Recent Advances in the Detection of Food Toxins Using Mass Spectrometry.

Edibles are the only source of nutrients and energy for humans. However, ingredients of edibles have undergone many physicochemical changes during preparation and storage. Aging, hydrolysis, oxidation, and rancidity are some of the major changes that not only change the native flavor, texture, and taste of food but also destroy the nutritive value and jeopardize public health. The major reasons for the production of harmful metabolites, chemicals, and toxins are poor processing, inappropriate storage, and microbial spoilage, which are lethal to consumers. In addition, the emergence of new pollutants has intensified the need for advanced and rapid food analysis techniques to detect such toxins. The issue with the detection of toxins in food samples is the nonvolatile nature and absence of detectable chromophores; hence, normal conventional techniques need additional derivatization. Mass spectrometry (MS) offers high sensitivity, selectivity, and capability to handle complex mixtures, making it an ideal analytical technique for the identification and quantification of food toxins. Recent technological advancements, such as high-resolution MS and tandem mass spectrometry (MS/MS), have significantly improved sensitivity, enabling the detection of food toxins at ultralow levels. Moreover, the emergence of ambient ionization techniques has facilitated rapid in situ analysis of samples with lower time and resources. Despite numerous advantages, the widespread adoption of MS in routine food safety monitoring faces certain challenges such as instrument cost, complexity, data analysis, and standardization of methods. Nevertheless, the continuous advancements in MS-technology and its integration with complementary techniques hold promising prospects for revolutionizing food safety monitoring. This review discusses the application of MS in detecting various food toxins including mycotoxins, marine biotoxins, and plant-derived toxins. It also explores the implementation of untargeted approaches, such as metabolomics and proteomics, for the discovery of novel and emerging food toxins, enhancing our understanding of potential hazards in the food supply chain.

Paraoxonase Mimic by a Nanoreactor Aggregate Containing Benzimidazolium Calix and l-Histidine: Demonstration of the Acetylcholine Esterase Activity.

An anion-mediated preorganization approach was used to design and synthesize the benzimidazolium-based calix compound R1⋅2 ClO4 - . X-ray crystallography analysis revealed that the hydrogen-bonding interactions between the benzimidazolium cations and N,N-dimethylformamide (DMF) helped R1⋅2 ClO4 - encapsulate DMF molecule(s). A nanoreactor, with R1⋅2 ClO4 - and l-histidine (l-His) as the components, was fabricated by using a neutralization method. The nanoreactor could detoxify paraoxon in 30 min. l-His played a vital role in this process. Paraoxonase is a well-known enzyme used for pesticide degradation. The Ellman's reagent was used to determine the percentage inhibition of the acetylcholinesterase (AChE) activity in the presence of the nanoreactor. The results indicated that the nanoreactor inhibited AChE inhibition.

Metal-Organocatalyst for Detoxification of Phosphorothioate Pesticides: Demonstration of Acetylcholine Esterase Activity.

In recent years, transition metal complexes have been developed for catalytical degradation of a phosphate ester bond, particularly in RNA and DNA; however, less consideration has been given for development of complexes for the degradation of a phosphorothioate bond, as they are the foremost used pesticides in the environment and are toxic to human beings. In this context, we have developed copper complexes of benzimidazolium based ligands for catalytical degradation of a series of organophosphates (parathion, paraoxon, methyl-parathion) at ambient conditions. The copper complexes (assigned as N1-N3) were characterized using single X-ray crystallography which revealed that all three complexes are mononuclear and distorted square planner in geometry. Further, the solution state studies of the prepared complexes were carried out using UV-visible absorption, fluorescence spectroscopy, and cyclic voltametry. The complexes N1 and N2 have benzimidazolium ionic liquid as base attached with two 2-mercapto-benzimidazole pods, whereas complex N3 contains a nonionic ligand. The synthesized copper complexes were evaluated for their catalytic activity for degradation of organophosphates. It is interesting that the complex containing the ionic ligand efficiently degrades phosphorothioate pesticides, whereas complex N3 was not found to be appropriate for degradation due to a weaker conversion rate. The organophosphate degradation studies were monitored by recording absorbance spectra of parathion in the presence of catalyst, i.e., copper complexes with respect to time. The parathion was hydrolyzed into para-nitrophenol and diethyl thiophosphate. Moreover, to analyze the inhibition activity of the pesticides toward acetylcholine esterase enzyme in the presence of prepared metal complexes, Ellman's assay was performed and revealed that, within 20 min, the inhibition of acetylcholine esterase enzyme decreases by up to 13%.

