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In this study, silk fibroin as a highly promising naturally occurring biopolymer extracted from silkworm cocoon is applied to mechanically reinforce silica aerogels. To this aim, two different approaches for the incorporation of silk fibroin into the silica network are compared: (1) a one-step acid catalyzed and (2) a two-step acid-base catalyzed sol–gel reaction. The total organosilane concentration, as well as the SF to silane mass fractions, regulated the hybridization process to proceed either through a one-step or two-step sol–gel reaction. In both processes, for an efficient chemical mixing the silk fibroin components with the silane phase, a silane coupling agent, 5-(trimethoxysilyl) pentanoic acid (TMSPA), comprising carboxylic acid groups and a pentyl hydrocarbon chain has been used. For a low organosilane content (3.4 mmol) along with a high SF to silane mass ratio (15–30%), the gelation of the silane and silk fibroin phases took place in a one-pot/one-step process in the presence of an acid catalyst in an entirely aqueous system. In the two-step synthesis approach, which was applied for high initial silane contents (17 mmol), and low SF to silane mass ratios (1–4%), first, the gelation of the silk fibroin phase was triggered by addition of an acid catalyst followed by a more pronounced condensation of the silane catalyzed by the addition of the base. Both synthesis approaches led to materials with promising mechanical properties—being 1) the one-step process resulting in gels with much better compressibility (up to 70% of strain), low density (0.17–0.22 g cm −3 ) and three orders of magnitude improvement in the Young’s modulus (13.5 MPa) compared to that of the pristine silica aerogel but with rather high shrinkage (30–40%). The two-step process in principle could result in the hybrid aerogel with interesting bulk density (0.17–0.28 g cm −3 ) with lower shrinkage (10%), but the resultant aerogel was stiff and fragile. Also, both approaches led to a significant reduction in the time required to prepare strong hybrid aerogels compared to conventional hybrid polymer-silica aerogels with the utilization of an entirely aqueous synthesis approach for a wide range of applications. Highlights Silk fibroin (SF) biopolymer is an interesting biopolymer for mechanical reinforcement of silica aerogel. Two sustainable sol–gel based approaches are proposed for hybridization of silica with SF. Hybrids obtained by the one step sol–gel synthesis approach demonstrate better mechanical performance. Molar ratio of SF to organosilanes is the most determinant factor for resulting final properties. Both synthesis approaches led to significant reduction in the time required for preparation of strong hybrid aerogels.

In this study, we have developed novel biomimetic silica composite aerogels and cryogels for the first time, drawing inspiration from the natural diatom’s silicification process. Our biomimetic approach involved the modification of tyrosinase-mediated oxidized silk fibroin (SFO) surfaces with polyethyleneimine (PEI). This modification introduced ample amine groups onto the SF polymer, which catalyzed the silicification of the SFO-PEI gel surface with silicic acid. This process emulates the catalytic function of long-chain polyamines and silaffin proteins found in diatoms, resulting in a silica network structure on the primary SFO-PEI network gel’s surface. The SFO-PEI gel matrix played a dual role in this process: (1) It provided numerous amine functional groups that directly catalyzed the silicification of silicic acid on the porous structure’s exterior surface, without encapsulating the created silica network in the gel. (2) It served as a flexible mechanical support facilitating the creation of the silica network. As a result, the final ceramic composite exhibits a mechanically flexible nature (e.g., cyclic compressibility up to 80% strain), distinguishing it from conventional composite aerogels. By mimicking the diatom’s silicification process, we were able to simplify the development of silica-polymer composite aerogels. It eliminates the need for surfactants, multi-step procedures involving solvent exchange, and gel washing. Instead, the reaction occurs under mild conditions, streamlining the composite aerogels fabrication process.

In recent years, smart/stimuli-responsive hydrogels have drawn tremendous attention for their varied applications, mainly in the biomedical field. These hydrogels are derived from different natural and synthetic polymers but are also composite with various organic and nano-organic fillers. The basic functions of smart hydrogels rely on their ability to change behavior; functions include mechanical, swelling, shaping, hydrophilicity, and bioactivity in response to external stimuli such as temperature, pH, magnetic field, electromagnetic radiation, and biological molecules. Depending on the final applications, smart hydrogels can be processed in different geometries and modalities to meet the complicated situations in biological media, namely, injectable hydrogels (following the sol-gel transition), colloidal nano and microgels, and three dimensional (3D) printed gel constructs. In recent decades smart hydrogels have opened a new horizon for scientists to fabricate biomimetic customized biomaterials for tissue engineering, cancer therapy, wound dressing, soft robotic actuators, and controlled release of bioactive substances/drugs. Remarkably, 4D bioprinting, a newly emerged technology/concept, aims to rationally design 3D patterned biological matrices from synthesized hydrogel-based inks with the ability to change structure under stimuli. This technology has enlarged the applicability of engineered smart hydrogels and hydrogel composites in biomedical fields. This paper aims to review stimuli-responsive hydrogels according to the kinds of external changes and t recent applications in biomedical and 4D bioprinting.

