Lei Yang

Bio: Lei Yang is an academic researcher from Purdue University. The author has contributed to research in topics: Emulsion & Nisin. The author has an hindex of 3, co-authored 3 publications receiving 167 citations.

Carbohydrate nanoparticle‐mediated colloidal assembly for prolonged efficacy of bacteriocin against food pathogen

Abstract: The goal of this study was to demonstrate the ability of carbohydrate nanoparticle-stabilized emulsion to prolong the efficacy of bacteriocin against food pathogens. An amphiphilic, negatively charged carbohydrate nanoparticle, phytoglycogen octenyl succinate (PG-OS), was used to form oil-in-water emulsion for delivering bacteriocin nisin against the food pathogen Listeria monocytogenes. Dynamic light scattering test showed that in emulsion all PG-OS nanoparticles were adsorbed at the surface of oil droplets. Zeta-potential analysis indicated an effective adsorption of positively charged nisin molecules at the surface of PG-OS interfacial layer. Nisin depletion model showed that, during 50 days of storage, the anti-listerial activity of nisin-containing PG-OS-stabilized emulsion was substantially greater than that of nisin solution. In contrast, the emulsion stabilized with a neutral, small-molecule surfactant (Tween 20) or negatively charged, hyperbranched carbohydrate polymer (modified starch) was either ineffective or less effective than the nanoparticle-stabilized emulsion to retain nisin activity during storage.

Emulsion stabilized with phytoglycogen octenyl succinate prolongs the antimicrobial efficacy of ε-poly-l-lysine against Escherichia coli O157:H7

Abstract: ɛ-Poly- l -lysine (EPL) is a food-grade cationic antimicrobial compound with a wide antimicrobial spectrum against bacteria, yeasts, and molds. However, EPL can be subject to rapid depletion after initial application and lose activity quickly. To address this problem, this study used Escherichia coli O157:H7 and tryptic soy agar (TSA) deep-well depletion model to evaluate the prolonged antibacterial efficacy of EPL stabilized with emulsions formed by three types of emulsifier: (1) phytoglycogen octenyl succinate (PG-OS), an amphiphilic carbohydrate particulate; (2) waxy corn starch octenyl succinate (WCS-OS), an amphiphilic hyperbranched polysaccharide; and (3) Tween 20, a neutral small-molecule surfactant. During 20 days of storage at 4 °C, the residual antibacterial efficacy of EPL in PG-OS emulsion was the greatest. In contrast, Tween-20 and WCS-OS emulsions were not as effective as PG-OS emulsion to retain antibacterial activity. Meanwhile, equilibrium dialysis showed the greatest EPL retention with PG-OS emulsion, suggesting the impact of electrostatic and structural properties of emulsifiers at the oil-water interface on prolonged EPL efficacy against E. coli O157:H7.

Engineering POLYTAC Nanoparticles for Bioorthogonal Click Reaction-Enforced Protein Degradation and Breast Cancer Therapy

Abstract: PROteolysis TArgeting Chimeras (PROTACs) have been extensively explored for targeted protein degradation and cancer therapy. However, clinic translation of the conventional small molecular PROTACs is challenged by their unfavorable pharmacokinetic profiles and the systemic toxicity due to on-target but off-tumor protein degradation. Herein we presented a tumor microenvironment-activatable polymeric PROTAC (namely POLYTAC) nanoplatform for tumor-specific PROTAC delivery and combinatory cancer therapy. The POLYTAC nanoparticles were engineered by integrating metalloproteinase-liable poly(ethylene glycol) shell, intracellular acidity-responsive hydrophobic core and reduction-activatable PROTACs into one nanoplatform. The resultant POLYTAC nanoparticles can specifically accumulate at the tumor site and release the PROTACs inside the tumor cells for protein degradation. The POLYTAC nanoparticles can be further engineered for bioorthogonal click reaction-enforced tumor-specific delivery of the PROTACs. In combination with photodynamic therapy, we demonstrated that the bioorthogonal POLYTAC nanoparticles remarkably suppressed tumor growth by synergistically inducing cellular apoptosis of the tumor cells in mouse model of MDA-MB-231 breast cancer. The POLYTAC approach might pave the way for tumor-targeted protein degradation and translation of PROTAC-based cancer therapy.

