Polysaccharide-Based Hybrid Self-Healing Hydrogel Supports the Paracrine Response of Mesenchymal Stem Cells

Transdermal Delivery of Niacin Through Polysaccharide Films Ameliorates Cutaneous Flushing in Experimental Wistar Rats

BACKGROUND

Niacin, an established therapeutic for dyslipidemia, is hindered by its propensity to induce significant cutaneous flushing when administered orally in its unmodified state, thereby constraining its clinical utility.

OBJECTIVE

This study aimed to fabricate, characterize, and assess the in-vitro and in-vivo effectiveness of niacin-loaded polymeric films (NLPFs) comprised of carboxymethyl tamarind seed polysaccharide. The primary objective was to mitigate the flushing-related side effects associated with oral niacin administration.

METHODS

NLPFs were synthesized using the solvent casting method and subsequently subjected to characterization, including assessments of tensile strength, moisture uptake, thickness, and folding endurance. Surface characteristics were analyzed using a surface profiler and scanning electron microscopy (SEM). Potential interactions between niacin and the polysaccharide core were investigated through X-ray diffraction experiments (XRD) and Fourier transform infrared spectroscopy (FTIR). The viscoelastic properties of the films were explored using a Rheometer. In-vitro assessments included drug release studies, swelling behavior assays, and antioxidant assays. In-vivo efficacy was evaluated through skin permeation assays, skin irritation assays, and histopathological analyses.

RESULTS

NLPFs exhibited a smooth texture with favorable tensile strength and moisture absorption capabilities. Niacin demonstrated interaction with the polysaccharide core, rendering the films amorphous. The films displayed slow and sustained drug release, exceptional antioxidant properties, optimal swelling behavior, and viscoelastic characteristics. Furthermore, the films exhibited biocompatibility and non-toxicity towards skin cells.

CONCLUSION

NLPFs emerged as promising carrier systems for the therapeutic transdermal delivery of niacin, effectively mitigating its flushing-associated adverse effects.

Advances in Hydrogel-Based Drug Delivery Systems

Hydrogels, with their distinctive three-dimensional networks of hydrophilic polymers, drive innovations across various biomedical applications. The ability of hydrogels to absorb and retain significant volumes of water, coupled with their structural integrity and responsiveness to environmental stimuli, renders them ideal for drug delivery, tissue engineering, and wound healing. This review delves into the classification of hydrogels based on cross-linking methods, providing insights into their synthesis, properties, and applications. We further discuss the recent advancements in hydrogel-based drug delivery systems, including oral, injectable, topical, and ocular approaches, highlighting their significance in enhancing therapeutic outcomes. Additionally, we address the challenges faced in the clinical translation of hydrogels and propose future directions for leveraging their potential in personalized medicine and regenerative healthcare solutions.

Highly Biocompatible Smart Injectable Hydrogel for the Management of Rheumatoid Arthritis

Rheumatoid arthritis (RA) is a chronic inflammatory disease that severely affects joints and restricts locomotion. Various treatment regimens are available for RA, providing short-term relief from pain, but long-term relief from the disease is still not available. Evidently, cytokines play a crucial role in the pathophysiology of the disease. However, aberrant immune responses, genetic dispositions, viral infections, or toxicants are some possible causative mediators of RA. The synovial fluid of rheumatoid arthritis patients encompass cytokines, especially osteoclastogenic cytokines, and invasion factors such as macrophage colony-stimulating factor (M-CSF) and the receptor activator of NF-κB ligand (RANKL). Moreover, tumor necrosis factor-α (TNF-α) and interleukins (IL-1, 6, and 17) intensify osteoclast differentiation and activation. Therefore, in order to restrict the cytokine expression, we used budesonide as a therapeutic lead and encapsulated it into a highly biocompatible hydrogel system. The hydrogel system developed by us is enzyme-responsive and provides sustained drug release flow over an extended period of time. This hydrogel is characterized by ζ-potential analysis, field-emission scanning electron microscopy (FE-SEM), and attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy, and it is further encapsulated with budesonide (glucocorticoids) for therapeutic purposes. Evidently, Bud-loaded ER-hydrogel showed improvement in joint physiology compared to the disease group and downregulated the inflammatory markers.

