Intramedullary Spinal Epidermoid Cyst-A Rare Cause of Spastic Paraparesis.

Spinal intramedullary epidermoids are rare intramedullary lesions of the spinal cord. They may be congenital or acquired with the congenital type often associated with spinal dysraphism and other spinal anomalies. The clinical presentation depends on the level of the involvement of the spinal cord. Management of these lesions is surgical excision. We report a case of intramedullary spinal epidermoid who presented with spastic paraparesis.

Molecular Dynamics Simulations Help Determine the Molecular Mechanisms of Lasioglossin-III and Its Variant Peptides' Membrane Interfacial Interactions.

Lasioglossin-III (LL-III) is a potent broad-spectrum antimicrobial peptide used in diverse antimicrobial applications. In this work, coarse-grained and all-atom molecular dynamics simulation strategies were used in tandem to interpret the molecular mechanisms involved in the interfacial dynamics of LL-III and its recombinant variants during interactions with diverse cell membrane systems. Our results indicate that the membrane charges act as the driving force for initiating the membrane-peptide interactions, while the hydrophobic or van der Waals forces help to reinforce the membrane-peptide bindings. The optimized charge-hydrophobicity ratio of the LL-III peptides helps ensure their high specificity toward bacterial membranes compared to mammalian membrane systems, which also helps explain our experimental observations. Overall, we hope that our work gives new insight into the antimicrobial action of LL-III peptides and that the adopted simulation strategy will help other scientists and engineers extract maximal information from complex molecular simulations using minimal computational power.

Stereogenic Harmony Fabricated Mechanoresponsive Homochiral Triphenylalanine Analogues with Synergistic Antibacterial Performances: A Potential Weapon for Dermal Wound Management.

The wound recovery phenomenon remains as one of the long challenging concerns worldwide. In search of user-friendly dressing materials, in this report, we fabricated a rational combinatorial strategy utilizing stereogenic harmony in a triphenylalanine fragment and appending it to δ-amino valeric acid at the N-terminus (hydrogelators I-VII) such that a potential scaffold could be fished out from the design. Our investigations revealed that all the hydrogelators displayed not only excellent self-healing performance as well as high mechanical strength at physiological pH but also mechanical stress-triggered gel-sol-gel transition properties. The structural and morphological investigation confirmed the presence of ß-sheet-like assemblies stabilized by intermolecular H-bonding and π-π interactions. Moreover, these scaffolds showed substantial antibacterial as well as antifungal efficacy against common wound pathogens, i.e, four Gram-positive bacteria (Staphylococcus aureus, Streptococcus mutans, B. subtilis, E. fecalis), four Gram-negative bacteria (Escherichia coli, Klebsiella pneumonia, P. aerugonosa, Proteus spp.), and two fungal strains (C. albicans and A. niger). The manifestation of consistent antioxidant properties might be due to the enhancement of amphiphilicity in hydrogelators, which has led to the generation of reactive oxygen species (ROS) in a facile manner, a probable mechanism to damage the microbial membrane, the driving force behind the antimicrobial efficacy. Also, the constructs exhibited proteolytic resistance and remarkable biocompatibility toward mammalian cells. Thus, based on the above benchmarks, the homochiral hydrogelator IV was seived out from a pool of seven, and we proceeded toward its in vivo evaluation using full-thickness excisional wounds in Wister rats. The scaffolds also accentuated the re-epithelialization as well in comparison to the negative control, thereby facilitating the wound closure process in a very short span of time (10 days). Overall, our in vitro and in vivo analysis certifies hydrogelator IV as an ideal dressing material that might hold immense promise for future wound care management.

A Homochiral Diphenylalanine Analog Based Mechanoresponsive Hydrogel: An Insight Towards Its Wound Healing Efficacy.