Applications of nanotechnology in food packaging and food safety: Barrier materials, antimicrobials and sensors

Abstract: In this article, several applications of nanomaterials in food packaging and food safety are reviewed, including: polymer/clay nanocomposites as high barrier packaging materials, silver nanoparticles as potent antimicrobial agents, and nanosensors and nanomaterial-based assays for the detection of food-relevant analytes (gasses, small organic molecules and food-borne pathogens). In addition to covering the technical aspects of these topics, the current commercial status and understanding of health implications of these technologies are also discussed. These applications were chosen because they do not involve direct addition of nanoparticles to consumed foods, and thus are more likely to be marketed to the public in the short term.

Combatting antibiotic-resistant bacteria using nanomaterials.

Abstract: The dramatic increase in antimicrobial resistance for pathogenic bacteria constitutes a key threat to human health. The Centers for Disease Control and Prevention has recently stated that the world is on the verge of entering the "post-antibiotic era", one where more people will die from bacterial infections than from cancer. Recently, nanoparticles (NPs) have emerged as new tools that can be used to combat deadly bacterial infections. Nanoparticle-based strategies can overcome the barriers faced by traditional antimicrobials, including antibiotic resistance. In this tutorial review, we have highlighted multiple nanoparticle-based approaches to eliminate bacterial infections, providing crucial insight into the design of elements that play critical roles in creating antimicrobial nanotherapeutics. In particular, we have focused on the pivotal role played by NP-surface functionality in designing nanomaterials as self-therapeutic agents and delivery vehicles for antimicrobial cargo.

Nano-Strategies to Fight Multidrug Resistant Bacteria-"A Battle of the Titans".

Abstract: Infectious diseases remain one of the leading causes of morbidity and mortality worldwide. The WHO and CDC have expressed serious concern regarding the continued increase in the development of multidrug resistance among bacteria. Therefore, the antibiotic resistance crisis is one of the most pressing issues in global public health. Associated with the rise in antibiotic resistance is the lack of new antimicrobials. This has triggered initiatives worldwide to develop novel and more effective antimicrobial compounds as well as to develop novel delivery and targeting strategies. Bacteria have developed many ways by which they become resistant to antimicrobials. Among those are enzyme inactivation, decreased cell permeability, target protection, target overproduction, altered target site/enzyme, increased efflux due to over-expression of efflux pumps, among others. Other more complex phenotypes, such as biofilm formation and quorum sensing do not appear as a result of the exposure of bacteria to antibiotics although, it is known that biofilm formation can be induced by antibiotics. These phenotypes are related to tolerance to antibiotics in bacteria. Different strategies, such as the use of nanostructured materials, are being developed to overcome these and other types of resistance. Nanostructured materials can be used to convey antimicrobials, to assist in the delivery of novel drugs or ultimately, possess antimicrobial activity by themselves. Additionally, nanoparticles (e.g., metallic, organic, carbon nanotubes, etc.) may circumvent drug resistance mechanisms in bacteria and, associated with their antimicrobial potential, inhibit biofilm formation or other important processes. Other strategies, including the combined use of plant-based antimicrobials and nanoparticles to overcome toxicity issues, are also being investigated. Coupling nanoparticles and natural-based antimicrobials (or other repurposed compounds) to inhibit the activity of bacterial efflux pumps; formation of biofilms; interference of quorum sensing; and possibly plasmid curing, are just some of the strategies to combat multidrug resistant bacteria. However, the use of nanoparticles still presents a challenge to therapy and much more research is needed in order to overcome this. In this review, we will summarize the current research on nanoparticles and other nanomaterials and how these are or can be applied in the future to fight multidrug resistant bacteria.