Post-Implantation Stiffening by a Bioinspired, Double-Network, Self-Healing Hydrogel Facilitates Minimally Invasive Cell Delivery for Cartilage Regeneration

Injectable hydrogels have demonstrated advantages in cartilage repair by enabling the delivery of cells through a minimally invasive approach. However, several injectable hydrogels suffer from rapid degradation and low mechanical strength. Moreover, higher mechanical stiffness in hydrogels can have a detrimental effect on post-implantation cell viability. To address these challenges, we developed an in situ forming bioinspired double network hydrogel (BDNH) that exhibits temperature-dependent stiffening after implantation. The BDNH mimics the microarchitecture of aggrecan, with hyaluronic acid-conjugated poly(N-isopropylacrylamide) providing rigidity and Schiff base crosslinked polymers serving as the ductile counterpart. BDNHs exhibited self-healing property and enhanced stiffness at physiological temperature. Excellent cell viability, long time cell proliferation, and cartilage specific matrix production were observed in the chondrocytes cultured in the BDNH hydrogel. Evidence of cartilage regeneration in a rabbit cartilage defect model using chondrocyte-laden BDNH has suggested it to be a potential candidate for cartilage tissue engineering.

Macromolecule-based hydrogels nanoarchitectonics with mesenchymal stem cells for regenerative medicine: A review

The role of regenerative medicine in clinical therapies is becoming increasingly vital. Under specific conditions, mesenchymal stem cells (MSCs) are capable of differentiating into mesoblastema (i.e., adipocytes, chondrocytes, and osteocytes) and other embryonic lineages. Their application in regenerative medicine has attracted a great deal of interest among researchers. To maximize the potential applications of MSCs, materials science could provide natural extracellular matrices and provide an effective means to understand the various mechanisms of differentiation for the growth of MSCs. Pharmaceutical fields are represented among the research on biomaterials by macromolecule-based hydrogel nanoarchitectonics. Various biomaterials have been used to prepare hydrogels with their unique chemical and physical properties to provide a controlled microenvironment for the culture of MSCs, laying the groundwork for future practical applications in regenerative medicine. This article currently describes and summarizes the sources, characteristics, and clinical trials of MSCs. In addition, it describes the differentiation of MSCs in various macromolecule-based hydrogel nanoarchitectonics and highlights the preclinical studies of MSCs-loaded hydrogel materials in regenerative medicine conducted over the past few years. Finally, the challenges and prospects of MSC-loaded hydrogels are discussed, and the future development of macromolecule-based hydrogel nanoarchitectonics is outlined by comparing the current literature.

Injectable Bone Cement Reinforced with Gold Nanodots Decorated rGO-Hydroxyapatite Nanocomposites, Augment Bone Regeneration

Interest in the development of new generation injectable bone cements having appropriate mechanical properties, biodegradability, and bioactivity has been rekindled with the advent of nanoscience. Injectable bone cements made with calcium sulfate (CS) are of significant interest, owing to its compatibility and optimal self-setting property. Its rapid resorption rate, lack of bioactivity, and poor mechanical strength serve as a deterrent for its wide application. Herein, a significantly improved CS-based injectable bone cement (modified calcium sulfate termed as CS_mod ), reinforced with various concentrations (0-15%) of a conductive nanocomposite containing gold nanodots and nanohydroxyapatite decorated reduced graphene oxide (rGO) sheets (AuHp@rGO), and functionalized with vancomycin, is presented. The piezo-responsive cement exhibits favorable injectability and setting times, along with improved mechanical properties. The antimicrobial, osteoinductive, and osteoconductive properties of the CS_mod cement are confirmed using appropriate in vitro studies. There is an upregulation of the paracrine signaling mediated crosstalk between mesenchymal stem cells and human umbilical vein endothelial cells seeded on these cements. The ability of CS_mod to induce endothelial cell recruitment and augment bone regeneration is evidenced in relevant rat models. The results imply that the multipronged activity exhibited by the novel-CS_mod cement would be beneficial for bone repair.

Construction of a cellulose-based high-performance adhesive with a crosslinking structure bridged by Schiff base and ureido groups