Deciphering the most promising strategy for the evolution of potential wound-healing therapeutics is one of the greatest challenging affairs to date. The development of peptide-based smart scaffolds with innate antimicrobial, anti-inflammatory, and antioxidant properties is an appealing way out. Aligned to the goal a set of Hydrogelators I-IV were developed utilizing the concept of chiral orchestration in diphenylalanine fragment, such that the most potent construct with all the bench marks namely mechanoresponsiveness, biocompatibility, consistent antimicrobial and antioxidant properties, could be fished out from the design. Interestingly, our in vitro Antifungal and Lipid peroxidation analysis identified the homochiral isomer Boc-δ-Ava-L-Phe-L-Phe-OH (Hydrogelator I), as an ideal candidate for the wound healing experiment, so we proceeded for the in vivo histopathological and antioxidant measurements in Wister rats. Indeed the wound images obtained from the different sets of animals on the 14th day of treatment demonstrated that with increased recovery time, hydrogelator I displayed a significant reduction in the lesion diameter compared to the marketed drug, and negative control. Even the histopathological measurements using H & E staining demonstrated diminished tissue destruction, neutrophil infiltration necrosis, and lymphatic proliferation in the hydrogelators, in comparison to others, backed by in vivo lipid peroxidation data. Overall our investigation certifies hydrogelator I as an effective therapeutic for managing the wound healing complication.

Post-partum paraplegia following spinal anaesthesia: a report of two rare cases.

Pregnancy and lumbar puncture are rare instances that can precipitate sudden onset paraplegia in patients with otherwise slow-growing intradural tumours. Surgeons and anaesthesiologists should be aware of the etiological factors leading to pregnancy- and delivery-related rapid tumour growth and its complications. Lumbar puncture-related complications leading to acute precipitation of neurological symptoms must be addressed promptly for favourable outcome in such patients. We describe the report of two patients who developed acute onset paraparesis after spinal anaesthesia for caesarean section. Both were found to be having undiagnosed spinal tumours and managed surgically. We recommend urgent MRI in cases of acute onset non-resolving paraparesis in the peripartum period, for timely diagnosis and management of this rare clinical entity.

Design and Evaluation of Short Bovine Lactoferrin-Derived Antimicrobial Peptides against Multidrug-Resistant Enterococcus faecium.

Enterococcus faecium has become an important drug-resistant nosocomial pathogen because of widespread antibiotic abuse. We developed short and chemically simple antimicrobial peptides (AMPs) with a selective amino acid composition, fixed charge, and hydrophobicity ratio based on the core antimicrobial motif of bovine lactoferrin (LfcinB6). Among these peptides, 5L and 6L (both 12 residues long) demonstrated a narrow spectrum and high antibacterial activity against drug-resistant E. faecium isolates with a minimal inhibitory concentration (MIC) that ranged from 4-16 µg/mL. At 32 µg/mL, peptides 5L and 6L inhibited E. faecium strain C68 biofilm formation by 90% and disrupted established biofilms by 75%. At 40 µg/mL, 5L reduced 1 × 107E. faecium persister cells by 3 logs within 120 min of exposure, whereas 6L eliminated all persister cells within 60 min. At 0.5× MIC, 5L and 6L significantly downregulated the expression of a crucial biofilm gene ace by 8 folds (p = 0.02) and 4 folds (p = 0.01), respectively. At 32 µg/mL, peptides 5L and 6L both depolarized the E. faecium membrane, increased fluidity, and eventually ruptured the membrane. Physiologically, 5L (at 8 µg/mL) altered the tricarboxylic acid cycle, glutathione, and purine metabolism. Interestingly, in an ex vivo model of porcine skin infection, compared to no treatment, 5L (at 10× MIC) effectively eliminated all 1 × 106 exponential (p = 0.0045) and persister E. faecium cells (p = 0.0002). In conclusion, the study outlines a roadmap for developing narrow-spectrum selective AMPs and presents peptide 5L as a potential therapeutic candidate to be explored against E. faecium.

Chiral Orchestration: A Tool for Fishing Out Tripeptide-Based Mechanoresponsive Supergelators Possessing Anti-Inflammatory and Antimicrobial Properties.

