Kannan Badri Narayanan

Wound healing is frequently perceived as a straightforward biological process; in practice, however, it remains a major challenge in clinical medicine due to the intricate, overlapping phases of hemostasis, inflammation, proliferation, and tissue remodeling

Three-dimensional (3D) bioprinting has emerged as a versatile biofabrication strategy that enables the precise, spatiotemporally controlled co-deposition of living cells, biomaterials, and bioactive agents, including growth factors, cytokines, and extracellular matrix (ECM) components, into geometrically defined 3D constructs. By translating digital design models derived from computed tomography (CT), magnetic resonance imaging (MRI), or computational modeling directly into physical tissue architectures, 3D bioprinting facilitates the assembly of hierarchically organized constructs that closely recapitulate the structural, mechanical, and functional characteristics of native tissues. The principal 3D bioprinting strategies are broadly classified into scaffold-based and scaffold-free approaches. Engineered bioinks, whether formulated as cell-laden natural, synthetic, or composite polymer hydrogels, tissue-derived decellularized ECM (dECM) components, or pure cellular spheroids and organoids, constitute the cornerstone of these biofabrication platforms. Scaffold-based 3D bioprinting comprises extrusion-based, droplet-based (inkjet and drop-on-demand), light-based vat photopolymerization (stereolithography and digital light processing), and laser-assisted bioprinting based on laser-induced forward transfer (LIFT). Each of these modalities imposes distinct constraints on bioink rheology, crosslinking mechanisms, spatial resolution, throughput, and post-printing cell viability; consequently, a specific 3D bioprinting strategy is selected according to the specific requirements of the target tissue application. Scaffold-free 3D bioprinting and bioassembly techniques, including the Kenzan method, aspiration-assisted bioprinting, magnetic bioprinting, and other field-directed tissue assembly approaches, enable the fabrication of spheroid- and organoid-based constructs without the necessity for exogenous biomaterial scaffolds. Because native tissues exhibit diversity in cellular composition, ECM architecture, mechanical properties, and physiological function, no individual bioprinting platform or bioink formulation serves as a universal 3D bioprinting solution. The engineering of biomimetic tissue constructs, therefore, requires the selection of application-tailored fabrication approaches. Under this biofabrication paradigm, 3D bioprinting has been applied across a wide range of tissue engineering targets, including skin, bone, cartilage, osteochondral interfaces, cardiac and vascular tissue, neural structures, ocular, dental, and adipose tissue. This review discusses recent advances in scaffold-based and scaffold-free 3D bioprinting applications for tissue engineering and regenerative medicine across diverse tissue systems.

Immunobiologics or biologics have revolutionized the therapeutic paradigm of autoimmune and inflammatory diseases by selectively targeting and modulating dysregulated immune pathways. Compared with conventional broad-spectrum immunosuppressants, biologics provide a more specific and mechanism-based rational approach, often associated with improved efficacy and reduced adverse events. This review provides a comprehensive overview of the repertoire of therapeutic biologics, their mechanisms of action, pivotal clinical trials, and clinical applications. We discuss biologics targeting T-cell activation, depletion, and adhesion, as well as agents neutralizing pro-inflammatory cytokines, including tumor necrosis factor (TNF), interleukin (IL)-1, IL-6, IL-12, IL-17, IL-22, and IL-23, in addition to B-cell-directed therapies and IgE-modulating agents. Evidence from randomized clinical trials and observational studies highlights the profound therapeutic impact of these agents across a broad spectrum of immune-mediated diseases, including rheumatoid arthritis, psoriasis, systemic lupus erythematosus (SLE), ankylosing spondylitis, chronic spontaneous urticaria, asthma, ulcerative colitis, Crohn’s disease, and other forms of inflammatory bowel disease (IBD). Pharmacodynamic parameters, including receptor-binding affinity and downstream pathway modulation, are critical determinants of therapeutic efficacy, whereas pharmacovigilance remains indispensable for monitoring risks such as immunogenicity, opportunistic infections, and manufacturing-related variability. Continuous regulatory oversight by agencies such as the United States Food and Drug Administration (FDA) and the European Medicines Agency (EMA) safeguards standards of safety, efficacy, and quality. In parallel, the expanding development of biosimilars offers a key opportunity to enhance affordability and broaden global access to biologic therapies. Despite substantial clinical progress, important challenges persist, including disease heterogeneity, variability in therapeutic response, long-term safety concerns, and issues of cost-effectiveness. Future directions emphasize precision medicine strategies, including biomarker-guided treatment, rationally designed biologic combinations, next-generation antibody engineering, and the development of high-quality biosimilars to improve therapeutic durability, safety, and accessibility equity. By integrating mechanistic insights with clinical outcomes, this review underscores the transformative role of immunobiologics and delineates strategies to optimize their application in the management of autoimmune and inflammatory diseases.