Aerogel‐based biomaterials are increasingly being considered for biomedical applications due to their unique properties such as high porosity, hierarchical porous network, and large specific pore surface area. Depending on the pore size of the aerogel, biological effects such as cell adhesion, fluid absorption, oxygen permeability, and metabolite exchange can be altered. Based on the diverse potential of aerogels in biomedical applications, this paper provides a comprehensive review of fabrication processes including sol‐gel, aging, drying, and self‐assembly along with the materials that can be used to form aerogels. In addition to the technology utilizing aerogel itself, it also provides insight into the applicability of aerogel based on additive manufacturing technology. To this end, how microfluidic‐based technologies and 3D printing can be combined with aerogel‐based materials for biomedical applications is discussed. Furthermore, previously reported examples of aerogels for regenerative medicine and biomedical applications are thoroughly reviewed. A wide range of applications with aerogels including wound healing, drug delivery, tissue engineering, and diagnostics are demonstrated. Finally, the prospects for aerogel‐based biomedical applications are presented. The understanding of the fabrication, modification, and applicability of aerogels through this study is expected to shed light on the biomedical utilization of aerogels. Aerogel‐based biomaterials are increasingly being considered for biomedical applications due to their unique properties such as high porosity, hierarchical porous network, and large specific pore surface area. Based on the diverse potential of aerogels, this paper provides a comprehensive review of fabrication processes, materials, and additive manufacturing along with the biomedical application utilizing aerogel technology.

This review highlights recent advancements in the synthesis, processing, properties, and applications of 2D‐material integrated hydrogels, with a focus on their performance in bone‐related applications. Various synthesis methods and types of 2D nanomaterials, including graphene, graphene oxide, transition metal dichalcogenides, black phosphorus, and MXene are discussed, along with strategies for their incorporation into hydrogel matrices. These composite hydrogels exhibit tunable mechanical properties, high surface area, strong near‐infrared (NIR) photon absorption and controlled release capabilities, making them suitable for a range of regeneration and therapeutic applications. In cancer therapy, 2D‐material‐based hydrogels show promise for photothermal and photodynamic therapies, and drug delivery (chemotherapy). The photothermal properties of these materials enable selective tumor ablation upon NIR irradiation, while their high drug‐loading capacity facilitates targeted and controlled release of chemotherapeutic agents. Additionally, 2D‐materials ‐infused hydrogels exhibit potent antibacterial activity, making them effective against multidrug‐resistant infections and disruption of biofilm generated on implant surface. Moreover, their synergistic therapy approach combines multiple treatment modalities such as photothermal, chemo, and immunotherapy to enhance therapeutic outcomes. In bio‐imaging, these materials serve as versatile contrast agents and imaging probes, enabling their real‐time monitoring during tumor imaging. Furthermore, in bone regeneration, most 2D‐materials incorporated hydrogels promote osteogenesis and tissue regeneration, offering potential solutions for bone defects repair. Overall, the integration of 2D materials into hydrogels presents a promising platform for developing multifunctional theragenerative biomaterials. 2D nanomaterials, with their ultrathin structures and unique properties, have revolutionized hydrogel‐based therapies for bone regeneration and disease treatment. This review discusses advancements in integrating 2D materials like graphene and MXene into hydrogels, enhancing their mechanical properties, drug release capabilities, and therapeutic efficacy in bone repair, cancer treatments, and antibacterial applications.