Deciphering the most promising strategy for the evolution of microbial infection and inflammation-based therapeutics is one of the most challenging affairs to date. Development of peptide-based smart supergelators with innate antimicrobial and anti-inflammatory activities is an appealing way out. In this work, the hydrogelators Boc-δ-Ava-(X)-Phe-(Y)-Phe-OH (I: X = Y = L; II: X = L; Y = D; III: X = D; Y = L; IV: X = Y = D, Ava: δ-amino valeric acid) have been designed and fabricated by strategic chiral tuning to investigate the effect of alternation of configuration(s) of Phe residues in governing the fashion of self-aggregation and macroscopic properties of peptides. Interestingly, all of the molecules formed mechanoresponsive hydrogels under physiological conditions with a nanofibrillar network. The spectroscopic experiments confirmed the conformation of the hydrogelators to be supramolecular ß-sheets formed through the self-association of S-shaped constructs stabilized by noncovalent interactions. Indeed, the present work demonstrates a rational approach toward regulating the mechanical integrity of the hydrogels through systematic inclusion of d-amino acids at appropriate positions in the sequence. The hydrogelators were found to possess antimicrobial activity against both Gram-positive bacteria (Staphylococcus aureus and Streptococcus mutans) and Gram-negative bacteria (Escherichia coli and Klebsiella pneumonia) while retaining their biocompatibility toward mammalian cells (as revealed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), hemolysis, and lipid peroxidation assays). These scaffolds also exhibited anti-inflammatory activities, as observed through in vitro MMP2/MMP9 inhibition studies and in vivo animal models, namely, the rat pouch model for acute inflammation. We anticipate that the discovery of these intelligent materials with multifunctional capabilities holds future promise as preferential therapeutics for the treatment of bacterial infections as well as associated inflammations arising alone or as side effects of biomaterial implants.

Structural characterization with light scattering: A tool for rationally designing protein formulations.

Here we explore the possibility of using light scattering technologies as an analytical tool for understanding structural features of a protein that might be responsible for initiating aggregative interactions. Using widely independent complementary experimental and computational techniques, we found that interaction parameters like Km in particular possess good correlation with residue specific descriptors for the model protein Bovine Serum Albumin. Such information can help rationally design protein engineering and/or formulation strategies for prolonged shelf-life of such products.

Rational design of a scalable bioprocess platform for bacterial cellulose production.

Bacterial cellulose (BC) has been gaining importance over the past decades as a versatile material that finds applications in diverse industries. However, a secured supply is hindered by the slow production rate and batch-to-batch variability of the yield. Here, we report a rational approach for characterising the BC production process using Design of Experiment (DoE) methodology to study the impact of different parameters on desired process attributes. Notably, we found that the carbon source used for bacterial growth significantly impacts the interplay between the process variables and affects the desired outcomes. We therefore, propose that the highest priority process outcome in this study, the yield, is a function of the carbon source and optimal reactor design. Our systematic approach has achieved projected BC yields as high as ∼40 g/L for Gluconacetobacter hansenii 53582 grown on sucrose as the carbon source compared to the widely reported yields of ∼10 g/L.

A Novel Platform for Evaluating the Environmental Impacts on Bacterial Cellulose Production.

Bacterial cellulose (BC) is a biocompatible material with versatile applications. However, its large-scale production is challenged by the limited biological knowledge of the bacteria. The advent of synthetic biology has lead the way to the development of BC producing microbes as a novel chassis. Hence, investigation on optimal growth conditions for BC production and understanding of the fundamental biological processes are imperative. In this study, we report a novel analytical platform that can be used for studying the biology and optimizing growth conditions of cellulose producing bacteria. The platform is based on surface growth pattern of the organism and allows us to confirm that cellulose fibrils produced by the bacteria play a pivotal role towards their chemotaxis. The platform efficiently determines the impacts of different growth conditions on cellulose production and is translatable to static culture conditions. The analytical platform provides a means for fundamental biological studies of bacteria chemotaxis as well as systematic approach towards rational design and development of scalable bioprocessing strategies for industrial production of bacterial cellulose.

Quantitative proteome profiles help reveal efficient xylose utilization mechanisms in solventogenic Clostridium sp. strain BOH3.

Development of sustainable biobutanol production platforms from lignocellulosic materials is impeded by inefficient five carbon sugar uptake by solventogenic bacteria. The recently isolated Clostridium sp. strain BOH3 is particularly advantaged in this regard as it serves as a model organism which can simultaneously utilize both glucose and xylose for high butanol (>15 g/L) production. Strain BOH3 was, therefore, investigated for its metabolic mechanisms for efficient five carbon sugar uptake using a quantitative proteomics based approach. The proteomics data show that proteins within the CAC1341-1349 operon play a pivotal role for efficient xylose uptake within the cells to produce butanol. Furthermore, up-regulation of key enzymes within the riboflavin synthesis pathway explained that xylose could induce higher riboflavin production capability of the bacteria (e.g., ∼80 mg/L from glucose vs. ∼120 mg/L from xylose). Overall results from the present experimental approach indicated that xylose-fed BOH3 cultures are subjected to high levels of redox stress which coupled with the solvent stress-trigger a sporulation response within the cells earlier than the glucose-fed cultures. The study lays the platform for metabolic engineering strategies in designing organisms for efficient butanol and other value-added chemicals such as riboflavin production. Biotechnol. Bioeng. 2017;114: 1959-1969. © 2017 Wiley Periodicals, Inc.