This study focuses on the synthesis, characterization, and comparative analysis of pure Zinc Oxide (ZnO), Silver-doped ZnO (Ag-ZnO), Copper-doped ZnO (Cu-ZnO), and silver-Copper co-doped ZnO (Ag-Cu-ZnO) nanomaterials, synthesized via the hydrothermal method. Structural, optical, and antibacterial properties were thoroughly investigated. The average crystallite size was found to be from ~ 22.7 nm to ~ 32.7 nm. UV-Vis spectroscopy indicated improved light absorption in the visible range for doped samples, with the optical band gap decreasing from 3.19 eV for pure ZnO to 3.15 eV (Cu-ZnO), 3.09 eV (Ag-ZnO), and 3.08 eV (Ag-Cu-ZnO). Photoluminescence spectra show dynamic quenching due to the inclusion of metal doping. Antibacterial studies showed improved activity for doped samples compared to pure ZnO. The catalytic activities of these nanomaterials for alcohol oxidation were also assessed, revealing that Ag-Cu-ZnO exhibited the highest catalytic efficiency, achieving complete (100%) conversion of benzoin to benzil with a 90% isolated yield, owing to the combined effects of Ag and Cu ions. Cu-ZnO showed better activity than Ag-ZnO, achieving ~ 87% conversion, but was less effective than the co-doped sample, while pure ZnO displayed the lowest reactivity (~ 72% conversion). These findings emphasize the potential of pristine and doped ZnO nanomaterials for advanced antibacterial and catalytic applications, particularly in environmental remediation.

Edible polymeric composite hydrogel films offer a promising solution for cultured meat production. These films are made by incorporating natural polysaccharides, synthetic biocompatible polymers, and antioxidants within the scaffolds. This approach can help combat global climate change and meet the increasing demand for sustainable food sources. The utilization of edible polysaccharides in the fabrication of hydrogels is a cost-effective and sustainable approach, which serves as effective scaffolding in the cultivation of meat. The polymeric composite hydrogel films, designated as "CSCP" (curcumin-starch-carrageenan-PVA) with varying concentrations of polymers, consist of curcumin (an antioxidant and coloring agent), starch (potato), kappa (κ)-carrageenan, and poly(vinyl alcohol) (PVA), with PVA being classified as generally recognized as safe (GRAS) for use in food applications. These edible polymeric composite hydrogel films were prepared with glycerol, serving as a plasticizer, and succinic acid, a crosslinker, through solvent casting and thermal treatment methods. Analytical techniques, including field-emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, and tensile strength testing, were employed to evaluate the morphology, crystalline nature, composition, and mechanical properties of the fabricated CSCP scaffolds. The incorporation of glycerol and succinic acid facilitates the plasticizing and cross-linking of the polymeric materials via hydroxyl and carboxyl group interactions during film formation. Increasing the potato starch content in the CSCP-2 composite hydrogel film reduced its mechanical strength. This is because the starch disrupted the polymer's crystalline regions. The resulting amorphous structure improved the film's flexibility and elasticity. Nevertheless, the increased potato starch content adversely affects interfacial adhesion, reducing tensile strength. The swelling ratio of the CSCP-2 composite hydrogel film slightly decreases with higher potato starch content, which limits hydrogen bonding interactions with water. Notably, the CSCP composite hydrogel films support adhesion and proliferation of bovine muscle satellite cells (MuSCs) with good cytocompatibility for up to 21 days. However, a slight decrease in metabolic activity on CSCP-2 films was observed. This was likely due to nutrient depletion and limited oxygen diffusion caused by cell multilayering. Overall, the starch-based edible CSCP composite hydrogel films exhibit significant potential as scaffolds for culturing bovine muscle satellite cells (myosatellite cells), paving the way for large-scale production of three-dimensional (3D) cultured meat.

Nanotopography refers to the intricate surface characteristics of materials at the sub-micron (<1000 nm) and nanometer (<100 nm) scales. These topographical surface features significantly influence the physical, chemical, and biological properties of biomaterials, affecting their interactions with cells and surrounding tissues. The development of nanostructured surfaces of polymeric nanocomposites has garnered increasing attention in the fields of tissue engineering and regenerative medicine due to their ability to modulate cellular responses and enhance tissue regeneration. Various top-down and bottom-up techniques, including nanolithography, etching, deposition, laser ablation, template-assisted synthesis, and nanografting techniques, are employed to create structured surfaces on biomaterials. Additionally, nanotopographies can be fabricated using polymeric nanocomposites, with or without the integration of organic and inorganic nanomaterials, through advanced methods such as using electrospinning, layer-by-layer (LbL) assembly, sol–gel processing, in situ polymerization, 3D printing, template-assisted methods, and spin coating. The surface topography of polymeric nanocomposite scaffolds can be tailored through the incorporation of organic nanomaterials (e.g., chitosan, dextran, alginate, collagen, polydopamine, cellulose, polypyrrole) and inorganic nanomaterials (e.g., silver, gold, titania, silica, zirconia, iron oxide). The choice of fabrication technique depends on the desired surface features, material properties, and specific biomedical applications. Nanotopographical modifications on biomaterials’ surface play a crucial role in regulating cell behavior, including adhesion, proliferation, differentiation, and migration, which are critical for tissue engineering and repair. For effective tissue regeneration, it is imperative that scaffolds closely mimic the native extracellular matrix (ECM), providing a mechanical framework and topographical cues that replicate matrix elasticity and nanoscale surface features. This ECM biomimicry is vital for responding to biochemical signaling cues, orchestrating cellular functions, metabolic processes, and subsequent tissue organization. The integration of nanotopography within scaffold matrices has emerged as a pivotal regulator in the development of next-generation biomaterials designed to regulate cellular responses for enhanced tissue repair and organization. Additionally, these scaffolds with specific surface topographies, such as grooves (linear channels that guide cell alignment), pillars (protrusions), holes/pits/dots (depressions), fibrous structures (mimicking ECM fibers), and tubular arrays (array of tubular structures), are crucial for regulating cell behavior and promoting tissue repair. This review presents recent advances in the fabrication methodologies used to engineer nanotopographical microenvironments in polymeric nanocomposite tissue scaffolds through the incorporation of nanomaterials and biomolecular functionalization. Furthermore, it discusses how these modifications influence cellular interactions and tissue regeneration. Finally, the review highlights the challenges and future perspectives in nanomaterial-mediated fabrication of nanotopographical polymeric scaffolds for tissue engineering and regenerative medicine.