Biomass-based adhesives are considered to be the preferred alternative to formaldehyde-type wood adhesives due to their wide range of sources, low cost, and sustainability. Herein, an environmentally friendly Schiff base cross-linked compact three-dimensional network structure bio-adhesive (DAC-PEI-U) derived from polyethyleneimine (PEI), urea, and cellulose was successfully prepared, verifying by detailed FTIR, NMR, and XPS analysis. Schiff base bridging between aldehyde groups in dialdehyde cellulose (DAC) and amino groups in polyurea (PEIU) not only constructed crosslinking networks but also endowed adhesives with good adhesion property. The dry bond strength of DAC-PEI-U adhesive reached 2.71 MPa, and the wet shear strength was 1.51 MPa (hot water) and 1.34 MPa (boiling water), respectively. It not only improves the water resistance and bonding process, but also displays simple synthesis and low cost. The improved performance of DAC-PEI-U adhesive is attributed to the generation of hyperbranched cross-linking structure in the adhesive system, which results in increased cross-linking density and promotes the formation of dense cross-sections in the curing adhesive. This work paves a solid way for developing cellulose-based wood adhesives with wet bonding properties, thus holding great potential as an alternative to formaldehyde-type adhesives in wood-based panel and indoor panel bonding industries.

Polysaccharides-Based Injectable Hydrogels: Preparation, Characteristics, and Biomedical Applications

Polysaccharides-based injectable hydrogels are a unique group of biodegradable and biocompatible materials that have shown great potential in the different biomedical fields. The biomolecules or cells can be simply blended with the hydrogel precursors with a high loading capacity by homogenous mixing. The different physical and chemical crosslinking approaches for preparing polysaccharide-based injectable hydrogels are reviewed. Additionally, the review highlights the recent work using polysaccharides-based injectable hydrogels as stimuli-responsive delivery vehicles for the controlled release of different therapeutic agents and viscoelastic matrix for cell encapsulation. Moreover, the application of polysaccharides-based injectable hydrogel in regenerative medicine as tissue scaffold and wound healing dressing is covered.

Protease-responsive hydrogel, cross-linked with bioactive curcumin-derived carbon dots, encourage faster wound closure

The pharmacological effects of curcumin can be ascribed to its dose-dependent activity. Therapeutic application of curcumin is hindered by its poor solubility and low bioavailability. Carbon dots are gaining attention in biomedical applications in view of their unique photo-physical properties. Some carbon dots derived from bioactive molecules have shown superior activity than the parent compound. With an aim to address the limitations of curcumin, herein we compared the wound healing activity of curcumin-derived carbon dots (CurCD) with curcumin. The improved solubility and stability of CurCD, combined with its superior proliferative, proangiogenic and anti-bacterial activity suggested that CurCD would be more beneficial than curcumin in wound healing. To enable the sustained release of CurCD at the wound site, a protease-responsive hydrogel (GHCD) was prepared with CurCD acting as a cross-linker. A comparative study using a skin excision model revealed that GHCD supported faster wound closure with improved angiogenesis and complete restoration of the epithelium. Apart from the establishment of CurCD as a wound healing agent, the study provides a novel carbon dot based approach for molecules with limitations of solubility and bioavailability.

Manufacturing of self-standing multi-layered 3D-bioprinted alginate-hyaluronate constructs by controlling the cross-linking mechanisms for tissue engineering applications

3D bioprinting of self-supporting stable tissue and organ structure is critically important in extrusion-based bioprinting system, especially for tissue engineering and regenerative medicine applications. However, the development of self-standing bioinks with desired crosslinking density, biocompatibility, tunable mechanical strength and other properties like self-healing, in situ gelation, drug or protein incorporation is still a challenge. In this study, we report a hydrogel bioink prepared from alginate (Alg) and hyaluronic acid (HA) crosslinked through multiple crosslinking mechanisms, i.e., acyl-hydrazone, hydrazide interactions and calcium ions. These Alg-HA gels were highly dynamic and shear-thinning with exceptional biocompatibility and tunable mechanical properties. The increased dynamic nature of the gels is mainly chemically attributed to the presence of acyl-hydrazone bonds formed between the amine groups of the acyl-hydrazide of alginate and the monoaldehyde of the hyaluronic acid. Among the different combinations of Alg-HA gel compositions prepared, the A5H5 (Alginate-acyl-hydrazide: HA-monoaldehyde, ratio 50:50) one showed a gelation time of ~60 s, viscosity of ~400 Pa.s (at zero shear rate), high stability in various pH solutions and increased degradation time (>50 days) than the other samples. The A5H5 gels showed high printability with increased post-printing stability as observed from the 3D printed structures (e.g., hollow tube (~100 layers), porous cube (~50 layers), star, heart-in, meniscus and lattice). The scanning electron microscopy analysis of the 3D constructs and hydrogels showed the interconnected pores (~181 µm) and crosslinked networks. Further, the gels showed sustained release of 5-amino salicylic acid and bovine serum albumin. Also, the mechanical properties were tuned by secondary crosslinking via different calcium concentrations. In vitro assays confirmed the cytocompatibility of these gels, where the 3D bioprinted lattice and tubular (~70 layers) constructs demonstrated high cell viability under fluorescence analysis. In in vivo studies, Alg-HA gel showed high biocompatibility (>90%) and increased angiogenesis (3 folds) and reduced macrophage infiltration (2-fold decrease), demonstrating the promising potential of these hydrogels in 3D bioprinting applications for tissue engineering and regenerative medicine with tunable properties.