Direct conversion of xylan to butanol by a wild-type Clostridium species strain G117.

Lignocellulosic biomass has great potential for use as a carbon source for the production of second-generation biofuels by solventogenic bacteria. Here we describe the production of butanol by a newly discovered wild-type Clostridium species strain G117 with xylan as the sole carbon source for fermentation. Strain G117 produced 0.86 ± 0.07 g/L butanol and 53.4 ± 0.05 mL hydrogen directly from 60 g/L xylan provided that had undergone no prior enzymatic hydrolysis. After process optimization, the amount of butanol produced from xylan was increased to 1.24 ± 0.37 g/L. In contrast to traditional acetone-butanol-ethanol (ABE) solventogenic fermentation, xylan supported fermentation in strain G117 and negligible amount of acetone was produced. The expression of genes normally associated with acetone production (adc and ctfB2) were down-regulated compared to xylose fed cultures. This lack of acetone production may greatly simplify downstream separation process. Moreover, higher amount of butanol (2.94 g/L) was produced from 16.99 g/L xylo-oligosaccharides, suggesting a major role for strain G117 in butanol production from xylan and its oligosaccharides. The unique ability of strain G117 to produce a considerable amount of butanol directly from xylan without producing undesirable fermentation byproducts opens the door to the possibility of cost-effective biofuels production in a single step. Biotechnol. Bioeng. 2016;113: 1702-1710. © 2016 Wiley Periodicals, Inc.

Strategies for production of butanol and butyl-butyrate through lipase-catalyzed esterification.

In this study, a fermentation process for production of butanol and butyl-butyrate by using Clostridium sp. strain BOH3 is developed. This strain is able to produce butyric acid and butanol when it ferments 60 g/L xylose. Meanwhile, it also excreted indigenous lipases (induced by olive oil) which naturally convert butyric acid and butanol into 1.2 g/L of butyl-butyrate. When Bio-OSR was used as both an inducer for lipase and extractant for butyl-butyrate, the butyl-butyrate concentration can reach 6.3 g/L. To further increase the yield, additional lipases and butyric acid are added to the fermentation system. Moreover, kerosene was used as an extractant to remove butyl-butyrate in situ. When all strategies are combined, 22.4 g/L butyl-butyrate can be produced in a fed-batch reactor spiked with 70 g/L xylose and 7.9 g/L butyric acid, which is 4.5-fold of that in a similar system (5 g/L) with hexadecane as the extractant.

Differential diagnosis of BPOP arising in relation to patella.

INTRODUCTION: Solitary exostosis is common at the metaphysis of long bones, and rarely may it develop in the lower pole of the patella. Usually it stops growing after skeletal maturity unless complicated. When the growth continues after skeletal maturity, other rare possibilities need to be considered such as bizarre parosteal osteochondromatous proliferation (BPOP). Though solitary exostosis is common at the metaphysis of long bones, very rarely it also develops in lower pole of the patella. Usually they stop growing after skeletal maturity unless complicated. When it starts after skeletal maturity and continues to grow, other rare possibilities like bizarre parostealosteochondromatousproliferation (BPOP) are to be thought of. CASE REPORT: 21 years male student presented with anterior midline painless progressive swelling over right knee joint of one year duration which was hard, non-tender, fixed to patella but mobile with patella. X ray showed midline heterogeneously radio-opaque swelling attached to inferolateral aspect of the anterior surface of patella. Patellar out line is fully maintained except the narrow site of tumour attachment. After exposing through midline incision, the swelling was found to incorporate the patellar tendon completely and an anterior vertical midline cleavage was found. The mass was deliberately detached along the cleavage and from intact patellar tendon. Almost full range of knee movement is obtained in operation table. Immediate post operative 10° quadriceps lag was corrected with quadriceps setting exercises in two weeks time. Histopathological examination demonstrated thin layer of cartilage cover, irregular lamellar bone in deeper zone and spindle cells between them without cytoplasmic atypia. Plenty of cartilage cells in different stages of maturation are seen without column formation. Marrow elements are absent. Periosteum could not be demonstrated and there was no other evidence of malignancy. Features simulate 'bizarre parosteal osteochondromatous proliferation'. There is no recurrence in five years of follow up. CONCLUSION: When exostosis like lesions arise from unusual site and at an unusual age group, other rare conditions need to be investigated. Though the final diagnosis of BPOP is obtained after careful histo-pathological examination, the clinico-radiological findings are also relevant. As literature search indicates, this is possibly second incidence where BPOP arised from sesamoid bone and first from patella.

