with G1 dendrimer providing the optimal balance of efficacy, selectivity, and translational potential.

Despite advances in scaffold development, many current biomaterials suffer from limited processability or poor biological performance. To address this, we previously introduced two novel triazine-trione (TATO)-based thermosets, T-ene and T-yne, as candidates for tissue engineering applications. In the present study, we aim to comprehensively evaluate the initial cellular response of bone marrow mesenchymal stem/stromal cells (BMSC) on TATO materials and their osteogenic potential, with a particular focus on their suitability for bone tissue engineering applications. Both T-ene and T-yne demonstrated biocompatibility comparable to polycaprolactone (PCL), as assessed by in vitro cell behavior and the chorioallantoic membrane (CAM) assay. Transcriptomic profiling via RNA sequencing of BMSC cultured on the materials revealed upregulation of mitotic processes in cells on T-ene compared to T-yne and PCL. Expression profiling of 92 osteogenic genes after 14 days in osteogenic media showed distinct gene regulation patterns in BMSC on the TATO materials compared to PCL. However, osteogenic differentiation assays, such as Alkaline Phosphatase activity and Alizarin Red R staining, showed no significant differences among the groups. These results suggest that T-ene and T-yne are promising, formable, and biocompatible candidates for use in bone tissue engineering applications.

In this study, a near-infrared (NIR)-responsive hydrogel based on ethylenediamine (EDA)-functionalized Gellan Gum was developed through a simple preparation method. This hydrogel incorporates in situ synthesized polydopamine (pDA) and was loaded with first- and second-generation antimicrobial bis-MPA polyester dendrimers (TMP-G1-[Cys]6 and MP-G2-[Cys]12), bearing cysteamine hydrochloride as peripheral functional groups. The intrinsic ability of pDA to scavenge reactive oxygen species (ROS) and convert NIR light at 810 nm into heat imparted radical scavenging activity and photothermal properties to the systems. It has been demonstrated that, due to the noncovalent interactions with both GG-EDA and pDA, dendrimers are retained differently within the sample depending on their molecular weight and the number of terminal positive charges. This difference in retention influences their antimicrobial activity against Pseudomonas aeruginosa and Staphylococcus aureus. In particular, it has been shown that the NIR-induced photothermal effect plays a crucial role in triggering the activity of the sample loaded with the most retained dendrimer, which possesses the highest number of terminal positive charges. The high physiological fluid absorption capacity makes these materials ideal for wound exudate management. In addition, their resistance to hydrolytic degradation can be exploited to reduce the frequency of dressing changes, potentially improving patient comfort. The dendrimer-loaded samples demonstrated low cytotoxicity toward human fetal dermal mesenchymal stromal cells (FD-MSCs) and human epidermal keratinocytes (HaCaT). These findings suggest that GG-EDA@pDA+TMP-G1-[Cys]6 or TMP-G2-[Cys]12 could be promising candidates for the treatment of infected skin wounds.

Metal plates are commonly used for the fixation of metacarpal fractures, but are associated with complications such as tendon adhesions that impair finger mobility. AdhFix, a novel osteosynthesis material, may reduce these complications, but its biomechanical performance in the metacarpal region remains untested. This study aimed to evaluate internal bending moments during postoperative rehabilitation and assess the biomechanical potential of AdhFix in treating comminuted metacarpal shaft fractures using a human cadaveric model. In five cadaveric hands, unstable shaft fractures of the second, third, and fourth metacarpals were simulated using a 3 mm osteotomy gap and stabilized with polyether ether ketone (PEEK) plates and stainless-steel cortical screws. A custom 3D-printed guide ensured accurate osteotomy and screw positioning. Tendon loading was simulated by pulling flexor digitorum profundus tendons until fingertip-to-palm contact was achieved, followed by wrist flexion using 100 N of force on the flexor carpi radialis and ulnaris tendons. Bending of the fixation was captured using stereographic imaging, and internal bending moments were calculated via finite element modeling. After removal of the PEEK plate, the procedure was repeated using AdhFix for fixation. Maximum internal bending moments were 6.14 ± 2.03 Nmm during finger flexion and 3.37 ± 1.64 Nmm during wrist flexion. AdhFix demonstrated mechanical integrity under both conditions with no observed failure. Statement of Clinical Significance: AdhFix may provide a mechanically stable alternative to conventional plates during early rehabilitation, potentially reducing tendon adhesions and preserving finger mobility.