Design of Injectable Poly(γ-glutamic acid)/Chondroitin Sulfate Hydrogels with Mineralization Ability

Biocompatible hydrogels are considered promising agents for application in bone tissue engineering. However, the design of reliable hydrogels with satisfactory injectability, mechanical strength, and a rapid biomineralization rate for bone regeneration remains challenging. Herein, injectable hydrogels are fabricated using hydrazide-modified poly(γ-glutamic acid) and oxidized chondroitin sulfate by combining acylhydrazone bonds and ionic bonding of carboxylic acid groups or sulfate groups with calcium ions (Ca²⁺). The resulting hydrogels display a fast gelation rate and good self-healing ability due to the acylhydrazone bonds. The introduction of Ca²⁺ at a moderate concentration enhances the mechanical strength of the hydrogels. The self-healing capacity of hydrogels is improved, with a healing efficiency of 87.5%, because the addition of Ca²⁺ accelerates the healing process of hydrogels. Moreover, the hydrogels can serve as a robust template for biomineralization. The mineralized hydrogels with increasing Ca²⁺ concentration exhibit rapid formation and high crystallization of apatite after immersion in simulated body fluid. The hydrogels containing the aldehyde groups possess good bioadhesion to the bone and cartilage tissues. With these superior properties, the developed hydrogels demonstrate potential applicability in bone tissue engineering.

Recent Progress in Biopolymer-Based Hydrogel Materials for Biomedical Applications

Hydrogels from biopolymers are readily synthesized, can possess various characteristics for different applications, and have been widely used in biomedicine to help with patient treatments and outcomes. Polysaccharides, polypeptides, and nucleic acids can be produced into hydrogels, each for unique purposes depending on their qualities. Examples of polypeptide hydrogels include collagen, gelatin, and elastin, and polysaccharide hydrogels include alginate, cellulose, and glycosaminoglycan. Many different theories have been formulated to research hydrogels, which include Flory-Rehner theory, Rubber Elasticity Theory, and the calculation of porosity and pore size. All these theories take into consideration enthalpy, entropy, and other thermodynamic variables so that the structure and pore sizes of hydrogels can be formulated. Hydrogels can be fabricated in a straightforward process using a homogeneous mixture of different chemicals, depending on the intended purpose of the gel. Different types of hydrogels exist which include pH-sensitive gels, thermogels, electro-sensitive gels, and light-sensitive gels and each has its unique biomedical applications including structural capabilities, regenerative repair, or drug delivery. Major biopolymer-based hydrogels used for cell delivery include encapsulated skeletal muscle cells, osteochondral muscle cells, and stem cells being delivered to desired locations for tissue regeneration. Some examples of hydrogels used for drug and biomolecule delivery include insulin encapsulated hydrogels and hydrogels that encompass cancer drugs for desired controlled release. This review summarizes these newly developed biopolymer-based hydrogel materials that have been mainly made since 2015 and have shown to work and present more avenues for advanced medical applications.

Mechanical Integrity in a Dynamic Interpenetrating Hydrogel Network of Supramolecular Peptide-Polysaccharide Supports Enhanced Chondrogenesis

Tissue engineering demands intelligently designed scaffolds that encompass the properties of the target tissues in terms of mechanical and bioactive properties. An ideal scaffold for engineering a cartilage tissue should provide the chondrocytes with a favorable 3D microarchitecture apart from possessing optimal mechanical characteristics such as compressibility, energy dissipation, strain stiffening, etc. Herein, we used a unique design approach to develop a hydrogel having a dynamic interpenetrating network to serve as a framework to support chondrocyte growth and differentiation. An amyloid-inspired peptide amphiphile (1) was self-assembled to furnish kinetically controlled nanofibers and incorporated in a dynamic covalently cross-linked polysaccharide network of carboxymethyl cellulose dialdehyde (CMC-D) and carboxymethyl chitosan (CMCh) using Schiff base chemistry. The dynamic noncovalent interaction played a pivotal role in providing the desired modulation in the structure and mechanical properties of the double-network hydrogels that are imperative for cartilage scaffold design. The adaptable nature supported shear-induced extrusion of the hydrogel and facilitated various cellular functions while maintaining its integrity. The potential of the as-developed hydrogels to support in vitro chondrogenesis was explored using human chondrocytes. Evidence of improved cell growth and cartilage-specific ECM production confirmed the potential of the hydrogel to support cartilage tissue engineering while reaffirming the significance of mimicking the biophysical microenvironment to induce optimal tissue regeneration.