Site specific immobilization of a potent antimicrobial peptide onto silicone catheters: evaluation against urinary tract infection pathogens.

Bacterial colonization of urinary catheters is a common problem leading to Catheter Associated Urinary Tract Infections (CAUTIs) in patients, which result in high treatment costs and associated complications. Due to the advantages of antimicrobial peptides (AMPs) compared to most other antimicrobial molecules, an increasing number of AMP-coated surfaces is being developed but their efficacy is hindered by suboptimal coating methods and loss of peptide activity upon surface tethering. This study aims to address this issue by employing a methodic approach that combines a simple selective chemical immobilization platform developed on a silicone catheter with the choice of a potent AMP, Lasioglossin-III (Lasio-III), to allow site specific immobilization of Lasio-III at an effective surface concentration. The Lasio-III peptide was chemically modified at the N-terminal with a cysteine residue to facilitate cysteine-directed immobilization of the peptide onto a commercial silicone catheter surface via a combination of an allyl glycidyl ether (AGE) brush and polyethylene glycol (PEG) based chemical coupling. The amount of immobilized peptide was determined to be 6.59 ± 0.89 µg cm-2 by Sulfo-SDTB assay. The AMP-coated catheter showed good antimicrobial activity against both Gram positive and negative bacteria. The antimicrobial properties of the AMP-coated catheter were sustained for at least 4 days post-incubation in a physiologically relevant environment and artificial urine and prevented the biofilm growth of E. coli and E. faecalis. Adenosine tri-phosphate leakage and propidium iodide fluorescence studies further confirmed the membranolytic mode of action of the immobilized peptide. To the best of our knowledge, this is the first proof-of-concept study that reports the efficacy of AMP immobilization by sulfhydryl coupling on a real catheter surface.

Design of short membrane selective antimicrobial peptides containing tryptophan and arginine residues for improved activity, salt-resistance, and biocompatibility.

Antimicrobial peptides (AMPs) kill microbes by non-specific membrane permeabilization, making them ideal templates for designing novel peptide-based antibiotics that can combat multi-drug resistant pathogens. For maximum efficacy in vivo and in vitro, AMPs must be biocompatible, salt-tolerant and possess broad-spectrum antimicrobial activity. These attributes can be obtained by rational design of peptides guided by good understanding of peptide structure-function. Toward this end, this study investigates the influence of charge and hydrophobicity on the activity of tryptophan and arginine rich decamer peptides engineered from a salt resistant human ß-defensin-28 variant. Mechanistic investigations of the decamers with detergents mimicking the composition of bacterial and mammalian membrane, reveal a correlation between improved antibacterial activity and the increase in tryptophan and positive residue content, while keeping hemolysis low. The potent antimicrobial activity and high cell membrane selective behavior of the two most active decamers, D5 and D6, are attributed to an optimum peptide charge to hydrophobic ratio bestowed by systematic arginine and tryptophan substitution. D5 and D6 show surface localization behavior with binding constants of 1.86 × 10(8) and 2.6 × 10(8) M(-1) , respectively, as determined by isothermal calorimetry measurements. NMR derived structures of D5 and D6 in SDS detergent micelles revealed proximity of Trp and Arg residues in an extended structural scaffold. Such potential cation-π interactions may be critical in cell permeabilization of the AMPs. The fundamental characterization of the engineered decamers provided in this study improves the understanding of structure-activity relationship of short arginine tryptophan rich AMPs, which will pave the way for future de novo design of potent AMPs for therapeutic and biomedical applications.

