Topical Antibiotic Elution in a Collagen-Rich Hydrogel Successfully Inhibits Bacterial Growth and Biofilm Formation In Vitro

Synthetic and biopolymers-based antimicrobial hybrid hydrogels: a focused review

The constantly accelerating occurrence of microbial infections and their antibiotic resistance has spurred advancement in the field of material sciences and has guided the development of novel materials with anti-bacterial properties. To address the clinical exigencies, the material of choice should be biodegradable, biocompatible, and able to offer prolonged antibacterial effects. As an attractive option, hydrogels have been explored globally as a potent biomaterial platform that can furnish essential antibacterial attributes owing to its three-dimensional (3D) hydrophilic polymeric network, adequate biocompatibility, and cellular adhesion. The current review focuses on the utilization of different antimicrobial hydrogels based on their sources (natural and synthetic). Further, the review also highlights the strategies for the generation of hydrogels with their advantages and disadvantages and their applications in different biomedical fields. Finally, the prospects in the development of hydrogels-based antimicrobial biomaterials are discussed along with some key challenges encountered during their development and clinical translation.

Successful topical treatment of human biofilms using multiple antibiotic elution from a collagen-rich hydrogel

Chronic non-healing wounds significantly strain modern healthcare systems, affecting 1-2% of the population in developed countries with costs ranging between $28.1 and $96.8 billion annually. Additionally, it has been established that chronic wounds resulting from comorbidities, such as peripheral vascular disease and diabetes mellitus, tend to be polymicrobial in nature. Treatment of polymicrobial chronic wounds with oral and IV antibiotics can result in antimicrobial resistance, leading to more difficult-to-treat wounds. Ideally, chronic ulcers would be topically treated with antibiotic combinations tailored to the microbiome of a patient's wound. We have previously shown that a topical collagen-rich hydrogel (cHG) can elute single antibiotics to inhibit bacterial growth in a manner that is nontoxic to mammalian cells. Here, we analyzed the microbiology of cultures taken from human patients diagnosed with diabetes mellitus suffering from chronic wounds present for more than 6 weeks. Additionally, we examined the safety of the elution of multiple antibiotics from collagen-rich hydrogel in mammalian cells in vivo. Finally, we aimed to create tailored combinations of antibiotics impregnated into cHG to successfully target and treat infections and eradicate biofilms cultured from human chronic diabetic wound tissue. We found that the majority of human chronic wounds in our study were polymicrobial in nature. The elution of multiple antibiotics from cHG was well-tolerated in mammalian cells, making it a potential topical treatment of the polymicrobial chronic wound. Finally, combinations of antibiotics tailored to each patient's microbiome eluted from a collagen-rich hydrogel successfully treated bacterial cultures isolated from patient samples via an in vitro assay.

In vitro elution of amikacin from four hydrogel preparations: A pilot study

OBJECTIVE

To determine in vitro elution of amikacin from poloxamer 407 NF, 1% carboxymethylcellulose (CMC), 3% CMC, 5% CMC, and control (sterile water).

STUDY DESIGN

Descriptive in vitro.

SAMPLE POPULATION

Triplicate samples from each experimental group.

METHODS

Amikacin solution was prepared in poloxamer 407 NF, 1% CMC, 3% CMC, 5% CMC, or sterile water. Then, 1 ml of phosphate-buffered saline (PBS) was added to each of three aliquots per base and the samples were incubated at 37°C. PBS was removed and replaced at 1, 4, 8, 12, 24, 48, 72, 96, 120, 144, 168, 192, 216, and 240 hours and amikacin concentration was measured.

RESULTS

The highest median concentration of amikacin in the eluent of poloxamer 407 NF, 3% CMC, and 5% CMC was observed at 48 hours: 3300, 3030, and 2190 μg/ml, respectively. The highest median concentration of amikacin in the eluent of 1% CMC and sterile water were observed at 1 hour: 13300 and 15600 μg/ml, respectively. Median eluent concentration of amikacin exceeded 2000 μg/ml (the reported minimum inhibitory concentration [MIC] of certain biofilm-producing methicillin-resistant Staphylococcus pseudintermedius) from 24 to 96 hours for poloxamer 407 NF, 24-72 hours for 3% CMC, 48-72 hours for 5% CMC, 1-4 hours for 1% CMC, and 1-4 hours for sterile water.

CONCLUSION

Amikacin elution from tested substances reached or exceeded target MIC during the 240 hours tested.

CLINICAL SIGNIFICANCE

Hydrogel-amikacin solutions may be useful topical treatment options for some infected wounds. In vivo safety and efficacy should be evaluated.