Inflammation is a multifaceted biological response of the immune system against various harmful stimuli, including pathogens (such as bacteria and viruses), cellular damage, toxins, and natural/synthetic irritants. This protective mechanism is essential for eliminating the cause of injury, removing damaged cells, and initiating the repair process. While inflammation is a fundamental component of the body’s defense and healing process, its dysregulation can lead to pathological consequences, contributing to various acute and chronic diseases, such as autoimmune disorders, cancer, metabolic syndromes, cardiovascular diseases, neurodegenerative conditions, and other systemic complications. Generally, non-steroidal anti-inflammatory drugs (NSAIDs), corticosteroids, disease-modifying anti-rheumatic drugs (DMARDs), antihistamines, biologics, and colchicine are used as pharmacological agents in the management of inflammatory diseases. However, these conventional treatments often have limitations, including adverse side effects, long-term toxicity, and drug resistance. In contrast, enzyme-based therapeutics have emerged as a promising alternative due to their high specificity, catalytic efficiency, and ability to modulate inflammatory pathways with reduced side effects. These enzymes function by scavenging reactive oxygen species (ROS), inhibiting cytokine transcription, degrading circulating cytokines, and blocking cytokine release by targeting exocytosis-related receptors. Additionally, their role in tissue repair and regeneration further enhances their therapeutic potential. Most natural anti-inflammatory enzymes belong to the oxidoreductase class, including catalase and superoxide dismutase, as well as hydrolases such as trypsin, chymotrypsin, nattokinase, bromelain, papain, serratiopeptidase, collagenase, hyaluronidase, and lysozyme. Engineered enzymes, such as Tobacco Etch Virus (TEV) protease and botulinum neurotoxin type A (BoNT/A), have also demonstrated significant potential in targeted anti-inflammatory therapies. Recent advancements in enzyme engineering, nanotechnology-based enzyme delivery, and biopharmaceutical formulations have further expanded their applicability in treating inflammatory diseases. This review provides a comprehensive overview of both natural and engineered enzymes, along with their formulations, used as anti-inflammatory therapeutics. It highlights improvements in stability, efficacy, and specificity, as well as minimized immunogenicity, while discussing their mechanisms of action and clinical applications and potential future developments in enzyme-based biomedical therapeutics.

Hydrogels are highly versatile biomaterials that play a crucial role in personal wound care and regenerative medicine

Meningitis is the acute or chronic inflammation of the protective membranes, surrounding the brain and spinal cord, and this inflammatory process spreads throughout the subarachnoid space. The traditional drug delivery methods pose a disadvantage in limiting the capacity of crossing the blood–brain barrier (BBB) to reach the central nervous system (CNS). Hence, it is imperative to develop novel approaches that can overcome these constraints and offer efficient therapy for meningitis. Nanoparticle (NP)-based therapeutic approaches have the potential to address the limitations such as penetrating the BBB and achieving targeted drug release in specific cells and tissues. This review highlights recent advancements in nanotechnology-based approaches, such as functionalized polymeric nanoparticles, solid lipid nanoparticles (SLNs), nanostructured lipid carriers, nanoemulsions, liposomes, transferosomes, and metallic NPs for the treatment of meningitis. Recently, bionics has emerged as a next-generation technology in the development of novel ideas from biological principles, structures, and interactions for neurological and neuroinfectious diseases. Despite their potential, more studies are needed to ensure the safety and efficacy of NP-based drug delivery systems focusing on critical aspects such as toxicity, immunogenicity, and pharmacokinetics. Therefore, this review addresses current treatment strategies and innovative nanoparticle approaches, and it discusses future directions for efficient and targeted meningitis therapies.