Heme deficiency sensitizes yeast cells to oxidative stress induced by hydroxyurea.

Hydroxyurea (HU) has a long history of clinical and scientific use as an antiviral, antibacterial, and antitumor agent. It inhibits ribonucleotide reductase and reversibly arrests cells in S phase. However, high concentrations or prolonged treatment with low doses of HU can cause cell lethality. Although the cytotoxicity of HU may significantly contribute to its therapeutic effects, the underlying mechanisms remain poorly understood. We have previously shown that HU can induce cytokinesis arrest in the erg11-1 mutant of fission yeast, which has a partial defect in the biosynthesis of fungal membrane sterol ergosterol. Here, we report the identification of a new mutant in heme biosynthesis, hem13-1, that is hypersensitive to HU. We found that the HU hypersensitivity of the hem13-1 mutant is caused by oxidative stress and not by replication stress or a defect in cellular response to replication stress. The mutation is hypomorphic and causes heme deficiency, which likely sensitizes the cells to the HU-induced oxidative stress. Because the heme biosynthesis pathway is highly conserved in eukaryotes, this finding, as we show in our separate report, may help to expand the therapeutic spectrum of HU to additional pathological conditions.

Novel Cell-Killing Mechanisms of Hydroxyurea and the Implication toward Combination Therapy for the Treatment of Fungal Infections.

We have previously reported that an erg11 mutation affecting ergosterol synthesis and a hem13 mutation in the heme synthesis pathway significantly sensitize the fission yeast Schizosaccharomyces pombe to hydroxyurea (HU) (1, 2). Here we show that treatment with inhibitors of Erg11 and heme biosynthesis phenocopies the two mutations in sensitizing wild-type cells to HU. Importantly, HU synergistically interacts with the heme biosynthesis inhibitor sampangine and several Erg11 inhibitors, the antifungal azoles, in causing cell lethality. Since the synergistic drug interactions are also observed in the phylogenetically divergent Saccharomyces cerevisiae and the opportunistic fungal pathogen Candida albicans, the synergism is likely conserved in eukaryotes. Interestingly, our genetic data for S. pombe has also led to the discovery of a robust synergism between sampangine and the azoles in C. albicans Thus, combinations of HU, sampangine, and the azoles can be further studied as a new method for the treatment of fungal infections.

Identifying the Long-Term Role of Inducible Nitric Oxide Synthase after Contusive Spinal Cord Injury Using a Transgenic Mouse Model.

Inducible nitric oxide synthase (iNOS) is a potent mediator of oxidative stress during neuroinflammation triggered by neurotrauma or neurodegeneration. We previously demonstrated that acute iNOS inhibition attenuated iNOS levels and promoted neuroprotection and functional recovery after spinal cord injury (SCI). The present study investigated the effects of chronic iNOS ablation after SCI using inos-null mice. iNOS-/- knockout and wild-type (WT) control mice underwent a moderate thoracic (T8) contusive SCI. Locomotor function was assessed weekly, using the Basso Mouse Scale (BMS), and at the endpoint (six weeks), by footprint analysis. At the endpoint, the volume of preserved white and gray matter, as well as the number of dorsal column axons and perilesional blood vessels rostral to the injury, were quantified. At weeks two and three after SCI, iNOS-/- mice exhibited a significant locomotor improvement compared to WT controls, although a sustained improvement was not observed during later weeks. At the endpoint, iNOS-/- mice showed significantly less preserved white and gray matter, as well as fewer dorsal column axons and perilesional blood vessels, compared to WT controls. While short-term antagonism of iNOS provides histological and functional benefits, its long-term ablation after SCI may be deleterious, blocking protective or reparative processes important for angiogenesis and tissue preservation.

Neglected epiphyseal injuries of the distal end of the radius with ulnar impaction: analysis of distal osteotomy of both bones using a dorsal midline approach.