Antibacterial Soy Protein Isolate Prepared by Quaternization

Soy protein isolate (SPI) is green, high-yield natural plant protein, which is widely applied in industry (packing material and adhesives) and tissue engineering. It is meaningful to improve the antibacterial property of soy protein isolate to fabricate versatile safe products to meet people's requirements. In this study, quaternized soy protein isolate (QSPI) was synthesized by the reaction between 2,3-epoxypropyltrimethylammonium chloride (EPTMAC) and SPI. The positive charged (17.8 ± 0.23 mV) quaternary ammonium groups endow the QSPI with superior antibacterial properties against multiple bacteria in vitro and in vivo. Notably, QSPI maintains its good biocompatibility and promotes bacterial-infected wound healing in rat models. Furthermore, QSPI possesses superior water solubility in a broad pH range than raw SPI. Altogether, this soy protein isolate derivative with antibacterial property and superior water solubility may extend the application of SPI in industry and tissue engineering.

Spontaneous Gelation of Adhesive Catechol Modified Hyaluronic Acid and Chitosan

Spontaneously formed hydrogels are attracting increasing interest as injectable or wound dressing materials because they do not require additional reactions or toxic crosslinking reagents. Highly valuable properties such as low viscosity before external application, adequate filmogenic capacity, rapid gelation and tissue adhesion are required in order to use them for those therapeutic applications. In addition, biocompatibility and biodegradability are also mandatory. Accordingly, biopolymers, such as hyaluronic acid (HA) and chitosan (CHI), that have shown great potential for wound healing applications are excellent candidates due to their unique physiochemical and biological properties, such as moisturizing and antimicrobial ability, respectively. In this study, both biopolymers were modified by covalent anchoring of catechol groups, and the obtained hydrogels were characterized by studying, in particular, their tissue adhesiveness and film forming capacity for potential skin wound healing applications. Tissue adhesiveness was related to o-quinone formation over time and monitored by visible spectroscopy. Consequently, an opposite effect was observed for both polysaccharides. As gelation advances for HA-CA, it becomes more adhesive, while competitive reactions of quinone in CHI-CA slow down tissue adhesiveness and induce a detriment of the filmogenic properties.

Collagen-based formulations for wound healing: A literature review

Wounds have always been the point of concern owing to the involvement of infections and the level of severity. Therefore, the management of wounds always requires additional effort for comprehensive healing and subsequent removal of the scar from the wound site. The role of biomaterials in the management of chronic wounds has been well established. One of such biomaterials is collagen (Col) that is considered to be the crucial component of most of the formulations being developed for wound healing. The role of Col extracted from marine invertebrates remains an unmarked origin of the proteinaceous constituent in the evolution of innovative pharmaceuticals. Col is a promising, immiscible, fibrous amino acid of indigenous origin that is ubiquitously present in extracellular matrices and connective tissues. There are different types of Col present in the body such as type I, II, III, IV, and V however the natural sources of Col are vegetables and marine animals. Its physical properties like high tensile strength, adherence nature, elasticity, and remodeling contribute significantly in the wound healing process. Col containing formulations such as hydrogels, sponges, creams, peptides, and composite nanofibers have been utilized widely in wound healing and tissue engineering purposes truly as the first line of defense. Here we present the recent advancements in Col based dosage forms for wound healing. The Col based market of topical preparations and the published reports identify Colas a useful biomaterial for the delivery of pharmaceuticals and a platform for tissue engineering.

Advancements in release-active antimicrobial biomaterials: A journey from release to relief

Escalating medical expenses due to infectious diseases are causing huge socioeconomic pressure on mankind globally. The emergence of antibiotic resistance has further aggravated this problem. Drug-resistant pathogens are also capable of forming thick biofilms on biotic and abiotic surfaces to thrive in a harsh environment. To address these clinical problems, various strategies including antibacterial agent delivering matrices and bactericidal coatings strategies have been developed. In this review, we have discussed various types of polymeric vehicles such as hydrogels, sponges/cryogels, microgels, nanogels, and meshes, which are commonly used to deliver antibiotics, metal nanoparticles, and biocides. Compositions of these polymeric matrices have been elaborately depicted by elucidating their chemical interactions and potential activity have been discussed. On the other hand, various implant/device-surface coating strategies which exploit the release-active mechanism of bacterial killing are discussed in elaboration. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Cardiovascular Disease Implantable Materials and Surgical Technologies > Nanomaterials and Implants Therapeutic Approaches and Drug Discovery > Nanomedicine for Infectious Disease.

Collagen in Wound Healing

Normal wound healing progresses through inflammatory, proliferative and remodeling phases in response to tissue injury. Collagen, a key component of the extracellular matrix, plays critical roles in the regulation of the phases of wound healing either in its native, fibrillar conformation or as soluble components in the wound milieu. Impairments in any of these phases stall the wound in a chronic, non-healing state that typically requires some form of intervention to guide the process back to completion. Key factors in the hostile environment of a chronic wound are persistent inflammation, increased destruction of ECM components caused by elevated metalloproteinases and other enzymes and improper activation of soluble mediators of the wound healing process. Collagen, being central in the regulation of several of these processes, has been utilized as an adjunct wound therapy to promote healing. In this work the significance of collagen in different biological processes relevant to wound healing are reviewed and a summary of the current literature on the use of collagen-based products in wound care is provided.