An injectable hydrogel having proteoglycan-like hierarchical structure supports chondrocytes delivery and chondrogenesis

The ECM of cartilage is composed of proteoglycans (PG) that contain glycosaminoglycan (GAG), aggrecan, hyaluronic acid (HA) and other molecular components which play an important role in regulating chondrocyte functions via cell-matrix interactions, integrin-mediated signalling etc. Implantation of chondrocytes encapsulated in scaffolds that mimic the micro-architecture of proteoglycan, is expected to enhance cartilage repair. With an aim to create a hydrogel having macromolecular structure that resembles the cartilage-specific ECM, we constructed a hierarchal structure that mimic the PG. The bottle brush structure of the aggrecan was obtained using chondroitin sulphate and carboxymethyl cellulose which served as GAG and core protein mimic respectively. A proteoglycan-like structure was obtained by cross-linking it with modified chitosan that served as a HA substitute. The physico-chemical characteristics of the above cross-linked injectable hydrogel supported long term human articular chondrocyte subsistence and excellent post-injection viability. The chondrocytes encapsulated in the PMH expressed significant levels of articular cartilage specific markers like collagen II, aggrecan, GAGs etc., indicating the ability of the hydrogel to support chondrocyte differentiation. The biocompatibility and biodegradability of the hydrogels was confirmed using suitable in vivo studies. The results revealed that the PG-mimetic hydrogel could serve as a promising scaffold for chondrocyte implantation.

Self-Healing Hydrogels: Preparation, Mechanism and Advancement in Biomedical Applications

Polymeric hydrogels are widely explored materials for biomedical applications. However, they have inherent limitations like poor resistance to stimuli and low mechanical strength. This drawback of hydrogels gave rise to ''smart self-healing hydrogels'' which autonomously repair themselves when ruptured or traumatized. It is superior in terms of durability and stability due to its capacity to reform its shape, injectability, and stretchability thereby regaining back the original mechanical property. This review focuses on various self-healing mechanisms (covalent and non-covalent interactions) of these hydrogels, methods used to evaluate their self-healing properties, and their applications in wound healing, drug delivery, cell encapsulation, and tissue engineering systems. Furthermore, composite materials are used to enhance the hydrogel's mechanical properties. Hence, findings of research with various composite materials are briefly discussed in order to emphasize the healing capacity of such hydrogels. Additionally, various methods to evaluate the self-healing properties of hydrogels and their recent advancements towards 3D bioprinting are also reviewed. The review is concluded by proposing several pertinent challenges encountered at present as well as some prominent future perspectives.

Tunable, conductive, self-healing, adhesive and injectable hydrogels for bioelectronics and tissue regeneration applications

Conductive hydrogels are attracting considerable interest in view of their potential in a wide range of applications that include healthcare and electronics. Such hydrogels are generally incorporated with conductive materials/polymers. Herein, we present a series of conductive hydrogels (Ch-CMC-PDA), prepared with no additional conductive material. The hydrogels were synthesized using a combination of chitosan, cellulose (CMC) and dopamine (DA). The conductivity (0.01-3.4 × 10^-3 S cm^-1) in these gels is attributed to ionic conductivity. Very few conductive hydrogels are endowed with additional properties like injectability, adhesiveness and self-healing, which would help to widen their scope for applications. While the dynamic Schiff base coupling in our hydrogels facilitated self-healing and injectable properties, polydopamine imparted tissue adhesiveness. The porosity, rheological, mechanical and conductive properties of the hydrogels are regulated by the CMC-dialdehyde-polydopamine (CMC-D-PDA) content. The hydrogel was evaluated in various bioelectronics applications like ECG monitoring and triboelectric nanogenerators (TENG). The ability of the hydrogel to support cell growth and serve as a template for tissue regeneration was confirmed using in vitro and in vivo studies. In summary, the integration of such remarkable features in the ionic-conductive hydrogel would enable its usage in bioelectronics and biomedical applications.

