Three-dimensional (3D) bioprinting using biocompatible polymers has emerged as a revolutionary technique in tissue engineering and regenerative medicine. These biopolymers mimic the extracellular matrix (ECM) and enhance cellular behavior. The current review presents recent advancements in additive manufacturing processes including Stereolithography (SLA), Fused Filament Fabrication (FFF), Selective Laser Sintering (SLS), and inkjet printing. It also explores the fundamentals of 3D printing and the properties of biocompatible polymers for 3D bioprinting. By mixing biopolymers, enhancing rheological characteristics, and adding bioactive components, further advancements have been made for organ transplantation, drug development, and tissue engineering. As research progresses, the potential for 3D bioprinting to fundamentally transform the healthcare system is becoming obvious and clear. However, the therapeutic potential of printed structures is hindered by issues such as material anisotropy, poor mechanical properties, and the need for more biocompatible and biodegradable architectures. Future research should concentrate on optimizing the 3D bioprinting process using sophisticated computational techniques, systematically examining the characteristics of biopolymers, customizing bioinks for different cell types, and exploring sustainable materials.

The transition from three-dimensional (3D) to four-dimensional (4D)-bioprinting marks a significant advancement in tissue engineering and drug delivery. 4D-bioprinting offers the potential to more accurately mimic the adaptive qualities of living tissues due to its dynamic flexibility. Structures created with 4D-bioprinting can change shape in response to internal and external stimuli. This article reviews the background, key concepts, techniques, and applications of 4D-bioprinting, focusing on its role in tissue scaffolding and drug delivery. We discuss the limitations of traditional 3D-bioprinting in providing customized and sustained medication release. Shape memory polymers and hydrogels are examples of new responsive materials enabled by 4D-bioprinting that can enhance drug administration. Additionally, we provide a thorough analysis of various biopolymers used in drug delivery systems, including cellulose, collagen, alginate, and chitosan. The use of biopolymers in 4D-printing significantly increases material responsiveness, allowing them to react to stimuli such as temperature, light, and humidity. This capability enables complex designs with programmable shape and function changes. The expansion and contraction of hydrogels in response to temperature changes offer a practical method for controlled drug release. 4D-bioprinting has the potential to address significant challenges in tissue regeneration and medication administration, spurring ongoing research in this technology. By providing precise control over cell positioning and biomaterial integration, traditional 3D-bioprinting has evolved into 4D-bioprinting, enhancing the development of tissue constructs. 4D-bioprinting represents a paradigm shift in tissue engineering and biomaterials, offering enhanced possibilities for creating responsive, adaptive structures that address clinical needs. Researchers can leverage the unique properties of biopolymers within the 4D-printing framework to develop innovative approaches for tissue regeneration and drug delivery, leading to advanced treatments in regenerative medicine. One potential future application is in vivo tissue regeneration using bioprinted structures that can enhance the body’s natural healing capabilities.

The treatment adherence of narcotics-addicted individuals with reduced incidences of relapse can be enhanced by a sustained drug release formulation of antinarcotics. So far, different drug formulations have been reported with sustained drug release periods of 28 and 35 days. To further enhance this duration, different formulations of injectable hydrogels (IHs) have been developed by combining low molecular weight (LMW) and high molecular weight (HMW) chitosan (CS) with guar gum (GG) and crosslinking them by sodium bi phosphate dibasic. The structural, morphological, and physicochemical properties of LMW-CS IH, and HMW-CS IH were evaluated using Fourier transform infrared spectroscopy (FT-IR), thermo-gravimetric analysis (TGA), scanning electron microscopy (SEM), and rheological, swelling, and biodegradation analysis. The HMW-CS IH showed high crosslinking, increased thermal stability, high mechanical strength, elevated swelling, and low biodegradation. The antinarcotic drugs naltrexone (NTX) and disulfiram (DSF) were loaded separately into the HMW-CS IH and LMW-CS IH. The release of NTX and DSF was investigated in phosphate buffer saline (PBS) and ethanol (0.3%, 0.4%, and 0.5%) over a 56-day period using an UV spectrophotometer. The drug release data were tested in zero-order, first-order, and Korsemeyer–Peppas mathematical models. In PBS, all prepared formulations followed non-Fickian drug release, while in ethanol, only NTX HMW-CS IH followed non-Fickian release in all three different concentrations of ethanol.

Background: Candida auris is a significant global health concern, due to its rapid transmission, high mortality rate, and resistance to commonly available antifungal drugs. Methodology: During the current study, a cationic polymeric hydrogel was developed using chitosan (CS), polyethylene glycol (PEG), and methacrylic acid (MAA). The respective solutions were mixed in a volumetric ratio of 2:1:1. After characterization, the hydrogel was assessed using antifungal, antibiofilm, and hemocompatibility assays. Results: The hydrodynamic radius of 554.7 ± 90.1 nm and zeta potential of 15.6 ± 1.09 mV indicate the ideal size and charge for topical applications and in vivo studies, respectively. The formulation exhibited improved thermal stability, enhanced swelling, and a drug release profile for non-Fickian diffusion. The hydrogel effectively inhibited fungal growth in agar plates (42 ± 7.31 mm zone of inhibition), with a mean IC₅₀ of 15.17 ± 4.01 μg/mL and MIC of 29.30 ± 11.72 μg/mL. Calcofluor white (CFW) staining showed diffuse irregular yeast cells, suggesting increased membrane permeability, eventually leading to cell death. The hemocompatibility assay revealed no visible agglutination or hemolysis at the MIC value. The formulation exhibited significantly reduced biofilm formation compared to the growth control (p < 0.05). Additionally, in silico analysis revealed that MAA showed superior oral bioavailability, no inhibitory activity on cytochrome P450 enzymes, and low potential for toxicity through nuclear receptor signaling pathways. Conclusions: Cationic hydrogels show promise as potential antifungal treatments. The development of cost-effective and improved therapeutic methods is crucial to combat this deadly pathogen and to improve patient outcomes.