BACKGROUND: To evaluate results of a technique for treating neglected epiphyseal injuries of the distal radius with ulnar impaction. MATERIALS AND METHODS: This retrospective study involved six cases (four males; two females), all of whom sustained the primary injury during childhood (range 9-12 years of age). All presented with wrist deformity and ulnar-sided wrist pain. They were managed with osteotomy of the distal radius, osteotomy and shortening of the ulna, harvesting the bone grafts, and distal radioulnar joint (DRUJ) reduction performed simultaneously through a dorsal midline approach. Mean follow-up was 30 months (range 24-36). RESULTS: Deformity correction and pain relief was observed in all patients. Flexion arc increased from an average of 60° to 102.5°, supination from an average of 31.67° to 67.50°, and pronation from an average of 30.83° to 61.67°. The mean preoperative DASH score was 87.5, which improved to 18.72 postoperatively. CONCLUSION: Neglected epiphyseal injuries of the distal radius are difficult to manage and many variations are described for handing each of the associated problems. Our technique provides an option for managing this injury with an easy surgical approach, single incision, and cost effectiveness. All the four components of the surgery, which include osteotomy of the distal radius, osteotomy of the ulna, harvesting the bone grafts, and DRUJ reduction were done through a single incision and in a single sitting. Level of evidence IV.

Fluorescent Chemosensors for Selective and Sensitive Detection of Phosmet/Chlorpyrifos with Octahedral Ni(2+) Complexes.

The hexadentate ligands H2L1-L3 with mixed S, N, O donor sites and possessing substituents having either "no" or electron-releasing/withdrawing nature at terminal ends are synthesized. The ligands H2L1-L3 were tested for binding with library of metal ions, wherein maximum efficiency was observed with Ni(2+), and it motivated us to prepare the Ni(2+) complexes. The ligand H2L1 underwent deprotonation and formed binuclear complex when interacted with Ni(2+) as evident from its crystal structure. The H2L2 and H2L3 having electron-withdrawing/electron releasing groups, respectively, were also deprotonated; however, they afforded mononuclear complexes with Ni(2+) ion. This signifies the importance of steric parameters instead of electronic factors in these particular cases. Impressed by differential behavior of complexes of H2L1 and H2L2/H2L3 with Ni(2+) and their photophysical and electrochemical properties, all the metal complexes were studied for their chemosensing ability. Nowadays with increased use of organophosphate, there is alarming increase of these agents in the environment, and thus we require efficient technique to estimate the level of these agents with high sensitivity and selectivity in aqueous medium. The Ni(2+) complexes with hydrophobic nature were suspended into aqueous medium for testing them as sensor for organophosphate. The (L1)2.(Ni(2+))2 could sense phosmet with detection limit of 44 nM, whereas L2.Ni(2+) and L3.Ni(2+) exhibited the detection limits of 62 and 71 nM, respectively, for chlorpyrifos.

Contralateral reversed distal femoral locking plate for fixation of subtrochanteric femoral fractures.

PURPOSE: Subtrochanteric fractures of the femur are being managed successfully with various intramedullary and extramedulary implants with reasonable success. However, these implants require precise placement under image intensifier guidance, which exposes the surgeon to substantial amount of radiation. It also restricts the management of these fractures at peripheral centers where facility of image intensifiers is not available. Keeping this in mind we designed this study to identify if contralateral reversed distal femoral locking plate can be used successfully without the use of image intensifier. METHODS: Twenty-four consecutive patients (18 men and 6 women) with a mean age of 28 years (range 19-47 years) suffering subtrochanteric fractures of the femur underwent open reduction and internal fixation with reversed contralateral distal femoral locking plate. The outcome was assessed at the mean follow-up period of 3.2 years (range 2-4.6 years) using the Harris hip score. RESULTS: Twenty-one fractures united with the primary procedure, with a mean time of consolidation being 11 weeks (range, 9-16 weeks). One patient developed superficial suture line infection, which resolved with oral antibiotics. Another patient had a fall 3 weeks after surgery and broke the plate. Repeat surgery with reversed distal femoral locking compression plate was performed along with bone grafting and the fracture united. Two cases had nonunion, which went in for union after bone grafting. The mean Harris hip score at the time of final follow-up was 90.63 (range 82-97). CONCLUSION: The reversed contralateral distal femoral plate is a biomechanically sound implant, which when used for fixation of the subtrochanteric fractures with minimal soft tissue stripping shows results comparable to those achieved by using other extramedullary implants as well as intramedullary devices. The added advantage of this implant is its usability in the absence of an image intensifier.

A fluorescent and colorimetric sensor for nanomolar detection of Co2+ in water.

A new disulfide-based, imine-linked fluorescent receptor 1 was processed into organic nanoparticles (ONPs) with an average particle size of 79 nm. The photophysical properties of the ONPs were evaluated by UV/Vis absorption spectroscopy. Receptor 1 selectively recognized Co(2+) ions in water with a detection limit down to 88 nm.