In this study we develop novel type of antibacterial chitosan-propolis NPs to improve theantimicrobial activity against various pathogens. To this aim, we primarily extracted propolis with methylal and ethanol as green solvents and its encapsulation with chitosan NPs. The developed propolis loaded chitosan NPs indicated antimicrobial and anti-biofilm properties against various gram positive and negative . FTIR revealed the successful encapsulation of the propolis extract with Ethanol (PE) and Methylal (PM) into the chitosan nano career matrix. HPLC and GC-MASS also confirmed the presence of flavonoids and phenols compounds of propolis extracted with both solvents. In addition, we confirmed the total phenolic and flavonoid compounds in propolis by calorimetric method of Folin–Ciocalteu and aluminum trichloride complex formation assays, respectively. PE-CH and PM-CH were optimized regarding physicochemical properties such as particle size, zeta potential, and poly dispersity index (PDI) index. DLS and SEM micrographs confirmed a spherical morphology in a range of 360–420 nm with Z potential values of 30–48 mV and PDI of 0.105–0.166 for PE-CH and PM-CH, respectively. The encapsulation efficiency was evaluated using colorimetric analysis, with median values ranging from 90 to 92%. The MIC values within the range of 2 to 230 µg/ml and MBC values between 3 to 346 μg/ml against both gram-positive and negative bacteria. While both PE and PM showed a significant reduction in the number of E. coli, S. aureus, and S. epidermidis , the use of PE-CH and PM-CH led to a statistically significant and greater reduction in number of E. coli, S. aureus, and S. epidermidis strains on the biofilm, pre-formed biofilm and planktonic phases. Besides, the DPPH assay showed significant antioxidant activity for these NPs within the range of 36 to 92%. MTT assay for MHFB-1, HFF, L929, MDF, and MCF-7 cells exhibited statistically significant differences in each other that show the IC50 between 60–160 µg/ml for normal cells and 20 for cancer cells. Finally the present study indicated that both PM and PM-CH greater than PE and PE-CH in which contain high flavonoid and phenolic contents with a high antioxidation potential antioxidant properties, which could be beneficial for cell proliferation and antibiotic and anticancer applications.

The application of silica mesoporous structures in drug delivery and the removal of pollutants and organic compounds through catalytic reactions is increasing due to their unique characteristics, including high loading capacities, tunable pores, large surface areas, sustainability, and so on. This review focuses on very well-studied class of different construction mesoporous silica nano(particles), such as MCM-41, SBA-15, and SBA-16. We discuss the essential parameters involved in the synthesis of these materials with providing a diverse set of examples. In addition, the recent advances in silica mesoporous structures for drug delivery and catalytic applications are presented to fill the existing gap in the literature with providing some promising examples on this topic for the scientists in both industry and academia active in the field. Regarding the catalytic applications, mesoporous silica particles have shown some promises to remove the organic pollutants and to synthesize final products with high yields due to the ease with which their surfaces can be modified with various ligands to create appropriate interactions with target molecules. In the drug delivery process, as nanocarriers, they have also shown very good performance thanks to the easy surface functionalization but also adjustability of their porosities to providing in-vivo and in-vitro cargo delivery at the target site with appropriate rate.

2D Nanomaterials‐Integrated Hydrogels In article number 2403204, Hajar Malek and co‐workers discuss advancements in 2D nanomaterial integrated hydrogels, focusing on their synthesis, properties, and bone‐related applications. These hydrogels exhibit tunable mechanical properties, strong NIR absorption, and controlled release, making them ideal for cancer therapy, antibacterial applications, bio‐imaging, and bone regeneration, highlighting their potential as multifunctional theragenerative biomaterials.

Aerogel‐Based Biomaterials In light of the diverse capabilities of aerogels, article number 2204681 by Solmaz Karamikamkar, Han‐Jun Kim, Ali Khademhosseini, and co‐workers, presents a thorough examination of the fabrication processes, materials, and additive manufacturing techniques associated with aerogel technology. Additionally, it presents an extensive survey of the diverse biomedical applications that leverage the potential of aerogels, with a particular emphasis on addressing various diseases.

The high toxicity/volatility and low biodegradation of phenolic compounds are serious concerns in terms of environmental and health impact—their recommended max. value for drinking water is 0.005 mg/L. They are usually removed from effluents by adsorption, but they show a complex interaction behavior with adsorbents, because the hydroxyl group and the hydrophobic aromatic ring are very close. In this work, the versatility of Si chemistry was explored to tailor the surface chemistry of silica aerogels and improve their adsorption performance towards phenolic compounds. Methyltrimethoxysilane and tetramethylorthosilicate were combined to adjust the hydrophobicity of the obtained aerogels. In the next stage, β-cyclodextrin, with its highly hydrophobic cavity, was grafted into the gels to improve the capturing of aromatic rings. For a sustainable linkage of β-cyclodextrin to silica, the methyltrimethoxysilane/tetramethylorthosilicate precursor system was modified by adding an epoxy functionalized silane. A first screening of the adsorption performance shows a 1.5–2-fold increase of the adsorption capacity and removal efficiencies of the epoxy-cyclodextrin-modified aerogel toward phenol and p -cresol when compared to aerogel counterpart without modification. Freundlich isotherm model was the most suitable to describe the equilibrium data of aerogels with or without β-cyclodextrin, with the curves showing favorable profiles, more evident in the case of aerogels with β-cyclodextrin. Apart from the improving of the sorption capacity for phenolic compounds (achieving a maximum of 60 mg g −1 in the case of p -cresol), the utilization of the biodegradable β-cyclodextrin moiety obtained from natural and sustainable resources is a further asset of the epoxy-cyclodextrin-modified aerogel. Graphical Abstract