Bioprinting allows for the fabrication of tissue-like constructs by precise architecture and positioning of the bioactive hydrogels with living cells. This study was performed to determine the effect of very low concentrations of alginate (0.1, 0.3, and 0.5% w/v) on bioprinting of bone marrow mesenchymal stem cells (BMSC) in gelatin methacryloyl (GelMA; 5% w/v)/alginate blend. Furthermore, while GelMA was photocrosslinked in all bioprinted constructs, the effect of crosslinking alginate with calcium chloride on the physical and biological characteristics of the constructs was investigated. The inclusion of low-concentration alginate improved the viscosity and printability of the formulation as well as the compressive modulus of the hydrogels, particularly when ionically crosslinked with calcium chloride, compared with the group in that alginate was not crosslinked. However, the stability and degradability of 3D printed scaffolds that were only photocrosslinked were comparable to those that were additionally crosslinked with calcium chloride. Noteworthily, ionic crosslinking of alginate deteriorated the viability of BMSC. Morphology and growth of BMSC were improved by adding a low alginate concentration; however, ionic crosslinking of alginate affected these factors adversely. The findings of this study underscore the significance of carefully evaluating the crosslinking strategy used in conjunction with cell-laden GelMA/alginate hydrogel to achieve balanced physical and biological properties as well as less complicated post-bioprinting processing.

Metal fixation is currently the standard of care for treating bone fractures surgically, as it provides ample stability to the healing bone. However, metal components have been associated with soft tissue adhesions and are generally not patient specific. A novel light-curable bone fixation method, called AdhFix, overcomes these disadvantages by allowing for in situ customizability and demonstrating a lack of soft tissue adhesions. Previous studies on this fixation technique have demonstrated the maximum bending and torsional moments in monotonic failure tests in dry conditions. However, this fixation has yet to be tested cyclically in a more physiological environment, which would represent an important step to assessing the clinical efficacy of this technology. This study aims to test the novel fixation method cyclically at relevant force levels in a controlled near-physiological environment. Midshaft osteotomies were performed on ovine proximal phalanges which were then fixated with the AdhFix osteosynthesis technique. The constructs were tested cyclically in four-point bending for 12,600 cycles, representing 6 weeks of rehabilitation, or until failure, while submerged in Ringer solution at 37°C. The samples were divided into four groups, each tested with a different peak force. The peak forces were based on safety factors (Group 1: 100x, Group 2: 150x, Group 3: 175x, Group 4: 250x) of a physiological bending moment present in a human proximal phalanx osteosynthesis during rehabilitation exercises, determined in a previous study. All samples survived at the lowest peak moment (Group 1), whereas all failed at the highest peak force (Group 4). Kaplan-Meier curves represented the survival probability as a function of the number of cycles for each group, and a log-rank test revealed that the survival curves were significantly different (p < 0.001). The difference in patch height between the failures and survivors was not statistically significant (p = 0.113), but the final cycle displacement amplitude was statistically different (p < 0.001). This study found that this novel osteosynthesis method can survive a clinically relevant number of cycles at a force level 100× the bending loads involved in typical non-weight-bearing rehabilitation exercises. Further studies are needed to confirm safety for other conditions.

Antimicrobial resistance is a global health crisis, necessitating novel antibacterial strategies. Polycations, particularly polyester dendrimers, are promising due to their structural precision and membrane-disruptive mechanisms. However, existing dendrimers lack versatility in charge distribution, limiting their antibacterial efficacy. Here, we report two families of cationic polyester dendrimers (up to the third generation) with either internal or combined internal and external charges compared with traditional bis-MPA dendrimers bearing only external cations. These heterofunctional dendrimers, built from AB₂C monomers, carry up to 45 charges at the highest generation. Internal propargyl amines were introduced via CuAAC chemistry, while external β-alanine provided complementary charges in the second family. Dendrimers with both internal and external charges showed superior antibacterial activity against Gram-positive and Gram-negative bacteria while maintaining biocompatibility. The second-generation dendrimer (G2-(PA-NH₃⁺)₉-(β-Ala-NH₃⁺)₁₂) exhibited bacteriostatic and bactericidal activity at 10–21 μM and enhanced Escherichia coli sensitivity, with favorable biodegradation, highlighting their promise as antimicrobials where charge distribution is key for efficacy.

A novel composite patch osteosynthesis technique (CPT) has demonstrated promising ex vivo biomechanical performance in small tubular bones. To bridge the gap toward clinical evaluations, this study compared the stability of the CPT to a stainless-steel locking plate (LP) in an experimental in vivo ovine bilateral proximal phalanx fracture model. Eight sheep underwent a midline osteotomy with a 4.5 mm circular unicortical defect in the lateral proximal phalanx of both front limbs, treated with the CPT (n = 8) or the LP (n = 8). A half-limb walking cast, or a custom off-loading hoof shoe, was used for postoperative protection. Implant stability was assessed by post-surgery X-ray evaluations and post-euthanasia (16 weeks) dual-energy X-ray absorptiometry (DXA). At week one, all CPT implants demonstrated mechanical failure, while all LPs remained overall intact. Mean BMD was 0.45 g/cm² for CPT and 0.60 g/cm² for LP in the fracture area (p = 0.078), and 0.37 g/cm² vs. 0.41 g/cm² in the distal epiphysis (p = 0.016), respectively. In conclusion, the CPT demonstrated indications of inferior stability compared to the LP in this fracture model, which may limit its clinical applicability in weight-bearing or high-load scenarios and in non-compliant patients.