Highly sensitive ratiometric chemosensor for selective 'naked-eye' nanomolar detection of Co(2+) in semi-aqueous media.

An easy-to-prepare chemosensor, (E)-1-(phthalazine-4-yl)-2-(1-(pyridine-2-yl)ethylidene) hydrazine (3), structurally characterized by single X-ray crystallography, is developed for the selective and sensitive detection of Co(2+) in aqueous media. Chemosensor 3 shows both absorption and fluorescence responses to Co(2+) by forming a 1:1 complex (among the surveyed metal ions) with a detection limit down to 50 nM. It can also be used as a 'naked-eye' sensor due to the outstanding visible and emission color changes from yellow to red and blue to orange, respectively.

Long term results after surgical management of posterior wall acetabular fractures.

BACKGROUND: Posterior wall fractures are the most common of all acetabular fractures, and there is universal consensus that displaced fractures are best treated with anatomical reduction and stable internal fixation. Though early and mid term results for such studies are available, few shed light on long term results. This study was performed to evaluate long term functional and radiological outcomes in patients with posterior wall acetabular fractures and to determine factors that may contribute adversely to a satisfactory final outcome. MATERIALS AND METHODS: We retrospectively analysed the hospital records for patients who underwent open reduction and internal fixation (ORIF) for posterior wall acetabular fractures. Twenty-five patients (20 men, five women), including one with bilateral posterior wall fracture, with a mean age of 41.28 ± 7.16 years (range 25-60 years) and a mean follow-up of 12.92 ± 6.36 years (range 5-22 years) who met the inclusion criteria formed the study cohort. Matta's criteria were used to grade postoperative reduction and final radiological outcome. Functional outcome at final follow-up was assessed according to d'Aubigné and Postel score. RESULTS: Anatomic reduction was achieved in 22 hips, imperfect in four and poor in none. Radiological outcome at final follow-up revealed excellent results in ten hips, good in eight, fair in five and poor in three. The final d'Aubigné and Postel scores were excellent in 14 hips, good in six and fair and poor in three each. Patients with anatomical reduction had a favourable functional and radiological long term outcome. However, the presence of associated injuries in lower limbs and a body mass index (BMI) >25 adversely affected the final functional outcome. Osteonecrosis was seen in three patients, heterotopic ossification in two and Morel Lavallee lesion in one. One patient had postoperative sciatic nerve palsy, which recovered 6 weeks after surgery. CONCLUSION: Anatomic postoperative reduction leads to optimal functional and radiological outcome on long term follow-up; however, the presence of associated lower-limb injuries and BMI >25 adversely affects a satisfactory final outcome in patients with posterior wall acetabular fractures. LEVEL OF EVIDENCE: (Level 4) Retrospective case series.

Ankle fusion with centralisation of the fibula after distal tibia bone tumour resection.

BACKGROUND: Management of distal tibial tumours with limb salvage surgery poses a challenge for the orthopaedic surgeon. This study was done to evaluate the results of fibular centralisation as a technique to reconstruct defects that occurred after resection at this site. MATERIALS AND METHODS: Nine patients with a mean age of 23.2 years (range 17-34) with diagnosis of osteosarcoma in four patients, Ewing's sarcoma in two, giant cell tumour in two and chondrosarcoma in one patient underwent surgical treatment for tumour in the distal tibia. All patients had wide resection of the tumour and ankle arthrodesis with centralisation of the fibula. Patients were assessed clinico-radiologically for bone union, infection and complications. The final functional outcome was estimated according to Musculoskeletal Tumor Society (MSTS) scores. RESULTS: The mean age at the time of surgery was 23.2 years (17-34). There were five females and four males. The mean follow-up was 37 months (range 28-54 months). One of the patients with osteosarcoma had a recurrence a year after limb salvage surgery, underwent above-knee amputation, and died 18 months later due to metastasis. One patient developed leg length discrepancy. The mean MSTS score was 22.75 (range 17-27). CONCLUSION: Fibular centralisation is a durable reconstruction tool for defects of the distal tibial metaphysis with an acceptable functional outcome. It is an inexpensive and simple procedure, with a low rate of late complications, and reproducible results. LEVEL OF EVIDENCE: IV Retrospective case series.

Peritoneal Malignant Mesothelioma Metastasizing to Lymph Node in Young Male-a Case Report.