Antimicrobial functionalization of silicone surfaces with engineered short peptides having broad spectrum antimicrobial and salt-resistant properties.

Catheter-associated urinary tract infections (CAUTIs) are often preceded by pathogen colonization on catheter surfaces and are a major health threat facing hospitals worldwide. Antimicrobial peptides (AMPs) are a class of new antibiotics that hold promise in curbing CAUTIs caused by antibiotic-resistant pathogens. This study aims to systematically evaluate the feasibility of immobilizing two newly engineered arginine/lysine/tryptophan-rich AMPs with broad antimicrobial spectra and salt-tolerant properties on silicone surfaces to address CAUTIs. The peptides were successfully immobilized on polydimethylsiloxane and urinary catheter surfaces via an allyl glycidyl ether (AGE) polymer brush interlayer, as confirmed by X-ray photoelectron spectroscopy and water contact angle analyses. The peptide-coated silicone surfaces exhibited excellent microbial killing activity towards bacteria and fungi in urine and in phosphate-buffered saline. Although both the soluble and immobilized peptides demonstrated membrane disruption capabilities, the latter showed a slower rate of kill, presumably due to reduced diffusivity and flexibility resulting from conjugation to the polymer brush. The synergistic effects of the AGE polymer brush and AMPs prevented biofilm formation by repelling cell adhesion. The peptide-coated surface showed no toxicity towards smooth muscle cells. The findings of this study clearly indicate the potential for the development of AMP-based coating platforms to prevent CAUTIs.

Immobilization studies of an engineered arginine-tryptophan-rich peptide on a silicone surface with antimicrobial and antibiofilm activity.

With the rapid rise of antibiotic-resistant-device-associated infections, there has been increasing demand for an antimicrobial biomedical surface. Synthetic antimicrobial peptides that have excellent bactericidal potency and negligible cytotoxicity are promising targets for immobilization on these target surfaces. An engineered arginine-tryptophan-rich peptide (CWR11) was developed, which displayed potent antimicrobial activity against a broad spectrum of microbes via membrane disruption, and possessed excellent salt resistance properties. A tethering platform was subsequently developed to tether CWR11 onto a model polymethylsiloxane (PDMS) surface using a simple and robust strategy. Surface characterization assays such as attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), X-ray photoelectron spectroscopy (XPS), and energy-dispersive X-ray spectroscopy (EDX) confirmed the successful grafting of CWR11 onto the chemically treated PDMS surface. The immobilized peptide concentration was 0.8 ± 0.2 µg/cm(2) as quantitated by sulfosuccinimidyl-4-o-(4,4-dimethoxytrityl) butyrate (sulfo-SDTB) assay. Antimicrobial assay and cytotoxic investigation confirmed that the peptide-immobilized surface has good bactericidal and antibiofilm properties, and is also noncytotoxic to mammalian cells. Tryptophan-arginine-rich antimicrobial peptides have the potential for antimicrobial protection of biomedical surfaces and may have important clinical applications in patients.

Immobilization of polybia-MPI by allyl glycidyl ether based brush chemistry to generate a novel antimicrobial surface.

Significant efforts towards the covalent immobilization of antimicrobial peptides (AMPs) on biomaterial surfaces are under way to render implantable biodevices with antimicrobial functionalities. Towards this aim, we studied the potential and effectiveness of a novel AMP candidate, polybia-MPI (Pmpi), for immobilization on a silicon substrate using allyl glycidyl ether (AGE) based polymerization chemistry. A statistical Design of Experiment (DoE) platform was developed to quantitatively understand the effects of different immobilization parameters on the final tethered peptide surface concentration. Our platform demonstrates efficient tethering of Pmpi up to ∼10 µg cm-2 on silicon wafers. Concentration dependent antimicrobial activities of the 'AGE-Pmpi'-tethered surfaces were observed, where a 70% reduction in bacterial colonies was achieved at a Pmpi surface concentration of 4.47 µg cm-2. The 'AGE-Pmpi'-tethered surfaces retained their antibacterial property after 3 days of incubation in artificial urine, and a 4-fold reduction in biofilm formation was also evident, as determined by ellipsometry. FESEM and ATP leakage assay showed that the immobilized Pmpi compromised bacterial membrane integrity but showed negligible cytotoxicity against human red blood cells.