The pH-responsive Microsphere Fibers' Controlled Drug Release Properties and their Microfluidic Preparation

Prigodich Rychlik^*
*Correspondence: Prigodich Rychlik, Department of Clinical Genetics, Gachon University, Seongnam-si 13120, Republic of Korea, Email:

Introduction

The development of advanced drug delivery systems has become increasingly significant in modern medicine. One promising avenue of research involves the use of pH-responsive microsphere fibers, which are capable of controlled drug release in response to changes in the surrounding pH levels. This property is particularly advantageous for targeting specific disease sites, such as tumors, which often exhibit an acidic microenvironment. By integrating microfluidic techniques for the preparation of these fibers, researchers can achieve precise control over their size, morphology and drug encapsulation efficiency. This article explores the characteristics, preparation methods and applications of pH-responsive microsphere fibers, highlighting their potential in enhancing therapeutic efficacy and patient compliance [1].

Drug Delivery Systems (DDS) are designed to improve the bioavailability, therapeutic index and patient compliance of pharmaceutical compounds. Traditional methods of drug administration often suffer from limitations such as rapid clearance from the body, nonspecific distribution and adverse side effects. Consequently, there has been a shift toward developing systems that can release drugs in a controlled manner, tailored to the needs of the patient and the characteristics of the disease. Controlled release mechanisms can be classified into various categories, including diffusion-controlled, swellingcontrolled and chemically triggered systems. Among these, pH-responsive systems are particularly appealing for applications in cancer therapy, where the tumor microenvironment is often significantly more acidic than healthy tissues. This localized difference in pH can be exploited to achieve sitespecific drug release, thereby enhancing therapeutic efficacy and reducing systemic toxicity [2].

Description

pH-responsive microsphere fibers are typically composed of biocompatible and biodegradable polymers, such as Polylactic Acid (PLA), Polycaprolactone (PCL), or natural polymers like chitosan and alginate. These materials can be functionalized to incorporate pH-sensitive moieties, such as carboxylic acid groups, which undergo conformational changes in response to pH variations. The pH-responsive behavior of these fibers is primarily due to the ionization of functional groups within the polymer matrix. At a higher pH (e.g., physiological pH), the carboxylic groups remain deprotonated, maintaining a stable structure. Conversely, in an acidic environment, these groups become protonated, leading to swelling, degradation, or dissolution of the polymer matrix, which subsequently triggers the release of encapsulated drugs. The fibrous structure increases the surface area available for drug loading and release, promoting efficient drug diffusion. The ability to fine-tune fiber composition allows for tailored release kinetics, enabling sustained or immediate release as needed. Many of the materials used in these fibers are naturally derived or designed to be biocompatible, minimizing adverse reactions in the body [3].

Microfluidics is a technology that manipulates small volumes of fluids, often at the microscale. This approach has revolutionized various fields, including biomedical engineering, by allowing for precise control over reactions, mixing and particle formation. The ability to fabricate structures at the microscale can lead to improved reproducibility and scalability of drug delivery systems. Coaxial electrospinning involves the use of two concentric nozzles to simultaneously spin two different solutions: one containing the polymer and the other containing the drug or pH-responsive agent. The resulting fibers can encapsulate the drug within a polymer matrix, enabling controlled release in response to pH changes. In this method, microfluidic devices generate uniform droplets that contain the polymer and drug solution. Upon solidification, these droplets form microspheres that can be further processed into fibers. This technique allows for precise control over droplet size and composition, impacting the final properties of the microsphere fibers. Emerging techniques such as 3D printing and bioprinting enable the fabrication of complex fiber structures with tailored porosity and drug distribution. This approach allows for the creation of scaffolds that can mimic the extracellular matrix, further enhancing drug release properties and cellular interactions [4].

In addition to cancer, pH-responsive microsphere fibers can also be utilized in antimicrobial treatments. By encapsulating antibiotics and releasing them in response to the acidic conditions typically found in infected tissues, these fibers can help combat infections more effectively. Wound healing applications benefit from the use of pH-responsive fibers, which can release growth factors or anti-inflammatory agents in response to the acidic environment of chronic wounds. This targeted approach can accelerate the healing process and improve patient outcomes. The incorporation of antigens within pHresponsive fibers offers a novel approach to vaccination. By controlling the release of antigens in response to pH changes in the body, these systems can enhance immune responses and provide sustained antigen delivery. The transition from laboratory-scale microfluidic fabrication to industrial-scale production poses significant challenges. The biocompatibility and safety of these materials must be rigorously tested before clinical application, often leading to lengthy approval processes. The behavior of these fibers in vivo can be influenced by numerous biological factors, necessitating extensive preclinical studies. Customizing drug release profiles based on individual patient characteristics or specific disease states [5].

Conclusion

pH-responsive microsphere fibers represent a promising advancement in the field of controlled drug delivery. Their unique properties allow for targeted drug release in response to localized pH changes, significantly enhancing therapeutic efficacy and minimizing side effects. The integration of microfluidic techniques for their preparation offers precise control over fiber characteristics, paving the way for innovative applications in cancer therapy, wound healing and more. As research continues to address the existing challenges and explore new applications, pH-responsive microsphere fibers hold the potential to revolutionize drug delivery systems, ultimately improving patient outcomes and the overall effectiveness of therapeutic interventions.

Acknowledgement

We thank the anonymous reviewers for their constructive criticisms of the manuscript.

Conflict of Interest

The author declares there is no conflict of interest associated with this manuscript.

References

1. Huang, Jun, Youqi Wang, Ping Liu and Jinzhi Li, et al. "Kneading-dough-inspired quickly dispersing of hydrophobic particles into aqueous solutions for designing functional hydrogels." Gels 9 (2023): 242.

   Google Scholar, Crossref, Indexed at

2. DeFail, Alicia J., Howard D. Edington, Stacey Matthews and Wen‐Chi C. Lee, et al. "Controlled release of bioactive doxorubicin from microspheres embedded within gelatin scaffolds." J Biomed Mater Res A 79 (2006): 954-962.

   Google Scholar, Crossref, Indexed at

3. Yue, Shuai, Xiaoting Sun, Ning Wang and Yaning Wang, et al. "SERS–fluorescence dual-mode pH-sensing method based on Janus microparticles." ACS Appl Mater Interfaces 9 (2017): 39699-39707.

   Google Scholar, Crossref, Indexed at

4. Tan, Rachel Yie Hang, Choy Sin Lee, Mallikarjuna Rao Pichika and Sit Foon Cheng, et al. "PH responsive polyurethane for the advancement of biomedical and drug delivery." Polym 14 (2022): 1672.

   Google Scholar, Crossref, Indexed at

5. Zhang, Min, Jia Liu, Ying Kuang and Qilin Li, et al. "Ingenious pH-sensitive dextran/mesoporous silica nanoparticles based drug delivery systems for controlled intracellular drug release." Int J Biol Macromol 98 (2017): 691-700.

   Google Scholar, Crossref, Indexed at