Designing Hydrogels for 3D Cell Culture Using Dynamic Covalent Crosslinking

Designing simple biomaterials to replicate the biochemical and mechanical properties of tissues is an ongoing challenge in tissue engineering. For several decades, new biomaterials have been engineered using cytocompatible chemical reactions and spontaneous ligations via click chemistries to generate scaffolds and water swollen polymer networks, known as hydrogels, with tunable properties. However, most of these materials are static in nature, providing only macroscopic tunability of the scaffold mechanics, and do not reflect the dynamic environment of natural extracellular microenvironment. For more complex applications such as organoids or co-culture systems, there remain opportunities to investigate cells that locally remodel and change the physicochemical properties within the matrices. In this review, advanced biomaterials where dynamic covalent chemistry is used to produce stable 3D cell culture models and high-resolution constructs for both in vitro and in vivo applications, are discussed. The implications of dynamic covalent chemistry on viscoelastic properties of in vitro models are summarized, case studies in 3D cell culture are critically analyzed, and opportunities to further improve the performance of biomaterials for 3D tissue engineering are discussed.

Self-crosslinking hyaluronic acid-carboxymethylcellulose hydrogel enhances multilayered 3D-printed construct shape integrity and mechanical stability for soft tissue engineering

One of the primary challenges in extrusion-based 3D bioprinting is the ability to print self-supported multilayered constructs with biocompatible hydrogels. The bioinks should have sufficient post-printing mechanical stability for soft tissue and organ regeneration. Here, we report on the synthesis, characterization and 3D printability of hyaluronic acid (HA)-carboxymethylcellulose (CMC) hydrogels cross-linked through N-acyl-hydrazone bonding. The hydrogel's hydrolytic stability was acquired by the effects of both the prevention of the oxidation of the six-membered rings of HA, and the stabilization of acyl-hydrazone bonds. The shear-thinning and self-healing properties of the hydrogel allowed us to print different 3D constructs (lattice, cubic and tube) of up to 50 layers with superior precision and high post-printing stability without support materials or post-processing depending on their compositions (H7:C3, H5:C5 and H3:C7). Morphological analyses of different zones of the 3D-printed constructs were undertaken for verification of the interconnection of pores. Texture profile analysis (TPA) (hardness (strength), elastic recovery, etc) and cyclic compression studies of the 3D-printed constructs demonstrated exceptional elastic properties and fast recovery after 50% strain, respectively, which have been attributed to the addition of CMC into HA. A model drug quercetin was released in a sustained manner from hydrogels and 3D constructs. In vitro cytotoxicity studies confirmed the excellent cyto-compatibility of these gels. In vivo mice studies prove that these biocompatible hydrogels enhance angiogenesis. The results indicate that controlling the key properties (e.g. self-crosslinking capacity, composition) can lead to the generation of multilayered constructs from 3D-bioprintable HA-CMC hydrogels capable of being leveraged for soft tissue engineering applications.

Bactericidal Characteristics of Bioinspired Nontoxic and Chemically Stable Disordered Silicon Nanopyramids

Controlling bacterial growth using artificial nanostructures inspired from natural species is of immense importance in biomedical applications. In the present work, a low cost, fast processing, and scalable anisotropic wet etching technique is developed to fabricate the densely packed disordered silicon nanopyramids (SiNPs) with nanosized sharp tips. The bactericidal characteristics of SiNPs are assessed against strains implicated in nosocomial and biomaterial-related infections. Compared to the bare silicon with no antibacterial activities, SiNPs of 1.85 ± 0.28 μm height show 55 and 75% inhibition of Escherichia coli (Gram-negative) and Bacillus subtilis (Gram-positive) bacteria, whereas the silicon nanowires (SiNWs) fabricated using a metal-assisted chemical etching method show 50 and 58% inhibition of E. coli and B. subtilis. The mechanistic studies using a scanning electron microscope and live/dead bacterial cell assay reveal cell rupture and predominance of dead cells on contact with SiNPs and SiNWs, which confirms their bactericidal effects. Chemical stability and cell viability studies demonstrate the biocompatible nature of SiNP and SiNW surfaces. Owing to their capability to kill both Gram-negative and positive bacteria and minimal toxicity to murine fibroblast cells, SiNPs can be used as an antibacterial coating on medical devices to prevent nosocomial and biomaterial-related infections.