Peritoneal malignant mesothelioma is an uncommon neoplasm with a poor prognosis. We hereby report a case of a 20-year-old male, first diagnosed on biopsy with axillary lymph node metastasis. He presented with abdominal pain and axillary lymphadenopathy, with no history of asbestos exposure. CECT showed peritoneal thickening and ascites. Ascitic fluid cytology showed reactive morphology. The diagnosis of metastatic deposits of malignant mesothelioma was made on histopathology and confirmed by immunohistochemistry. Tumor cells were immune-reactive for CK 5/6, calretinin, D2-40, and WT1 and negative for TTF1, CK 20, and CD 3. This case report has two important highlights-(i) unusual presentation with axillary lymph node metastasis leading to diagnostic dilemma in a young male with no asbestos exposure history and (ii) confirmatory diagnostic role of IHC in Peritoneal malignant mesothelioma.

Cytodiagnostic Dilemma in a Lung Mass as the First Presentation of Testicular Mixed Germ Cell Tumor Metastasis.

Testicular mixed germ cell tumors (TMGCTs) are rare malignant tumors comprising of two or more types of germ cell tumors. Their onset may be undetectable and the patient may first present with symptoms of metastasis. We hereby report a case of a young male who presented with respiratory discomfort and had no symptoms of primary testicular tumor. CT-guided FNAC lung revealed mainly necrotic, keratinous debris with a focus of chondromyxoid stroma. Differential diagnoses of components of teratoma, squamous cell carcinoma and inclusion cyst was considered. FNAC was reported out for the possible presence of teratoma components. Retrospectively, physical examination and subsequent USG revealed testicular tumor. The case led to a diagnostic dilemma as the patient presented with no prior history suggestive of metastasis from testicular mixed germ cell tumor. The aim of the current case report is to alert the pathologists and clinicians about this uncommon clinical presentation and diagnostic relevance of FNA. It highlights that FNA lung revealing keratinous material should always be searched for the possibility of teratoma component.

Artificial groundwater recharge zones mapping using remote sensing and GIS: a case study in Indian Punjab.

Artificial groundwater recharge plays a vital role in sustainable management of groundwater resources. The present study was carried out to identify the artificial groundwater recharge zones in Bist Doab basin of Indian Punjab using remote sensing and geographical information system (GIS) for augmenting groundwater resources. The study area has been facing severe water scarcity due to intensive agriculture for the past few years. The thematic layers considered in the present study are: geomorphology (2004), geology (2004), land use/land cover (2008), drainage density, slope, soil texture (2000), aquifer transmissivity, and specific yield. Different themes and related features were assigned proper weights based on their relative contribution to groundwater recharge. Normalized weights were computed using the Saaty's analytic hierarchy process. Thematic layers were integrated in ArcGIS for delineation of artificial groundwater recharge zones. The recharge map thus obtained was divided into four zones (poor, moderate, good, and very good) based on their influence to groundwater recharge. Results indicate that 15, 18, 37, and 30 % of the study area falls under "poor," "moderate," "good," and "very good" groundwater recharge zones, respectively. The highest recharge potential area is located towards western and parts of middle region because of high infiltration rates caused due to the distribution of flood plains, alluvial plain, and agricultural land. The least effective recharge potential is in the eastern and middle parts of the study area due to low infiltration rate. The results of the study can be used to formulate an efficient groundwater management plan for sustainable utilization of limited groundwater resources.

A Review of Potential Therapies to Attenuate Bone Mineral Density Loss in Obese Individuals Prior to Total Joint Replacement Surgery.

The focus of this review is to examine therapeutic interventions which may be used to increase bone mineral density (BMD), reduce bone loss, and ultimately reduce complications in obese patients prior to total joint replacement (TJR). It is recommended that obese patients lose weight prior to surgery to reduce post-surgical complications, but weight loss can also increase bone loss and fracture risk in older individuals. In this review, we investigate potential therapies to improve bone density and reduce bone loss including exercise therapy, parathyroid hormone (PTH), estrogen, bisphosphonate, and calcitonin treatment in obese patients prior to TJR. Our review of existing literature found that treatment with PTH increased total body BMD in both men and women with osteoporosis; exercise therapy in combination with weight loss prevents the weight loss-induced increase in bone turnover and attenuates the weight loss-induced decrease in BMD; and estrogen, bisphosphonate, and calcitonin reduce bone resorption.

Fabrication of FRET based nano sensor from biomass-derived fluorescent carbon quantum dots and naphthalimide for ratiometric detection of nitric oxide: To examine nitrite levels in meat samples.

