Aptamer-Functionalized Natural Protein-Based Polymers as Innovative Biomaterials

Advantages of Material Biofunctionalization Using Nucleic Acid Aptamers in Tissue Engineering and Regenerative Medicine

Material engineering is a fundamental issue in the applications of materials in the medical field. One of the aspects of material engineering is incorporating recognition sites on the surface of biomaterials, which plays an essential role in increasing the efficiency of tissue engineering scaffolds in various aspects. The application of peptides and antibodies to establish the recognition and adhesion sites has limitations, such as fragility and instability under physical and chemical processes. Therefore, synthetic ligands such as nucleic acid aptamers have received much attention for easy synthesis, minimal immunogenicity, high specificity, and stability under processing. Due to the effective role of these ligands in increasing the efficiency of engineered constructs in this study, the advantages of nucleic acid aptamers in tissue engineering will be reviewed. Aptamer-functionalized biomaterials can attract endogenous stem cells to wounded areas and organize their actions to facilitate tissue regeneration. This approach harnesses the body's inherent regeneration potential to treat many diseases. Also, increased efficacy in controlled release, slow and targeted drug delivery are important issues in drug delivery for tissue engineering approaches which can be achieved by incorporating aptamers in drug delivery systems. Aptamer-functionalized scaffolds have very applications, such as diagnosis of cancer, hematological infections, narcotics, heavy metals, toxins, controlled release from the scaffolds, and in vivo cell tracing. Aptasensors, as a result of many advantages over other traditional assay methods, can replace older methods. Furthermore, their unique targeting mechanism also targets compounds with no particular receptors. Targeting cell homing, local and targeted drug delivery, cell adhesion efficacy, cytocompatibility and bioactivity of scaffolds, aptamer-based biosensor, and aptamer-functionalized scaffolds are the topics that will be examined in this review study.

Novel nucleic acid aptamer gold (Au)-nanoparticles (AuNPs-AptHLA-G5-1 and AuNPs-AptHLA-G5-2) to detect the soluble human leukocyte antigen G5 subtype (HLA-G5) in liquid samples

Background

The human leukocyte antigen G5 subtype (HLA-G5) is a major histocompatibility complex (MHC) molecule that is selectively expressed at the maternal-foetal tissue interface and is required for the successful implantation of the in vitro fertilized embryo. It is critical to detect HLA-G5, especially HLA-G5 expression in embryo fluid, during in vitro embryo incubation and culture. However, the specificity and sensitivity of traditional ELISA methods to detect sHLA-G5 are insufficient. This work aimed to explore novel nucleic acid aptamer gold (Au)-nanoparticles to detect soluble HLA-G5 in liquid samples.

Methods

Soluble HLA-G5 was obtained using a prokaryotic expression system, and two novel aptamers (HLA-G5-Apt1 and HLA-G5-Apt2) detecting HLA-G5 were screened by the Systematic Evolution of Ligands by Exponential Enrichment (SELEX) method. Small (10 nm) gold nanoparticles (AuNPs) were incubated with AptHLAs to form two novel nucleic acid aptamers: Au-nanoparticles (AuNPs-AptHLA-G5-1 and AuNPs-AptHLA-G5-2).

Results

The results showed that AptHLA-G5-1 and AptHLA-G5-2 have a high affinity for HLA-G5 and can detect its presence in liquid samples. Using the colorimetric sensing method, AuNPs-AptHLA-G1 had a detection limit as low as 20 ng/mL (recovery range between 98.7% to 102.0%), while AuNPs-AptHLA-G2 had a detection limit as low as 20 ng/mL (recovery range between 98.9% to 103.6%).

Conclusions

Our work demonstrates that novel AuNPs are efficient detectors for HLA-G5 and are useful for diagnosis and treatment in the field of obstetrics-gynaecology.

Aptamer-functionalized hydrogels: An emerging class of biomaterials for protein delivery, cell capture, regenerative medicine, and molecular biosensing

Molecular recognition is essential to the development of biomaterials. Aptamers are a unique class of synthetic ligands interacting with not only their target molecules with high affinities and specificities but also their complementary sequences with high fidelity. Thus, aptamers have recently attracted significant attention in the development of an emerging class of biomaterials, that is, aptamer-functionalized hydrogels. In this review, we introduce the methods of incorporating aptamers into hydrogels as pendant motifs or crosslinkers. We further introduce the functions of these hydrogels in recognizing proteins, cells, and analytes through four applications including protein delivery, cell capture, regenerative medicine, and molecular biosensing. Notably, as aptamer-functionalized hydrogels have the characteristics of both aptamers and hydrogels, their potential applications are broad and beyond the scope of this review. This article is categorized under: Biology-Inspired Nanomaterials > Nucleic Acid-Based Structures Implantable Materials and Surgical Technologies > Nanomaterials and Implants Therapeutic Approaches and Drug Discovery > Emerging Technologies.

Sustained Release Systems for Delivery of Therapeutic Peptide/Protein

Peptide/protein therapeutics have been significantly applied in the clinical treatment of various diseases such as cancer, diabetes, etc. owing to their high biocompatibility, specificity, and therapeutic efficacy. However, due to their immunogenicity, instability stemming from its complex tertiary and quaternary structure, vulnerability to enzyme degradation, and rapid renal clearance, the clinical application of protein/peptide therapeutics is significantly confined. Though nanotechnology has been demonstrated to prevent enzyme degradation of the protein therapeutics and thus enhance the half-life, issues such as initial burst release and uncontrollable release kinetics are still unsolved. Moreover, the traditional administration method results in poor patient compliance, limiting the clinical application of protein/peptide therapeutics. Exploiting the sustained-release formulations for more controllable delivery of protein/peptide therapeutics to decrease the frequency of injection and enhance patient compliance is thus greatly meaningful. In this review, we comprehensively summarize the substantial advancements of protein/peptide sustained-release systems in the past decades. In addition, the advantages and disadvantages of all these sustained-release systems in clinical application together with their future challenges are also discussed in this review.

Advanced nanomedicine and cancer: Challenges and opportunities in clinical translation

Cancer has reached pandemic dimensions in the whole world. Although current medicine offers multiple treatment options against cancer, novel therapeutic strategies are needed due to the low specificity of chemotherapeutic drugs, undesired side effects and the presence of different incurable types of cancer. Among these new strategies, nanomedicine arises as an encouraging approach towards personalized medicine with high potential for present and future cancer patients. Therefore, nanomedicine aims to develop novel tools with wide potential in cancer treatment, imaging or even theranostic purposes. Even though numerous preclinical studies have been published with successful preliminary results, promising nanosystems have to face multiple obstacles before adoption in clinical practice as safe options for patients with cancer. In this MiniReview, we provide a short overview on the latest advances in current nanomedicine approaches, challenges and promising strategies towards more accurate cancer treatment.