Nanoclay-induced bacterial flocculation for infection confinement

Secondary Structure Stabilization of Macrocyclic Antimicrobial Peptides via Cross-Link Swapping

Lactam cross-links have been employed to stabilize the helical secondary structure and enhance the activity and physiological stability of antimicrobial peptides; however, stabilization of β-sheets via lactamization has not been observed. In the present study, lactams between the side chains of C- and N-terminal residues have been used to stabilize the β-sheet conformation in a short ten-residue analogue of chicken angiogenin-4. Designed using a combination of molecular dynamics simulations and Markov state models, the lactam cross-linked peptides are shown to adopt stabilized β-sheet conformations consistent with simulated structures. Replacement of the peptide side-chain Cys-Cys disulfide by a lactam cross-link enhanced the broad-spectrum antibacterial activity compared to the parent peptide and exhibited greater propensity to induce proinflammatory activity in macrophages. The combination of molecular simulations and conformational and biological analyses of the synthetic peptides provides a useful paradigm for the rational design of therapeutically active peptides with constrained β-sheet structures.

Self-Therapeutic Nanomaterials: Applications in Biology and Medicine

Over past decades, nanotechnology has contributed to the biomedical field in areas including detection, diagnosis, and drug delivery via opto-electronic properties or enhancement of biological effects. Though generally considered inert delivery vehicles, a plethora of past and present evidence demonstrates that nanomaterials also exude unique intrinsic biological activity based on composition, shape, and surface functionalization. These intrinsic biological activities, termed self-therapeutic properties, take several forms, including mediation of cell-cell interactions, modulation of interactions between biomolecules, catalytic amplification of biochemical reactions, and alteration of biological signal transduction events. Moreover, study of biomolecule-nanomaterial interactions offers a promising avenue for uncovering the molecular mechanisms of biology and the evolution of disease. In this review, we observe the historical development, synthesis, and characterization of self-therapeutic nanomaterials. Next, we discuss nanomaterial interactions with biological systems, starting with administration and concluding with elimination. Finally, we apply this materials perspective to advances in intrinsic nanotherapies across the biomedical field, from cancer therapy to treatment of microbial infections and tissue regeneration. We conclude with a description of self-therapeutic nanomaterials in clinical trials and share our perspective on the direction of the field in upcoming years.

Low-Swelling Adhesive Hydrogel with Rapid Hemostasis and Potent Anti-Inflammatory Capability for Full-Thickness Oral Mucosal Defect Repair

Full-thickness oral mucosal defects are accompanied by significant blood loss and frequent infections. Instead of conventional therapies that separate hemostasis and anti-inflammation in steps, emerging hydrogels can integrate multiple functions for the successive process after defect including hemostasis/inflammatory phase, proliferative phase, and remodeling phase. However, these functions can be easily compromised by rapid swelling and degradation of hydrogels in wet oral environment. Herein, a low-swelling adhesive hydrogel with rapid hemostasis and potent anti-inflammatory capability was developed using a dual cross-linking strategy as well as a safe and facile fabrication method. It was double cross-linked hydrogel consisting of gelatin methacrylate (GelMA), nanoclay, and tannic acid (TA) (referred to as GNT). GNT hydrogel exhibited low-swelling (one-eighth of that of GelMA), excellent stretchability (211.86%), and good adhesive properties (5 times the adhesive strength of GelMA). Physicochemical characterization illuminated the close interactions among the three components. A systematic investigation of the therapeutic effects of GNT hydrogels was performed. In vitro and in vivo experimental results demonstrated the potent hemostatic property and excellent antibacterial and anti-inflammatory effects of GNT hydrogels. The RNA sequencing analysis results for rat full-thickness oral mucosal samples showed that GNT reduced inflammation levels by down-regulating the expression of multiple inflammation-related pathways, including TNF and IL-17 pathways. It also enhanced the expression levels of tissue regeneration-related genes and thus accelerated defective mucosal repair. More importantly, the therapeutic effects of GNT were superior to those of a commercial oral tissue repair membrane when applied for full-thickness oral mucosal defect repair in rabbits. In summary, the prepared low-swelling adhesive GNT hydrogel with rapid hemostasis and potent anti-inflammatory is a promising therapy for full-thickness mucosal defect in the moist and dynamic oral environment.

Engineered Nanotechnology: An Effective Therapeutic Platform for the Chronic Cutaneous Wound

The healing of chronic wound infections, especially cutaneous wounds, involves a complex cascade of events demanding mutual interaction between immunity and other natural host processes. Wound infections are caused by the consortia of microbial species that keep on proliferating and produce various types of virulence factors that cause the development of chronic infections. The mono- or polymicrobial nature of surface wound infections is best characterized by its ability to form biofilm that renders antimicrobial resistance to commonly administered drugs due to poor biofilm matrix permeability. With an increasing incidence of chronic wound biofilm infections, there is an urgent need for non-conventional antimicrobial approaches, such as developing nanomaterials that have intrinsic antimicrobial-antibiofilm properties modulating the biochemical or biophysical parameters in the wound microenvironment in order to cause disruption and removal of biofilms, such as designing nanomaterials as efficient drug-delivery vehicles carrying antibiotics, bioactive compounds, growth factor antioxidants or stem cells reaching the infection sites and having a distinct mechanism of action in comparison to antibiotics-functionalized nanoparticles (NPs) for better incursion through the biofilm matrix. NPs are thought to act by modulating the microbial colonization and biofilm formation in wounds due to their differential particle size, shape, surface charge and composition through alterations in bacterial cell membrane composition, as well as their conductivity, loss of respiratory activity, generation of reactive oxygen species (ROS), nitrosation of cysteines of proteins, lipid peroxidation, DNA unwinding and modulation of metabolic pathways. For the treatment of chronic wounds, extensive research is ongoing to explore a variety of nanoplatforms, including metallic and nonmetallic NPs, nanofibers and self-accumulating nanocarriers. As the use of the magnetic nanoparticle (MNP)-entrenched pre-designed hydrogel sheet (MPS) is found to enhance wound healing, the bio-nanocomposites consisting of bacterial cellulose and magnetic nanoparticles (magnetite) are now successfully used for the healing of chronic wounds. With the objective of precise targeting, some kinds of "intelligent" nanoparticles are constructed to react according to the required environment, which are later incorporated in the dressings, so that the wound can be treated with nano-impregnated dressing material in situ. For the effective healing of skin wounds, high-expressing, transiently modified stem cells, controlled by nano 3D architectures, have been developed to encourage angiogenesis and tissue regeneration. In order to overcome the challenge of time and dose constraints during drug administration, the approach of combinatorial nano therapy is adopted, whereby AI will help to exploit the full potential of nanomedicine to treat chronic wounds.