Nitric oxide (NO) is a ubiquitous, gaseous, free radical signaling molecule which plays a key role in physiological and pathological processes. Literature reports revealed that the conventional methods such as colorimetry, electron paramagnetic resonance (EPR), electrochemical etc. to detect NO are costly, time consuming and lack resolution, particularly in aqueous or biological system. Thus, in this context, herein we have developed covalently linked biomass derived carbon quantum dots (CQDs) and naphthalimide based nano sensor system for FRET based ratiometric detection of nitric oxide (NO) in pure aqueous media. The CQDs derived from orange peels were characterized using UV-visible absorption, fluorescence spectroscopy, PXRD, TEM, FT-IR and zeta potential studies. Further, the obtained CQDs were functionalized with amine functionality, and subsequently linked with naphthalimide derivative (5) using terephthaldehyde through covalent bond formation. The conjugation of naphthalimide (5) and functionalized CQDs was studied using DLS, zeta potential, FT-IR and time resolved fluorescence spectroscopy. The excitation of developed nano sensor system at λex 360 nm results in fluorescence emission at λem 530 nm which establishes the FRET pair between the CQDs and naphthalimide unit. However, in the presence of NO, the observed FRET pair abolishes due to the cleavage of NO susceptible imine bond. The developed sensor demonstrates high selectivity towards NO with limit of detection (LOD) and limit of quantification (LOQ) of 15 nM and 50 nM respectively. Further, the developed sensor system was also utilized for indirect detection of nitrite (NO2-) in food samples for food safety and monitoring.

Quantitative and qualitative analysis of ochratoxin-A using fluorescent CQDs@DNA-based nanoarchitecture assembly to monitor food safety and quality.

Ochratoxin A (OTA), a mycotoxin formed by various fungi, such as Aspergillus and Penicillium species, is dangerous to human health. Thus, to circumvent the risk of OTA ingestion, the recognition and quantification of OTA levels are of great significance. A perusal of the literature has revealed that the integration of DNA/Carbon Quantum Dot (CQD)-based hybrid systems may exhibit the unique electronic and optical properties of nanomaterials/nanoarchitecture and consequent recognition properties. Herein, we developed the CQDs@DNA-based hybrid nanoarchitecture system for the selective detection of OTA, which exhibits modulation in the emission spectrum after interaction with OTA, with a significant binding constant (Ka = 3.5 × 105 M-1), a limit of detection of 14 nM, limit of quantification of 47 nM and working range of 1-10 µM. The mechanism for sensing the OTA has been corroborated using fluorescence, UV-visible absorption spectroscopy, and FTIR techniques, demonstrating the binding mode of CQD@DNA hybrid nano-architecture assembly with OTA. Further, we demonstrated the sensing ability of developed CQDs@DNA-based nanoarchitecture assembly towards the quantification of OTA in real food monitoring analysis for real-time applications, which makes this developed nanoarchitecture assembly the potential candidate to conveniently monitor food safety and quality for human health.

Galvanic Displacement Reaction Enabled Specific and Sensitive Detection of Bacteria with a Digital Photocorrosion GaAs/AlGaAs Biosensor.

The conjugation of ionic gold with bacterial antibodies makes it possible to induce a specific interaction between targeted bacteria and the surface of a GaAs/AlGaAs biochip. The process of immobilization is based on a galvanic displacement reaction (GDR) involving electron transfer between GaAs and Au3+ ions that leads to the formation of a Au-Ga alloy anchoring bacteria to the biochip surface. The GDR-based immobilization of Escherichia coli on biochips comprising a stack of GaAs/AlGaAs nanolayers (dGaAs = 12 nm, dAlGaAs = 10 nm) was confirmed by X-ray photoelectron spectroscopy and atomic force microscopy-based infrared experiments. We report the successful application of this approach for highly sensitive detection of E. coli with a digital photocorrosion (DIP) biosensor. The photoluminescence (PL) monitored DIP of GaAs/AlGaAs nanolayers results in the formation of a PL intensity maximum whose temporal appearance depends on the electric charge transfer between bacteria and the biochip. The formation of a robust bacteria-biochip interface achieved with the GDR process allowed us to observe the role of bacteria on the temporal position of a PL intensity maximum related to the etching of two pairs of GaAs/AlGaAs nanolayers extending up to 24 nm below the biochip surface. We demonstrate the attractive detection of E. coli at 250 CFU/mL, and we discuss the potential of this approach for designing a family of biosensors addressing the quasi-continuous monitoring of a water environment for the presence of pathogenic bacteria.